Field Relationships, Geochemistry, Zircon Ages and Evolution of a Late Archaean to Palaeoproterozoic Lower Crustal Section in the Hengshan Terrain of Northern China

The Hengshan complex forms part of the central zone of the North China Craton and consists predominantly of ductilely-deformed late Archaean to Palaeoproterozoic high-grade, partly migmatitic, granitoid orthogneisses, intruded by mafic dykes of gabbroic composition. Many highly strained rocks were previously misinterpreted as supracrustal sequences and represent mylonitized granitoids and sheared dykes. Our single zircon dating documents magmatic granitoid emplacement ages between 2.52 Ga and 2.48 Ga, with rare occurrences of 2.7 Ga gneisses, possibly reflecting an older basement. A few granitic gneisses have emplacement ages between 2.35 and 2.1 Ga and show the same structural features as the older rocks, indicating that the main deformation occurred after -2.1 Ga. Intrusion of gabbroic dykes occurred at -1920 Ma, and all Hengshan rocks underwent granulite-facies metamorphism at 1.88-1.85 Ga, followed by retrogression, sheafing and uplift. We interpret the Hengshan and adjacent Fuping granitoid gneisses as the lower, plutonic, part of a late Archaean to early Palaeoproterozoic Japan-type magmatic arc, with the upper, volcanic part represented by the nearby Wutai complex. Components of this arc may have evolved at a continental margin as indicated by the 2.7 Ga zircons. Major deformation and HP metamorphism occurred in the late Palaeoproterozoic during the Luliang orogeny when the Eastern and Western blocks of the North China Craton collided to form the Trans-North China orogen. Shear zones in the Hengshan are interpreted as major lower crustal discontinuities post-dating the peak of HP metamorphism, and we suggest that they formed during orogenic collapse and uplift of the Hengshan complex in the late Palaeoproterozoic （〈1.85 Ga）.     

~(40)Ar-~(39)Ar Age of K-feldspar from K-feldspar Granite in the Qiaohuote Copper Deposit, Bayanbulak, Xinjiang, and Its Geological Significance

By using the 40Ar-39Ar chronological method to date K-feldspar from K-feldspar granite in the Qiaohuote copper district, the authors obtained a plateau age of 274.78±0.44 Ma and an isochron age of 272.7±3.0 Ma. Because there is no tectonic deformation overprinted or hydrothermal alteration in the K-feldspar granite intrusion after its emplacement, the 40Ar-39Ar age represents the crystallization age of K-feldspar in K-feldspar granite, i.e. the late crystallization age of the K-feldspar granite intrusion, which indicates that the K-feldspar granite formed in the intraplate extensional stage during the Early Permian. Moreover, based on the spatial relationship between the K-feldspar granite intrusion and copper orebodies, variations of copper ore grade, REE characteristics of K-feldspar granite and copper ores, and H and O isotopic compositions of fluid inclusions in copper ores, the metallogenesis of the Qiaohuote copper deposit is directly related to intrusive activities of the K-feldspar granite, and     

Kinematics of syn-tectonic unconformities and implications for the tectonic evolution of the Hala'alat Mountains at the northwestern margin of the Junggar Basin,Central Asian Orogenic Belt

The Hala’alat Mountains are located at the transition between the West Junggar and the Junggar Basin.In this area,rocks are Carboniferous,with younger strata above them that have been identified through well data and high-resolution 3D seismic profiles.Among these strata,seven unconformities are observed and distributed at the bases of:the Permian Jiamuhe Formation,the Permian Fengcheng Formation,the Triassic Baikouquan Formation,the Jurassic Badaowan Formation,the Jurassic Xishanyao Formation,the Cretaceous Tugulu Group and the Paleogene.On the basis of balanced sections,these unconformities are determined to have been formed by erosion of uplifts or rotated fault blocks primarily during the Mesozoic and Cenozoic.In conjunction with the currently understood tectonic background of the surrounding areas,the following conclusions are proposed:the unconformities at the bases of the Permian Jiamuhe and Fengcheng formations are most likely related to the subduction and closure of the Junggar Ocean during the late Carboniferous-early Permian;the unconformities at the bases of the Triassic Baikouquan and Jurassic Badaowan formations are closely related to the late Permian-Triassic Durbut sinistral slip fault;the unconformities at the bases of the middle Jurassic Xishanyao Formation and Cretaceous Tugulu Group may be related to reactivation of the Durbut dextral slip fault in the late Jurassic-early Cretaceous,and the unconformity that gives rise to the widely observed absence of the upper Cretaceous in the northern Junggar Basin may be closely related to large scale uplift.All of these geological phenomena indicate that the West Junggar was not calm in the Mesozoic and Cenozoic and that it experienced at least four periods of tectonic movement.     

Chemostratigraphy of Flood Basalts in the Garze-Litang Region and Zongza Block: Implications for Western Extension of the Emeishan Large Igneous Province, SW China

The Late Permian Emeishan Large Igneous Province (ELIP) is commonly regarded as being located in the western part of the Yangtze craton, SW China, with an asymmetrical shape and a small area. This area, however, is just a maximum estimation because some parts of the ELIP were not recognized or dismembered and destroyed during the Triassic to Cenozoic tectonism. In this paper, the chemostratigraphical data of the Zongza block, the Garze-Litang belt and the Songpan-Garze block suggest that the Late Permian basalts in these areas have remarkable similarities to the ELIP basalts in petrography and geochemistry. Flood basalts in the Sanjiangkou area are composed of the lower part of the low-Ti (LT) tholeiite and the upper part of the high-Ti (HT) tholeiite, which is the same as the flood basalts on the western margin of the Yangtze craton. Flood basalts in the Zongza and Songpan-Garze areas, which are far from the Yangtze craton, consist of HT tholeiite only. This is the same as the flood basalts within the Y     

Permo-Triassic high-pressure metamorphism in the central western Korean Peninsula,and its link to Paleo-Tethyan Ocean closure: Key issues revisited

Permo-Triassic high-pressure(HP) mafic granulites, together with the Bibong retrogressed eclogite,preserved along the central western Korean Peninsula provide important insights into the Late Permian to Triassic collisional orogeny in northeast Asia. The metamorphic pressureetemperatureetime(P-T-t)paths of these rocks, however, remain poorly constrained and even overestimated, owing to outdated geothermobarometers and inaccurate isopleth techniques. Here we evaluate the metamorphic Pe T conditions of Triassic HP mafic granulites including those in Baekdong, Sinri and Daepan and the Bibong Triassic retrogressed eclogite in the Hongseong area, and the Permo-Triassic Samgot mafic granulite in the Imjingang Belt of the central western Korean Peninsula through the application of modern phase equilibria techniques. The Baekdong and Samgot mafic granulites and the Bibong retrogressed eclogite yield a range of 12.0 -16.0 kbar and 800 -900℃, representing HP granulite facies conditions. The Sinri and Daepan granulites from the Hongseong area show relatively lower grade metamorphic conditions between HP granulite and normal granulite facies, and are characterized by sub-isothermal decompression during exhumation. The similarities in the metamorphic ages and the post-collisional igneous activity from the central western Korean Peninsula indicate that the Triassic ages represent the retrograde stage of the metamorphic Pe T paths. In contrast, the Late Permian metamorphic ages, which are older than protolith ages of the post-collisional igneous rocks, correspond to the possible prograde stage of metamorphism. The P-T-t paths presented in this paper, together with the metamorphic ages and post-orogenic igneous events reported from these areas suggest trace of the subduction, accretion and exhumation history, and indicate a tectonic linkage among the northeast Asian continents during the Paleo-Tethyan Ocean closure.     

Emplacement Mechanism of the Akebasitao Pluton: Implications for Regional Tectonic Evolution of West Junggar, NW China

Late Carboniferous to Early Permian A-type granites are extensively distributed throughout the West Junggar region, NW China, and the Akebasitao pluton is extremely distinguished among these plutons. In this paper, we reported new anisotropy of magnetic susceptible (AMS) data combine with detailed field study and audio magnetotelluric (AMT) sounding to assess the three-dimensional shape and magmatic emplacement mechanism of the Akebasitao pluton. The geological features and the AMT sounding indicate that the pluton had a slightly oblique movement of magma from northwest to southeast, which was most likely to correspond to an asymmetrical torch with a laccolith-shaped upper part, and a lower part formed by sub-vertical “root” that was located within its northwestern part, probably controlled by the NE-trending Anqi fault. The AMS fabrics of all the specimens reveal a low Pj value (mean of 1.02) and a low T value (mean of ?0.024), suggesting that the deformation of the AMS ellipsoid is relatively weak. The specimens exhibit both oblate and prolate shapes of the AMS ellipsoid. Magnetic lineations and foliations are randomly distributed throughout the pluton without any preferred orientation. These AMS patterns indicate that the pluton formed in a relatively stable structural environment with no regional extrusion. Therefore, we propose a complex emplacement process in which the magmas reached the shallower crust levels via deep-faults and subsequently occupied the room created by doming, accompanied by stoping near the pluton roof. Additionally, the regional tectonic setting was relatively stable during the emplacement of the Akebasitao pluton, indicating the termination of compressional orogeny during the late Late Carboniferous in the West Junggar region. This conclusion perfectly coincides with the regional tectonic paleogeography, magmatic system, and paleostress field.     

REVIEWS

Genesis of the so-called Bentong–Raub Suture of Malay Peninsula does not fit to the model of subduction-related collision. It has evolved from transpression tectonics resulting closure and exhumation of the inland basin which underwent extensive back-arc extension during Triassic. Crust having similar thickness (average ~35 km) below entire Malay Peninsula nagate collision of two separate continental blocks rather supports single continental block that collided with South China continental block during Permo-Triassic. Westward subduction of intervening sea (Proto South China Sea) below Malay Peninsula resulted in widespread I- and S-Type granitization and volcanism in the back-arc basins during Triassic. Extensive occurrence of Permo-Triassic Pahang volcanics of predominantly rhyolitic tuff suggest its derivation from back-arc extension. Back-arc extension, basin development and sedimentation of the central belt of the peninsula continued until Cretaceous. A-Type granite of metaluminous to peraluminous character indicates their emplacement in an intraplate tectonic setting. Malay Peninsula suffered an anticlockwise rotation due to the rifting of Luconia–Dangerous Grounds from the east Asia in the Late Cretaceous–Early Tertiary. Extensive ductile and brittle deformation including crustal segmentation, pull-apart fracturing and faulting occurred during the closure and exhumation of the basins developed in the peninsula during Late Cretaceous–Early Tertiary. Crustal shortening in the central belt of the peninsula has been accomodated through strike-slip displacement, shearing and uplift.     

广西花岗岩时代讨论

Distributed in Guangxi Province are granites of the Szipao, the Hsuehfengian and the other three periods. Hereynian and Indosinian granites are treated in this paper as produets of a single eycle because the Permian granitism in Guangxi is thought to be eontinuity of the late Paleozoic magmatism. Although the Darongshan granite is found to have intruded into the upper Permian, but it yields an age of 231--289 m.y. This discrepaney may be due to, among other things, an inappropriate age division between the Permian and Triassic periods as set in the International Geochronological Table, and to a strong contamination.     

Lower Triassic Inorganic Carbon Isotope Excursion in Chaohu, Anhui Province, China

This paper reports a Lower Triassic carbon isotope profile from the North Pingdingshan Section in Chaohu, Anhui Province, China, which was stituated in a deep part of the Lower Yangtze carbonate rapm. The δ(^13C) excursion shows two periods from the Permian-Triassic boundary to the lower Spathian substage, corresponding to the ecosystem undergoing evolution and recovery after the end-Permian mass extinction and related events.The first period starts at the δ(^13C) depletion caused by the mass extinction and evolves with a gradual δ(^13C) increase resulting from the development of some disaster taxa during the Induan. The strong Smithian δ(^13C) depletion in the second period might be formed by the collapse of the disaster ecosystem and the biotic recovery occurred with the explosive increase of bioproductivity in the Spathian. Thus the δ(^13C) excursion in the Lower Triassic expresses patterns of biotic evolution and recovery during the eratic ecosystem that followed the great end-Permian mass extinction.     

Geochronology,Petrogenesis and Tectonic Setting of the Late Jurassic I-type Granites in the North Qinling Orogenic Belt,Central China

The North Qinling Orogenic Belt(NQOB) is a composite orogenic belt in central China. It started evolving during the Meso–Neoproterozoic period and underwent multiple stages of plate subduction and collision before entering intra-continental orogeny in the Late Triassic. The Meso–Cenozoic intra-continental orogeny and tectonic evolution had different responses in various terranes of the belt, with the tectonic evolution of the middle part of the belt being particularly controversial. The granites...     

A Late Jurassic–Early Cretaceous metamorphic core complex,Strandja Massif,NW Turkey

In the eastern part of the Strandja Massif constituting the east end of the Rhodope Massif, the amphibolite facies basement rocks intruded by Permian metagranites are juxtaposed against the greenschist facies cover metasediments of Triassic-Middle Jurassic protolith age. The distinct metamorphic break between the basement and cover rocks requires a missing metamorphic section. The boundary between the two groups of rocks is a ductile to brittle extensional shear zone with kinematic indicators exhibiting a top to the E/NE shear sense. Footwall rocks are cut by weakly metamorphosed and foliated granite bodies which are clearly distinguished from the Permian metagranites by their degree of deformation, cross-cutting relations and syn-tectonic/kinematic character. Also, hangingwall rocks were intruded by unmetamorphosed and weakly foliated leucogranites. ⁴⁰Ar/³⁹Ar data indicate that the ductile deformation from 156.5 to 143.2 Ma (Middle Oxfordian-Earliest Berriasian) developed during the syn-tectonic plutonism in the footwall. Deformation, and gradual/slower cooling-exhumation survived until to 123 Ma (Barremian). The mylonitic and brittle deformation in the detachment zone developed during Oxfordian-Earliest Berriasian time (155.7–142.6 Ma) and Early Valanginian-Aptian time (136–118.7 Ma), respectively. Our new field mapping and first ⁴⁰Ar/³⁹Ar ages demonstrate the existence of an extensional core complex of Late Jurassic-Early Cretaceous age not previously described in the Rhodope/Strandja massifs.     

Deformation history and timing of granite emplacement in the Butchers Hill — Helenvale region,northern Hodgkinson Province,Queensland

Granite plutons of the Whypalla Supersuite in the Butchers Hill — Helenvale region of north Queensland were intruded into the upper crust of the Hodgkinson Formation during contractional deformation associated with the Permian‐Triassic Hunter‐Bowen Orogeny. A four‐stage structural history has been resolved for the area, with fabric overprinting relationships, porphyroblast‐matrix microstructural geometries and isotopic ages being consistent with granite emplacement during D₄ shortening at ca 274 Ma. Microstructural relationships suggest the possibility of a minor syn‐D₃ phase of granite emplacement. The deformation‐emplacement history of the Butchers Hill — Helenvale area is consistent with that recognised regionally for the Hodgkinson Province, indicating province‐wide synchronous syntectonic granite intrusion during a major phase of contractional deformation. Intense syn‐emplacement deformation partitioning was ongoing in the country rocks during progressive D₄ and was associated with upward translation of country rock from the microscale to the macroscale along D₄ cleavages and shears. Kinematic indicators show that this progressive uplift, at the scale of the area examined, was east‐side‐up.     

青海同仁县江里沟钨-铜多金属矿床地质特征和成矿模式

江里沟钨铜多金属矿床位于西秦岭西段,矿床形成时的大地构造背景为三叠纪南部大洋俯冲的岛弧带。矿区由主矿区和周围几个矿点组成,出露的地层主要为下三叠统隆务河群和下二叠统大关山群。多金属矿化主要与矿区南部一个多期侵位的复式花岗岩岩体有关。主矿区以钨、铜矽卡岩矿化为主,分布在岩体北西部附近围岩地层中,同时发现在岩体中有裂隙矿化、石英脉型矿化和浸染状矿化几种型式。主矿区具有典型的成矿分带性特征,表现在成矿元素分带、成矿蚀变分带和成矿构造分带。据此建立了矿床斑岩-矽卡岩-热液脉型综合成矿模式。     

内蒙古化德地区二叠纪—三叠纪侵入岩年代学及地球化学特征：对古亚洲洋东段构造演化的制约

本文对华北克拉通北缘中段内蒙古化德地区二叠纪—三叠纪5个花岗质侵入体进行了岩相学、地球化学、锆石U Pb年代学以及Sr Nd Hf同位素研究。结果表明本次所研究的岩体主要起源于华北克拉通古老下地壳的部分熔融,八音察汗岩体形成于早二叠世（276±1 Ma）,在岩浆上升过程中发生了岩浆混合作用;白音特拉岩体形成于中二叠世（270±1 Ma）,为地壳加厚作用下变质杂砂岩部分熔融形成的S型花岗岩;毛忽庆岩体形成于晚二叠世（254±1 Ma）,为I型花岗岩;张万良岩体与康家地岩体分别形成于早三叠世（248±1 Ma）和晚三叠世（229±1 Ma）,两者均为A型花岗岩。综合前人研究,本文认为研究区在早二叠世—晚三叠世经历了古亚洲洋向华北板块俯冲、俯冲 同碰撞、持续碰撞以及造山后的伸展4个阶段,古亚洲洋东段在研究区的闭合时间应为中二叠世晚期。     

广西海洋山花岗岩体侵位构造特征

花岗岩是大陆地壳的重要组成部分,是地球动力学演化的示踪剂。花岗岩体侵位构造的研究对于揭示花岗岩体的变形历史和侵位机制具有重要的科学价值。本文研究了海洋山花岗岩体的内部构造、与岩浆侵位应力有的围岩构造及热接触变质带特征,探讨了岩体和围岩的应变状态。研究发现,从岩浆侵位到冷凝固结,海洋山花岗岩体经历了液态流动、塑性变形和“半固态”冷凝阶段的演化。岩体各单元的应变类型分别是单轴压扁、平面应变、单轴压缩,     

Late Permian–early Middle Triassic back-arc basin development in West Qinling,China

The Late Permian–early Middle Triassic strata of the northern West Qinling area, northeastern Tibetan Plateau, are composed of sediment gravity flow deposits. Detailed sedimentary facies analysis indicates these strata were deposited in three successive deep-marine environments. The Late Permian–early Early Triassic strata of the Maomaolong Formation and the lowest part of the Longwuhe Formation define a NW–SE trending proximal slope environment. Facies of the Early Triassic strata composing the middle and upper Longwuhe Formation are consistent with deposition in a base-of-slope apron environment, whereas facies of the Middle Triassic Anisian age Gulangdi Formation are more closely associated with a base-of-slope fan depositional environment. The lithofacies and the spatial–temporal changes in paleocurrent data from these strata suggest the opening of a continental margin back-arc basin system during Late Permian to early Middle Triassic time in the northern West Qinling. U–Pb zircon ages for geochemically varied igneous rocks with diabasic through granitic compositions intruded into these deep-marine strata range from 250 to 234 Ma. These observations are consistent with extensional back-arc basin development and rifting between the Permian–Triassic Eastern Kunlun arc and North China block during the continent–continent collision and underthrusting of the South China block northward beneath the Qinling terrane of the North China block. Deep-marine sedimentation ended in the northern West Qinling by the Middle Triassic Ladinian age, but started in the southern West Qinling and Songpan-Ganzi to the south. We attribute these observations to southward directed rollback of Paleo-Tethys oceanic lithosphere, continued attenuation of the West Qinling on the upper plate, local post-rift isostatic compensation in the northern West Qinling area, and continued opening of a back-arc basin in the southern West Qinling and Songpan-Ganzi. Rollback and back-arc basin development during Late Permian to early Middle Triassic time in the West Qinling area explains: the truncated map pattern of the Eastern Kunlun arc, the age difference of deep-marine sediment gravity flow deposits between the Late Permian–early Middle Triassic northern West Qinling and the late Middle Triassic–Late Triassic southern West Qinling and Songpan-Ganzi, and the discontinuous trace of ophiolitic rocks associated with the Anyemaqen-Kunlun suture.     

U–Pb geochronology and petrology of the late Paleozoic Gil Marquez pluton: magmatism in the Variscan suture zone,southern Iberia,during continental collision and the amalgamation of Pangea

The origin of plutonic complexes that stitch suture zones developed during collision is not well understood. In southern Iberia, the Pulo du Lobo suture zone (PDLZ) is intruded by the syn- to postcollisional Gil Marquez pluton (GMP), thought to be part of the Sierra Norte Batholith. U–Pb (LA-ICPMS, zircon) data on various phases of the GMP yield from oldest to youngest: (1) a 354.4 ± 7.6 Ma unfoliated gabbro; (2) a 345.6 ± 2.5 Ma foliated intermediate phase; (3) a 346.5 ± 5.4 Ma unfoliated porphyritic granite; (4) a 335.1 ± 2.8 Ma unfoliated biotite granite. This sequence is consistent with cross-cutting relationships observed in the field. The range in ages is consistent with interpretations that the GMP is part of the composite (ca. 350–308 Ma) SNB. Inherited ages preserved in the GMP intermediate and felsic phases indicate that its magmas traversed through South Portuguese Zone and PDLZ crust during emplacement. The ca. 345 Ma emplacement of the late kinematic foliated intermediate phase constrains the age of late-stage strike slip deformation within the PDLZ, and the lack of a foliation in the older gabbro indicates that is was not proximal to a shear zone neither at the time of emplacement, nor during its subsequent history. The unfoliated porphyritic granite and unfoliated biotite granite cut the foliation of the intermediate phase indicating emplacement during the waning stages of collision, while the ca. 335 Ma biotite granite intrudes the Santa Ira Flysch, thereby providing a tight constraint for the latest stage of deformation in the PDLZ.     

兴蒙造山带南缘东段和龙地区Ⅰ型花岗岩锆石U-Pb定年、地球化学特征及其地质意义

本文对兴蒙造山带南缘东段和龙地区八家子岩体和勇新岩体进行了岩相学、地球化学、LA-ICP-MS U-Pb定年和Sr-Nd同位素研究,以便制约该区的区域构造演化。锆石测年结果显示,八家子石英闪长岩结晶年龄为257.8±0.9Ma,形成于晚二叠世早期,勇新二长花岗岩的结晶年龄为243.2±1.1Ma和238.5±2.8Ma,形成于中三叠世。八家子石英闪长岩为钠质钙碱系列、偏铝质的Ⅰ型花岗岩类,富集轻稀土(LREEs)和大离子亲石元素(LILEs,Cs、Ba、K和Sr),亏损重稀土(HREEs)和高场强元素(HFSEs,Nb、Ta和P),结合Sr-Nd同位素特征显示其为壳源成因,形成于俯冲环境下,是玄武质下地壳部分熔融的产物。勇新二长花岗岩富硅、铝和钾,为高钾钙碱性系列、偏铝质-弱过铝质的Ⅰ型花岗岩,富集轻稀土(LREEs)及大离子亲石元素(LILEs,Cs、K、Sr),亏损重稀土(HREEs)和高场强元素(HFSEs,Nb、Ta、P和Ti),结合Sr-Nd同位素特征显示其为壳源成因,形成于同碰撞环境下,是玄武质下地壳部分熔融的产物。花岗岩的侵位反映了研究区晚二叠世早期古亚洲洋板块俯冲于华北克拉通之下,中三叠世华北克拉通与兴凯地块碰撞拼合,说明古亚洲洋应闭合于晚二叠世末期-早三叠世期间。     

40Ar/39Ar hornblende dating of a microgranodiorite dyke: implications for early Permian extension in the Moldanubian Zone of the Bohemian Massif

Laser fusion ⁴⁰Ar/³⁹Ar ages of titanian pargasite from a microgranodiorite dyke swarm in the southern Bohemian Massif effectively date the early Permian (late Autunian) emplacement of dykes into a cool Moldanubian crust. This intrusion represents the youngest magmatic phase recorded in this part of the Moldanubian Zone. Strontium and neodymium isotopic ratios of microgranodiorites point to magma derivation from re-melting the lower crustal rocks with a possible component of upper mantle composition. Spatial and temporal association of the dykes with movements on a major N-S (NNE-SSW) tectonic discontinuity (Blanice-Kaplice-Rödl fault zone) suggests that their emplacement corresponds to the maximum age of fault movements associated with the E/W-oriented extension in this part of the Bohemian Massif.     

Relationships between magmatism and extension along the Autun–La Serre fault system in the Variscan Belt of the eastern French Massif Central

The ENE–WSW Autun Shear Zone in the northeastern part of the French Massif Central has been interpreted previously as a dextral wrench fault. New field observations and microstructural analyses document a NE–SW stretching lineation that indicates normal dextral motions along this shear zone. Further east, similar structures are observed along the La Serre Shear Zone. In both areas, a strain gradient from leucogranites with a weak preferred orientation to highly sheared mylonites supports a continuous Autun–La Serre fault system. Microstructural observations, and shape and lattice-preferred orientation document high-temperature deformation and magmatic fabrics in the Autun and La Serre granites, whereas low- to intermediate-temperature fabrics characterize the mylonitic granite. Electron microprobe monazite geochronology of the Autun and La Serre granites yields a ca. 320 Ma age for pluton emplacement, while mica ⁴⁰Ar-³⁹Ar datings of the Autun granite yield plateau ages from 305 to 300 Ma. The ca. 300 Ma ⁴⁰Ar-³⁹Ar ages, obtained on micas from Autun and La Serre mylonites, indicate the time of the mylonitization. The ca. 15-Ma time gap between pluton emplacement and deformation along the Autun–La Serre fault system argue against a synkinematic pluton emplacement during late orogenic to postorogenic extension of the Variscan Belt. A ductile to brittle continuum of deformation is observed along the shear zone, with Lower Permian brittle faults controlling the development of sedimentary basins. These results suggest a two-stage Late Carboniferous extension in the northeastern French Massif Central, with regional crustal melting and emplacement of the Autun and La Serre leucogranites around 320 Ma, followed, at 305–295 Ma, by ductile shearing, normal brittle faulting, and subsequent exhumation along the Autun–La Serre transtensional fault system.