J Charafeddine

D Pradon

S Alfayad

S Chevallier

M Khalil

Toward Bio-Kinematic for Secure Use of Rehabilitation Exoskeleton

Keywords: bio-kinematic, rehabilitation exoskeleton, muscular co-contraction, joint angles

Introduction

Neurological lesions cause spasticity, which leads to movement disorders, as in celebrity palsy (CP) or stroke (S). These patients could benefit from the most advanced rehabilitation techniques, such as mechatronic systems and exoskeletons. Unfortunately, these systems face a control problem when dealing with movement disorders. An ideal control strategy is to follow a co-robotic approach where the patient and the exoskeleton collaborate to complete a task. The control should detect the patient intention, capture his variability, ensure the stability, characterize the deviation induced by a change of speed in the movement [START_REF] Pons | Rehabilitation exoskeletal robotics[END_REF]. To provide this collaboration, the first challenge is to determine the specific admissible range for each joint, then to optimize the movement amplitude that avoids the patient pain. Regarding the two control methods described in the literature, either the control using impedance or using EMG interpretation, both have not studied the influence of the admissible joint range [START_REF] Yan | Review of assistive strategies in powered lower-limb orthoses and exoskeletons[END_REF]. To overcome this issue, we propose to rely on the direct measurement of biokinematic signals, and to find the causes of the movement changes. The activity of muscle cocontraction, around a joint, generates its movement. This activity allows the detection of the patient intention [START_REF] Shiavi | Electromyographic signals during gait: criteria for envelope filtering and number of strides[END_REF] and ensures articular stability [START_REF] Kellis | Muscle co-activation around the knee in drop jumping using the co-contraction index[END_REF]. Co-contraction indexes (CCI) are not suitable for a proper control strategy since each patient needs different solutions to minimize their movement disorders. We propose a new index, called neuro-motor index (NMI), serves to integrate the possibilities and variabilities of patient walking. This index avoids the fatigability while using the technical aids (such as the exoskeleton). We examine the accuracy and efficiency of the NMI under three walking speeds.

Methods

Subjects and data acquisition

Nine healthy subjects, without history of neuromusculoskeletal impairments (five males and four females with age of 45± 7 years), were recorded in Gait Laboratory (Raymond Poincaré Hospital, Garches, France). A bio-kinematics study was conducted in a large room; where the patients walked a straight line for 10 meters. The acquisition system includes:

• Video equipment to record the front and the profile of the patient. • An optoelectronic system to measure the segment kinematics and the joint angles of the knee and the hip steps with respect to each foot (left and right).

• Ground force platforms to record dynamics (recording of ground reaction forces and the moments). • An electromyographic system to record muscle activity. Electrodes were placed at the level of two biarticular muscle groups (quadriceps and hamstrings) for the knee and the hip on each leg (left and right). Everything was synchronized and connected to a computer for data acquisition. Kinematic measurements and electromyographic data were taken and recorded for three rhythms velocities (fast, normal and slow) and for 11 walking cycles at each velocity.

Signal Processing

The raw EMG signals were band-pass filtered (10-400 Hz), full-wave rectified, low-pass filtered using a Butterworth filter (4 th order) from 4 till 6 Hz cut-off frequency according to the subject cadence [START_REF] Shiavi | Electromyographic signals during gait: criteria for envelope filtering and number of strides[END_REF], and normalized by the detected maximal voluntary contraction (MVC) of each muscle on gait trials [START_REF] Kellis | Muscle co-activation around the knee in drop jumping using the co-contraction index[END_REF]. The kinematic data is filtered using a Butterworth filter (4 th order, 6 Hz cut-off frequency) connected to the acquisition system, then they are segmented in 1001 values for knee and hip joints to obtain matrices with fixed dimensions which are equal to those of recorded EMG matrices. Then, their mean and variance are estimated. The CCIs have been continuously computed using a sliding window with an overlap of 10 points and with a single point increment.

Proposed neuro-motor index (NMI)

This index is a sliding evaluation of muscle cocontraction during a gait [START_REF] Souissi | Comparison of methodologies to assess muscle cocontraction during gait[END_REF] derived from the combination between the CCIs proposed by [START_REF] Frost | Cocontraction in three age groups of children during treadmill locomotion[END_REF], [START_REF] Unnithan | Cocontraction and phasic activity during GAIT in children with cerebral palsy[END_REF] (denoted CCI1) and by [START_REF] Hesse | Lower limb muscle activity in ambulatory children with cerebral palsy before and after the treatment with Botulinum toxin A[END_REF] (denoted CCI2). They are combined together by a nonlinear regression Rm (t), of the quadriceps and hamstring EMGs. The regression is estimated with a Hermitian polynomial model He (t).

NMI (t) = { ! " CCI1 (t ) + ! "

Rm(t) CCI2 (t ) }

Where: Rm (t) = h1 (t) f0 + h2 (t) p0 + h3(t) f1 + h4 (t) p1

And the peaks are identified with:

argmin t | f'(t)| With: f (t) = EMGantago (t) ∩ EMGago (t) ; h1, h2, h3, h4 ∈ He (t);
and p0 and p1 are the tangents to f0 and f1.

Validation with canonical correlation analysis

The canonical correlation (CCA) is a multivariable statistical method used to extract the underlying correlation of two sets of data [START_REF] Larimore | Canonical variate analysis in identification, filtering, and adaptive control[END_REF]. To test the reliability of the NMI, CCA is applied at EMG-joint angles acquired during the gait cycle, at three velocities on the healthy subjects.

Results and discussion

On data from healthy subjects, with three velocities (slow, normal, and fast), CCA is applied for knee and hip gait angles (right and left). Regarding CCI1 and CCI2, the correlation points show an obvious variability from one velocity to another, moreover, the percentage of correlation is weak and so far from a linear relation, but regarding NMI the correlation points show strong similarity under the three velocities (Fig. 2). In other words, the percentage of correlation is very high and the correlation is almost linear (Fig. 1).

Conclusions

In this paper, we have proposed a bio-kinematic strategy to ensure rehabilitation with mechatronic systems. We have investigated the efficiency of a new neuro-motor index (NMI) by applying a canonical correlation analysis to extract his relation with the joint walking angles (for hip and knee). Also to ensure its effectiveness and its preference, against the CCIs, by studying it on several speeds. It is an important factor to describe the gait pathology by evaluating the inefficiency of movement. This latest can be a requirement to work with CP and stroke patients, laying a solid ground for the control of rehabilitation exoskeleton. Future work will focus on introducing this index on a control strategy for this type of mechatronic device.

Fig. 1 .

 1 Fig.1 . Illustration of correlation applied at three groups (Θ, I); Θ represents the knee joint angle during the complete gait cycle, and I represents NMI, the corralationequasi-linear.

Fig. 2

 2 Fig. 2 CCA applied at the knee angles for one healthy subject and the indexes (CCI1, CCI2, and MNI), for three different velocities during eleven complete gait cycles. Error bars indicate standard deviation. NMI present a corr (CCA)V=0.98 between three speeds


Emmanuelle Homonnay
email: homonnay@geoazur.unice.fr

Jean-Marc Lardeaux

Michel Corsini

Asmae El Bakili

Delphine Bosch

Olivier Bruguier

Mohamed Ouazzani-Touhami

Arc-related high-K magmatism in the Ceuta Peninsula (Internal Rif, Spain): discovery and consequences

Keywords: Rif belt, Alboran domain, Ceuta Peninsula, arc magmatism, U-Pb dating

We document the occurrence of micro-diorite magmatic sills, with magmatic enclaves, in the Ceuta Peninsula within metapelites from the Lower Sebtides units (Internal Rif). All magmatic rocks show a primary magmatic mineralogy and geochemical signature diagnostic for high-K calc-alkaline to shoshonitic island arc magmatism. Moreover, these rocks are significantly affected by secondary metamorphic transformations under greenschist-to amphibolite-facies conditions, regionally dated at c. 21 Ma. Geometric relationships between the sills and the main regional foliation, developed under intermediate-pressure granulite-facies conditions at c. 28 Ma, demonstrate that the sills emplaced during the late stage of this main tectonic event. New U-Pb in situ analyses of monazite performed on the micro-diorite sills provide an age of 20.64 ± 0.19 Ma, coherent with this chronological framework and interpreted as the age of greenschist-facies re-equilibration. The discovery of pre-Miocene high-K calc-alkaline to shoshonitic arc-related magmatism is clearly consistent with the subduction context proposed for the Alboran Basin evolution, according to geophysical investigations. In this framework, the Lower Sebtides units could be considered as part of the upper plate of the subduction system, while the Upper Sebtides must be regarded as the lower subducted plate.

Introduction

Located in the western tip of the Mediterranean, the Gibraltar arc consists of the Alboran Basin surrounded by the Betic (in Spain) and the Rif (in Morocco) orogenic belts built, since late Mesozoic time, in the context of Africa and Eurasia plate convergence (Fig. 1). Today, the geodynamic evolution of the internal zone of these cordilleras (i.e. the Alboran domain) is considered to be the result of subduction followed by slab rollback, which produced the opening of a back-arc basin (e.g. [START_REF] Royden | Evolution of the retreating subduction boundaries formed during continental collision[END_REF][START_REF] Lonergan | Origin of the Betic-Rif mountain belt[END_REF][START_REF] Faccenna | Lateral slab deformation and the origin of the western Mediterranean arcs[END_REF][START_REF] Faccenna | Mantle dynamics in the Mediterranean[END_REF][START_REF] Spakman | A tomographic view on western Mediterranean geodynamics[END_REF][START_REF] Vergés | Tethys-Atlantic interaction along the Iberia-Africa plate boundary: the Betic-Rif orogenic system[END_REF][START_REF] Bezada | Evidence for slab rollback in westernmost Mediterranean from improved upper mantle imaging[END_REF][START_REF] Van Hinsbergen | Origin and consequences of western Mediterranean subduction, rollback, and slab segmentation[END_REF]. Such a scenario with a retreating slab, migrating behind the orogenic wedge is also assumed in other domains of the Mediterranean such as the Calabrian arc (e.g. [START_REF] Faccenna | History of subduction and back-arc extension in the Central Mediterranean[END_REF][START_REF] Faccenna | Extensional tectonics on Sardinia (Italy): insights into the arc-back-arc transitional regime[END_REF] or the Aegean arc (e.g. [START_REF] Jolivet | Cenozoic geodynamic evolution of the Aegean[END_REF][START_REF] Jolivet | Aegean tectonics: strain localisation, slab tearing and trench retreat[END_REF].

Numerous geological, petrological, geochemical and geochronological studies were carried out on the internal zones of the Betic and the Rif belts in order to constrain the geodynamic evolution of the Alboran domain (e.g. Beccaluva et al. 2007;[START_REF] Duggen | Geochemical zonation of the Miocene Alboran Basin volcanism (westernmost Mediterranean): geodynamic implications[END_REF][START_REF] Conticelli | Trace elements and Sr-Nd-Pb isotopes of K-rich, shoshonitic, and calc-alkaline magmatism of the Western Mediterranean Region: genesis of ultrapotassic to calc-alkaline magmatic associations in a post-collisional geodynamic setting[END_REF][START_REF] Lustrino | The Central-Western Mediterranean: anomalous igneous activity in an anomalous collisional tectonic setting[END_REF][START_REF] Carminati | Geodynamic evolution of the central and western Mediterranean: tectonics vs. igneous petrology constraints[END_REF]. However, in spite of these detailed studies, no expression of arc-related calc-alkaline magmatism has ever been documented so far in the Internal Rif. In this paper we unravel for the first time the occurrence of subduction-related magmatism in the Ceuta Peninsula, located in the internal zone of the Rif belt.

Geological context

The Rif Cordillera, located in the northern part of Morocco, consists of stacked sedimentary and metamorphic units thrust onto foreland basins. Classically, three main structural domains are recognized in this orogenic system (Fig. 1b): (i) the External zone, (ii) the Flysch zone and (iii) the Internal zone (or Alboran domain, see [START_REF] Michard | The correlations between the Rifan-Betic Mountain Belt and the Alps, and their consequences[END_REF][START_REF] Chalouan | The Rif belt[END_REF]. The Internal Rif consists of three units, namely, from top to bottom, the Dorsale calcaire, the Ghomarides unit and the Sebtides unit (Fig. 1b, e.g. [START_REF] Chalouan | The Rif mountain building (Morocco): a new tectonic scenario[END_REF]. The Sebtides unit is composed of a stack of high-to low-grade metamorphic rocks, subdivided into the pre-Permian Lower Sebtides and the Palaeozoic to Triassic Upper Sebtides [START_REF] Chalouan | The Rif belt[END_REF]. In the Ceuta area, two sub-units are distinguished in the Lower Sebtides: the Ceuta Upper Unit (CUU) and the Monte Hacho Lower Unit (MHLU).

The CUU is composed of migmatitic metapelites containing peridotite lenses and boudins of high-to ultra-high-pressure granulites at its base [START_REF] Kornprobst | Contribution à l'étude pétrographique et structurale de la zone interne du Rif (Maroc septentrional)[END_REF][START_REF] Galdeano | Diamond and coesite in ultrahighpressure-ultrahigh-temperature granulites from Ceuta, Northern Rif, northwest Africa[END_REF], 2013), overthrust upon the migmatitic orthogneisses of the MHLU (Fig. 2, [START_REF] Kornprobst | Contribution à l'étude pétrographique et structurale de la zone interne du Rif (Maroc septentrional)[END_REF][START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF].

Thrust tectonics developed under intermediate-pressure granulite-facies metamorphism before Miocene time, probably during Oligocene time [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF]. In this domain, three ductile deformation stages (D1-D3) have been identified, where S1-S3 foliations are associated with distinctive metamorphic assemblages [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF]. In both Lower Sebtides units, an S2 composite foliation, bearing a well-developed stretching lineation L2, is the dominant regional fabric whatever the lithology. In the uppermost unit, pre-D2 fabrics (i.e. D1/S1) are locally preserved in volumes (i.e. lozenge-shaped blocks) that escaped overprinting by the pervasive S2. In both units, D3 structures consist of localized normal ductile shear zones associated with an S3 foliation. Detailed microstructural, mineralogical and geochronological investigations [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF] demonstrate that:

(1) D1 was contemporaneous with high-pressure/high-temperature metamorphic conditions (high-pressure granulite facies) of unknown age; (2) D2 developed, contemporaneously with thrust tectonics, under intermediate-pressure granulite-facies conditions (7-10 kbar and 780-820 °C) before 28 Ma; (3) D3 is characterized by metamorphic re-equilibration at the boundary between amphibolite-and greenschist-facies conditions (400-550 °C and 1-3 kbar) during early Miocene time (i.e. c. 21 Ma).

In the most western part of the Ceuta area, the Upper Sebtides (Federico units) underwent an Alpine, probably Oligocene, highpressure/low-temperature metamorphism typical of subduction zone conditions [START_REF] Bouybaouene | High-pressure, low-temperature metamorphism in the Sebtides nappes, northern Rif, Morocco[END_REF][START_REF] Goffe | Metamorphic cookeite in Alpine metapelites from Rif, northern Morocco, and the Betic Chain, southern Spain[END_REF][START_REF] Michard | Late Hercynian-Mesozoic thinning in the Alboran domain: metamorphic data from the northern Rif, Morocco[END_REF][START_REF] Janots | Evolution of the REE mineralogy in HP-LT metapelites of the Sebtide complex, Rif, Morocco: monazite stability and geochronology[END_REF].

3. Evidence for high-K calc-alkaline magmatism in the Lower Sebtides

3.a. Field observations

Metapelites from the CUU present a main NE-striking (N30 to N50) S2 foliation plane, gently to moderately dipping (20 to 50°) towards the NW (Fig. 2). This foliation is marked by the alternation of quartz-feldspars and garnet-biotite-sillimanite-rich levels as well as by the alternation of centimetric quartzo-feldspathic leucosomes and biotite-sillimanite mesosomes (Fig. 3a). This main D2 deformation episode, synchronous with partial melting of the metapelites, is also contemporaneous with the thrusting of the CUU over the MHLU [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF].

In these metapelites we found several pluricentimetric to plurimetric magmatic sills parallel to the main S2 foliation plane (Fig. 3a,b,c). In these 'micro-granitoid' sills we recognized two types of enclaves: (1) enclaves of migmatitic metapelites (i.e. host rock, Fig. 4a) and (2) granular to microgranular magmatic enclaves (Fig. 4b). The cores of the magmatic sills are clearly not deformed and contain a well-preserved microgranular porphyric texture (Fig. 3d). On the other hand, the edges of the sills display preferred mineral orientation interpreted as a magmatic flow-fabric (Fig. 3b,c,e). This interpretation is supported by enclave alignments parallel to the main foliation of the surrounding rocks (Fig. 3b). These structural observations are typical for syn-to late-tectonic (i.e. D2 deformation event) magma emplacement. In such a case, the magmatic sills were emplaced in thermal equilibrium with the surrounding metapelites.

3.b. Petrographic observations

The magmatic sills present a microgranular porphyric texture, while magmatic fluidality is visible in thin-sections from the edges of the sills (Fig. 5a). The sills contain a primary magmatic assemblage essentially composed of feldspars, quartz, biotites and oxides (ilmenite and magnetite). Feldspars occur as subhedral to anhedral large-sized grains (1-5 mm) (Fig. 5b) and present a magmatic zonation. They are predominantly plagioclases (An 7 -An 25 ), which exhibit polysynthetic twinning. K-feldspars (orthoclase, microcline) are observed in minor amounts and orthoclase shows Carlsbad twinning. In the groundmass, xenomorphic quartz grains show wavy extinctions. Biotite appears as small (< 1 mm) brown, strongly pleochroic grains in the groundmass or as minute inclusions in large plagioclase grains (Fig. 5b). In the largest biotite grains, needle-shaped rutile developed along cleavage planes. In addition, we frequently observed a 'ghost' mineral with a rectangular or rhomboidal shape (around 5 mm), which is totally replaced by an association of chlorite, muscovite and epidote (Fig. 5c). Although the nature of this mineral cannot be definitely determined, the secondary mineral association together with the mineral shapes strongly suggests a primary magmatic amphibole or a primary magmatic pyroxene. Indeed, in one thin-section we recognized one fragment of a rectangular-shaped pyroxene within the pseudomorphic aggregate. Magnetite occurs as more or less rhombohedral isotropic crystals in the groundmass, while ilmenite is found as elongated dark brown frequently altered grains. Accessory minerals are titanite, apatite, monazite and zircon. This primary magmatic mineral association of plagioclase þ quartz þ K-feldspar þ biotite þ Fe-Ti oxide þ Fe-Mg-mineral (amphibole and/or pyroxene) indicates a moderately differentiated magmatic rock (micro-granodiorite or micro-diorite). The lack of primary magmatic muscovite or aluminium silicates together with the presence of amphibole or pyroxene, Fe-Ti oxides and titanite in the magmatic association is typical for calc-alkaline magmas, i.e. Hybrid Late Orogenic (H LO ) or Hybrid Continental Arc (H CA ) magmatic series in the mineralogical/petrogenetic classification of [START_REF] Barbarin | Granitoids: main petrogenetic classifications in relation to origin and tectonic setting[END_REF] and thus of mixed (crustal þ mantle) origin. Most magmatic minerals underwent secondary metamorphic transformations (Fig. 5c). Feldspars are partly or totally replaced by patches of albite and white mica. White micas also occur as radial aggregates along magmatic grain boundaries. Chlorite forms pseudomorphic patches within magmatic phases. In some samples, epidote developed at the expense of primary Fe-Mg magmatic minerals. 2 3 :586 8 6 C6 9CC 5 : 8 1 2565 7 9CC 2 3 :586 8 6 .0 255 6 / C 2C D3 6 C C C96 ,2 3 :586 ,6 C6 7 D 6 2 2: 23 6 2C The magmatic enclaves display a magmatic mineral association of plagioclase, amphibole, pyroxene and minor quartz (Fig. 6). Plagioclase occurs as lath-shaped crystals that show polysynthetic twinning. Amphibole is anhedral, green coloured and pleochroic with, when observable, an extinction angle of about 20°. Millimetre-sized pyroxene grains occur as anhedral crystals and are largely replaced by secondary metamorphic minerals. Quartz grains, with irregular grain boundaries, are scattered in the matrix. Accessory magmatic minerals include magnetite and/or ilmenite, titanite and zircon. Secondary metamorphic minerals are well developed; plagioclases are frequently converted to fine-grained white mica, while amphibole and pyroxene are partly or completely pseudomorphosed by muscovite, chlorite and epidote.

The development of a secondary metamorphic mineral association (i.e. white mica þ chlorite þ quartz þ albite ± epidote assemblage) in the magmatic sills and their enclaves attests to a severe metamorphic re-equilibration at the boundary between amphibolite-and greenschist-facies conditions (i.e. synchronous with the D3 tectonic event; see [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF] for discussion). Thus, both the magmatic sills and surrounding metapelites are affected by D3 metamorphism, and consequently, field observations together with petrographic analysis are compatible with syn-to late-D2 and pre-D3 magmatic sill emplacement.

3.c. Geochemical investigations

Because the magmatic sills are significantly affected by D3 metamorphism, in order to investigate the geochemical characteristics of these magmatic rocks we sampled the magmatic rocks only in the largest and best-preserved sill. In this sill, in view of outcrop quality, we found only two samples of micro-granitoids with well-preserved magmatic texture (SEB12-04 and CEU14-05) and one enclave (CEU17-23E), also very well preserved. These three samples were selected for major-and trace-element chemical analyses. Bulk rock compositions were obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS), for major and trace elements, respectively, on rock powders at the Geochemical and Petrographical Research Centre in Nancy (SARM laboratory, CNRS-CRPG; Table 1) following the procedure described in [START_REF] Carignan | Routine analyses of trace elements in geological samples using flow injection and low pressure on-line liquid chromatography coupled to ICP-MS: a study of geochemical reference materials BR, DR-N, UB-N, AN-G and GH[END_REF].

In the total alkalis versus silica classification (i.e. TAS diagram after Le [START_REF] Maitre | Igneous Rocks: A Classification and Glossary of Terms[END_REF]), the 'micro-granitoid' samples are micro-diorites, while the microgranular enclave is a less differentiated micro-gabbrodiorite (Fig. 7a). Moreover, with respect to SiO 2 and K 2 O (i.e. in the classification of [START_REF] Peccerillo | Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey[END_REF], all these magmatic rocks have a geochemical signature typical for high-K calc-alkaline magmas (Fig. 7b).

However, the identification of the geochemical characteristics of magmatic rocks re-equilibrated during regional metamorphism is still delicate because of the mobility of the chemical elements during fluid-assisted metamorphism [START_REF] Bridgwater D Ed | Fluid Movements -Element Transport and the Composition of the Deep Crust[END_REF][START_REF] Ferry | A historical review of metamorphic fluid flow[END_REF]. Numerous studies have already shown that major elements as well as some trace elements, mainly large ion lithophile elements (LILE) (e.g. Rb, Cs, Sr, Ba) and light rare earth elements (LREE) (e.g. La, Ce, Nd), are considered to be the most mobile elements under greenschist-and amphibolite-facies conditions, whatever the considered lithology [START_REF] Bridgwater D Ed | Fluid Movements -Element Transport and the Composition of the Deep Crust[END_REF][START_REF] Potdevin | Diffusion model for magmatic reaction. An example of amphibole breakdown in the trachytic dome of Monac (French Massif Central)[END_REF][START_REF] Lawrie | Geochemical characterisation of a polyphase deformed, altered, and high grade metamorphosed volcanic terrane: implications for the tectonic setting of the Svecofennides, south-central Finland[END_REF][START_REF] Ague | Mass transfer during Barrovian metamorphism of pelites, southcentral Connecticut; I, Evidence for changes in composition and volume[END_REF][START_REF] Ague | Fluid infiltration and transport of major, minor, and trace elements during regional metamorphism of carbonate rocks, Wepawaug Schist, Connecticut, USA[END_REF][START_REF] Roser | An evaluation of elemental mobility during metamorphism of a turbidite sequence (Greenland Group, New Zealand)[END_REF][START_REF] Brewer | Metamorphic overprinting of Sm-Nd isotopic systems in volcanic rocks: the Telemark Supergroup, southern Norway[END_REF][START_REF] Masters | Regional-scale fluid flow and element mobility in Barrow's metamorphic zones, Stonehaven, Scotland[END_REF][START_REF] Zheng | Chemical geodynamics of continental subduction-zone metamorphism: insights from studies of the Chinese Continental Scientific Drilling (CCSD) core samples[END_REF]. Therefore, in order to improve the characterization of the geochemical signature of the studied samples, we selected diagrams suitable for magmatic rocks, using only minor and trace elements considered immobile during metamorphic processes.

First, in the [START_REF] Winchester | Geochemical discrimination of different magma series and their differentiation products using immobile elements[END_REF] magmatic rock classification including its modification by [START_REF] Pearce | A user's guide to basalt discrimination diagrams[END_REF], based on immobile element ratios such as Zr/Ti versus Nb/Y, the studied samples range in the field of gabbroic and dioritic rock types (Fig. 8a). Second, we used the accurate Th-Co diagram proposed by [START_REF] Hastie | Classification of altered volcanic island arc rocks using immobile trace elements: development of the Th-Co discrimination diagram[END_REF] for magmatic rocks transformed under greenschist-facies conditions (Fig. 8b) and the Th/Yb versus Ta/ Yb diagram (Fig. 8c) from [START_REF] Pearce | Role of the sub-continental lithosphere in magma genesis at active continental margins[END_REF]. In these diagrams, the three samples are micro-gabbrodiorites and diorites, whereas their compositions still have a geochemical signature typical for the high-K to shoshonitic series.

Trace-element discriminant diagrams are often considered an important way to determine the tectonic environment of magma formation [START_REF] Pearce | Role of the sub-continental lithosphere in magma genesis at active continental margins[END_REF][START_REF] Pearce | Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[END_REF]. However, traceelement compositions are also a function of source components and the crystallization history of the melts [START_REF] Rollinson | Using Geochemical Data: Evaluation, Presentation, Interpretation[END_REF][START_REF] Frost | A geochemical classification for granitic rocks[END_REF]. Since trace-element diagrams can discriminate various tectonic settings, the composition of the studied samples was plotted on some of these diagrams (Fig. 9). In the discriminant diagrams proposed by [START_REF] Pearce | Tectonic setting of basic volcanic rocks determined using trace element analyses[END_REF] and [START_REF] Pearce | Trace element characteristics of lavas from destructive plate boundaries[END_REF] (Ti/ Zr/Y in Fig. 9a and Cr versus Y in Fig. 9b, respectively), the three samples plot in the calc-alkaline and volcanic arc fields. In the Th/ Hf versus Ta/Hf diagram [START_REF] Schandl | Application of high field strength elements to discriminate tectonic settings in VMS environments[END_REF], samples plot in the active continental margin field (Fig. 9c). Moreover, the two micro-diorites typically have an intermediate rock composition.

Consequently, we felt it was also interesting to confront their chemical signatures with discriminant diagrams established for granitoids. In the Nb versus Y diagram from [START_REF] Pearce | Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[END_REF], the two samples plot in the volcanic arc and syn-collisional granitoid field (Fig. 9d), while using the more accurate Ta versus Yb diagram proposed by [START_REF] Pearce | Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[END_REF] to distinguish between volcanic arc and syn-collisional granitoids, our samples plot in the volcanic arc granitoid field (Fig. 9e).

Altogether, the geochemical characters of the studied sills are consistent with a high-K calc-alkaline magma formed within a continental magmatic arc.

U-Pb dating

4.a. Analytical method

U-Th-Pb dating was performed on monazites and one xenotime from the micro-diorite SEB12-04. In situ analyses were achieved on thin-sections, in order to keep the microstructural context of the analysed minerals. Prior to LA-ICP-MS in situ U-Th-Pb analyses, minerals were examined with backscattered electrons (BSE) (Fig. 10), using a scanning electron microscope (SEM) at the CRHEA in Sophia Antipolis (Valbonne, France), to reveal the internal structure of the minerals. The operating conditions were 15 kV accelerating voltage and a 17 nA beam current. In situ U-Th-Pb analyses were performed at Geosciences Montpellier (University of Montpellier, France) by laser ablation (LA)-ICP-MS using a Lambda Physik CompEx 102 Excimer laser coupled to an Element XR sector field ICP-MS at the AETE-ISO regional facility (OSU OREME). Laser spot sizes were 15 μm. Before analysis, the laser was first fired to clean the sample surface (ten pulses). The targeted mineral was subsequently ablated under ultrapure helium in a 15 cm 3 circular-shaped ablation cell with an energy density of 12 J/cm 2 at a frequency of 2 Hz during 45 s. A gas blank was measured during 15 s before each analysis. Analyses of unknown monazite grains were bracketed by analyses of the Manangotry monazite standard [START_REF] Poitrasson | Electron microprobe and LA-ICP-MS study of monazite hydrothermal alteration: implications for U-Th-Pb geochronology and nuclear ceramics[END_REF]. Repeated analyses of this reference mineral were used to correct for inter-element fractionation and for mass bias factor corrections (see details in [START_REF] Bosch | Building an island-arc crustal section: time constraints from a LA-ICP-MS zircon study[END_REF]. Quoted ratios (see Table 2) correspond to measured ratios corrected for background and mass discrimination (+ elemental fractionation for the 206 Pb/ 238 U ratios). All ages have been calculated using the U and Th decay constants recommended by [START_REF] Steiger | Subcommission on geochronology: convention on the use of decay constants in geo-and cosmochronology[END_REF]. Analytical data were plotted and ages were calculated using the IsoplotEx program [START_REF] Ludwig | Mathematical-statistical treatment of data and errors for 230 Th/U geochronology[END_REF]. Individual analyses in Table 2 and in Concordia plots (Fig. 11) are ± 1σ errors, and uncertainties in ages are quoted in the text at the 2σ level.

4.b. Results

Eighteen monazites and one xenotime were analysed from the sample SEB12-04. Under BSE imaging, 11 monazites display a homogeneous structure (Fig. 10a), whereas seven show either a light grey core surrounded by a dark grey rim (Fig. 10b; mnz3, mnz12, mnz13) or irregular light grey patches (Fig. 10c; mnz 2, mnz9, mnz16, mnz18) suggesting recrystallization of preexisting minerals (e.g. [START_REF] Bosch | Monazite "in situ" 207 Pb/ 206 Pb geochronology using a small geometry high-resolution ion probe. Application to Archaean and Proterozoic rocks[END_REF]. The monazites sometimes contain inclusions (mnz1, 3-6, 15-18; Fig. 10c) and have a rounded or elongated shape. The shape of the monazite, and lack of oscillatory zoning, is not consistent with crystallization from a melt, as observed for magmatic monazite (e.g. [START_REF] Bruguier | Miocene incorporation of peridotite into the Hercynian basement of the Maghrebides (Edough massif, NE Algeria): implications for the geodynamic evolution of the Western Mediterranean[END_REF]). The xenotime is homogeneous, rounded in shape with undulant rims. Thirty-nine analyses were performed on 18 monazite grains (see Table 2) and two analyses were performed on the xenotime grain identified in the thin-section. Despite the observed differences in internal structures, most monazite analyses display a single alignment in the Concordia diagram and provide an intercept age of 20.7 ± 0.19 Ma (Fig. 11b). The xenotime analysis also plots along this alignment, suggesting that the monazite and xenotime are coeval. Two grains (mnz3 and mnz16) are significantly older with apparent 206 Pb-238 U ages ranging from 241.3 ± 8.8 Ma to 225.7 ± 7.4 Ma (Table 2; Fig. 11a). It is noteworthy that mnz16 displays a heterogeneous age distribution in which Miocene and older domains are present. The BSE imaging of this grain is not consistent with a core-like structure but, on the contrary, suggests recrystallization processes. On that basis, the c. 21 Ma age is interpreted as reflecting monazite growth or resetting of the U-Pb system of preexisting minerals under metamorphic conditions. Older ages are interpreted as partial updating of minerals that were most likely snatched from deep-seated material by the dioritic magma.

4.c. Age interpretations

Most of the dated minerals yield an age of c. 21 Ma. In the Ceuta Peninsula, this age is now well documented and is associated with the D3 tectonic event, developed at the boundary between amphibolite-and greenschist-facies conditions, and which corresponds to the development of ductile extension [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF]. Interestingly, in the investigated micro-diorite, the dated monazites and xenotime are systematically in textural equilibrium with the secondary metamorphic phases in the groundmass as well as in inclusions within magmatic minerals, the latter being totally replaced by muscovite and chlorite (Fig. 10d).

Geological consequences

We report for the first time the occurrence of calc-alkaline magmatic sills in the Ceuta Peninsula (Internal Rif). Sampled microdiorites and micro-gabbrodiorites show a primary magmatic mineralogy and a geochemical signature diagnostic for high-K calc-alkaline to shoshonitic island arc magmatism. Field observations based on geometric relationships between the micro-diorite sills and the main regional foliation S2, developed under intermediate-pressure granulite-facies conditions before 28 Ma [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF], demonstrate that the magmatic sills emplaced during the late stage of the D2 tectonic event.

Furthermore, these magmatic rocks are fully metamorphosed under greenschist-facies metamorphic conditions. The latter, depicted at the regional scale, is coeval with an early Miocene D3 extensional tectonic event [START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF]. Hence, syn-to late-D2 and pre-D3 magmatic sill emplacement is consistent with the magmatic monazite U-Pb age resetting at c. 21 Ma. The significance of this pre-Miocene high-K calc-alkaline magmatism must now be envisioned and discussed within the framework of the geodynamic context presently held for the Alboran domain. Following geophysical investigations, and particularly tomographic studies [START_REF] Blanco | The P-wave velocity structure of the mantle below the Iberian Peninsula: evidence for subducted lithosphere below southern Spain[END_REF][START_REF] Gutscher | Evidence for active subduction beneath Gibraltar[END_REF][START_REF] Timoulali | New evidence of delamination in the Western Alboran Sea: geodynamic evolution of the Alboran domain and its margins[END_REF][START_REF] Villaseñor | Subduction and volcanism in the Iberia-North Africa collision zone from tomographic images of the upper mantle[END_REF], the Betic-Rif orogen that surrounds the Alboran Basin is regarded as an emblematic example of a subduction-controlled orogeny followed by slab rollback leading to the opening of the Alboran back-arc basin (e.g. [START_REF] Faccenna | Lateral slab deformation and the origin of the western Mediterranean arcs[END_REF][START_REF] Spakman | A tomographic view on western Mediterranean geodynamics[END_REF][START_REF] Vergés | Tethys-Atlantic interaction along the Iberia-Africa plate boundary: the Betic-Rif orogenic system[END_REF][START_REF] Bezada | Evidence for slab rollback in westernmost Mediterranean from improved upper mantle imaging[END_REF][START_REF] Van Hinsbergen | Origin and consequences of western Mediterranean subduction, rollback, and slab segmentation[END_REF]. In this geodynamic framework, slab rollback of the Tethyan oceanic Our structural and geochronological data reveal that, in the Ceuta area, high-temperature metamorphism and calcalkaline magmatism are, at least in part, synchronous. This is consistent with the thermal behaviour of supra-subduction magmatic arcs. Indeed, in numerous examples of active or extinct arcs, regional metamorphism is coeval with arc building, and heat input is related to continuous or episodic emplacement of magmatic intrusions [START_REF] Miyashiro | Evolution of metamorphic belts[END_REF][START_REF] Ernst | Systematics of large-scale tectonics and age progressions in Alpine and Circum-Pacific blueschist belts[END_REF][START_REF] Schiffman | Active metasomatism in the Cerro Prieto geothermal system, Baja California, Mexico: a telescoped low-pressure, low-temperature metamorphic facies series[END_REF][START_REF] Aguirre | A low-grade metamorphic model for the Miocene volcanic sequences in the Andes of central Chile[END_REF][START_REF] Willner | A counterclockwise PTt path of high-pressure/low-temperature rocks from the Coastal Cordillera accretionary complex of south-central Chile: constraints for the earliest stage of subduction mass flow[END_REF][START_REF] Willner | Pressure-temperature evolution of a late Palaeozoic paired metamorphic belt in north-central Chile (34°-35°30 0 S)[END_REF]. The small volume of magmatic rocks identified up to now could be the result of a weakly productive magmatic arc or be the result of a difficulty in identifying these rocks in the field.

Furthermore, in the northern Rif, the Upper Sebtides located westward of the Ceuta Peninsula underwent an Oligocene highpressure/low-temperature metamorphism [START_REF] Bouybaouene | High-pressure, low-temperature metamorphism in the Sebtides nappes, northern Rif, Morocco[END_REF][START_REF] Goffe | Metamorphic cookeite in Alpine metapelites from Rif, northern Morocco, and the Betic Chain, southern Spain[END_REF][START_REF] Michard | Late Hercynian-Mesozoic thinning in the Alboran domain: metamorphic data from the northern Rif, Morocco[END_REF][START_REF] Janots | Evolution of the REE mineralogy in HP-LT metapelites of the Sebtide complex, Rif, Morocco: monazite stability and geochronology[END_REF]) and thus must be considered as the lower plate subducted beneath the Lower Sebtides (Fig. 12). The tectonic coupling between the Upper and Lower Sebtides defines a typical example of 'paired metamorphic belts' (Brown, 2010 and references therein). Indeed, island arc and back-arc regions are recognized as a suitable tectonic setting for the development of regional high-temperature/ low-pressure metamorphism [START_REF] Miyashiro | Evolution of metamorphic belts[END_REF][START_REF] Oxburgh | Thermal structure of island arcs[END_REF][START_REF] Ernst | Blueschist metamorphism and P-T regimes in active subduction zones[END_REF]. This metamorphism developed in the upper plate of the subduction zone is the counterpart of the high-pressure/low-temperature metamorphism widespread within the down-going lower plate (Fig. 12).

After the development of the paired metamorphic belts, during early Miocene time, the Upper Sebtides underwent normal faulting associated with back-arc extension and opening of the Alboran Basin (Fig. 12; [START_REF] Comas | The origin and tectonic history of the Alboran Basin: insights from leg 161 results[END_REF][START_REF] Platt | Exhumation of the Ronda peridotite and its crustal envelope: constraints from thermal modelling of a P-T-time array[END_REF][START_REF] Martínez-García | From extension to shortening: tectonic inversion distributed in time and space in the Alboran Sea, Western Mediterranean[END_REF][START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF]. Post-subduction deformation is thus observed in the studied area; however, this deformation is not strong enough to reverse the initial relationships between the Upper and Lower Sebtides. At the scale of the Betic-Rif orogen, published magmatic studies mostly deal with recent magmatic episodes within the Neogene volcanic province widespread in the eastern part of the Alboran domain [START_REF] Duggen | Geochemical zonation of the Miocene Alboran Basin volcanism (westernmost Mediterranean): geodynamic implications[END_REF]see Lustrino et al. 2011 for a review). Up to now, earlier magmatic events were only described in the Betic Cordilleras (e.g. [START_REF] Bellon | Chronologie du magmatisme Neogene des Cordilleres Betiques (Espagne meridionale)[END_REF][START_REF] Torres-Roldan | An early Miocene arctholeiitic magmatic dyke event from the Alboran sea: evidence for precollision subduction and back-arc crustal extension in the westernmost Mediterranean[END_REF][START_REF] Turner | Magmatism associated with orogenic collapse of the Betic-Alboran Domain, SE Spain[END_REF][START_REF] Duggen | Magmatic evolution of the Alboran region: the role of subduction in forming the western Mediterranean and causing the Messinian Salinity Crisis[END_REF][START_REF] Lustrino | The Central-Western Mediterranean: anomalous igneous activity in an anomalous collisional tectonic setting[END_REF][START_REF] Esteban | Insights into extensional events in the Betic Cordilleras, southern Spain: new fission-track and U-Pb SHRIMP analyses[END_REF]) and more precisely in the Malaga area (SW Betic), as tholeiitic and calc-alkaline basaltic andesite dykes. K-Ar and Ar-Ar geochronological investigations on these rocks reveal two age groups: (1) 30-38 Ma, which corresponds to calcalkaline dyke emplacement during the subduction process, and (2) 17.4-19.8 Ma, interpreted as K-Ar system resetting due to a wide-scale thermal event. Furthermore, a high-K to shoshonitic magmatic episode occurred between 16 and 8 Ma, in the eastern Rif and Betics and in the Alboran Sea. It is related to the slab rollback and marks the position of the deep subducted lithosphere beneath the Alboran Basin [START_REF] Gill | Depleted arc volcanism in the Alboran Sea and shoshonitic volcanism in Morocco: geochemical and isotopic constraints on Neogene tectonic processes[END_REF][START_REF] Duggen | Post-collisional transition from subduction-to intraplate-type magmatism in the westernmost Mediterranean: evidence for continental-edge delamination of subcontinental lithosphere[END_REF].

The new data we obtained in the northern Rif are in agreement with this interpretation proposed for the Betic chains, and all together support a model of subduction-related orogeny for the Betic/Rif Cordilleras.

Conclusions

We described for the first time a high-K calc-alkaline magmatism in the Lower Sebtides (Internal Rif). Our structural and petrographic observations with geochronological data demonstrate that: (i) pre-Miocene high-K calc-alkaline to shoshonitic micro-diorite sills emplaced in the Ceuta Peninsula within the Lower Sebtides (Internal Rif) during high-temperature/medium-pressure metamorphism (i.e. D2 deformation event); (ii) these newly recognized magmatic rocks have a primary magmatic mineralogy and geochemical signature diagnostic of island arc magmatism; (iii) the micro-diorite sills display a secondary medium-temperature/ low-pressure metamorphic episode (i.e. D3 deformation event), which led to monazite U-Pb age resetting at c. 21 Ma. The presence of arc-related magmatism, probably Oligocene in age, is not surprising in the nowadays widely accepted subduction system for the Gibraltar arc formation. Therefore, in such a framework, the so-called Lower Sebtides correspond to the upper plate of the subduction system, whereas the Upper Sebtides may be considered as the lower plate of the subduction system.

Fig. 1 .

 1 Fig. 1. (Colour online) (a) Location of the Gibraltar arc and Alboran Basin in the framework of the Western Mediterranean and peri-Mediterranean orogenic belts (light green). (b) Structural map of the Gibraltar arc.

Fig. 2 .

 2 Fig. 2. (Colour online) Geological map showing the location of the magmatic sill within the structural framework of the Ceuta Peninsula (modified after Homonnay et al. 2018). CUU -Ceuta Upper Unit; MHLU -Monte Hacho Lower Unit; CSZ -Ceuta Shear Zone. See Figure 1b for location.

Fig. 3 .

 3 Fig. 3. (Colour online) Field observations. (a) Decametric sill parallel to the main S2 metapelite foliation plane. (b) Edge of the sill with magmatic fluidality and enclave alignments parallel to the main S2 foliation plane. (c) Contact between the micro-diorite sill and the metapelite. (d) Microgranular porphyric texture preserved in the core of the sill. (e) Magmatic mineral orientation (underlined by white dashed lines) within the micro-diorite sill.

Fig. 4 .

 4 Fig. 4. (Colour online) Enclaves observed within the micro-diorite sill. (a) Metapelite enclave. (b) Magmatic enclave with microgranular texture.

Fig. 5 .

 5 Fig. 5. (Colour online) Thin-section photomicrographs of the micro-diorite sills. (a) Magmatic mineral fluidality marked by white dashed lines (plane-polarized light). (b) Microgranular porphyric texture (plane-polarized light). (c) Typical 'ghost' mineral totally replaced by muscovite and chlorite ± quartz (cross-polarized). fspfeldspar; btbiotite; oxoxide; qtzquartz; msmuscovite; chlchlorite.

Fig. 6 .

 6 Fig. 6. (Colour online) Thin-section photomicrograph of a magmatic enclave (planepolarized light). The micro-porphyric texture is underlined by crystals of amphibole (amph), pyroxene (px) and oxides (ox). The domains in white correspond to plagioclase and minor quartz.

Fig. 7 .

 7 Fig. 7. (Colour online) Rock classification diagrams using major elements. (a) TAS diagram for igneous rocks after Cox et al. (1979). (b) Rock series discriminant diagram from Peccerillo & Taylor (1976).

Fig. 8 .

 8 Fig. 8. (Colour online) (a) Zr/Ti versus Nb/Y diagram from Pearce (1996) modified after Winchester & Floyd (1977). (b) Th-Co discriminant diagram for altered volcanic island arc rocks, using immobile trace elements, from Hastie et al. (2007). (c) Th/Yb versus Ta/ Yb diagram after Pearce (1983).

Fig. 9 .

 9 Fig. 9. (Colour online) (a) Ti/Zr/Y discriminant diagram from Pearce & Cann (1973). Afield of island arc tholeiites; Bfield of MORB, arc tholeiites and calc-alkaline magmas; Cfield of calc-alkaline magmas; Dfield of within-plate magmas. (b) Cr versus Y discriminant diagram between MORB, volcanic arc basalts (VAB) and within-plate basalts (WPB) from Pearce (1982). (c) Th/Hf versus Ta/Hf diagram from Schandl & Gorton (2002). (d) Nb versus Y tectonic discriminant diagram for granitoid rocks[START_REF] Pearce | Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[END_REF]. (e) Ta versus Yb tectonic discriminant diagram for granitoid rocks[START_REF] Pearce | Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[END_REF].

Fig. 10 .

 10 Fig. 10. (Colour online) Backscattered electron (BSE) and microscopic images of monazite grains in the micro-diorite sill. Locations of U-Th-Pb analyses are circled in BSE images. (a) Homogeneous monazite grain. (b) Monazite grain exhibiting light grey core and dark grey rim. (c) Monazite grain with light grey patches and inclusion. (d) Microscopic photo of a monazite (mnz3) surrounded by chlorite (chl) and muscovite (ms).

Fig. 11 .

 11 Fig. 11. (Colour online) (a) Concordia diagram for U-Pb analyses on monazites and xenotime. (b) Tera-Wasserburg diagram close-up of young U-Pb analyses.

Fig. 12 .

 12 Fig. 12. (Colour online) Schematic cross-section of the Rif belt (modified from Chalouan et al. 2008). HP/LT: high pressure/ low temperature. HT/LP: high temperature/ low pressure.

Table 1 .

 1 Chemical analyses: major elements (wt %), minor and trace elements (ppm)

	Geological Magazine
	Sample	SEB12-04	CEU14-05	CEU17-23E
		micro-diorite	micro-diorite	enclave
	SiO 2	59.2	61.1	54.0
	Al 2 O 3	19.2	17.9	15.9
	Fe 2 O 3 (t)	8.1	7.0	8.0
	MnO	0.1	0.1	0.1
	MgO	2.5	2.3	5.9
	CaO	1.3	1.7	7.3
	Na 2 O	1.3	1.0	3.1
	K 2 O	3.3	3.6	2.1
	TiO 2	1.0	0.9	0.6
	P 2 O 5	0.0	0.2	0.7
	LOI	4.2	4.6	1.6
	TOTAL	100.1	100.3	99.4
	Ba	502.6	403.3	835.8
	Co	20.1	15.6	26.3
	Cr	113.0	97.0	198.6
	Er	3.2	2.8	_
	Eu	1.6	1.4	_
	Ga	26.5	23.9	22.1
	Hf	5.8	4.7	3.0
	La	47.8	41.9	_
	Lu	0.5	0.4	_
	Nb	15.5	14.0	9.2
	Nd	42.2	35.2	_
	Pb	21.9	17.1	13.0
	Pr	11.1	9.3	_
	Rb	131.1	147.1	55.9
	Sc	20.8	18.1	21.7
	Sm	8.2	6.9	_
	Sr	117.0	77.9	478.9
	Ta	1.3	1.4	0.6
	Tb	1.0	0.9	_
	Th	15.9	13.3	8.9
	U	3.1	3.2	_
	V	158.7	137.3	212.8
	Y	32.0	27.5	18.8
	Yb	3.0	2.9	3.0
	Zr	219.0	169.8	98.8

  Consequently, monazite ages at c. 21 Ma cannot be interpreted as the ages of magma crystallization but, on the contrary, are related to the late-D3 stage of metamorphism characterized by metamorphic re-equilibration, associated with fluid circulation, during early Miocene time. Resetting of monazite ages during greenschist-facies metamorphism and related fluid activity is clearly demonstrated (e.

g.

[START_REF] Williams | Resetting monazite ages during fluid-related alteration[END_REF][START_REF] Seydoux-Guillaume | Low-temperature alteration of monazite: fluid mediated coupled dissolution-precipitation, irradiation damage, and disturbance of the U-Pb and Th-Pb chronometers[END_REF]

) and was already outlined on metamorphic rocks from the Internal Rif

[START_REF] Montel | Preservation of old U-Th-Pb ages in shielded monazite: example from the Beni Bousera Hercynian kinzigites (Morocco)[END_REF][START_REF] Janots | Evolution of the REE mineralogy in HP-LT metapelites of the Sebtide complex, Rif, Morocco: monazite stability and geochronology[END_REF][START_REF] Michard | Pressure-temperature-time constraints on the Maghrebide mountain building: evidence from the Rif-Betic transect (Morocco, Spain), Algerian correlations, and geodynamic implications[END_REF][START_REF] Negro | Thermal structure of the Alboran Domain in the Rif (northern Morocco) and the Western Betics (southern Spain). Constraints from Raman spectroscopy of carbonaceous material[END_REF][START_REF] Chalouan | The Rif belt[END_REF][START_REF] Rossetti | Timing and modes of granite magmatism in the core of the Alboran Domain (Rif chain, northern Morocco): implications for the Alpine evolution of the western Mediterranean[END_REF][START_REF] Gueydan | Oligo-Miocene thinning of the Beni Bousera peridotites and their Variscan crustal host rocks, Internal Rif, Morocco[END_REF][START_REF] Homonnay | Miocene crustal extension following thrust tectonic in the Lower Sebtides units (internal Rif, Ceuta Peninsula, Spain): implication for the geodynamic evolution of the Alboran domain[END_REF]

and also in the Internal Betic

[START_REF] Acosta-Vigil | Age of anatexis in the crustal footwall of the Ronda peridotites[END_REF]

.

Table 2 .

 2 Results of the U-Th-Pb LA-ICP-MS analysis of monazite and xenotime from the micro-diorite sill SEB12-04

	Apparent ages (Ma)

Pb*radiogenic lead.

Acknowledgements. The field work was supported by the FP7-IRSES-MEDYNA project.


William Derigent

Duncan Mcfarlane

Hind BRIL E L Haouzi

Intelligent Products through a SOHOMA prism

Keywords:

In the framework of the SOHOMA 2020 special session "SOHOMA 10 th -year anniversary", this paper aims to make a review of the evolution of one important concept studied in the SOHOMA community, namely the Intelligent Product concept. This paper is not review of Intelligent Products -there are several of these already -but rather examines the history of the development of this concept through the 1 st to 9 th editions of SOHOMA, while also proposing future developments on this concept.

Introduction

In the framework of the IMS (Intelligent Manufacturing Systems) community, and as demonstrated by the Auto ID Centre developments in 2000-2003, the related concepts of Internet of Things and Intelligent Products sought to connect physical objects with digital information and even "intelligence" associated with the object. Indeed, substantial information distribution improves data accessibility and availability compared to centralized architectures. Product information may be allocated both within fixed databases and/or within the product itself, thus leading to products with informational and/or decisional abilities, referred as "Intelligent Products". This concept has been widely discussed over more than two decades, beginning in 1997when several authors separately presented the notion of product intelligence to describe an alternative, product-oriented way in which supply chains and automated manufacturing might work (see [START_REF] Wong | The Intelligent Product Driven Supply Chain[END_REF]- [START_REF] Morel | Special issue on intelligent manufacturing[END_REF]. The models proposed described manufacturing and supply chain operations in which parts, products or orders (collections of products) would monitor and potentially influence their own progress through the industrial supply chain. The supply chain model based around product intelligence provided a conceptual focus for these developments. A very simple search on Google Scholar1 of articles related to this concept reveals that more than 300 papers have been published on the subject since 2000. This number does not include articles related to "intelligent product" design (more related to the mechanical engineering field or the smart "PSS" field). Many different definitions of "Intelligent Products" have been proposed. A comparison of the different types is provided in [START_REF] Mcfarlane | Product intelligence in industrial control: Theory and practice[END_REF]. Reviews also exist [START_REF] Meyer | Intelligent Products: A survey[END_REF].The objective of this paper is not to produce yet another review on Intelligent Products. In the framework of SOHOMA 2020, it rather aims at underlining 1) how the SOHOMA community helped to develop and spread this concept, via scientific proposals and industrial applications, 2) how the SOHOMA community is shaping the future of the intelligent product concept. [START_REF] Mcfarlane | The impact of automatic identification on supply chain operations[END_REF] Methodology applied in this paper SOHOMA contributions related to the domain of the "Intelligent Product" have been analyzed from SOHOMA 11 to SOHOMA 19 via a careful exploration of the proceedings. In our point of view, the concept of Intelligent Product is mainly related to 2 subfields : The first one is the asset management thanks to the Intelligent Products which has been extensively studied, leading to advanced asset management systems, most of the time dedicated to product tracking in logistics. A second important use of the intelligent product concept is the product-driven control of manufacturing systems, where the product is an actor of its future in the manufacturing process. Both aspects are, from our point of view, two important and complementary aspects of the same concept. Both are moreover needed requirements to ensure the resilience of production systems [START_REF] Srinivasan | Identifying the requirements for resilient production control systems[END_REF].

The first step of the methodology is thus to extract relevant papers from the proceedings. Each paper related to one of the previous concepts (or in a session related to the Intelligent Product) was taken into account, and keywords saved. Citation numbers were extracted from Google Scholar. As our objective is to process this extraction via adapted tools, keywords have been 'normalized'. Indeed, there are many keywords that describe identical to very similar concepts (e.g. product-driven control, product-driven automation and product-driven systems). The raw extraction is cleansed and completed before the next step.

The second step aims to define a conceptual map called a co-occurrence network. Co-occurrence networks are generally used to provide a graphic visualization of potential relationships between people, organizations, concepts, biological organisms or other entities represented within written material. The generation and visualization of co-occurrence networks has become practical with the advent of electronically stored text compliant to text mining2 . In this paper, a co-occurrence network based on similar keywords in the extracted papers is produced and analyzed.

The next section first introduces the general co-occurrence network and details the different identified clusters in different subsections. The last part of this section uses the form of this network to foresee a possible future trend in the Intelligent Product field.

3

History of the intelligent product concept in SOHOMA Intelligent products (IP) are present in SOHOMA from the beginning as showed in table1 (presented in the annexes). This table lists per year all the papers extracted from SOHOMA Proceedings, with a total of 49 papers. However, the number of publications is not even through time, as depicted fig. 1 The co-occurrence network based on keywords is done via an automatic processing executed via VOSviewer, a specific software tool dedicated to bibliometrics network. Other tools exist like R and its bibliometrics package, Pajek, Sci2, Cytoscape, etc. VOSviewer has been selected due to its user-friendly interface and its ability to process easily bibliographic databases 3 . This network is presented on fig. 3 where it is clear that these clusters are strongly interrelated yet still have independent threads. It is composed Cluster 6 is far from the others, meaning it is not too interlinked with the other ones. It can thus be interpreted as a relatively new cluster and new research field as well. The annual distribution of IP papers in each cluster is shown fig. 2. It can be seen that, from the beginning, papers have been published on PDS and PLIM themes in the SOHOMA conferences. In this respect, the theme PI within the framework of IP has been addressed later, in 2014. The more recent cluster is the DT one, where papers have been proposed from 2018. In the rest of this section, the different clusters are detailed, focusing on the timeline of the related research works. Only the clusters related to core SOHOMA research fields are tackled. Each reference cited hereafter is coming from SOHOMA conference proceedings.

3.1

Cluster 1: Product-Driven Systems

Product-Driven Systems are defined in [START_REF] Trentesaux | Product-driven control: a state of the art and future trends[END_REF] as a way to optimize the whole product lifecycle by dealing with products, whose informational content is permanently bound to their virtual or material contents and thus are able to influence decisions made about them, participating actively to different control processes in which they are involved throughout their life cycle . They introduce some examples highlighting the way PDS can improve the global product lifecycle performance in the design phase, production phase or use phase. Designing a PDS is a challenge involving three fundamentals aspects: functions, architecture, and interactions.

Intelligent products are the core of a PDS. The functional features given to the intelligent products in the PDS are then essential when designing the PDS. Research works in this area are also intertwined with Cluster 2 and will therefore be described later. The architecture of a PDS in another facet of the PDS design and many research works address this issue. In particular, [START_REF] Dubromelle | Service oriented architecture for holonic isoarchic and multicriteria control[END_REF] present the PROSIS framework, an evolution of PROSA, where the Staff Holon is replaced by a Simulation. In this Isoarchic architecture, Ambient Control Entity (ACE), located near the resource Holon, allows each I_Holon (informational part of a Product Holon) to call ambient services related to decision making or communication. Guided by the idea that all distributed intelligent approaches are mimicking nature and human behavior, several researchers also explored bio-inspiration to build PDS. For example, [START_REF] Herrera | Viable system model approach for holonic product driven manufacturing systems[END_REF] define a control architecture based on the Viable System Model called PDS-VSM exhibiting interesting recursive properties as natural structures like living organisms do.

Bio-inspiration has been also widely used in the framework of the third and last aspect of a PDS, i.e interactions. Several bio-inspired approaches have been proposed in the past, as Ant Colony Optimization and the Firefly Algorithm. [START_REF] Adam | Volatile knowledge to improve the self-adaptation of autonomous shuttles in flexible job shop manufacturing system[END_REF] propose a mechanism inspired from the stigmergy using the notion of volatile knowledge. Mobile products can share with each other information (knowledge) about their environment, whose confidence decrease through time. This mechanism allows to propagate knowledge about perturbations and to return to normal situation in a distributed way without a coordinator. Negotiation approaches are investigated in [START_REF] Mezgebe | A Negotiation Scenario Using an Agent-Based Modelling Approach to Deal with Dynamic Scheduling[END_REF]. They propose a negotiation heuristic based on the notion of critical ratio ((Due_date -current_date) / total shop time remaining). Products are negotiating their schedules with other products by exchanging this value. The collaboration mechanism between Intelligent Products can also be formalized using Multi-criteria Decision Making (MCDM) techniques. In [START_REF] Dubromelle | Service oriented architecture for holonic isoarchic and multicriteria control[END_REF], [START_REF] Zimmermann | Using analytic hierarchical process for scheduling problems based on smart lots and their quality prediction capability[END_REF], the collaboration mechanism is based on the AHP/ANP (Analytic Hierarchy Process / Analytic Network Process).

PDS have pros and cons. They are highly agile and reactive, and they allow for a potentially greater involvement of the end customer. However, they are not widely accepted in industries because of the lack of performance proofs, mainly due to their myopic behavior, allowing them to make decisions locally efficient but inconsistent with the global objective. This nevertheless depends highly on the use case and working conditions. Indeed, performances of a distributed architecture can be as good as with a centralized driving solution as stated in [START_REF] Raileanu | A JADE environment for product driven automation of holonic manufacturing[END_REF]. To help PDS to be less myopic, [START_REF] Cardin | Myopia of service oriented manufacturing systems: Benefits of data centralization with a discrete-event observer[END_REF] illustrates how the centralization of data via a discrete-event observer can help to achieve better decisions. This notions of "discrete-event observer" is an online simulation model running in parallel of the manufacturing system observed. One can note that this notion is not so far from the notion of Digital Twin that arises years later.

Another strategy to counter this myopia is to mix predictive scheduling and reactive control. A state of the art was produced in this respect [START_REF] Cardin | Coupling predictive scheduling and reactive control in manufacturing: State of the art and future challenges[END_REF] and several works of the SOHOMA community address this issue. [START_REF] Gaham | An evolutionary simulationoptimization approach to product-driven manufacturing control[END_REF] propose a PDS employing a scheduling rule-based evolutionary simulation-optimization strategy to dynamically select the most appropriate local decision policies to be used by the products, when disturbances appear. The originality is to choose decision policies (i.e dispatch rules) instead of fixed schedules, allowing more flexibility on the product level. Another problem is to know when to switch from the predictive scheduling to the reactive one, and when to come back. Since the decision is not binary, a fuzzy model of the switching mechanism is used in [START_REF] Li | Fuzzy decision-making method for product holons encountered emergency breakdown in productdriven system: An industrial case[END_REF], [START_REF] Derigent | Application of measurement-based AHP to product-driven system control[END_REF]. A last method proposed by the SOHOMA community in the framework of PDS is to bring some robustness into the scheduling strategies, thanks to operational research works dealing with scheduling under uncertainties [START_REF] Aubry | Product driven systems facing unexpected perturbations: How operational research models and approaches can be useful?[END_REF].

Systems evolve and PDS also do, meaning their architecture, configuration, states can change through time. To react as correctly as possible, a fine understanding of the system evolution is needed. Giving these learning abilities to a PDS is a central challenge in a world where manufacturing systems will constantly change and be reconfigured thanks to Industry 4.0 technologies. It is also the opportunity to transform PDS into Predictive Manufacturing Systems as defined in [START_REF] Babiceanu | Manufacturing operations, internet of things, and big data: Towards predictive manufacturing systems[END_REF]. [START_REF] Thomas | An approach to data mining for product-driven systems[END_REF] state that the synchronization of physical and information flows in a PDS implies that large data volumes may be exploited to create the necessary knowledge and information for product decision-making. The study illustrates how product information can be processed via neural networks to obtain shop-floor knowledge, i.e. a function computing the lead time of a product from the beginning of its manufacturing to the input queue of a bottleneck. This function can then be integrated into the product memory for further uses. [START_REF] Bouazza | A model for manufacturing scheduling optimization through learning intelligent products[END_REF] consider that Intelligent Products should also be able to reuse their past experiences to enhance their decisional performances. Past experiences are then stored and Reinforcement Learning (here a Q-learning algorithm) is then used to select the best action a product may do in each situation.

Some industries are willing to use these techniques and some SOHOMA articles describe applications of PDS via some case studies in the manufacturing industry [START_REF] Zimmermann | A Case Study of Intelligent Manufacturing Control Based on Multiagents System to Deal with Batching and Sequencing on Rework Context[END_REF], [START_REF] Queiroz | An agent-based industrial cyber-physical system deployed in an automobile multi-stage production system[END_REF].

As a conclusion, PDS are advanced manufacturing systems that can lead to a better agility and reactivity, with a better integration of the end customer. SOHOMA explored this area and bring many contributions form the proof of concept to valuable implementations in industry and generic framework architectures (PDS architectures, interactions between products, coupling of centralized and decentralized decision-making, machine learning and so on).

Cluster 2: Product Lifecyle Information Management

The other facet of the Intelligent Product is related to the data. It is a cluster as important as the first one, with many contributions made in this field by the SOHOMA community. A first important research work is the paper of [START_REF] Mcfarlane | Intelligent products in the supply chain-10 years on[END_REF] which retraces the history of the Intelligent Products in the Supply Chain from 2002 to 2012. This paper cites the original definition of the Intelligent Product introduced in [1], [START_REF] Mcfarlane | Auto ID systems and intelligent manufacturing control[END_REF] 5 :

An Intelligent Product is a product (or part or order) that has part or all of the following five characteristics: 1. Possesses a unique identity 2. Is capable of communicating effectively with its environment 3. Can retain or store data about itself 4. Deploys a language to display its features, production requirements etc. 5. Is capable of participating in or making decisions relevant to its own destiny Two levels of product intelligence are commonly defined: IP level 1 regroups features 1 to 3, while IP level 2 covers the 5 features.

The management of product information all along its lifecycle is then referred as Product Lifecycle Information Management (PLIM) and ensured by Product Lifecycle Information Management Systems as detailed in [START_REF] Derigent | Situation Awareness in Product Lifecycle Information Systems[END_REF]. In the 2000s, the classic implementation of the intelligent product reflected the developments being made in the Cambridge AutoID centre. Indeed, a unique ID is stored on a low-cost RFID tag attached to the product. This ID can be resolved to a network pointer to a linked database and a decision-making software agent. This information is then available all along the supply chain or even all along the product lifecycle. Such systems can provide new services in different phases of the lifecycle, obviously in the manufacturing phase or logistic phase, but is not limited to. For example, as described in [START_REF] Cuthbert | Repair services for domestic appliances[END_REF], it could be used to provide new repair services for domestic appliances, by providing appliance lifecycle data and part designs respectively to diagnostic services and 3D printing services.

PLIM systems are basically distributed data management architectures. In this regard, several works and members of the SOHOMA community highly contributed to this field. Different architectures, messaging protocols and formats have been proposed as described in [START_REF] Derigent | End-of-life information sharing for a circular economy: Existing literature and research opportunities[END_REF]. The EPCIS architecture is one of the well-known distributed data management architecture, standardized by GS1 and specially adapted to product tracking in the supply chain [START_REF] Främling | Assessment of EPCIS standard for interoperable tracking in the supply chain[END_REF]. These manufacturing concepts have been also applied in other domains, as described in [START_REF] Ansola | IoT visibility software architecture to provide smart workforce allocation[END_REF], where the EPCIS standard has been applied to workforce management in hospitals, leading to the 'aTurnos' cloud-based solution 6 . DIALOG is another proposed architecture proposed by SOHOMA members, based on a multi-agent system distributed in every actor of a given supply chain. In this architecture, a specific messaging protocol initially called PMI (Product Messaging Interface) and further named QLM (Quantum Lifecycle Management) is used. As EPCIS, QLM is now a standard and is detailed in [START_REF] Kubler | QLM messaging standards: introduction and comparison with existing messaging protocols[END_REF]. This paper also underlines why such messaging standard are needed in Business-to-Business infrastructures and demonstrates via usecases how flexible QLM is, compared to the other existing messaging protocols.

The intelligence and as a result the information of the product can also be on the product itself. According to [START_REF] Sallez | The augmentation concept: How to make a product "active" during its life cycle[END_REF], product intelligence is not a primary function of a product, but comes as secondary functions (i.e. communicating, triggering, memorizing) that can be embedded in the product (also referred as "target system") but also available online. Because the activeness is linked with the target system, the secondary functions follow the product all along its lifecycle from manufacturing to recycling. These functions can be added or removed, moved into the target system or online, depending on the phase requirements [START_REF] Sallez | Proposition of an analysis framework to describe the "activeness" of a product during its life cycle part ii: Method and applications[END_REF]. As a result, several applications of the activeness concern different phases of the lifecycle. For example, the work of [START_REF] Basselot | Active monitoring of a product: A way to solve the "lack of information" issue in the use phase[END_REF] applies the activeness concept during the use phase, in order to give to the products augmented monitoring and analysing functions. It has also been used in the logistic phase and applied to smart containers, as will be described later.

To store the intelligence directly on the product, many different devices can be used, not only RFID, but also micro-computers or wireless sensor nodes. Because these devices have more computing power and memory than classic RFID tags, they can execute all or part of the product secondary functions. In [START_REF] Quintanilla | Evolution of a flexible manufacturing system: From communicating to autonomous product[END_REF], the evolution from communicating products (products equipped with RFID tags) to autonomous products is described. The authors provide a case study of a flexible manufacturing system where products are evolving from IP level 1 to IP level 2. Indeed, transport carriers, originally equipped with RFID tags, receive a miniaturized electronic device composed of a CPU, a RFID reader, some direction actuators, sensor, and a HMI. Works in the communicating materials or Physical Internet detailed after also use Wireless Sensor Nodes (WSNs) to realize the intelligent product concept.

Communicating materials are materials equipped with micro-electronic components, either RFID tags (Kubler, Derigent, Thomas, & Rondeau, 2011) or self-powered WSNs embedded into the material [START_REF] Mekki | Communicating Aircraft Structure for Solving Black-Box Loss on Ocean Crash[END_REF]. The interests of such material are diverse: (a) because of their data storing capacity, they can convey all information related to design, manufacturing and logistics, useful during the BOL (Beginning Of Life -design, manufacturing and construction) and the EOL (End Of Life -dismantlement and recycling) of a product; (b) given their ability to sense their environment and process related information, they can also be used during the MOL (Middle Of Life -exploitation and maintenance) as intelligent sensors, mainly to perform health monitoring. The material could be either wood, textile or concrete. First works dealing with communicating materials are addressing the data dissemination / data replication issues in this type of materials. Lately, the work of [START_REF] Wan | A holonic manufacturing approach applied to communicate concrete: Concept and first development[END_REF] aims to explore the monitoring capability of communicating materials, by developing concrete beams equipped with energy-aware WSNs. Indeed, this concrete beam can monitor its status in nearly real-time.

This last work shows that IP (Communicating materials and so on) can exhibit monitoring functions, and can be aggregated to build a global architecture, monitoring the whole system performances. This is another aspect of the Intelligent Product that has attracted attention in the SOHOMA community. In [START_REF] Taboun | Sink node embedded, multi-agent systems based cluster management in industrial wireless sensor networks[END_REF], a multi-agent system is embedded into wireless nodes, to manage a wireless data acquisition platform applied on industrial systems. In this architecture, each sink node manages a cluster of wireless sensors. Each sink node contains three interacting agents respectively responsible for configuring/reconfiguring the cluster, aggregating/filtering data and communicating with the previous agents/other sink nodes. This wireless architecture is illustrated on an oil and gas refinery. [START_REF] Trentesaux | Data Management Architectures for the Improvement of the Availability and Maintainability of a Fleet of Complex Transportation Systems: A State-of-the-Art Review[END_REF] deal with the development of data management systems for fleet of trains, able to gather, memorize, manipulate and communicate data coming from equipments. They demonstrate the interest of holonic semi-heterarchical architectures where each Holon is a product composing the whole system. From this conclusion, they develop the Surfer Data Management Architecture and apply it to train transportation [START_REF] Trentesaux | Foundation of the Surfer Data Management Architecture and its application to train transportation[END_REF]. In the same vein, distributed monitoring is explored in [START_REF] Morariu | Resource, service and product: Realtime monitoring solution for service oriented holonic manufacturing systems[END_REF]. The target system is a manufacturing shop floor, where each component of a system (resource of product) is linked to a monitoring agent. These agents then send monitoring data via a monitoring data stream, which are read, aggregated, and stored by a monitoring controller agent. Monitoring controller agent can also send their data via the monitoring data stream, and its data may be aggregated by another monitoring controller agent. This way to proceed is equivalent to previous architectures and highly scalable.

In SOHOMA community, these works on PLIM have been applied in manufacturing, supply chain [START_REF] Tsamis | Adaptive storage location assignment for warehouses using intelligent products[END_REF], but also in the agriculture and agri-food domain [START_REF] Cojocaru | Farm management information system as ontological level in a digital business ecosystem[END_REF], in the pharmaceutical [START_REF] Răileanu | Centralized HMES with environment adaptation for production of radiopharmaceuticals[END_REF] and building sectors [START_REF] Pǎtraşcu | Integrating agents and services for control and monitoring: Managing emergencies in smart buildings[END_REF], [START_REF] Thomson | Improving the delivery of a building[END_REF]. Finally, Information systems dealing with intelligent products have been proposed in SOHOMA with a specific importance given to the distribution of information on the product/on the network. EPCIS, DIALOG, the activeness concept or the communicating materials are among the main contributions presented in SOHOMA conferences.

Cluster 3: Physical Internet

The Physical Internet has been proposed in [START_REF] Montreuil | Toward a Physical Internet: meeting the global logistics sustainability grand challenge[END_REF] and formally defined as an open global logistics system leveraging interconnected supply networks through a standard set of modular containers, collaborative protocols and interfaces for increased efficiency and sustainability. The Physical Internet is present from the beginning of SOHOMA. First works on this theme can be found in 2011 [START_REF] Ballot | Physical internet enabled open hub network design for distributed networked operations[END_REF], where the new paradigm is introduced. and propose a bio-inspired method to build the Open Hub Network is proposed.

A first interesting finding is that concepts of Physical Internet and Intelligent Product are not merged at the beginning, at least in works presented in SOHOMA. The first time both concepts are found merged in SOHOMA works is in [START_REF] Sallez | On the activeness of physical internet containers[END_REF], with the main idea to realize the notion of PI-Container (smart container used in the Physical Internet Paradigm) via the application of the activeness concept to a normal container. The article describes the concept of PI-Container activeness and detail the different needed information and interaction possibilities a "active" PI-Container should include. A later paper [START_REF] Rahimi | Framework for smart containers in the physical internet[END_REF] goes deeper into this concept and propose a guide to represent and analyze collectives of PI-Containers and their inner interactions. Indeed, a simple PI-Container can be assembled with other PI-Containers to form a Composite one. Going further into the study of PI-container, [START_REF] Krommenacker | On the usage of wireless sensor networks to facilitate composition/decomposition of physical internet containers[END_REF] address the problem of composition/decomposition of PI-Containers. In their approach, they consider the PI-Container as a normal container equipped with a wireless sensor node. A Collective of PI-Containers is then equivalent to a wireless sensor network and can identify its real composition from information collected on the network. This information combined with an optimization process leads to a 3D map of the containers composing the collective, called a VoC (Virtualization of Container).

A second interesting finding is that concepts from the PDS cluster have also been applied to the Physical Internet. For example, the PROSIS architecture detailed previously is first applied in an intralogistics context in [START_REF] Pujo | Wireless holons network for intralogistics service[END_REF]. In this work, authors introduce the concept of Wireless Holons Network, constituted by mobile Holons (shuttles, moving products) and fixed Holons (workstations). Mobile Holon are the one equipped with a WSN mote. As in the classic PROSIS approach, ACEs (Ambient Control Entities) placed on the workstations can provide ambient services to the mobile Holons. Following this first proposal, [START_REF] Pujo | Wireless holons network for intralogistics service[END_REF], [START_REF] Pujo | Cyber-Physical Logistics System for Physical Internet[END_REF] address more directly the Physical Internet and propose an adaptation of the PROSIS framework to this domain.

As a conclusion, SOHOMA contributions to the Physical Internet relate to the introduction of the Intelligent Product to the Physical Internet: proposals described in the other clusters as the activeness concept or PDS architectures like PROSIS have been applied promisingly to this new field. The Intelligent Product introduction is helping to give the Physical Internet an orientation towards supporting customization as well as greater efficiencies in the supply chain.

3.4

Cluster 6: Towards Digital Twins at the core -One of the future trends?

Among all the clusters of interest, cluster 6 is the smallest in terms of number of papers. This cluster regroups keywords related to the virtual representation of the product and especially the keyword "Digital Twin", that has emerged recently in the manufacturing community (thus explaining the size of the cluster). Indeed, The Digital Twin is a new paradigm in simulation and modelling, defined by [START_REF] Glaessgen | The digital twin paradigm for future NASA and US Air Force vehicles[END_REF] 7 as "an integrated multi-physics, multi-scale, probabilistic simulation of a complex product [using] the best available physical models, sensor updates, etc., to mirror the life of its corresponding twin".

Moreover, as can be seen fig. 3, this cluster is the farthest from the others. It means that it has the least connection with the other clusters for the moment, in the IP community. It can be interpreted as a new field of research, interesting for IP community. However, Digital Twin has a wider spectrum than the IP community, and many other SOHOMA works and sessions have already addressed this field.

In [START_REF] Valckenaers | ARTI reference architecture -PROSA revisited[END_REF], the author discusses the history of PROSA and presents its evolution named ARTI -Activity Resource Type Instance. ARTI makes a strong separation between the Intelligent Agents and Intelligent Beings, emphasizing the fact that the Intelligent Beings are describing what is more than what is decided. In the framework of Industry 4.0, the reality of these intelligent beings could be represented by Digital Twins, which then become the unique "contact persons" to access the world-of-interest. The notion of Digital Twin thus becomes crucial generally for HMS (Holonic Manufacturing System) but also for PDS. One of the first exploration of the connection between ARTI and Digital Twin reported in SOHOMA is the work of [START_REF] Borangiu | Embedded digital twin for ARTI-type control of semi-continuous production processes[END_REF] in the context of semi-continuous production processes In authors propose a dynamic adaptation process of M-BOMs (manufacturing bill of materials) based on BIM Building Information Modeling (BIM) and CPS assets in building sector. The use of BIM assets and real time follow-up based on CPS paradigm could be a source of valuable data to support the planning and monitoring activities throughout building life cycle and pave the way of the introduction the digital twin as core system for those activities.

Digital Twin also begins to play a role in smart asset management, as underlined by [START_REF] Lu | From BIM towards digital twin: Strategy and future development for smart asset management[END_REF]. The authors propose a framework for future development of smart asset management during the operations and maintenance phase., integrating the concept of Digital Twin. They argue that the future framework should be divided into three layers (smart asset layer, smart asset integration layer, smart DT-enabled asset management layer). Compared to "old" PLIM systems, it appears a need to store and manage the lifecycle not only of data and information, but also of simulation models like the DTs, that should be easily connected to real-life data. This research theme is still new in SOHOMA but merging DT and IP is already stressed by SOHOMA papers as a future interesting field. SOHOMA contributed to this merge by proposing adapted control and information management architectures.

Conclusions

During the past 20 years, a lot of different works have been done in the world of Intelligent Products and in particular, over the last 10 years systems based around the Intelligent Product concept have undoubtedly found a home in the SOHOMA series of workshops. This paper has retraced the evolution of connected topics that have been gravitating around the IP concept for decades through the lens of SOHOMA, and this accurately reflects the fact that Intelligent Products are a broad concept rather than a specific industrial solution. This study also lists the number of IP related papers produced in the SOHOMA conferences (around 50). It demonstrated that, for ten years, this notion has been a rich concept for SOHOMA, as well in production control than in data management. The SOHOMA community has participated to this scientific adventure, evidenced by the important ratio of papers dedicated to this theme, even if less important these last years.

SOHOMA members have contributed to Intelligent Product research in a number of different areas (referred to as clusters in this paper). Three main clusters have been identified, as more representative contributions, thanks to a bibliography analysis: Product-Driven Systems, Product Lifecycle Information Systems and Physical Internet For each cluster, a synthesis of the works done by the community has been provided. One last and smallest cluster is perhaps related to one of the future trends of IP -namely the rapid take up in recent times of digital twins. This concept can be seen as encompassing as that it extends the perimeter of the intelligent product to intelligent "everything" and push for the emergence of new methods (for eamplex data sciences) and new requirements of real time, observation, data ming…In addition to these clusters we have observed a number of common methods and tools being used in the development of intelligent product based approaches: multi agent systems, traceability approaches and the development and deployment of embedded devices.

In the past, the advent of technologies as RFID tags and WSN helped to concretize the IP concept. In the future, the envisaged development of tools and methods associated with Industry 4.0, the development of infrastructure for IoT, human-object integration in industrial operations and the development of increasingly autonomous capabilities in industrial systems will certainly provide a fantastic playground for this concept, which will still evolve thanks to the never-ending work of passioned researchers.

  , going from 2 (SOHOMA 2017) to 8 (SOHOMA 2014). The proportion of these papers above the total number of SOHOMA papers goes from 24% in 2011 to 28% in 2014 and then goes down to 11% in 2019. Each paper in this field has been cited ~6 times, going up to 29 times for [8]. In the different proceedings, three parts are specifically dedicated to the IP (SOHOMA 2012 -Part II 'Intelligent Products'; SOHOMA 2013 -Part IV 'Intelligent Products'; SOHOMA 2015 -Part I 'Application of Intelligent Products') and two parts contains works related to the IP (SOHOMA 2014 -Part IV 'Physical Internet Containers; SOHOMA 2015 -Part II 'Recent Advances in Control for Physical Internet and Interconnected Logistics').

Fig. 1 .

 1 Fig. 1. Overview of the number of SOHOMA Papers on Intelligent Products

  of nodes representing the different paper keywords, and links representing relations between these nodes. The shorter the links, the more the keywords are used in the same papers. It is then possible to define clusters of keywords, based on their co-occurrence distance. In this paper, these clusters are interpreted as domains or categories in the IP research field. The network thus shows a total of 6 clusters:  Cluster 1: Product-Driven Systems (PDS) 4  Cluster 2: Product Lifecycle Information Management (PLIM)  Cluster 3: Physical Internet (PI)  Cluster 4: Multi-Agent Systems (MAS)  Cluster 5: Internet of Things (IoT)  Cluster 6: Digital Twin (DT) One first analysis would be on the type of the different clusters. Indeed, clusters 1 to 3 are related to research works originated from works in the IP field while clusters 4 to 5 are more related to theory, methods and tools used to realize the IP concept.

Fig. 2 .Fig. 3 .

 23 Fig. 2. Annual distribution of IP papers in each cluster

www.scholar.google.fr / search: allintitle: "intelligent products" OR "intelligent product"

https://en.wikipedia.org/wiki/Co-occurrence_network

Note that the complete list of references in *.bibtex/*.ris format as well as the VOSviewer files have been provided as supplementary material with the article submission.

These two citations are not extracted from SOHOMA proceedings.

https://www.aturnos.com/

This citation is not issued from SOHOMA proceedings.