Floor-age constraining of a tectonic paroxysm of the Pyrenean orogen. Late Middle Eocene mammal age of a faulted karstic filling of the Quercy phosphorites,south-western France

Abstract

Breaking effects of a Pyrenean compressive tectonic phase are recognised in northern Pyrenean foreland, such as in the Quercy Jurassic limestone platform. The age of this phase still remains poorly constrained. In the so-called Quercy phosphorites area, within the Prajoux—Mémerlin paleokarst system near the city of Cajarc, a clay filling shows a strike slip fault effect, close to N-S direction. According to an analysis of the mammal fauna and inferred chronology of the polyphased paleokarst infilling, the age of the faulted clay is late Middle Eocene, with a mammal age estimate of 41.5 Ma. This provides reliable precise floor-age constraining for the involved sismo-tectonic paroxysm, seemingly related to the Pyrenean tectonic compressive phase. © 2000 Editions scientifiques et médicales Elsevier SAS     

Brittle tectonism in relation to the Palaeogene evolution of the Thulean/NE Atlantic domain: a study in Ulster

The tectonic effects of the Thulean mantle plume on the opening of the North Atlantic Ocean is still poorly understood. An analysis of the brittle deformation affecting the Late Cretaceous Chalk and Lower Tertiary igneous formations cropping out in Ulster (Northern Ireland), part of the Thulean Province, leads to the recognition of two tectonic phases. Each of these phases is characterized by different stress regimes with similar trends of the horizontal maximum principal stress σ_H. The first phase, syn-magmatic and dominated by NE–SW to ENE–WSW extension, occurred during the Palaeocene. It is followed by a second post-magmatic phase, characterized initially by a probably Eocene strike-slip to compressional palaeo-stress regime with σ₁ (=σ_H) trending NE–SW to NNE–SSW associated with the partial reactivation (as reverse faults) of normal faults formed during the first phase NE–SW extension. This episode is postdated by an Oligocene extension, with σ_H (=σ₂) still striking NNE–SSW/NE–SW, which reactivated Eocene strike-slip faults as nearly vertical dip-slip normal faults. This Palaeogene tectonic evolution is consistent with the tectonic evolution of similar age in western Scotland and in the Faeroe Islands. In particular, the post-magmatic NE–SW compression is here related to the ‘Faeroe compressive event’, which is related to the earliest stages of drift of the Greenland plate.     

Les manifestations tectoniques synsédimentaires associées à la compression éocène en Tunisie : implications paléogéographiques et structurales sur la marge Nord-Africaine

In central Tunisia, a synsedimentary tectonic episode has been pointed out through the tectonic movements affecting the Late Palaeocene–Early Eocene successions. This tectonic episode has controlled, to a large extent, the palaeogeographic setting of the area during that period and confirmed the important effect induced by the Pyrenean shortening phase on the edge of the African plate, which obviously has witnessed a common history with the southern part of the European plate. To cite this article: A. El Ghali et al., C. R. Geoscience 335 (2003).     

Variation with depth of the stress tensor anisotropy inferred from microfault analysis

In order to study the Pyrenean tectonic phase, a quantitative method of stress analysis using microfault measurements is used on a calcareous plateau located in southern France. The method developed here allows the determination of several tectonic events and the evaluation of (with σ σ₂ σ₃).The Pyrenean compression is seen to occur in two stages, confirming previous geological studies.A recent canyon allows the study of the variation with depth of the R ratio on a vertical cross-section (300 m). With a simple model of gravity and tectonic stresses, the vertical variation of R can be used to estimate quantitatively the Pyrenean tectonic stresses. For realistic values of the parameters in this model, the horizontal tectonic stresses are obtained in the following range: 50–200 bar for the maximum horizontal principal stress, 10–25 bar for the other horizontal stress.These results seem to be consistent with in situ stress measurements, but they are much lower than those predicted by experimental rock mechanics.     

车镇地区下古生界碳酸盐岩潜山岩溶模式初探

构造分析和地层研究表明,潜山范围内岩溶垂向发育有限,但是潜山周缘岩溶深度很大。采用岩石学、地球化学分析等方法,对研究区岩溶作用进行了深入分析。共识别出3期岩溶作用,即寒武系冶里亮甲山组-凤山组沉积期岩溶、加里东期岩溶和印支燕山期岩溶。初步探讨了3期岩溶机制:沉积期古岩溶受控于沉积、成岩作用,以大气水、海水混合白云石化作用所形成的储集空间最为有利;加里东期古岩溶介质为大气水,以地表溶蚀为主,岩溶缝、孔、洞多为后期石炭-二叠系泥岩所充填;印支燕山期古岩溶为研究区主要岩溶发育期,受构造运动、内幕地层控制,岩溶介质主要为大气水,混有地下热液影响。     

An Alleghenian orocline: the Asturian Arc,northwestern Spain

The Asturian Arc was produced in the Early Permian by a large E–W dextral strike–slip fault (North Iberian Megashear) which affected the Cantabrian and Palentian zones of the northeastern Iberian Massif. These two zones had previously been juxtaposed by an earlier Kasimovian NW–SE sinistral strike–slip fault (Covadonga Fault). The occurrence of multiple successive vertical fault sets in this area favoured its rotation around a vertical axis (mille-feuille effect). Along with other parallel faults, the Covadonga Fault became the western margin of a proto-Tethys marine basin, which was filled with turbidities and shallow coal-basin successions of Kasimovian and Gzhelian ages. The Covadonga Fault also displaced the West Asturian Leonese Zone to the northwest, dragging along part of the Cantabrian Zone (the Picos de Europa Unit) and emplacing a largely pelitic succession (Palentian Zone) in what would become the Asturian Arc core. The Picos de Europa Unit was later thrust over the Palentian Zone during clockwise rotation. In late Gzhelian time, two large E–W dextral strike–slip faults developed along the North Iberian Margin (North Iberian Megashear) and south of the Pyrenean Axial Zone (South Pyrenean Fault). The block south of the North Iberian Megashear and the South Pyrenean Fault was bent into a concave, E-facing shape prior to the Late Permian until both arms of the formerly NW–SE-trending Palaeozoic orogen became oriented E–W (in present-day coordinates). Arc rotation caused detachment in the upper crust of the Cantabrian Zone, and the basement Covadonga Fault was later resurrected along the original fault line as a clonic fault (the Ventaniella Fault) after the Arc was completed. Various oblique extensional NW–SE lineaments opened along the North Iberian Megashear due to dextral fault activity, during which numerous granitic bodies intruded and were later bent during arc formation. Palaeomagnetic data indicate that remagnetization episodes might be associated with thermal fluid circulation during faulting. Finally, it is concluded that the two types of late Palaeozoic–Early Permian orogenic evolution existed in the northeastern tip of the Iberian Massif: the first was a shear-and-thrust-dominated tectonic episode from the Late Devonian to the late Moscovian (Variscan Orogeny); it was followed by a fault-dominated, rotational tectonic episode from the early Kasimovian to the Middle Permian (Alleghenian Orogeny). The Alleghenian deformation was active throughout a broad E–W-directed shear zone between the North Iberian Megashear and the South Pyrenean Fault, which created the basement of the Pyrenean and Alpine belts. The southern European area may then be considered as having been built by dispersal of blocks previously separated by NW–SE sinistral megashears and faults of early Stephanian (Kasimovian) age, later cut by E–W Early Permian megashears, faults, and associated pull-apart basins.     

Palaeontological age and correlations of the Tertiary deposits of the NW Iberian Peninsula: the tectonic evolution of a broken foreland basin

Ages of Cenozoic sedimentary basins yield information that can be used to infer detailed spatial and temporal evolution in the Alpine foreland. The Tertiary deposits of the NW Iberian Peninsula comprise the remains of a broken foreland basin (the West Duero Basin). This work constrains the timing of tectonic fragmentation and the evolution of the western termination of the Alpine Pyrenean–Cantabrian Orogen (NW Iberian Peninsula). The discovery of Issiodoromys cf. minor 1 and Pseudocricetodon in the lower formation of the Tertiary depression of Sarria (the Toral Formation) constrains its age to the late Early Oligocene (MP23–MP25), similar to its age in the El Bierzo depression (MP24–MP25). Sedimentation initiated in the NE of the study area at Oviedo during the Middle Eocene (Bartonian–Early Priabonian MP16–MP17) and migrated towards the west and south during the Early Oligocene. The Toral Formation was deposited in a foreland basin that connected the present day outcrops of the El Bierzo, Sarria and As Pontes Tertiary depressions. The basin was segmented during the westward migration of structural deformation associated with the Orogen, and the subsequent uplift of the Galaico–Leoneses Mountains. The present‐day height above reference level of the base of the Toral Formation has been used to quantify Alpine segmentation that took place after Early Oligocene times. Minimum tectonic uplift assessed is 960 m in the Cantabrian Mountains and 1050 m in the Galaico–Leoneses Mountains. Copyright © 2013 John Wiley & Sons, Ltd.     

Crustal scale balanced cross-sections of the Pyrenees; discussion

From surface and subsurface data, line-length and area balancing were used to construct four balanced and restored sections of the Pyrenees. In the Mesozoic cover, a thin-skinned tectonic model is used. In the basement an anticlinal stack geometry is applied for the foreland part of the thrust nappes. We present and discuss three possible models for the deep structures of the belt: a thin-skinned tectonic model, a thick-skinned tectonic model and an inhomogeneous strain model. The thrusts steepen downwards and the displacements die out in ductile deformation deep in the section. Therefore, we use the inhomogeneous strain model and we equal-area balance the surface of the continental crust.Hanging-wall sequence diagrams are constructed taking into account (1) the strong N-S thickness variations of the Mesozoic cover related to the Cretaceous drift of Spain and (2) the related crustal thinning of the North Pyrenean Zone superimposed upon a previous late Hercynian rise of the lower crust.The Moho step at the vertical of the North Pyrenean Fault results from the thinning of the North Pyrenean Zone. The thickening of both the Axial Zone and the North Pyrenean Zone during the Eocene compressional event preserved the step geometry.Calculated values of the minimum shortening range from 55 km in the western part of the belt to 80 km in the eastern part. Most of the shortening occurs south of the North Pyrenean Fault in the eastern part (Axial Zone) and north of the North Pyrenean Fault in the western part (Labourd thrust).     

深成古岩溶不整合构造系统构造岩相学与金属成矿

古岩溶风化壳和岩溶构造与生态环境资源和地球演化关系密切,对深成的古岩溶构造系统识别属关键科学问题和技术难题。在滇黔桂地区地表水岩溶作用形成了山顶侵蚀面、岩溶侵蚀相系和砖红壤岩溶风化壳;地下水岩溶作用形成了垂向岩溶构造相带、缓倾斜的侧向岩溶构造相带、隐伏岩溶相带及隐伏岩溶前锋面,它们为表生岩溶构造的物质组成。进行大比例尺构造岩相学填图和解析研究认为云南个旧表生岩溶构造系统具有“顶面红土型岩溶风化壳、上部垂向岩溶构造带、中部缓倾斜的侧向岩溶构造带、底部不透水层(花岗岩和变海相火山岩顶面)”4个构造岩相学垂向分带模型,它们继承了先存多期次岩溶作用和岩浆热液岩溶作用。这种垂向分带模式有助于重建深成的古岩溶不整合构造系统。深成的古岩溶不整合构造系统由古气成热水、古火山热水、古火山喷发-岩浆侵位有关的复合热液岩溶作用等叠加在先存岩溶构造系统上形成,发育上覆岩性封闭层,经历了埋藏成岩、热液叠加成岩和层间滑脱构造叠加改造等,具有显著多期次的热流体叠加改造和再造作用。深成古岩溶不整合构造系统属重要油气储层、(非)金属矿产的储集层。对云南个旧地区中—新生代岩溶构造系统、新疆乌拉根地区古近纪热水岩溶不整合构...     

Large-scale distributed deformation controlled topography along the western Africa–Eurasia limit: Tectonic constraints

In the interior of the Iberian Peninsula, the main geomorphic features, mountain ranges and basins, seems to be arranged in several directions whose origin can be related to the N–S plate convergence which occurred along the Cantabro–Pyrenean border during the Eocene–Lower Miocene time span. The Iberian Variscan basement accommodated part of this plate convergence in three E–W trending crustal folds as well as in the reactivation of two left-lateral NNE–SSW strike-slip belts. The rest of the convergence was assumed through the inversion of the Iberian Mesozoic Rift to form the Iberian Chain. This inversion gave rise to a process of oblique crustal shortening involving the development of two right lateral NW–SE shear zones. Crustal folds, strike-slip corridors and one inverted rift compose a tectonic mechanism of pure shear in which the shortening is solved vertically by the development of mountain ranges and related sedimentary basins. This model can be expanded to NW Africa, up to the Atlasic System, where N–S plate convergence seems also to be accommodated in several basement uplifts, Anti-Atlas and Meseta, and through the inversion of two Mesozoic rifts, High and Middle Atlas. In this tectonic situation, the microcontinent Iberia used to be firmly attached to Africa during most part of the Tertiary, in such a way that N–S compressive stresses could be transmitted from the collision of the Pyrenean boundary. This tectonic scenario implies that most part of the Tertiary Eurasia–Africa convergence was not accommodated along the Iberia–Africa interface, but in the Pyrenean plateboundary. A broad zone of distributed deformation resulted from the transmission of compressive stresses from the collision at the Pyrenean border. This distributed, intraplate deformation, can be easily related to the topographic pattern of the Africa–Eurasia interface at the longitude of the Iberian Peninsula.Shortening in the Rif–Betics external zones – and their related topographic features – must be conversely related to more “local” driven mechanisms, the westward displacement of the “exotic” Alboran domain, other than N–S convergence. The remaining NNW–SSE to NW–SE, latest Miocene up to Present convergence is also being accommodated in this zone straddling Iberia and Morocco, at the same time as a new ill-defined plate boundary that is being developed between Europe and Africa.     

A structural interpretation of a section of the Gavarnie nappe and its implications for Pyrenean geology

The Gavarnie nappe is a feature of the Tertiary Pyrenean orogen and is shown to consist of at least two thrust sheets of Palaeozoic rocks which are overlain by a southward-dipping sequence of Cretaceous and Eocene sediments, showing folded thrust structures. The Gavarnie nappe covers a basement and Mesozoic cover-rock sequence which is exposed in the tectonic windows of La Larri and the Troumouse Cirque. Here, previously unrecognized thrusts involving basement were responsible for folding the overlying Gavarnie nappe. These basement-involved thrusts climb up section westwards giving a westward lowering of the Gavarnie thrust along strike. The structural evolution of the Gavarnie nappe in a region extending from Heas in France to the Valle de Pineta in Spain can be explained in terms of a piggy-back thrusting sequence. On a regional scale, thrust-tectonic models may be used to explain the double vergence of the Pyrenean chain where early southward-directed thrusting was responsible for structures in the South Pyrenean zone. A later northward-directed back thrusting event, or rotation of southward-directed thrust sheets by the stacking of lower thrust horses, can explain the steepness of structures in the axial zone and the northward-verging North Pyrenean thrust zone. Both models suggest that prior to the Pyrenean orogeny, some of the Hercynian structures in the axial zone were flatter lying, and have been rotated to their present steepness during the Pyrenean orogeny.     

Alpine remagnetization and tectonic rotations in the French Pyrenees

A palaeomagnetic study of the 100 to 90 m.y. old alkaline igneous rocks of the French Pyrenees has in part revealed large between-site scatter caused by highly variable declination. Magnetomineralogical evidence suggests that the original titano-magnetite has undergone variable low-temperature oxidation through martitization and maghemitization processes, suggesting that the rocks have been remagnetized. When viewed in the context of the Upper Cretaceous–Lower Tertiary inclination pattern based on Portuguese palaeomagnetic data, it is concluded that the rocks most likely acquired their present magnetization during early Campanian–Maastrichtian time, i.e. 20-30 m.y. after their original cooling. On the other hand, this magnetization postdates a major phase of late Cretaceous compressive deformation. Subsequent strike-slip movement along the Pyrenean zone in the Lower Tertiary led to variable rotation of cover units along the orogenic belt, producing the inconsistent palaeomagnetic declination picture presently observed. It is concluded that the geological history of the alkaline rocks of the French Pyrenees, from the magmatic stage to the subsequent events of remagnetization and tectonic deformation, is strongly associated with the Alpine-age rotational instability of Iberia. The principal kinematic history of the Peninsula comprised ca. 40° counterclockwise rotation (relative to Europe) during Cenomanian– Turonian time (100–90 m.y. ago) followed by ca. 70° clockwise rotation in the early Campanian (ca. 75 m.y. ago).     

青海贵德盆地晚新生代沉积演化与青藏高原北部隆升

青海贵德盆地发育巨厚的新生代地层,并含较丰富的重要哺乳动物化石,对确定盆地及周边相似地层的年代和研究高原隆升过程具有重要的科学意义。本文结合哺乳动物采用典型剖面精确古地磁测年为基础的时间框架,对近11 Ma BP以来盆地沉积相进行了分析,划分出19个沉积岩相和湖泊、三角洲、辫状河流、水下扇三角洲和水上洪积扇5个沉积环境,以及8个沉积演化阶段。通过盆地沉积对构造隆升的响应探讨表明:>11～7.65Ma BP为高原构造稳定期,7.65～3.6Ma BP高原具阶段性逐步隆升构造特征,3.6～>2.6 Ma BP为高原整体快速隆升,2.6Ma BP左右高原大规模挤压断陷,1.8 Ma BP左右高原大规模整体快速隆升并使贵德盆地古湖被切穿排干,黄河在此诞生。     

Structural evolution of the Tuscan Nappe in the southeastern sector of the Apuan Alps metamorphic dome (Northern Apennines,Italy)

Structural analysis carried out in the Tuscan Nappe (TN) in the southeastern sector of the Apuan Alps highlights a structural evolution much more complex than that proposed so far. The TN has been deformed by structures developed during four deformation phases. The three early phases resulted from a compressive tectonic regime linked to the construction of the Apenninic fold‐and‐thrust‐belt. The fourth phase, instead, is connected with the extensional tectonics, probably related to the collapse of the belt and/or to the opening of the Tyrrhenian Sea. Our structural and field data suggest the following. (1) The first phase is linked to the main crustal shortening and deformation of the Tuscan Nappe in the internal sectors of the belt. (2) The second deformation phase is responsible for the prominent NW–SE‐trending folds recognized in the study area (Mt. Pescaglino and Pescaglia antiforms and Mt. Piglione and Mt. Prana synforms). (3) The direction of shortening related to the third phase is parallel to the main structural trend of the belt. (4) The interference between the third folding phase and the earlier two tectonic phases could be related to the development of the metamorphic domes. The two directions of horizontal shortening induced buckling and vertical growth of the metamorphic domes, enhancing the process of exhumation of the metamorphic rocks. (5) The exhumation of the Tuscan Nappe occurred mostly in a compressive tectonic setting. A new model for the exhumation of the metamorphic dome of the Apuan Alps is proposed. Its tectonic evolution does not fit with the previously suggested core complex model, but is due to compressive tectonics. Copyright © 2004 John Wiley & Sons, Ltd.     

桂西古岩溶型金矿地质特征

桂西地区自寒武纪至三叠纪发生了多次古侵蚀作用，已大致查明有11次沉积间断时期形成了古岩溶面，其中两次大范围的构造隆升及一次在裂谷拉张期相对持续时间较长的古水下岩溶作用，造成古生界为主的碳酸盐岩系溶蚀尤其强烈，形成大面积的古岩溶面。这些古岩溶面对微细粒浸染型金矿的控制非常明显，部分金矿床虽未直接产于古岩溶面，但其控矿断裂带多与深部古岩溶隐伏带有关系，古岩溶面起到间接控矿作用；主要金矿化的岩性有细碎屑岩、硅质岩、基性及中酸性侵入及喷出岩等，均为硅铝质岩系，而矿化最终底板均为古岩溶面下的碳酸盐岩系。金矿形成机制为：古岩溶潜山构造在后期叠加构造蚀变时，由地层淋滤出的金在古岩溶面及其影响带发生再富集而成矿。     

A new synthesis of Pyrenean seismicity and its tectonic implications

The Pyrenean range, which results from the convergence of the Iberian and Eurasian plates along the North Pyrenean fault, exhibits a permanent seismic activity with moderate magnitude events. From the end of the 1980s, seismic instrumentation has been deployed in the Pyrenees, making now possible the computation of improved seismicity maps. We have gathered all the arrival times published for the period 1989–1996 by the different Spanish and French institutions in charge of the seismic survey of the range, and reprocessed them in an homogeneous way, in order to obtain a coherent seismicity map over the whole range. Particular attention has been paid to the evaluation of the quality of the locations and to the focal depth determinations. The comparison with previous maps of the Pyrenean seismicity reveals significant improvements in both the quality of locations and the threshold of detection. The new seismicity map reveals that the North Pyrenean fault is active only in the western part of the range. In the central and eastern parts, the seismicity involves other tectonic units such as the Maladeta and Canigou granitic massifs, the North Pyrenean Frontal Thrust, the Tet fault and the volcanic units in Catalonia. Despite the short time interval considered, this new seismicity file may be a valuable tool for future tectonic studies.     

Ophicalcites from the northern Pyrenean belt: a field,petrographic and stable isotope study

Brecciated and fractured peridotites with a carbonate matrix, referred to as ophicalcites, are common features of mantle rocks exhumed in passive margins and mid-oceanic ridges. Ophicalcites have been found in close association with massive peridotites, which form the numerous ultramafic bodies scattered along the North Pyrenean Zone (NPZ), on the northern flank of the Pyrenean belt. We present the first field, textural and stable isotopic characterization of these rocks. Our observations show that Pyrenean ophicalcites belong to three main types: (1) a wide variety of breccias composed of sorted or unsorted millimeter- to meter-sized clasts of fresh or oxidized ultramafic material, in a fine-grained calcitic matrix; (2) calcitic veins penetrating into fractured serpentine and fresh peridotite; and (3) pervasive substitution of serpentine minerals by calcite. Stable isotopic analyses (O, C) have been conducted on the carbonate matrix, veins and clasts of samples from 12 Pyrenean ultramafic bodies. We show that the Pyrenean ophicalcites are the product of three distinct genetic processes: (1) pervasive ophicalcite resulting from relatively deep and hot hydrothermal activity; (2) ophicalcites in veins resulting from tectonic fracturing and cooler hydrothermal activity; and (3) polymictic breccias resulting from sedimentary processes occurring after the exposure of subcontinental mantle as portions of the floor of basins which opened during the mid-Cretaceous. We highlight a major difference between the eastern and western Pyrenean ophicalcites belonging, respectively, to the sedimentary and to the hydrothermal types. Our data set points to a possible origin of the sedimentary ophicalcites in continental endorheic basins, but a post-depositional evolution by circulation of metamorphic fluids or an origin from relatively warm marine waters cannot be ruled out. Finally, we discuss the significance of such discrepancy in the characteristics of the NPZ ophicalcites in the frame of the variable exhumation history of the peridotites all along the Pyrenean realm.     

Sedimentation,tectonism and volcanism relationships in two Andean basins of southern Peru

The intermontane basins of the Central Andes, formed from the first episode of the andine tectonic (peruvian phase, Santonian), are characterized by a clastic continental sedimentation, settled in a compressive tectonic context and containing volcanic intercalations. The two basins presented in this paper, have distinct ages and a different geodynamic context, each:

1. The Cuzco-Sicuam Basin, Maestrichtian-Paleocene in age, is a back-arc basin. A coarse grained red bed sedimentation appeared at the same time as the synsedimentary tectonic and volcanic activity increased in the source area.
2. The Moquegua Basin, Oligocene in age, is a fore-arc basin. After a compressive phase, the northeastern border of the basin shows high mobility, characterized by superposed alluvial fans. Within the basin, the coarse grained sediments are associated with volcanic tuffs.

In the two basins, the tectonism, the volcanism and the coarse grained sedimentation occured simultaneously. The coarse grained sedimentation does not appear to be linked with climatic changes, but with the increasing mobility of the source area. The relationship between tectonic regime and volcanic activity in the basin and in the source area is considered.     

Tectonics of the Northern Bresse region (France) during the Alpine cycle

Combining fieldwork and surface data, we have reconstructed the Cenozoic structural and tectonic evolution of the Northern Bresse. Analysis of drainage network geometry allowed to detect three major fault zones trending NE–SW, E–W and NW–SE, and smooth folds with NNE trending axes, all corroborated with shallow well data in the graben and fieldwork on edges. Cenozoic paleostress succession was determined through fault slip and calcite twin inversions, taking into account data of relative chronology. A N–S major compression, attributed to the Pyrenean orogenesis, has activated strike-slip faults trending NNE along the western edge and NE–SW in the graben. After a transitional minor E–W trending extension, the Oligocene WNW extension has structured the graben by a collapse along NNE to NE–SW normal faults. A local NNW extension closes this phase. The Alpine collision has led to an ENE compression at Early Miocene. The following WNW trending major compression has generated shallow deformation in Bresse, but no deformation along the western edge. The calculation of potential reactivation of pre-existing faults enables to propose a structural sketch map for this event, with a NE–SW trending transfer fault zone, inactivity of the NNE edge faults, and possibly large wavelength folding, which could explain the deposit agency and repartition of Miocene to Quaternary deformation.