Mariette Lisbonne

Séverine Diem

Alexandre De

Castro Keller

Jean Lefort

Luiza M Araujo

Patricia Hachem

Jean-Marie Fourneau

Stéphane Sidobre

Mitchell Kronenberg

Masuru Taniguchi

Alexandre De Castro Keller

Michel Dy

Philip Askenase #

Momtchilo Russo

B Boris Vargaftig

André Herbelin

Maria C Leite-De-Moraes
email: leite.de.moraes@necker.fr

Cutting Edge: Invariant Vα14 NKT Cells Are Required for Allergen-Induced Airway Inflammation and Hyperreactivity in an Experimental Asthma Model

Keywords: NKT cells, IL-4, Th2 lymphocytes, airway inflammation

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Allergic asthma is a chronic inflammatory disease which is increasing throughout the Western World. This airway inflammation is associated with a predominant Th2 response generating eosinophilia increased mucus production in the lung and airway hyperresponsiveness, and specific IgE antibody synthesis [START_REF] Wills-Karp | Immunologic basis of antigen-induced airway hyperresponsiveness[END_REF][START_REF] Umetsu | Asthma: an epidemic of dysregulated immunity[END_REF]. The production of Th2 cytokines, such as IL-4 and IL-5, is considered pivotal for the recruitment of eosinophils to the airways and for AHR which are characteristic of asthma. Adoptive transfer of effector Th2 cells into naive mice followed by exposure to inhaled antigens triggers eosinophilic inflammation, mucus hypersecretion and airway hyperresponsiveness, definitively demonstrating the capacity of immune Th2 cells to induce the asthma phenotype [START_REF] Cohn | Induction of airway mucus production By T helper 2 (Th2) cells: a critical role for interleukin 4 in cell recruitment but not mucus production[END_REF]. It is generally held that rapid generation of IL-4 supports the crucial antigenspecific Th2 cell differentiation. The exact source of this required IL-4 is not known, but besides Th2 cells themselves, cells like mast cells, basophils, g/d T cells and Natural Killer (NK) T lymphocytes are thought to be contributors to Th2 immune responses.

NKT cells, are a distinct subset of lymphocytes with NK markers and ab TCR, that regulate immune responses in several models of autoimmunity, infection and cancer [START_REF] Lisbonne | Invariant Va14 NKT lymphocytes: a doubleedged immuno-regulatory T cell population[END_REF]. They are selected and are restricted by the nonpolymorphic MHC class-I-like molecule CD1d and express an invariant Va14-Ja18 TCR chain [START_REF] Lisbonne | Invariant Va14 NKT lymphocytes: a doubleedged immuno-regulatory T cell population[END_REF][START_REF] Kawano | CD1d-restricted and TCR-mediated activation of valpha14 NKT cells by glycosylceramides[END_REF]. Since the stimulation of their TCR by glycolipid ligands, such as exogenous a-galactosylceramide (a-GalCer) presented in the context of CD1d molecules, promptly induces secretion of high concentrations of IL-4 [START_REF] Leite-De-Moraes | IL-4-producing NK T cells are biased towards IFN-gamma production by IL-12. Influence of the microenvironment on the functional capacities of NK T cells[END_REF], it has been proposed that they may participate in the differentiation of Th2 cells. Indeed, a-GalCer-stimulated NKT lymphocytes, in some cases, promote a protective Th2 immune response [START_REF] Singh | Cutting edge: activation of NK T cells by CD1d and alphagalactosylceramide directs conventional T cells to the acquisition of a Th2 phenotype[END_REF][START_REF] Miyamoto | A synthetic glycolipid prevents autoimmune encephalomyelitis by inducing TH2 bias of natural killer T cells[END_REF]. However, even though Th2 differentiation can be accomplished normally in NKT cell-deficient mice [START_REF] Chen | Impaired NK1+ T cell development and early IL-4 production in CD1-deficient mice[END_REF][START_REF] Smiley | Immunoglobulin E production in the absence of interleukin-4-secreting CD1-dependent cells[END_REF], it cannot be excluded that NKT cells influence the development of some immune responses involving Th2 cells.

In the present study, we demonstrate that the invariant Va14 (iVa14) NKT cell subset is required for airway eosinophilia, hyperresponsiveness, Th2 cytokine production, and elevated levels of IgE antibodies, in an experimental model of allergic asthma.

Materials and Methods

Mice.

Six-to eight-week-old male C57BL/6 wild type and Ja18 -/-(backcrossed at least 10 times in C57BL/6) (11) mice were bred in our own facilities. All mice were kept in well-controlled animal housing facilities and had free access to tap water and pellet food throughout the experimental period.

Antigen Immunization and Airway Challenge.

At one weekly intervals, animals were immunized by an intraperitoneal (day 0) and a subcutaneous (day 7) injection with 4 µg OVA (ICN Biomedicals, Inc, Ohio) adsorbed on 1.6 mg of aluminium hydroxide gel (Merck, Darmstadt, Germany) in 0.4 mL of sterile saline. Beginning on day 14 following the initial immunization, mice were anesthetized with ketamine anesthesia (Imalgene 1000, 35 mg/kg, Merial, Lyon, France) and airway challenged twice (days 14 and 21) intranasally with 10 µg of OVA in 50 µL of saline. Control mice received only saline at these times.

Twenty-four hours after the last intranasal challenge (day 22), each group consisting of 6 -20 mice was analyzed for eosinophil infiltration, airway hyperresponsiveness, cytokine levels and antibody production.

In some experiments, at one weekly intervals, animals were immunized by three intraperitoneal injections (days 0, 7 and 14) with 10 µg OVA adsorbed on 1.6 mg of aluminium hydroxide gel in 0.4 mL of sterile saline. Sera were collected on day 15 and storaged for IgE measurement.

Adoptive transfer.

Spleen cells from WT or Ja18 -/-mice were depleted of CD8 + T cells, CD62L + , and CD19 + B cells labeled with the corresponding mAbs with anti-rat immunoglobulin-coated magnetic beads (Dynal, Compiègne, France). Among the mAbs used for cell depletion CD8 (clone 53.67) and CD62L (clone Mel14) were purified in our laboratory while the anti-CD19 (clone 1D3) was purchased from BD-PharMingen(San Diego, CA). The enriched negative selected NKT spleen cell population (containing 10 5 iVa14 NKT cells, as assessed by CD1d/a-GalCer tetramers staining), as well as a negative control (equivalent numbers of similarly depleted spleen cells from Ja18 -/-mice) were injected i.v. into Ja18 -/-mice that had been immunized twice with OVA.

Blocking of NKT/CD1d cell interaction in vivo.

In some experiments, in addition to OVA immunization and challenge (as described above), separate groups of mice were also treated i.p. with 0.15 mg of blocking rat anti-CD1d mAb (clone 20H2) or control rat IgG (Sigma-Aldrich, Stonheim, Germany) per mouse on days -1, 0, +2, +6, +7, +9, +13, +14, +16, +20 and +21. No differences in the percentage of iVa14 NKTsplenocytes were observed following anti-CD1d or Ig treatment on day 22 when mice were sacrificed (data not shown).

Determination of Airway Hyperresponsiveness (AHR).

Airway responsiveness was assessed as previously described [START_REF] Russo | Suppression of asthma-like responses in different mouse strains by oral tolerance[END_REF]. Briefly, 24 h after the last challenge, conscious mice were placed into a plethysmograph chamber (Buxco Eletronics, Sharon,

Bronchoalveolar Lavage Fluid (BALF)

Immediately after assessment of AHR, mice were deeply anesthetized by i.p. injection of urethane (15 mg / 10 g body wt) (Sigma-Aldrich), blood collected and resulting serum stored.

Airways were washed twice with saline, and the BALF cell differential counts and percentages determined by Diff-Quik (Baxter-Dale AG, Dudingen, Germany) staining of cytospin slides. Two hundred cells per slide were counted. Aliquots of BALF were stored for cytokine measurement.

Determination of cytokines in BALF and of serial OVA-specific IgE

The levels of IL-4, IL-5, IL-13 and interferon (IFN)-g in BALF and OVA-specific IgE serum levels were assessed by ELISA as previously described (6, 12) OVA-specific IgE levels of 6 samples were related to an internal standard from pooled sera of hyperimmunized BALB/c mice.

Data were expressed as IgE index calculated as follows: IgE index = [OD sample -OD buffer only]/[OD positive control -OD buffer only].

Flow cytometric analysis.

Kinetic analysis of NKT cell activation after exposure to OVA was performed. In brief, 24 h after immunizations and/ or intranasal challenges, mice were sacrificed, splenocytes recovered and stained for 30 min in PBS containing 2% FCS and 0.01 M sodium azide and mCD1d-a-GalCer tetramer-APC. Tetramers were prepared in our laboratory from mCD1d/mß2m expression vector [START_REF] Matsuda | Tracking the response of natural killer T cells to a glycolipid antigen using CD1d tetramers[END_REF]. Cells were then incubated with appropriate dilutions of anti-CD4 PerCP-Cy-5.5 (clone RM4-5), anti-TCRab-FITC (clone H57-597) and anti-CD69-PE (H1.2F3), all purchased from PharMingen. Dead cells were excluded on the basis of forward and side scatter. At least 5x 10 5 live lymphoid cells were acquired in each run. Samples were analyzed on a FACScalibur (Becton Dickinson) using CellQuest software.

Statistical Analysis.

Nonparametric Mann-Whitney test was used to calculate significance levels for all measurements. p < 0.05 was considered statistically significant.

Results

Airway hyperreactivity and eosinophilic inflammation is reduced in Ja18 -/-mice.

A marked feature in this model of allergen-induced asthma is airway hyperreactivity (AHR) and massive airway inflammation observed following OVA-challenge. Our findings clearly demonstrate that OVA-sensitized and -challenged Ja18 -/-mice developed decreased AHR after methacholine inhalation as compared to OVA-sensitized and -challenged control mice (Fig. 1), implicating iVa14 NKT cells in AHR. The total cell number in BALF of Ja18 -/-mice following two intranasal OVA challenges was decreased by 42% compared to WT mice (Fig. 2A). The percentage of eosinophils, which account for the majority of cells in BALF from OVA-challenged mice (up to 65 %), was decreased by 58% in iVa14 NKT cell-deficient animals (Fig. 2B). Both macrophages and neutrophils also were reduced accounting for the overall decrease (2.6 ± 0.2 x 10 5 ± 0.2 vs. 1.7 ± 0.2 x 10 5 macrophages/ml and 2.2 ± 0.6 x 10 5 vs. 1.1 ± 0.1 x 10 5 neutrophils/ml in OVA-challenged WT vs. Ja18 -/-mice, respectively). Conversely, lymphocyte recruitment in BALF was not modified 7 ± 2 x 10 3 vs. 4.7 ± 2 x 10 3 lymphocytes/ml in OVA-challenged WT and Ja18 -/-mice, respectively). Among these lymphocytes, iVa14 NKT cells were also recruited to the lung of OVA-treated WT mice as assessed by RT-PCR analysis (data not shown).

Both IL-4 and IL-5 production are impaired in bronchoalveolar lavage fluid (BALF) of immunized Ja18 -/-mice.

IL-4 and IL-5 levels were markedly reduced in bronchoalveolar lavage fluid (BALF) collected 24 h after challenge from NKT cell-deficient mice as comparedto WT littermates (Fig. 2C and D). Impaired IL-5 production in response to OVA challenge was also observed in the serum of Ja18 -/-mice (Fig. 2E), showing a systemic defect in the production of this cytokine in the absence of NKT cells. IL-4 levels in the serum were below detection limits (< 10 pg/ml).

OVA-specific IgE secretion is markedly decreased in Ja18 -/-mice.

To assess the peripheral response to immunization and subsequent allergen challenge, we measured OVA-specific IgE levels in the sera using ELISA. OVA-immunized and challenged Ja18 - /-mice had one eighth (12.3 ± 9.7%) OVA-specific IgE compared to wild-type (WT) littermates, indicating that IgE production was severely affected (Fig. 2F). The failure to produce high levels of anti-OVA IgE was not due to the inability of of Ja18 -/-mice to produce this isotype, because in response to three OVA immunizations but without intranasal challenges they did effectively produce anti-OVA IgE (0.83 ± 0.10 and anti-OVA IgE titer for Ja18 -/-and 1.53 ± 0.22 for WT mice

).

Adoptive transfer of iVa14 NKT cells restores AHR development, airway eosinophilia as well

as IL-4, IL-5 and IgE production in Ja18 -/-mice.

To confirm the implication of iVa14 NKT cells in the severity of allergic asthma, we reconstituted OVA-sensitized Ja18 -/-mice with iVa14 NKT lymphocytes 24h before the first OVA airway challenge. Adoptive transfer of iVa14 NKT cells, but not of spleen cells from Ja18 -/-mice, fully restored the capacity of Ja18 -/-mice to develop AHR (Fig. 3A). Moreover, airway eosinophilia (Fig. 3B), both IL-4 (Fig. 3C) and IL-5 (Fig. 3D) production in the BALF as well as specific anti-OVA IgE (Fig. 3E) in the serum of OVA-sensitized and -challenged Ja18 -/-mice were restored by the adoptive transfer of iVa14 NKT cells.

iVa14 NKT cells are activated in OVA-treated mice.

We evaluated furthermore whether iVa14 NKT lymphocytes were activated during OVAinduced allergic asthma, as assessed by expression of the early activation marker CD69. Indeed, CD69 expression was up regulated on tetramer CD1d/a-GalCer + TCRab + splenocytes from OVAimmunized and -challenged mice on day 21 compared with those immunized with OVA but challenged with NaCl (Fig. 4A), demonstrating the activation of these cells following the OVA treatments. Similar results were obtained on day 14 after the first OVA challenge (data not shown).

iVa14 NKT cells mediate Th2 allergen-induced airway inflammation in a CD1d-dependent manner.

We have previously reported that NKT activation of iVa14 + NKT cells does not necessarily occur in a CD1d-dependent manner, but can also be induced by the pro-inflammatory cytokines IL-12 and IL-18 [START_REF] Leite-De-Moraes | A distinct IL-18-induced pathway to fully activate NK T lymphocytes independently from TCR engagement[END_REF]. To evaluate possible CD1d involvement in NKT cell participation in Th2 asthmatic responses, WT mice were treated with blocking anti-CD1d mAb, or with control rat IgG at several time points during OVA immunization and challenge. Figure 4B clearly shows that anti-CD1d treatment prevents the characteristic eosinophil recruitment to BALF observed after OVA challenge. Similarly, the secretion of both IL-4 (Fig. 4C) and IL-5 (Fig. 4D) levels in the BALF and of specific serum anti-OVA IgE antibodies (Fig. 4E) were diminished when CD1d-dependent interactions were blocked.

Discussion

Our experiments with Ja18 -/-mice clearly show that iVa14 NKT lymphocytes are required for the characteristic features of experimental allergic asthma, namely airway inflammation, BALF Th2 cytokine production and the secretion of high levels of specific anti-OVA IgE,that will ultimely induce AHR.

The failure of Ja18 -/-mice to develop the typical Th2 inflammation, AHR and IgE responses following OVA airway challenge is not due to a deficiency in Th2 responsiveness since these mice produce high levels of IgE in another protocol using three systemic immunizations with 2.5 higher doses of OVA. These data concur with previous reports showing that Ja18 -/-mice are not defective in IgE production [START_REF] Cui | Inhibition of T helper cell type 2 cell differentiation and immunoglobulin E response by lingand-activated Va14 natural killer T cells[END_REF]. Here, we used a protocol where all mice were similarly immunized with OVA and alum, and airway OVA challenge resulting in Th2 inflammation and AHR. Because we found that iVa14 NKT cells are present in the lung of OVA-challenged mice, it is possible that they are involved during challenge rather than necessarily during priming.

According to this postulate, we adoptively transferred WT iVa14 NKT cells just before OVA challenge, and then sufficed to restore the capacity of Ja18 -/-mice to fully develop airway eosinophilia, AHR, BALF cytokine and anti-OVA IgE production.

Our results differ from those of a previous study using another type of NKT cell-deficient mice, lacking CD1d molecules [START_REF] Korsgren | Natural killer cells determine development of allergen-induced eosinophilic airway inflammation in mice[END_REF], which demonstrated that allergen-specific IgE levels and eosinophilia were not different from those observed in WT mice. Discrepancies observed may be explained by the different experimental protocols (two versus multiple challenges, timing of mice sacrifice) as well as the genetic background of the mutant mice (129/Sv X C57BL/6 for CD1d -/-and C57BL/6 for Ja18 -/-mice). It is unlikely that the genotype (CD1d -/-versus Ja18 -/-mice ) is responsible for these differences since CD1d -/-mice (backcrossed with C57BL/6) and Ja18 -/-mice were similarly deficient in response to our protocol of immunization and challenge (data not shown). Moreover, in agreement with our results, it has recently been reported that both CD1d -/- and Ja18 -/-mice, backcrossed with BALB/c, develop neither AHR nor airway eosinophilia, Th2 cytokine production and high levels of IgE following OVA challenge [START_REF] Akbari | Essential role of NKT cells producing IL-4 and IL-13 in the development of allergen-induced airway hyperreactivity[END_REF]. Taken together, these results clearly demonstrate the requirement of iVa14 NKT cells in allergen-induced asthma.

Additionally, our findings show that iVa14NKT cells are present in lungs of OVA-treated mice, that they are systemically activated (up-regulation of CD69), and that their implication in this model is mediated through CD1d interactions. We and others have already demonstrated that NKT cells stimulated with a-GalCer favor Th2 or Th1 protective immune responses in experimental autoimmune diseases or tumors, respectively (4). In contrast, the present study underscores the capacity of activated iVa14 NKT cells to mediate a pathological Th2 allergy immune response in asthma. It is probable that this activation involves recognition of endogenous antigens associated with CD1d molecules, because OVA itself was unable to stimulate NKT cells neither from naïve nor from OVA-treated mice (day 22) (data not shown). Endogenous antigens capable of stimulating iVa14 NKT cells remain to be determined, but it has been suggested that the self-antigens, presumably glycolipids, that bind CD1d and together are recognized by Va14 + TCR of these cells.

In conclusion, we have demonstrated that iVa14 NKT cells mediate Th2 eosinophil airway inflammation and AHR in an allergen-induced asthma model. Thus, NKT cells may mediate or amplify the pathogenic Th2 inflammatory response and crucial airway hyperreactivity in allergic asthma, suggesting that depletion or blockade of NKT cells might be a possible option for the treatment of this disease.

Legends to Figures

  CT), and respiratory parameters were measured after 10 min of aerosol 150mM Methacholine administration (Sigma-Aldrich), delivered for 60 s. Airflow obstruction was expressed as enhanced pause (Penh), calculated as: Penh = [Te (expiratory time)/ Tr (relaxation time)]-1 x [Pef (peak expiratory flow)/ Pif (peak inspiratory flow)]. The values of Penh expressed per minute were averaged from three determinations recorded every 20 s.

Figure 1 .

 1 Figure 1. Decreased AHR development in Ja18 -/-mice.Airway reactivity to methacholine was measured one day after the last challenge with OVA (empty circles and squares) or NaCl (filled circles and squares) in bothWT (squares) and Ja18 -/- (circles) mice . Data represent the mean ± SEM enhanced pause (Penh) values from 6 to 20 mice.

Figure 2 .

 2 Figure 2. Marked decrease in specific airway eosinophilia, IL-4, IL-5 and anti-OVA IgE production in OVA-challenged Ja18 -/-mice. Total (A) and eosinophil cell counts (B) were determined in the BALF of Ja18 -/-and wildtype mice 24 h after the second NaCl or OVA challenge on day 22. Levels of IL-4 (C) and IL-5 (D) in BALF as well as IL-5 (E) and specific anti-OVA IgE antibodies (F) in serum were also measured 24 h after the second NaCl or OVA challenge.Data are means ± SEM from 6 to 20 mice per group. * p< 0.05, ** p< 0.01.

Figure 3 .

 3 Figure 3. Decreased AHR development, eosinophilia as well as IL-4, IL-5 and anti-OVA IgE production in Ja18 -/-mice are restored by adoptive transfer of NKT cells prior to challenge.Groups of OVA-immunized and challenged Ja18 -/-mice were adoptively transferred with enriched CD1d/a-GalCer tetramer positive splenocytes. Control Ja18 -/-mice were adoptively transfered with splenocytes from Ja18 -/-animals. A. Airway reactivity to methacholine was measured one day after the last challenge with OVA or NaCl in bothWT (squares) and Ja18 -/- (triangles) mice. Enriched CD1d/a-GalCer tetramer positive splenocytes (filled triangles) were adoptively transferred into OVA-immunized and challenged Ja18 -/-mice. Control Ja18 -/-mice were adoptively transfered with splenocytes obtained from Ja18 -/-animals (empty triangles ). Data represent the mean ± SEM enhanced pause (Penh) values from 5 to 10 mice. B to E. Twenty-four hours after the last OVA challenge, airway Eosinophil (B) numbers were evaluated and both IL-4 (C) and IL-5 (D) were measured in BALF. Serum levels of OVA-specific IgE (E) were determined by ELISA. Results represent means ± SEM from 5 to 10 mice. *p<0.05.

Figure 4 .

 4 Figure 4. OVA-immunization and -challenge activates iVa14 NKT cells, while anti-CD1d mAb treatment diminishes airway eosinophilic recruitment, Th2 cytokine levels and OVAspecific IgE production. A. Representative FACS profiles showing up regulation of CD69 expression on gated invariant Va14 CD1d/a-GalCer + TCRab + splenocytes recovered 24 h after the last OVA or NaCl challenge. B to E. Groups of C57BL/6 mice were treated with anti-CD1d mAb or control rat IgG (See Methods) and immunized with OVA and challenged with OVA or NaCl. 24 hours later, serum and BALF were collected. Eosinophil numbers (B) and both IL-4 (C) and IL-5 (D) were measured in BALF while OVA-specific IgE (E) were determined in the serum. Results represent means ± SEM from 5 to 10 mice. *p<0.05, **p<0.01.

  Figure 1

Acknowledgments

We are grateful to Dr. E. Schneider (CNRS FRE 2444, Paris) for helpful discussions and critical comments and E. Bardel for techinical assistance. We are especially indebted to Pharmaceutical Research Laboratory, Kirin Brewery Co., Ltd., for providing a-GalCer and to Dr Albert Bendelac (Princeton University, Princeton, NJ, USA) for the gift of 20H2 hybridoma.

Footnotes

This work was supported by institute funds from the CNRS, Université René Descartes -Paris V and Association pour la Recherche sur le Cancer (ARC) (4661).

Abbreviations

BALF: Bronchoalveolar Lavage Fluid; OVA: ovalbumin.


Mathieu ; Rodriguez

Davide ; Geoazur Nercessian

; Sakellariou

; Gorini

; Janin

D ' Acremont

; Lepourhiet

; Chamot- 4 Rooke

; Tsampouraki-Kraounaki

; Morfis

; Rousakis

; Henry

; Lurin

M Delescluse

; Briole

; Rigo

; Arsenikos

; Bulois

; Fernández-Blanco

; Beniest

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Evolution of the North Anatolian Fault from a diffuse to a localized shear zone in the North Aegean Sea during the Plio-Pleistocene

Keywords: Transform faults < TECTONOPHYSICS, Submarine tectonics and volcanism < TECTONOPHYSICS, Continental tectonics: strike-slip and transform < TECTONOPHYSICS Continental tectonics: strike-slip and transform, Transform faults, Normal faulting, 45 Tectonics and landscape evolution, Europe, Crustal imaging. 46 47 1-

published or not. The documents may come

Evolution of the North Anatolian Fault from a diffuse to a localized shear zone in the North Aegean Sea during the Plio-Pleistocene 57 Field studies reveal that continental transforms initiate as several hundreds of kilometers-wide 58 distributed areas of deformation, forming a shear zone that is composed of scattered oblique en-échelon 59 strands [START_REF] Tchalenko | Structural Analysis of the Dasht-e Bayaz (Iran) Earthquake 1043 Fractures[END_REF]Sengör et al., 2005;[START_REF] Wesnousky | The San Andreas and Walker Lane fault systems, western North America: 1059 transpression, transtension, cumulative slip and the structural evolution of a major transform plate 1060 boundary[END_REF][START_REF] Mann | Global catalogue, classification and tectonic origins of restraining-and releasing bends 922 on active and ancient strike-slip fault systems[END_REF]Sengör et 60 al., 2014). During fault initiation, motion is distributed over several individual fault segments. As finite 61 relative motion increases, fault strands progressively connect into continuous and localized strike-slip 62 fault segments. The increased connection of fault strands shapes narrower shear zones (<100-km-wide)

63
with local structural complexities in stepover (releasing or restraining bends). The localization of strike-64 slip segments leaves some initial oblique strands deactivated. The timing of strain localization within 65 the wide shear zone may differ from one fault segment to another. The lifetime of such shear systems in 66 the continental setting is in the order of 10 7 yrs [START_REF] Sengör | Continental transform faults: congruence and 1019 incongruence with normal plate kinematics[END_REF]. Analog models reproduce the 67 transition from an initial diffuse shear zone composed of Riedel faults to a localized fault formed by the 68 linkage of shear segments [START_REF] Tchalenko | Similarities between shear zones of different magnitudes[END_REF][START_REF] Dooley | Analogue modelling of intraplate strike-slip tectonics: a review and 774 new experimental results[END_REF][START_REF] Lefevre | Experimental evidence for crustal control 895 over seismic fault segmentation[END_REF].

69

The North Anatolian Fault system, located in the Eastern Mediterranean domain (Fig. 1, 2), is the 1200-70 km-long dextral strike-slip boundary between the Anatolian and Eurasian tectonic plates (Fig. 1, 2), 71 which connects the Anatolia-Arabia-Eurasia triple junction in the East [START_REF] Ferrari | Long-term 833 evolution of the North Anatolian Fault: new constraints from its eastern termination[END_REF] to

72
the Hellenic Subduction Zone [START_REF] Flerit | The mechanical interaction between the propagating 795 North Anatolian Fault and the back-arc extension in the Aegean[END_REF]Sakellariou et al., 2018;[START_REF] Ferentinos | Propagation and 789 termination of a strike slip fault in an extensional domain: The westward growth of the North Anatolian 790 Fault into the Aegean Sea[END_REF]. The

73

North Anatolian Fault triggers frequent earthquakes above Mw ∼7 (e.g. Izmit and Duzce events in 1999;

74 Hubert- [START_REF] Hubert-Ferrari | Seismic hazard in the Marmara Sea region following the 17 August 1999 Izmit 831 earthquake[END_REF][START_REF] Bulut | Structural setting along the Western 747 North Anatolian Fault and its influence on the 2014 North Aegean Earthquake (Mw 6.9)[END_REF] and its submarine segments are a potential source of 75 tsunamis [START_REF] Hébert | Tsunami hazard in the Marmara 824 Sea (Turkey): a numerical approach to discuss active faulting and impact on the Istanbul coastal areas[END_REF][START_REF] Reicherter | Holocene tsunamigenic sediments and tsunami modelling in 978 theThermaikos Gulf area (northern Greece)[END_REF][START_REF] Janin | Tsunamigenic potential of a 842 Holocene submarine landslide along the North Anatolian Fault (northern Aegean Sea, off Thasos 843 island): insights from numerical modelling[END_REF].

76

The North Anatolian Fault transects continental lithosphere with significant along-strike strength 77 variations, inherited from the successive geological events that shaped the Hellenides mountain belt 78 prior to its collapse. As such, the North Anatolian Fault is a relevant case-study of a post-orogenic 79 transform fault (Le [START_REF] Pourhiet | Links between long-term and short-term rheology of the 913 lithosphere: insights from strike-slip fault modelling[END_REF][START_REF] Jolivet | Transfer zones in Mediterranean back-arc regions and tear faults[END_REF].

80

The objective of this study is to constrain the structural evolution of the ~350-km-long segment of the 81 North Anatolian Fault crossing the North Aegean Sea (Fig. 3, 4), on the basis of a set of multibeam data 82 (Ypother cruises, 2013(Ypother cruises, -2016;;Sakellariou et al., 2018) and seismic-reflection profiles (NAFAS cruise, 83 2017; [START_REF] Rodriguez | Seismic profiles across 985 the North Anatolian Fault in the Aegean Sea[END_REF] vintage seismic lines published in [START_REF] Beniest | Interaction 733 between trench retreat and anatolian escape as recorded by neogene basins in the northern Aegean Sea. 734[END_REF].

84

The present dataset covers some of the major tectonic structures encountered in the North Aegean 85 Domain, namely the North Aegean Trough, the Edremit-Skyros Trough and the Evia Basin (Fig. 234).

86

There, the different steps of formation of the North Anatolian Fault remained poorly constrained due to 87 the lack of seismic-reflection and stratigraphic data [START_REF] Krijgsman | Mediterranean-Black Sea gateway exchange: scientific drilling workshop 887 on the BlackGate project[END_REF]. We define some regional 88 stratigraphic markers for the period spanning the Messinian to the present-day [START_REF] Laigle | North Aegean crustal deformation: an active 893 fault imaged to 10 km depth by reflection seismic data[END_REF]89 Beniest et al., 2016;[START_REF] Ferentinos | Propagation and 789 termination of a strike slip fault in an extensional domain: The westward growth of the North Anatolian 790 Fault into the Aegean Sea[END_REF] to reach a precision in the ages of tectonic events

98

The North Anatolian Fault is the plate boundary between Anatolia and Eurasia, with a current dextral 99 strike-slip rate of 23 mm.yr -1 (Le [START_REF] Le Pichon | The North Anatolian fault in the Sea of Marmara. 903[END_REF][START_REF] Reilinger | GPS constraints on continental deformation in the Africa-Arabia-Eurasia 981 continental collision zone and implications for the dynamics of plate interactions[END_REF][START_REF] Le Pichon | The Miocene-to-present kinematic evolution of the eastern 897 Mediterranean and Middle East and its implications for dynamics[END_REF]100 Pérouse et al., 2012;[START_REF] Müller | Velocity derived from GPS data 1993-2009[END_REF]. The finite amount of dextral motion along the North Anatolian

101

Fault is estimated to 85±5 km, with some ambiguities in areas where slip is distributed over several fault 102 strands (Sengör et al., 2005). The finite offset results from strike-slip rates that grew from ~3 mm.yr -1 103 in the earliest stages of formation of the fault system to near-current slip rates since the Early Pleistocene [START_REF] Ferrari | Long-term 833 evolution of the North Anatolian Fault: new constraints from its eastern termination[END_REF].

104

105

In this study, the North Aegean Domain is defined as the area bounded to the south by the North Cycladic et al., 2003).

110

The northern branch of the North Anatolian Fault crosses the Marmara Sea (i.e. the Main Marmara 112 connects the North Aegean Trough (Fig. 2). The North Anatolian Fault makes a ~30° bend at the 113 connection between the Saros Gulf and the North Aegean Trough [START_REF] Roussos | Structure of the Central North Aegean Trough: an active strike-988 slip deformation zone[END_REF]114 Koukouvelas & Aydin, 2002). The strike-slip rate of relative motion along the northern branch decreases 115 from 21.2 mm yr -1 at the Gulf of Saros to ~5 mm yr -1 at the Sporadhes archipelago [START_REF] Müller | Velocity derived from GPS data 1993-2009[END_REF].

116

The southern branch of the North Anatolian Fault crosses the Biga Peninsula and connects the Edremit-117 Skyros Trough in the Aegean Sea (Fig. 2). The strain distribution of the southern branch of the North 118 Anatolian Fault (Fig. 234) is diffuse onland in Turkey [START_REF] Sümer | Kinematics of the Havran-Balikesir Fault Zone 1038 and its implication on geodynamic evolution of the Southern Marmara Region, NW Anatolia[END_REF], whereas it is expressed as a 119 localized structure offshore [START_REF] Papanikolaou | 949 Active tectonics and seismic hazard in Skyros Basin, North Aegean Sea, Greece[END_REF]. The strike-slip rate along the southern branch 120 is on the order of 10 mm.yr -1 [START_REF] Müller | Velocity derived from GPS data 1993-2009[END_REF].

121

Both the North Aegean and the Edremit-Skyros Troughs reveal horsetail structures (Fig. 34). Horsetail 122 structures are commonly observed at the termination of strike-slip faults [START_REF] Basile | Transtensional faulting patterns ranging from pull-apart basins to 731 transform continental margins: an experimental investigation[END_REF]: they 123 consist in numerous oblique splays rooting on the main strike-slip faults and isolating a series of 124 transtensive basins. On one hand, the North Aegean Trough is ~150-km-long, up to 80-km-wide and 125 1600-m-deep [START_REF] Brooks | Structure and evolution of the Sporadhes basin of the North Aegean 738 trough, northern Aegean Sea[END_REF][START_REF] Papanikolaou | Morphotectonic structure of the 947 western part of the North Aegean Basin based on swath bathymetry[END_REF]Sakellariou et al., 2018;126 Ferentinos et al., 2018), running from the Lemnos Deep to the Sporadhes archipelago (Fig. 3,4). On the The formation of the North Anatolian Fault results from the influence of several geodynamic drivers,

127

135

including Arabia-Eurasia collision, the dynamics of the Hellenic trench retreat and the resulting 136 differential in gravitational potential between the Anatolian plateau and the Aegean Sea (Jolivet & 137 Faccenna, 2000;[START_REF] Faccenna | Slab detachment beneath eastern 781 Anatolia: A possible cause for the formation of the North Anatolian fault[END_REF][START_REF] Brun | Exhumation of high-pressure rocks driven by slab rollback[END_REF]Le Pourhiet et al., 2012;Jolivet et al., 138 2015;[START_REF] Brun | 740 The two-stage Aegean extension, from localized to distributed, a result of slab rollback acceleration[END_REF][START_REF] England | Constraints from GPS measurements on the dynamics 778 of deformation in Anatolia and the Aegean[END_REF].

139

Most of the constraints on the history of the North Anatolian Fault in the North Aegean Domain are 140 based on the study of the Marmara Sea and its surroundings. At least three successive major strike-slip 141 systems, evolving into a continuous frame of shearing of the continental lithosphere, have been

142
identified on the basis of seismic data tied to industrial wells [START_REF] Sengör | The geometry of the North Anatolian transform fault in the Sea of Marmara and its temporal 1016 evolution: implications for the development of intracontinental transform faults[END_REF][START_REF] Le Pichon | The South Marmara Fault[END_REF]143 2015).

144

A first diffuse strike-slip system emplaced in Late Serravalian-Tortonian (12-10 Ma), in the area that is 145 now enclosed between the Thrace basin and the Sakarya suture (Fig. 1, 2). A part of this first strike-slip 146 system is still active as the southern branch of the North Anatolian Fault, where the pattern of drainage 147 networks recorded a structural reorganization around 0.5-1. 3 Ma (Demoulin et al., 2013).

148

A second strike-slip system is evidenced at the South Marmara Fault and the Ganos segment, both 149 corresponding to positive flower structures formed at a restraining bend (Fig. 2; Le [START_REF] Le Pichon | The South Marmara Fault[END_REF]150 2015;[START_REF] Karakas | Crustal strain in the 865 Marmara pull-apart region associated with the propagation process of the North Anatolian Fault[END_REF]. These structures record the beginning of the localization of the North 151 Anatolian Shear System in the Pliocene [START_REF] Armijo | Westward propagation of the North Anatolian fault 729 into the northern Aegean: Timing and kinematics[END_REF][START_REF] Le Pichon | The South Marmara Fault[END_REF]2015). The South 152 Marmara Fault goes extinct around 3.5 Ma, while the Ganos segment is still active and forms a well-153 localized, >130-km-long dextral strike-slip fault [START_REF] Armijo | Westward propagation of the North Anatolian fault 729 into the northern Aegean: Timing and kinematics[END_REF].

154

The third, localized strike-slip system corresponds to the northern branch of the North Anatolian Fault, 155 expressed as the Main Marmara Fault in the Marmara Sea [START_REF] Le Pichon | The active main Marmara fault[END_REF]2003;Carton et al., 156 2007). Estimates of the age of the Main Marmara Fault range between 0.5 and 2.5 Ma (Rangin et al., 157 2004;[START_REF] Grall | Heat flow in the Sea of Marmara Central Basin: Possible implications for the tectonic evolution 813 of the North Anatolian Fault[END_REF][START_REF] Grall | Slip rate estimation along the western segment of the Main Marmara Fault over the last 405-816 490 ka by correlating mass transport deposits[END_REF][START_REF] Le Pichon | 907 Propagation of a strike-slip plate boundary within an extensional environment: the westward 3D shapes of metamorphic core complexes[END_REF]. The Main Marmara Fault crosses the Gelibolu 158 Peninsula and connects the Gulf of Saros at the entrance of the Aegean Sea through the Ganos strike-159 slip segment (Fig. 2; [START_REF] Mcneill | Extension of the North 926 Anatolian Fault into the North Aegean Trough: Evidence for transtension, strain partitioning, and 927 analogues for Sea of Marmara basin models[END_REF].

160
The age of formation of the North Aegean Trough and the Skyros-Edremit Trough is roughly 161 constrained in the Late Pliocene-Early Pleistocene [START_REF] Laigle | North Aegean crustal deformation: an active 893 fault imaged to 10 km depth by reflection seismic data[END_REF][START_REF] Beniest | Interaction 733 between trench retreat and anatolian escape as recorded by neogene basins in the northern Aegean Sea. 734[END_REF], a period 162 which encompasses several stages of evolution of the North Anatolian Fault.

163

Onland, a series of sedimentary basins (Fig. 2 [START_REF] Jolivet | Cenozoic geodynamic evolution of the Aegean[END_REF]Le Pourhiet et al., 2012;Jolivet et al., 2013).

177

As a result, the North Aegean lithosphere displays an unusual layering, with a shallow brittle ductile 178 transition (<10 km, Brun & Sokoutis, 2018) and a thinned lithospheric mantle. The Moho depth ranges 179 between 20 and 30 km [START_REF] Sodoudi | Lithospheric structure of the Aegean obtained from P and S 1029 receiver functions[END_REF]. Rayleigh wave anisotropy reveals the existence of a 180 thermal anomaly located right in between the two segments of the North Anatolian Fault in the North 181 Aegean domain, within the lower crust and the lithospheric mantle [START_REF] Endrun | Complex layered deformation within 776 the Aegean crust and mantle revealed by seismic anisotropy[END_REF].

216

Tectonic processes control the distribution of clastic sedimentary deposits in the study area (Fig. 6).

217

Prior to the onset of the North Anatolian Fault, scattered distal deltaic rivers flood the area, marked by 218 moderate incision along the thalweg. Since the onset of tectonic subsidence, the rivers form channel-219 levee systems close to the slope break and evolve downslope into canyons with V-shape morphologies 220 (Fig. 6a). The complex distribution of faults and basins within the North Aegean Trough results in a scar and block falls at the edge of the slope, fig. 6c) and their related mass transport deposits (marked a 223 chaotic-to-transparent seismic facies). Some of the steepest slopes display undulated seafloor (fig. 6b),

224

underlain by a series of wavy reflectors, which could be interpreted as sediment waves resulting from 225 creeping of sediments in interaction with bottom-current controlled deposition [START_REF] Faugères | Multiprocess generated sediment waves on the Landes Plateau (Bay of Biscay, North Atlantic)[END_REF]226 Shillington et al., 2012). The tectonic structures also influence the circulation of oceanic bottom-

227 currents.
Where the current intensity is strong, the axis of the current is associated with a rough seafloor,

228

which is an indicator of the strong sediment sorting. The attenuation of the intensity of the oceanic 229 currents promotes the building of a series of fault-controlled contourite drifts (sensu Rebesco et al., 230 2014). The architecture of these contourite drifts display typical sigmoid to mounded configurations 231 (Fig. 6e), characterized by important lateral thickness variations of the sedimentary layers, with pinched-232 out reflectors close to the current axis and thicker deposits away from it. Fluid escape features are 233 commonly observed close to the main faults and on the extrados of the main rollover structures (Fig. 4).

234

Fluid escape features are expressed as dense networks of conduits leading to small offsets of the 235 sedimentary layers or undulated to chaotic series of reflectors on the seismic dataset (Fig. 6d). At the 236 seafloor, the area of fluid escape form fields of coalescing circular depressions (Fig. 5e The Pleistocene stratigraphy has mainly been constrained on the basis of sequence stratigraphy studies, 272 investigating the influence of sea level variations and oceanic current activity using the architecture of 273 sedimentary bodies [START_REF] Sakellariou | Aegean Pleistocene landscapes above and below sea level: 996 palaeogeographic reconstruction and Hominin dispersals. Under the Sea: archeology and 997 palaeolandscapes of the continental shelf[END_REF][START_REF] Tripsanas | Late quaternary bottom-current activity in the south Aegean Sea reflecting 1050 climate-driven dense-water production[END_REF]. In the North Aegean 274 Domain, sequence stratigraphy studies in the Thermaïkos Gulf [START_REF] Lykousis | Sea-level changes and shelf break prograding sequences during the last 400 ka in 919 the Aegean margins: subsidence rates and palaeogeographic implications[END_REF] and offshore the Biga 275 Peninsula [START_REF] Isler | Seismic stratigraphy and Quaternary sedimentary 840 history of the northeast Aegean Sea[END_REF]

314

-Reflector C (~2 Ma): Reflector C corresponds to an erosive surface, dated between 1.6 and 2.1 Ma 315 from the volcanic deposits related to the Oros eruption (Pe- [START_REF] Pe-Piper | Paleomagnetic stratigraphy and radiometric dating 960 of the Pliocene volcanic rocks of Aegina, Greece[END_REF]Dietrich et al., 1988).

316

Sequence stratigraphy studies in the Evoikos Gulf suggest the age of reflector C to be closer to 2 Ma 332 & Martin, 1990;Sakellariou et al., 2018), runs parallel to the North Anatolian Fault in the area of Anatolian Fault and terminates at the tip of the Athos Peninsula (Fig. 34).

335

Seismic line 701 is perpendicular to the Athos splay (Fig. 8) and seismic line 702 crosses the area 336 between the main splay and the Medusa High (Fig. 9). The Main Splay runs across an area of chaotic 337 reflectors and forms a flower structure. The Athos Splay is an apparent normal fault dipping at 55° 338 southward, consistent with focal mechanisms at this location [START_REF] Kiratzi | Focal mechanisms of shallow earthquakes in the Aegean Sea and the 872 surrounding lands determined by waveform modelling: a new database[END_REF]. The footwall 339 reveals a buried tilted block (Fig. 8). A dense network of normal faults, most of them being blind on the 340 seafloor, connects into a set of three flower structures in the basin, located at the footwall of the Athos 341 Splay (Fig. 8). The Medusa High (Fig. 9) corresponds to an elongated push-up structure (Mascle & 342 Martin, 1990;Sakellariou et al., 2018). 348 [START_REF] Kourouklas | Analyzing the Correlations and 879 the Statistical Distribution of Moderate to Large Earthquakes Interevent Times in Greece[END_REF]. The Main Splay is sub-vertical and blind on the seafloor due to mass-wasting 349 sedimentation rates higher than its vertical slip-rate (~0.4-s TWT -thick package of mass transport 350 deposits on Line 603; Fig. 11). It forms a growth-synform structure on Line 602 (Fig. 10) and promotes 351 the uplift of the basement on line 603 (Fig. 11). The sedimentary cover of both flanks of the spindle-352 shape basin displays an undulated configuration upslope, which becomes more chaotic downslope.

353

The Sithonia Splay is a second strike-slip faut trending 60°NE. To the west, a network of normal faults, 354 dipping 20° to the North, roots diagonally to the Sithonia Splay and forms a horsetail structure offshore 355 the Kassandra Peninsula, where focal mechanisms indicate normal faulting [START_REF] Kourouklas | Analyzing the Correlations and 879 the Statistical Distribution of Moderate to Large Earthquakes Interevent Times in Greece[END_REF].

356

The multibeam map reveals two sedimentary basins along the Sithonia Splay: a first one, located on the 357 southern flank of the eastern segment of the fault and a second one, located on the northern flank of the 358 western segment of the fault (Fig. 5). The Sithonia Splay is subvertical in its central part, forming a 359 short-wavelength, symmetric growth-synform structure on Line 602 (Fig. 10). Line 603 indicates a toward the transtensional regime of the horsetail termination (Fig. 5).

363

The Main Splay of the North Anatolian Fault and the Sithonia Splay are separated by a Central Structural 364 High (Fig. 34). The Central Structural High is a ~50-km-long elongated feature, with two highs mass transport deposits (Fig. 12). The hinge of the rollover is dissected by numerous synthetic and 380 antithetic normal faults. These fault systems cross a field of coalescing circular depressions spreading 381 over ~200-km², which corresponds to a series of short-wavelength undulated reflectors on the seismic, 382 focused on the uppermost ~0.4 s TWT (Fig. 12). The field of circular depressions is interpreted as the 383 result of fluid escape (Fig. 34).

384

The Central Splay (Fig. 3-4), roots on the Central Structural High, then bends across the extrados of the

431

The second structure also corresponds to a tilted graben, located at the plateau isolated between the 432 North Aegean Trough and the Edremit-Skyros Trough (Fig. 18). This graben is referred to as the Venus (Fig. 14,15,16). Unconformity A (~0.5 Ma) is well expressed close to the oblique splay 1 and 481 marks an increase in subsidence at the hanging wall of this splay (Fig. 15). Unconformity A therefore 482 records the formation of the oblique splay 1 (Fig. 16). the Sporadhes Archipelago [START_REF] Müller | Velocity derived from GPS data 1993-2009[END_REF] may be the result of slip partitioning over each major 524 splay of the North Aegean Trough (Fig. 1). Domain provides a ground-truth validation of analog modeling tests performed by [START_REF] Basile | Transtensional faulting patterns ranging from pull-apart basins to 731 transform continental margins: an experimental investigation[END_REF].

527

In their models (Fig 20 ), a horsetail termination initially consists in an en-échelon normal fault system 528 trending perpendicular to the main strike-slip displacement zone, composed of oblique Riedel splays.

529

As the relative motion between the adjacent blocks increases, the Riedel splays progressively connects 530 the en-échelon normal fault system. For dextral motion, the first Riedel fault forms to the east of the

90

  comparable to the segments of the North Anatolian Fault observed in the Marmara Sea (Le Pichon et 91 al., 2014). Finally, we provide structural maps of the post-Messinian evolution of the North Aegean 92 Domain, from the Yeniçaga Fork east of Marmara to the Evia Basin in Greece (Fig. 2). Overall, our 93 structural reconstructions of the North Anatolian Fault document the strain localization within a post-94 orogenic continental shear zone and the time of effective formation of such tectonic plates.

106

  Detachment System, to the north by the Rhodope Detachment System, to the west by the Vardar Suture 107 Zone and to the East by the Yeniçağa fork (Fig. 1, 2). The total amount of slip-rate along the North 108 Anatolian Fault is accommodated by its northern and southern branches in the North Aegean Domain 109 (Fig. 1, 2; Le Pichon

  other hand, the Edremit-Skyros Trough is 70-km-long, up to 50-km-wide, and 1050-m-deep (Fig.3, 4;128[START_REF] Papanikolaou | 949 Active tectonics and seismic hazard in Skyros Basin, North Aegean Sea, Greece[END_REF]. There, the southern branch of the North Anatolian Fault acts as a marginal 129 structure, which bounds the southern flank of the trough over its entire length and splits into two 45 to 130 66-km-long oblique splays isolating sub-basins.

191 3 - 3 -

 33 Model used for the maps of the North Aegean Domain (Fig.1-4) combines data 186 from the Shuttle Radar Topography Mission (SRTM) at 3 seconds and the multibeam dataset acquired 187 during the Ypother oceanographic cruises between 2013-2016(Sakellariou et al., 2018)In this study, we present a new seismic-reflection dataset collected during the NAFAS (North Anatolian192Fault in the North Aegean Sea) expedition in summer 2017, onboard the R/V Tethys II. The expedition and partly explored in[START_REF] Beniest | Interaction 733 between trench retreat and anatolian escape as recorded by neogene basins in the northern Aegean Sea. 734[END_REF]. All the seismic-reflection profiles are displayed on the 196 figures with a vertical exaggeration of 14, with their related simplified cross-section at 1:1 scale.197Seismic reflection profiles were shot using a GI airgun and a 24-trace streamer with 400-m maximum 198 offset. The GI gun was triggered in harmonic mode (2 x 24 cubic inches) every 6s, with an acquisition 199 speed of 4.1 knots, leading to a shot interval of 12.5 m. The trace record length is 5500 ms with a 1-ms 200 sample interval. Only 8 out of 24 traces were working with a maximum offset of 200-m and a maximum 201 CDP (Common Depth Point) fold of 4. The depth of penetration of the signal reaches about 3 seconds 202 two-way travel time (TWT). The processing workflow consists in geometry setting, water-velocity 203 normal move-out, stacking, deconvolution and Kirchhoff finite difference post-stack migration. 204 205 Multibeam and interpretation of geological structures on seismic-reflection profiles 206 The geological mapping of tectonic structures is based on the seafloor signature of the structure on the 207 multibeam data and the expression of these features on the seismic-reflection lines (Fig. 5). The offshore 208 structural maps provided in this study (Fig. 4-5) are slightly modified from Papanikolaou et al. (2002; 209 2019) and Sakellariou et al. (2018), considering our new seismic dataset. 210 The North Aegean Domain is dominated by a large variety of strike-slip structures (Fig. 5): 211 -Negative flower structures: Most of the sub-basins isolated by the oblique splays within the horsetail 212 terminations correspond to negative flower structures. The negative flower structures are bounded by 213 normal faults of opposite dip and connect into a single strike-slip fault at depth. 214 -Transpressive structures: They correspond to positive flower structures and push-up structures, formed 215 by a set of strike-slip faults with a reverse component.

  identified the reflectors corresponding to MIS (Marine Isotopic Stage) 2 276 (18 ka) to MIS 12 (430 ka). Additional stratigraphic constraints are obtained from the study of contourite 12 306 characterized by distal channel systems (Proedrou & Papaconstantinou, 2004; Anastasakis & Piper, 307 2005). Anastasakis & Piper (2006) show the regional transition from terrestrial to full marine facies 308 occurred regionally at the boundary between the middle and upper Pliocene. A key reflector, labeled D, 309 seals the seismic unit interpreted as the episode of delta fan supply in the Aegean Sea (Fig. 7; Anastasakis 310 & Piper, 2005). This seismic unit is characterized by the signature of distal channel-levee systems, 311 marked by an alternation of minor downlap and onlap that reflects their successive avulsions. Reflector 312 D is the top reflector of a series of three high-amplitude reflectors sealing the systems of delta fans. The 313 reflector D is dated at ~2.8 Ma from Milos volcanics (Anastasakis & Piper, 2005).

317 than 1

 1 .6 Ma (a reflector distinct from C being dated at 1.6 Ma, Piper & Anastasakis, 2013).318-Reflector B (~1.3 Ma): Reflector B marks the onset of progradational wedges in the Aegean Sea, dated 319 around 1-1.4 Ma with lava flows[START_REF] Anastasakis | Late Neogene evolution of the western South Aegean volcanic 717 arc: sedimentary imprint of volcanicity around Milos[END_REF]. The age has been refined at 1.3-1.4 Ma 320 from sequence stratigraphy studies in the Evoikos Gulf[START_REF] Anastasakis | The changing architecture of sea-level lowstand deposits across 722 the Mid-Pleistocene transition: South Evoikos Gulf, Greece[END_REF]. 321 -Reflector A (~430-480 ka): Reflector A is defined by a set of sequence stratigraphic constraints 322 available in the North Aegean Domain. It corresponds to MIS 12 (~430-480 ka). Our picking and spatial 323 correlation of reflector A in the North Aegean Trough agrees with the work of Ferentinos et al. (2018). The connection between the Gulf of Saros and the North Aegean Trough 328 At the northeastern entrance of the North Aegean Trough, the Main Splay of the North Anatolian fault 329 makes a bend, which is expressed on the seafloor by a series of push-up ridges (Fig. 3-4). The Main 330 Splay forms a steep, ~5 to 10° slope, which is covered by an undulated seafloor. There, a set of secondary 331 fault splays connects along the main fault. A 15-km-long ridge, referred to as the Medusa High (Mascle

  The central segment of the North Aegean Trough offshore the Chalkidiki Peninsula345The Main Splay of the North Anatolian Fault runs within a 40-km-long, 15-km-wide, asymmetric 346 spindle-shaped trough (Fig.3-4). Focal mechanisms confirm the strike-slip motion along the strike of 347 the Main Splay and suggest a minor component of transtension locally[START_REF] Kiratzi | Focal mechanisms of shallow earthquakes in the Aegean Sea and the 872 surrounding lands determined by waveform modelling: a new database[END_REF]

365

  culminating at 700-m and 550-m depth. The Central Structural High appears as an antiform structure, 366 with undulations in the sedimentary cover (Fig. 10-11). The part of the antiform which is still exposed 367 at the seafloor corresponds to a basement high. A field of apparent normal faults with short and uneven 368 offsets is observed between the Central Structural High and the Sithonia Splay (Fig.10-11). 369 370 5-1-3-Termination of the horsetail in the Thermaïkos-Skopelos area 371 Offshore Skopelos, the geometry of the Main Splay of the North Anatolian Fault changes from a strike-372 slip fault to a low-angle normal fault (Fig. 3-4), which runs along Pelion and the Thermaïkos Gulf 373 (Laigle et al., 2000). The seismic reflection profile 103 (Fig. 12) crosses all the splays from Skopelos 374 Island to Kassandra Peninsula. We observe a large-scale rollover structure in the hanging wall of the 375 North Anatolian Fault, bending along the Main Splay, acting here as a north-dipping low-angle (~20°) 376 normal fault. Focal mechanisms however indicate pure strike-slip motion in this area (Kourouklas et al., 377 2022), which suggests that the normal fault is turning into a strike-slip fault. The configuration of the 378 low-angle normal fault isolates a 20-km long, 10-km-wide trough along the Main Splay, filled-in by 379

385

  rollover into a 25-km-long, 15-km-wide, 1450-m-deep trough, formed by a system of normal faults. The386normal fault scarps reach 350-m-high at the seafloor along the slope of the Gulf of Thermaïkos and 387 localize a system of slope-apron canyons. The seismic line 201 (Fig.13) crosses the area between the major low-angle (~35° dip) normal fault389where the North Anatolian Fault ends and the termination of the Sithonia Splay. The hanging wall forms 390 a syncline basin, filled-in by sediments characterized by the short-wavelength undulated facies formed 391 by fluid escape. The system of normal faults crossing the slope of the Gulf of Thermaïkos forms a series 392 of horst and graben (Fig.13). The termination of the Sithonia Splay is a set of two sub-parallel listric 393 faults, dipping 20° to 30° to the north, with their associated rollover structures dissected by synthetic 394 and antithetic normal faults (Fig. 13), consistent with the focal mechanisms at this location (of the Edremit-Skyros Trough (Southern Branch of the North Anatolian Fault) 398 The structure of the Edremit-Skyros horsetail is described in details in Papanikoalou et al. (2019). In 399 this study, we present three new seismic profiles, which cross all the key structures of the Edremit-400 Skyros Trough. 401 The seismic profile 801 (Fig. 14) crosses the Venus plateau, an oblique splay of the horsetail, the deepest 402 basin of the trough, here expressed as a growth syncline, and the main system of sub-parallel low-angle 403 (~25° dip) normal faults bounding the Skyros Island, which isolates a half-graben. The seismic line 802 404 (Fig 15) crosses the southern branch of the North Anatolian Fault and the southern edge of the Edremit-405 Skyros Trough. It reveals a series of angular unconformities associated to tilted blocks. On the seismic 406 profile 803 (Fig. 16), the oblique splays of the horsetail appear as normal faults isolating either half-407 grabens or growth synclines, dominantly filled-in by mass transport deposits. The subsidence increases 408 towards the Skyros Island. Normal faults segment the bulge of the growth-synclines. In this area, 409 sedimentation rates exceed the vertical slip-rate at the faults, resulting in their smooth aspect on the basin consists in a 90-km-long series of three subsiding basins, up to 1000-m deep, separated 414 by structural highs (Fig 3-4). On the seismic lines (Fig 17), all the Evia sub-basins appear as a series of 416 post-Messinian sediments reaches ~1 s (TWT). The series emplaced before the formation of the structure 417 display seismic facies typical of distal detritic sedimentation, while the syn-tectonic series display a 418 fanning configuration recording the progressive subsidence of the structure. Only minor Mass Transport 419 Deposits are observed within the growth structures, which results from the ~20° steep slope formed by 420 the main normal fault that does not allow the storage of sediments. The structural thresholds appear as 421 positive flower structures in line with the trend of the North Anatolian Fault, with uplifted segments of 422 the basement and a dense pattern of faults on their flanks. fault system buried in the offshore North Aegean Domain 425 The seismic lines collected during the NAFAS cruise in 2017 together with the compilation of vintage 426 seismic lines (Mascle & Martin, 1990; Beniest et al., 2016) reveal fossil structures buried under the 427 sediments of the North Aegean Domain and locally crosscut by the horsetail structures. 428 The first structure is encountered in the area of the connection between the Saros Gulf and the North 429 Aegean Trough, at the -W-E trending Athos splay (Fig 3-4). There, the seismic line 701 (Fig 8) reveals 430 a buried tilted block sealed by a series of onlap terminations of the sedimentary layers.

476

  of tectonic events in the North Aegean Sea436The series of angular unconformities labeled from A to D records the main tectonic events that shaped 437 the North Aegean Domain since the Messinian (Fig 7). 438 5-5-1. The North Aegean Trough 439 Unconformity D, dated at 2.8 Ma, records the end of the tectonic episode expressed by the series of 440 tilted blocks composed of the Athos (Fig. 8) and Venus (Fig. 18) grabens. This unconformity also marks 441 the deactivation of a series of push-up structures located in the area of the Central Structural High (line 442 603, Fig 11). At the termination of the Sithonia Splay (line 201, Fig 13) offshore Kassandra Peninsula, this unconformity marks the onset of a fanning configuration of the sediments and, therefore, the onset 444 of the tilt of the graben. 445 The second key angular unconformity C, dated at 2 Ma, is well identified by onlap terminations over 446 the underlying, tilted deposits in the North Aegean Trough (e.g. in the vicinity of Skopelos at line 103, 447 Fig 12). This unconformity marks the onset of the fanning configuration of the sediments observed all 448 along the Sithonia Splay (line 201, Fig 13; line 602-603, Fig 10-11), and hence, the formation of this 449 still-active splay within the North Aegean Trough. The amplitude of slope incision features remains 450 poorly disturbed by this tectonic episode (e.g. at the edge of the Thermaïkos Gulf, line 201, Fig 13), 451 which indicates a still rather low subsidence rate. 452 These unconformities D and C record the Late Pliocene-Early Pleistocene change in the pattern of strain 453 localization within the North Anatolian Shear Zone. These unconformities also pre-date the first stage 454 of the formation of the North Aegean horsetail structure, with the activation of the Sithonia Splay. 455 The third angular unconformity B, dated at ~1.3 Ma, records the formation of the termination of the 456 central splay (observed at line 103, Fig 12). Across the edge of the Thermaïkos Gulf, the 1.3 Myrs-old 457 unconformity corresponds to an increase in the amplitude of the slope incisions features (line 201, Fig 458 13), which indicates a major increase in the overall subsidence, the channels digging deeper to catch 459 their equilibrium line. The Mass Transport Deposits associated to this episode are the thickest (~0.2-0.3 460 s TWT) encountered within the North Aegean Domain since the Messinian. At the connection between 461 the North Aegean Trough and the Saros Gulf, the 1.3 Myrs-old unconformity records the formation of 462 the Athos Splay and the main uplift of the Medusa High (Fig 8-9). There, the mean vertical slip-rate of 463 the Athos normal fault increased from a 0.13 mm.yr -1 during the 2-1.3 Ma interval to 0.22 mm.yr -1 since 464 1.3 Ma. Overall, this set of observations indicates a major structural reorganization of the northern 465 branch of the North Anatolian Fault at 1.3 Ma, marked by a drastic increase in subsidence rates within 466 the sub-basins of the North Aegean Trough. 467 Finally, unconformity A, dated at ~0.5 Ma, records the onset of the Main Splay of the North Anatolian 468 Fault all across the North Aegean Trough (Ferentinos et al., 2018). The formation of the Main Splay is 469 best recorded offshore Skopelos (line 103, Fig 12), the segment of the fault running at the edge of the the Main Splay induced a change in the activity of the Sithonia Fault, with an increase of the vertical 472 slip-rate from 0.16 mm.yr -1 during the 1.3-0.48 Ma interval to 0.3 mm.yr -1 since 0.48 Ma. However, the 473 vertical slip-rate of the faults related to the Central Splay remained steady. The unconformity C (2 Ma) is onlapped by a tilted series of reflectors on the southern edge of the trough 477 (line 803, Fig. 16). This unconformity marks the first stages of the formation of the Southern branch of 478 the North Anatolian Fault offshore Skyros. Unconformity B (1.3 Ma) corresponds to the increase in the 479 subsidence rate (up to 0.45 mm.yr -1 ) at the hanging wall of the normal fault system running along Skyros 480 Island

  subsidence within the Evia Basin is dated between 2 and 1.[START_REF] Ma | This is coeval with the general increase of slip rate along the entire North Anatolian system 587 and the regional change in stress regime over the Aegean Sea. Further westward propagation and 588 localization along the northern and southern branches formed the North Aegean and Skyros-Edremit 589 Troughs as horsetail structures. The North Aegean Trough results from the formation of three successive 590 horsetails, formed at 2 Ma, 1.3 Ma and 0.5 Ma and propagating westward at a rate of 40 to 60 km[END_REF] Ma based on unconformities486B and C (Fig.17). This marks the base of the fanning configuration of the sedimentary infill. The main 487 formation episode of the Evia Basins is therefore coeval with the increase in subsidence at Corinth and 488 the first step of strain localization at both the northern and southern branches of the North Anatolian day configuration of the North Aegean Domain shows the gradual kinematic transition from 493 the strike-slip deformation that dominates in the northeastern Aegean Domain to the dip-slip 494 deformation encountered in the Northwest Aegean Domain (Mouslopoulou et al., 2007a,b). Our new 495 set of geological constraints allows us to refine the framework of strain localization of the North 496 Anatolian Shear Zone in the North Aegean Domain and highlights the westward propagation of the 497 strike-slip dominated area since the Late Miocene. The new geological constraints obtained from the seismic-reflection dataset are summarized in Figure 19 and integrated to the previously available 499 constraints on the geological events of the area. 500 501 6-1. Mode of formation of horsetail structures: the North Aegean and Edremit-Skyros Troughs 502 The formation of the horsetail terminations of both the northern and southern branches of the North 503 Anatolian Fault occurs in the frame of the westward propagation of the North Anatolian Fault within 504 the prevailing NNE-SSW to N-S extensional conditions of the western North Aegean Domain. The 505 horsetail configuration emplaces where the strike-slip fault connects a system of low-angle normal faults 506 inherited from the extensive stage. 507 The North Aegean and the Edremit-Skyros Troughs are horsetail terminations that are currently at 508 different steps of their development. Although the formation of both structures initiated at the same age 509 (~2 Ma), the lower slip rate along the southern branch of the North Anatolian Fault leads the Edremit-510 Skyros to be structurally less mature. This differential stage of horsetail structural evolution allows us 511 to investigate the tectonic and sedimentary processes at their origin. 512 On one hand, the Edremit-Skyros Trough corresponds to the evolution of a single horsetail structure. 513 The oblique splays of the Edremit-Skyros Trough formed first along the main detachment fault, then 514 migrated eastwards (oblique splay 1 formed at 0.5 Ma). 515 On the other hand, the North Aegean Trough consists in three horsetail basins (at the end of the Sithonia, 516 Central and Main Splays) that merged in a single one. Our seismic dataset highlights the successive 517 activation of the Sithonia Splay at 2 Ma, the Central Splay at 1.3 Ma and the Main Splay at 0.5 Ma, 518 which corresponds to the westward propagation of the northern branch of the North Anatolian Fault (Fig 519 18). The distance between the negative flower structure at the end of each splay is on the order of 30 to 520 50-km. This corresponds to the distance added to the northern branch of the North Anatolian Fault every 521 0.7-0.8 Ma in the frame of its westward propagation. The three main splays of the North Aegean Trough 522 have remained active since their inception. The decrease in slip rates observed in GPS measurements at 523

Figure 1 :Figure 3 : 653 Figure 4 :Figure 5 : 662 Figure 6 :Figure 7 : 668 Figure 8 :

 1365345662676688 Tectonic framework of the Eastern Mediterranean Sea (active faults from Kreemer and 639 Chamot-Rooke, 2004 and Chamot-Rooke et al., 2005). The tectonic escape of Anatolia results from 640 interactions between Arabia-Eurasia and the Hellenic trench retreat. NCDS: North Cycladic Detachment 641 System 642 643 Figure 2: a) Structural map of the segment of the North Anatolian Shear Zone in the North Aegean 644 Domain, modified after Lyberis (1984), Koukouvelas and Aydin (2002), Yalçin et al. (2016); 645 Sakellariou et al. (2018), Papanikolaou et al. (2002; 2019). The stress tensors are from Gürer et al. 646 (2016); Sümer et al. (2018). The location of the Late Miocene-Late Pliocene basins (Strymon, 647 Mygdonia, Drama, Orfanos, Prinos) is from Brun and Sokoutis (2018). b) Present-day stress tensors and 648 c) strain rate, from Floyd et al. (2010) and Konstantinou et al. (2016). 650 Topographic and bathymetric map of the North Aegean Domain and location of the seismic 651 lines published in this study (Sakellariou et al. 2018; Papanikolaou et al., 2002; 2019) 652 Structural map of the active faults of the North Aegean Trough and the Edremit-Skyros 654 Trough and the main sedimentary features (modified after Sakellariou et al. 2018; Papanikolaou et al., Criteria of identification of transtensive and transpressive strike-slip structures on the 659 multibeam and seismic-reflection dataset, with the examples of a) the Sithonia Splay and b) the Athos 660 Splay Classification of the facies of the main sedimentary features observed on the multibeam and 664 665 Stratigraphic correlation between the Myrtoon basin (Anastasakis and Piper, 2005), the Evia 666 Basin and the NW border of the Edremit-Skyros Trough 667 Seismic line 701 from the NAFAS cruise, crossing the Athos Splay and the North Anatolian 669 Fault at the entrance of the North Aegean Trough. See figure 3 for location.

Figure 9 :Figure 10 :Figure 11 : 680 Figure 12 : 687 688Figure 14 :Figure 15 :Figure 16 :Figure 17 :

 910116801268714151617 Seismic line 702 from the NAFAS cruise, crossing the Medusa High and the North Anatolian 673 674 Seismic line 602 from the NAFAS cruise, crossing the main splay of the North Anatolian 675 Fault, the central high and the Sithonia splay within the North Aegean Trough. See figure 3 for location. 676 677 Seismic line 603 from the NAFAS cruise, crossing the main splay of the North Anatolian 678 Fault, the central high and the Sithonia splay within the North Aegean Trough. See figure 3 for location. 679 Seismic line 103 from the NAFAS cruise, crossing the Main splay of the North Anatolian 681 Fault, the central splay and the western termination of the Sithonia Splay within the North Aegean 682 Trough. See figure 3 for location 684 Figure 13: Seismic line 201 from the NAFAS cruise, crossing the series of oblique splays dissecting 685 the slope at the edge of the Gulf of Thermaïkos and a field of fluid escape features. See figure 3 for 686 location. Seismic line 801 from the NAFAS cruise, crossing the Edremit-Skyros Trough. Seismic line 802 from the NAFAS cruise, crossing the Edremit-Skyros Trough. Seismic line 803 from the NAFAS cruise, crossing the Edremit-Skyros Trough. See figure 695 3 for location. 697 Seismic line 401 from the NAFAS cruise, crossing the main normal fault bounding the Evia 698 Basin and seismic line 301 crossing one of the structural thresholds identified within the Evia basin. See 699 inset and figure 3 for location. 704 Figure 19: Summary of the main steps of structural evolution of the North Anatolian Fault and the Gulf 705 of Corinth in the North Aegean Domain. 707 Figure 20: Analog (sandbox) models for the evolution of horsetail termination, from Basile and Brun 708 (1999), compared with the evolution of the North Aegean Trough horsetail (this study).

Figure 21 :

 21 Structural evolution of the North Anatolian Fault in the North Aegean Domain, compiling 712 field and offshore observations. This series of maps represents the present-day location of the faults that 713 used to be active at 4-3.5 Ma, 2 Ma, 1.3-0.8 Ma, 0.5 Ma. The past shorelines are not reconstructed. 714 Paleo-stress tensors from Sümer et al. (2018) and Lybéris (1984).

-Structure of the lithosphere in the North Aegean Domain

		differential subsidence are further observed in the Gulf of Thermaïkos and offshore the Chalkidiki
	167	peninsula (Varesis & Anastasakis, 2021).
	168
	169 2-3170 In the North Aegean Domain, the continental lithosphere keeps the record of a complex geological
	171	history, from the closure of Mesozoic Oceans (i.e. the Vardar and Pindos Oceans, Schettino & Turco,
	172	2011; Okay & Tüysuz, 1999) to the building of the Hellenides Mountain Belt and its subsequent collapse
	173	in the wake of the Early Cenozoic collision between Adria and Pelagonia domains (Handy et al., 2010).
	174	A series of metamorphic core complexes emplaced in the North Aegean Domain from the Late Eocene
	175	to the Middle Miocene (Rhodope Core complex, 45-Myrs-old; North Cycladic Detachment System, 15-
	176	20 Myrs-old; Jolivet &
		; namely the Strymon, Orfanos, Prinos, Drama, Sandanski,
	164	Mygdonia basins and grabens) formed in the Serravalian segmenting the Rhodope Metamorphic Core
	165	Complex until the Early Pliocene (Brun & Sokoutis, 2018). Traces of Late Miocene extension and

of the North Aegean Domain 247 4.1. The pre-Messinian period and the Messinian Event 248

  Field studies in the Thermaïkos, Thrace and Saros Basins document two Eocene to Oligocene silici-the North Aegean Domain, with a major angular unconformity at the Oligocene-Miocene boundary 252[START_REF] Beniest | Interaction 733 between trench retreat and anatolian escape as recorded by neogene basins in the northern Aegean Sea. 734[END_REF][START_REF] Varesis | Cenozoic marine basin evolution in the western North Aegean 1054 Trough margin: seismic stratigraphic evidence[END_REF]. Industrial wells located in the Prinos Basin During the Miocene, fluvial and floodplain deposits cover the North Aegean

	242 243 244 245 246 254 255 256 257 258 -Late Miocene Unit: 269 Piper & Anastasakis, 2013), we here focus on the major unconformities corresponding to the main tectonic episodes related to the evolution of the North Anatolian Shear Zone, i.e. the unconformities corresponding to a significant tilt of the seafloor. (Proedrou & Papaconstantinou, 2004) provide precise constraints on the ages of the geological events related to the Messinian Salinity Crisis, with the salt mobile unit dated between 5.97 and 5.33 Ma, and earliest traces of the Messinian stage dated around 7.15 Ma (Karakitsios et al., 2017). We identify on the seismic dataset the contact between the Late Miocene Unit and the Messinian Event according to the following criteria: 270 4.2. Plio-Pleistocene Period 4-Stratigraphy 253 271

, Papatheodorou 237 et al., 1993)

.

238

The clastic input to the North Aegean Sea implies that most of the structures related to the North

239

Anatolian Fault are growth structures. The timing of formation of the strike-slip structures is constrained 240 from the age of onset of the fanning of the sediments. Although many second-order unconformities 241 linked to periodic sea-level and climatic variations are encountered in the study area

[START_REF] Lykousis | Sea-level changes and shelf break prograding sequences during the last 400 ka in 919 the Aegean margins: subsidence rates and palaeogeographic implications[END_REF] 259 Domain (Melinte-Dobrinescu et al., 2009;[START_REF] Suc | Marine gateway vs. fluvial stream within the Balkans from 6 to 5 Ma[END_REF]

. Drilling sites in the Prinos Basin that reach 260 Tortonian layers document an alternation of marine shales and turbidites in a distal marine environment, 261 followed by sandstone with marl and coal intercalations

[START_REF] Karakitsios | Messinian salinity crisis record under 869 strong freshwater input in marginal, intermediate, and deep environments: the case of the North Aegean. 870 Palaegeography[END_REF] Varesis & Anastasakis, 262 2021)

. On seismic data, the Late Miocene Unit is expressed by a series of interbedded channel systems 263 (Fig.

7

).

264 -Messinian Event:

The Messinian is dominantly expressed as an erosive surface in the North Aegean 265 Domain (Fig.

7

), with a few evaporitic units scattered in some basins (e.g. Prinos;

Mascle & Martin, 266 1990;[START_REF] Proedrou | Prinos field-Greece, Aegean basin, structural traps: treatise of 967 petroleum geology, atlas of oil and gas fields[END_REF][START_REF] Proedrou | Prinos basin -a model for oil exploration[END_REF]

. Offshore Thermaïkos, the 267 thickness of the Messinian Unit displays important lateral variations, culminating at 0.8 s TWT

(Varesis 268 & Anastasakis, 2021)

.

  531horsetail and the subsequent splays propagate westwards. Accordingly, the en-échelon normal faults are 532 first captured in the overall horsetail structure in the east. The western en-échelon normal faults are 533 progressively captured within the horsetail structure during its maturation. While some grabens 534 associated to the en-échelon normal faults are captured by the oblique splays, others are crosscut by the 535 propagating main displacement zone. Once initiated, all the oblique splays remain active during the

	608	Seismic interpretation : M. Rodriguez; A. Janin; A. Lurin; C. Gorini; D. Sakellariou Figures:
	609	Geological expertise, integration of the results to the geological background: M. Rodriguez; D.
	610	Sakellariou; C. Gorini; P. Henry; C. Grall; A. Beniest; D. Fernandez Blanco; A. Rigo; C. Bulois; F.
	611	Chanier; F. Caroir; L. Lepourhiet
	612
	613	Data availability:
	614	Seismic reflexion dataset available on request to Dr. M. Rodriguez (rodriguez@geologie.ens.fr) and Dr
	615	M. Delescluse (delescluse@geologie.ens.fr).
	616	Multibeam dataset available on emodnet https://emodnet.ec.europa.eu/en/bathymetry
	617
	618
	536 619	lifetime of the horsetail.
	537 620
	538 621	6-2. The Plio-Pleistocene transition from a wide North Anatolian Shear Zone to a localized North
	539 622	Anatolian Fault
	540 623	Our structural analysis further highlights the Late Pliocene change in stress regime (Lyberis, 1984) at
	541 624	the scale of the North Aegean Domain (Fig. 21). From the Serravalian to the Late Pliocene, the North
	542 625	Anatolian Shear Zone consisted in a diffuse system of en-échelon normal faults connected through
	543 626	dextral transfer faults, thereby isolating a series of basins. These basins include a set of Late Miocene-
	544 627	Early Pliocene basins compartimentalizing the Rhodope Core complex (Brun & Sokoutis, 2018) and the
	545 628	series of basins identified at sea in the vicinity of the North Aegean Trough, including the Athos and
	546 629	Venus grabens, deactivated at 2.8 Ma (Fig. 21a).
	547 630	Our reconstructions at 2 and 1.3-0.8 Ma (Fig. 21b-c) show the period of transition from the wide shear
	548 631 637	zone to the two main branches of the North Anatolian Fault; i.e. the period of effective propagation of
	549 632 638	the North Anatolian Fault in the North Aegean Sea. This transition is roughly coeval with the
	633
	634
	635

550 deactivation of the South Marmara Fault dated by Le Pichon et al. (2015) and the subsequent activation 551 of the Main Marmara Fault. While propagating westward, the strike-slip segments of the North

Geophysical Journal International

dataset is complementary documented by a set of vintage seismic-reflection dataset collected in the 70's

. A second splay, referred to as the Athos Splay, runs at 40° with respect to the North

the Sithonia Splay (Fig.11). The westward increase of the subsidence corresponds to the transition

This framework of structural evolution of the horsetail terminations encountered in the North Aegean

Brun, J.-P. & Sokoutis, D., 2018. Core complex segmentation in North Aegean, a dynamic view.

Dietrich, V.J., Mercolli, I., Oberhänsli, R., 1988. Dazite, High-Alumina Basalte und Andesite als

Gueydan, F., Okay, A. I., Oberhänsli, R., Pourteau, A., Augier, R., Gadenne, L., Driussi, O., 2013.

and deformation fields in the North Aegean domain, Greece, and implications for fault kinematics,