^(40)Ar/^(39)Ar Thermochronological Constraints on the Timing of Collisional Orogeny in the Mian-Lite Collision Belt,Southern Qinling Mountains

Silurian, Devonian and Carboniferous geological bodies in the Mianxian-Lueyang (Mian-Lue) collisional belt (MLB) and its neighbouring areas, southern Qinling Mountains, China, show similar characteristics of having undergone deformation of two stages. The earlier one, which is inferred to be related to collisional orogeny between the Yangtze and Sino-Korean palaeocontinents based on previous geological data, is responsible for large-scale, north-verging recumbent folds and overthrusts, and associated with low greenschist fades metamorphism. 40Ar/39Ar dating of three muscovite samples taken from different localities yields plateau ages of 226.9±0.9 and 219.5±1.4 Ma and an apparent age of 194.5±3.0 Ma. Thus, the late Triassic collision between the Yangtze and Sino-Korean palaeocontinents has been constrained.

A Paleogeographic and Depositional Model for the Neogene Fluvial Succession, Pishin Belt, Northwest Pakistan: Effect of Post Collisional Tectonics on Sedimentation in a Peripheral Foreland Setting

Detailed facies analysis of the Neogene successions of the Pishin Belt （Katawaz Basin） has enabled documentation of successive depositional systems and paleogeographic settings of the basin formed by the collision of the northwestern continental margin of the Indian Plate and the Afghan Block. During the Early Miocene, subaerial sedimentation started after the final closure of the Katawaz Remnant Ocean. Based on detailed field data, twelve facies were recognized in Neogene successions exposed in the Pishin Belt. These facies were further organized into four facies associations i.e. channels, crevasse splay, natural levee and floodplain facies associations. Facies associations and variations provided ample evidence to recognize a number of fluvial architectural components in the succession e.g., low-sinuosity sandy braided river, mixed-load meandering, high-sinuosity meandering channels, single-story sandstone and/or conglomerate channels, lateral accretion surfaces （point bars） and alluvial fans. Neogene sedimentation in the Pishin Belt was mainly controlled by active tectonism and thrusting in response to the oblique collision of the Indian Plate with the Afghan Block of the Eurasian Plate along the Chaman-Nushki Fault. Post Miocene deformation of these formations successively caused them to contribute as an additional source terrain for the younger formations.

Pre-collision Granites and Post-collision Intrusive Assemblage of the Kelameili-Harlik Orogenic Belt

The main types of intrusive rocks in the Kelameili-Harlik Hercynian orogenic belt include calc-alkaline granites, diabase dykes, kaligranites and alkaline granites. Investigation in field geology, petrology, mineralogy and geochemistry shows that the calc-alkaline granites belong to the syntexis-type (or I-type) and were formed in a pre-collisional magmatic arc environment. In consideration of the fact that kaligranites have many features of alkaline granites with higher consolidation temperatures than the calc-alkaline granites and show a discontinuity of minor element and REE evolution in respect to the calc-alkaline granites, they could not have been derived by differentiation of magmas for the calc-alkaline granites, but are likely to have been generated in an environment analogous to that for alkaline granites. The triplet of basic dyke swarms, kaligranites and alkaline granites could be regarded as a prominent indication of the initial stage of post-collisional delamination and extension. These rocks might have originated from underplating and intraplating of mantle-derived magmas at varying levels with varying degrees of partial melting, mixing, and interchange of crustal and mantle materials

Tectonic Nature of the Northern Segment of the Jiao-Liao-Ji Belt:A Rift or Continental Collision Belt?

Objective The tectonic characteristics and evolution of the Paleoproterozoic Jiao-Liao-Ji belt have been extensively studied in recent decades （Fig. 1 a）. Two main models have been proposed for the formation of this belt： a continental-or arc-continent collisional belt, and the opening and closure of an intra-continental rift. The main reasons for these ongoing debates are own to the complex composition, including metamorphosed volcano-sedimentary rocks, multiple pulses of granitic magmatism, meta-mafic intrusions, and tectono- metamorphic history. In addition, earlier work focused on the geochronology and metamorphic evolution, whereas the source properties, petrogenesis, and tectonic setting of the metamorphosed volcano-sedimentary sequence and meta- mafic intrusions are poorly understood.

Tectonic Evolution of the Himalayan Collision Belt

This paper discusses the tectonic divisions of the Himalayan collision belt anddeals with the tectonic evolution of the collision belt in the context of crustal accretion in thefront of the collision belt, deep diapirism and thermal-uplift extension and deep material flow-ing of the lithosphere-backflowing. Finally it proposes a model of the tectonic evolution-progressive intracontinental deformation model-of the Himalayan belt.

Positioning the Southern Margin of Asia Prior to Its Collision with India: Paleomagnetic Constraints from Late Cretaceous Dykes in Gangdise Belt

The pre-collisional southern margin of Asia can be restored using paleomagnetic data from late Cretaceous rocks from the Lhasa terrane.However,the available data are based either on the red beds or on the intercalated thin layers of lava flows,both of which had been involved in strongly folding.Recent studies show clear evidence for the possibility of serious overprint hence the data could not be reliably used for tectonic interpretation.We report paleomagnetic data from diorite dykes and the grano-diorite country rock in the Gandise belt near the city of Lhasa.U–Pb isotopic dating indicates the intrusive rocks have an age of;2–86 Ma.Fifteen sites yield acceptable Ch RM directions which pass a reversal test.SEM and light microscope observations show primaryintergrowth relationship between magnetite and other minerals within the thin sections.AMS measurement defines a primary magma flow fabric for the intruded dykes and the country rocks.All the characteristics support that the Ch RMs are primary.The paleomagnetic pole calculated from the remanence of the dykes and the country rocks yields a paleolatitude of;4°N which provide a reliable constraint for the southern margin of Asia near Lhasa.Furthermore,the recorded declination shows significant counterclockwise rotation of;0°for the sampling location relative to the north.In consideration of the strike and tectonic setting of the dykes,the strike of the southern margin of Asia is restored which is compatible with the hypothesis of a quasi-linear margin of Eurasia prior to its collision with India.

Petrology, geochemistry and Ar-Ar geochronology of eclogites in Jinshajiang orogenic belt, Gonjo area, eastern Tibet and restriction on Paleo-Tethyan evolution

As one of the important Paleo-Tethys suture zones in eastern Tibet,the Jinshajiang orogenic belt is of great significance to study the tectonic evolution of the main suture zone of Paleo-Tethys.In this paper,eclogites developed in the Jinshajiang suture zone in Gonjo area,eastern Tibet,are selected as specific research objects,and petrological,geochemical and Ar-Ar geochronological analyses are carried out.The major element data of the whole rock reveals that the eclogite samples have the characteristics of picritic basalt-basalt and belong to the oceanic low potassium tholeiites.The results of rare earth elements and trace elements of the samples show that the protoliths of eclogites have characteristics similar to oceanic island basalt(OIB)or normal mid ocean ridge basalt(N-MORB).Muscovite(phengite)from two eclogite samples yield the Ar-Ar plateau ages of 247±2 Ma and 248±2 Ma respectively,representing the peak metamorphic age of eclogite facies and the timing of complete closure of the Jinshajiang Paleo-Tethys Ocean.Muscovite and biotite selected from the hosting rocks of eclogite yield the Ar-Ar plateau ages are 238±2 Ma and 225±2 Ma respectively,reflecting the exhumation age of eclogites and their hosting rocks.Combined with the zircon U-Pb dating data(244 Ma)of eclogites obtained in previous work,it can be concluded that the Jinshajiang Paleo-Tethys ocean was completely closed and arc-continent collision was initiated at about 248-244 Ma(T21).Subsequently,due to the large-scale arc(continent)-collision orogeney between Deqin-Weixi continental margin arc and Zhongza block(T31-T32),the eclogites were rapidly uplifted to the shallow crust.

胶辽吉造山带碰撞后岩浆作用:来自辽东-吉南地区巨斑状和球粒状花岗岩的约束

胶辽吉造山带辽东-吉南地区卧龙泉、双岔、八河川等巨斑状花岗岩体形成于造山峰期之后,记录了造山带演化的重要信息,对于探讨整个胶辽吉造山带构造演化具有重要意义。通过对巨斑状花岗岩研究,识别出局部侵入其中的球粒状花岗岩,并对采集自造山带东部和西部典型岩体的3件巨斑状花岗岩和1件球粒状花岗岩开展了岩相学、锆石U-Pb年代学、Lu-Hf同位素及主微量元素研究。结果显示巨斑状花岗岩具有硅含量相对较低、全碱较高、A/CNK值变化较大(0.86~1.19)等特征。虽然双岔巨斑状花岗岩中见有石榴子石,但全岩地球化学特征表现出准铝质、锆饱和温度较高等A型花岗岩特征;宝甸地区花岗岩中也有石榴子石,显示了S型花岗岩地球化学特征。卧龙泉和双岔巨斑状花岗岩体侵位时代为1880~1895Ma,球粒状花岗岩形成于1870±13Ma,宝甸地区巨斑状含石榴花岗岩侵位于1845±13Ma左右;来自这些锆石的原位εHf(t)值介于-3.6~+4.2之间,相应的二阶段模式年龄为2474~2730Ma。本研究认为,辽吉造山带碰撞后花岗质岩石成因较为复杂:球粒状花岗岩反映了岩浆过冷度较大、快速侵位至浅表过程;宝甸地区巨斑状花岗岩具有S型花岗岩特征;具有A型花岗岩特征的巨斑状花岗岩则反映了深部物质和加厚地壳均有贡献。结合前期报道的同时代碰撞后I型和A型花岗岩以及变质岩的研究等,本文认为辽东半岛巨斑状和球粒状花岗岩的产出与胶辽吉造山带碰撞后强烈的下地壳作用有关,反映了造山带去根垮塌、岩石圈伸展过程,代表了碰撞后花岗质岩浆作用。

吉林红旗岭晚三叠世镁铁超镁铁质侵入体矿物化学和岩石地球化学特征:对镍铜成矿的启示

吉林红旗岭镁铁超镁铁质侵入岩群位于中亚造山带东段南缘,由3个北西向岩带(I、II、III)组成,包括30多个小岩株,其中I-岩带的部分岩体伴有铜镍矿化,并且其1和7号岩体分别形成了中型和大型岩浆铜镍硫化物型矿床。矿床主要容矿岩石为辉橄岩、橄辉岩、斜方辉石岩、二辉石岩、苏长岩和辉长岩。主量元素方面,红旗岭岩群具有富镁(w(MgO)=20.7%~31.1%)、低钛(w(TiO_(2))=0.33%~0.79%)、低碱(w(K 2 O+Na 2 O)=0.60%~2.29%)和硅(w(SiO_(2))=40.0%~53.0%)变化范围大的特征;微量元素方面,红旗岭岩群呈现弱富集LREE和LILE(Th)以及亏损HREE和HFSE(Nb-Ta-Ti)。岩相学、地球化学和矿物(橄榄石、斜方辉石、单斜辉石、尖晶石、斜长石和角闪石)主微量元素特征表明,红旗岭岩群明显不同于洋岛型玄武岩、阿拉斯加型环状杂岩和科马提岩,但与岛弧玄武岩以及中亚造山带西段的“黄山西”和“黄山东”铜镍硫化物矿床的容矿超镁铁质岩相似,其母岩浆是一种富Mg、亏损Nb-Ta的岛弧拉斑玄武质熔体,形成于晚三叠世古亚洲洋闭合后伸展环境,演化过程中经历了地壳混染和分离结晶作用,含矿母岩浆可能经历了硫化物的“二次熔离”,最终形成了铂族元素(PGE)亏损型岩浆铜镍硫化物矿床。

东昆仑东段各玛龙闪长岩年代学、地球化学特征及成因分析

各玛龙地区位于东昆仑造山带东段南部,该地区构造活动与岩浆活动强烈。本文以两件花岗闪长岩和两件英云闪长岩为研究对象,开展LA-ICP-MS锆石U-Pb年代学和岩石全岩元素组成研究,探讨岩石成因类型和岩浆源区特征,分析闪长岩的构造演化环境。研究结果表明:两件具有代表性的闪长岩样品成岩年龄分别为405.3±1.1 Ma和405.8±1.2 Ma,说明成岩时代为早泥盆世;4件闪长岩样品具有高硅、高铝、高碱、贫钙、贫镁、弱过铝质特征,属于弱过铝质高钾钙碱性系列岩石;4件样品中未发育S型花岗岩的代表性矿物,并且Rb/Sr值为0.32~0.43,均小于0.9,A/CNK值为0.98~1.09,均小于1.1,符合I型花岗岩的地球化学特征;通过分析La-La/Sm图解与(Zr+Nb+Ce+Y)-(Na_(2)O+K_(2)O)/CaO图解,同时结合Nb/Ta、Zr/Hf、Nb/U、Rb/Sr、Ti/Y、Ti/Zr值,可以得知各玛龙地区闪长岩是由地壳岩石部分熔融形成的,并且可能伴有幔源物质的参与。结合前人研究及(Y+Nb)-Rb图解与Rb/30-Hf-Ta*3图解可知,各玛龙地区闪长岩形成于早泥盆世东昆仑造山带的后碰撞伸展环境。

Tectonic Evolution of an Early Precambrian High-Pressure Granulite Belt in the North China Craton

A large-scale high-pressure granulite belt (HPGB), more than 700 km long, is recognized within the metamorphic basement of the North China craton. In the regional tectonic framework, the Hengshan-Chengde HPGB is located in the central collision belt between the western block and eastern block, and represents the deep crustal structural level. The typical high-pressure granulite (HPG) outcrops are distributed in the Hengshan and Chengde areas. HPGs commonly occur as mafic xenoliths within ductile shear zones, and underwent multipile deformations. To the south, the Hengshan-Chengde HPGB is juxtaposed with the Wutai greenstone belt by several strike-slip shear zones. Preliminary isotopic age dating indicates that HPGs from North China were mainly generated at the end of the Neoarchaean, assocaited with tectonic assembly of the western and eastern blocks.

Kanfenggou UHP Metamorphic Fragment in Eastern Qinling Orogen and Its Relationship to Dabie-Sulu UHP and HP Metamorphic Belts, Central China

In the Central Orogenic Belt, China, two UHP metamorphic belts are discriminated mainly based on a detailed structural analysis of the Kanfenggou UHP metamorphic fragment exposed in the eastern Qinling orogen, and together with previous regional structural, petrological and geochronological data at the scale of the orogenic domain. The first one corresponds to the South Altun North Qaidam North Qinling UHP metamorphic belt. The other is the Dabie Sulu UHP and HP metamorphic belts. The two UHP metamorphic belts are separated by a series of tectonic slices composed by the Qinling rock group, Danfeng rock group and Liuling or Foziling rock group etc. respectively, and are different in age of the peak UHP metamorphism and geodynamic implications for continental deep subduction and collision. Regional field and petrological relationships suggest that the Kanfenggou UHP metamorphic fragment that contains a large volume of the coesite and microdiamond bearing eclogite lenses is compatible with the structures recognized in the South Altun and North Qaidam UHP metamorphic fragments exposed in the western part of China, thereby forming a large UHP metamorphic belt up to 1 000 km long along the orogen strike. This UHP metamorphic belt represents an intercontinental deep subduction and collision belt between the Yangtze and Sino Korean cratons, occurred during the Paleozoic. On the other hand, the well constrained Dabie Sulu UHP and HP metamorphic belts occurred mainly during Triassic time (250-220 Ma), and were produced by the intracontinental deep subduction and collision within the Yangtze craton. The Kanfenggou UHP metamorphic fragment does not appear to link with the Dabie Sulu UHP and HP metamorphic belts along the orogen. There is no reason to assume the two UHP metamorphic belts as a single giant deep subduction and collision zone in the Central Orogenic Belt situated between the Yangtze and Sino Korean cratons. Therefore, any dynamic model for the orogen must account for the development of UHP metamorphic rocks belonging to the separate two tectonic belts of different age and tectono metamorphic history.

Paleozoic tectonic evolution of the eastern Central Asian Orogenic Belt in NE China

The eastern Central Asian Orogenic Belt(CAOB)in NE China is a key area for investigating continental growth.However,the complexity of its Paleozoic geological history has meant that the tectonic development of this belt is not fully understood.NE China is composed of the Erguna and Jiamusi blocks in the northern and eastern parts and the Xing’an and Songliao-Xilinhot accretionary terranes in the central and southern parts.The Erguna and Jiamusi blocks have Precambrian basements with Siberia and Gondwana affinities,respectively.In contrast,the Xing’an and Songliao-Xilinhot accretionary terranes were formed via subduction and collision processes.These blocks and terranes were separated by the Xinlin-Xiguitu,Heilongjiang,Nenjiang,and Solonker oceans from north to south,and these oceans closed during the Cambrian(ca.500 Ma),Late Silurian(ca.420 Ma),early Late Carboniferous(ca.320 Ma),and Late Permian to Middle Triassic(260-240 Ma),respectively,forming the Xinlin-Xiguitu,Mudanjiang-Yilan,Hegenshan-Heihe,Solonker-Linxi,and Changchun-Yanji suture zones.Two oceanic tectonic cycles took place in the eastern Paleo-Asian Ocean(PAO),namely,the Early Paleozoic cycle involving the Xinlin-Xiguitu and Heilongjiang oceans and the late Paleozoic cycle involving the Nenjiang-Solonker oceans.The Paleozoic tectonic pattern of the eastern CAOB generally shows structural features that trend east-west.The timing of accretion and collision events of the eastern CAOB during the Paleozoic youngs progressively from north to south.The branch ocean basins of the eastern PAO closed from west to east in a scissor-like manner.A bi-directional subduction regime dominated during the narrowing and closure process of the eastern PAO,which led to“soft collision”of tectonic units on each side,forming huge accretionary orogenic belts in central Asia.

Structural Evolution of a Precambrian Segment: Example of the Paleoproterozoic Formations of the Mako Belt (Eastern Senegal, West Africa)

The western part of the Kedougou Kenieba Inlier is located in the West African Craton. It consists of paleoproterozoic NE-trending elongate belts (subprovinces) of metavolcanic and granitic rocks that alternate with metasedimentary belts. Major linear fault such as the MTZ which also approximate a north-easterly trend form the eastern boundaries. The field observations and geophysics analyses were completed by a microscopic study. Based on these data we define across this region four lithostructural domains from east to west. The western domain is structurally complex. The rocks of this domain have been subjected to a complex history of polyphase deformation and metamorphism. The structural analyse allow us to distinguished three deformation events. The deformation results in the formation of D1 thrust tectonic and D2 and D3 transcurrent tectonic. The structural evolution of the Mako Belt is characterized by deformation dominated by the intrusion of large TTG batholiths (D1) followed by basins formation and transpression accommodating oblique convergence and collision (D2 and D3). The change from thrusting (D1 deformation to transcurrent motion (D2 and D3) is recorded in the marginal basin of the central domain and in Tinkoto pull apart basin. The timing of these basins indicates a diachronous evolution. Deformation styles within the basin are compatible with a dextral transpression which terminated at ca 2090 Ma. Small extensional basins formed over the rocks of the Mako Belt are filled with continental detrital sedimentary rocks that show weak foliation and active felsic volcanism. We suggest that the sinistral transpressive tectonic associated with oblique subduction may have generated the pull-apart basin and subaqueous volcanism. In part these features are now related to terrain accretion, thrusting and strike slip movement during oblique convergence. The inversion of the large scale structural evolution from thrusting to strike slip is common to modern orogenies.

The final collision of the CAOB:Constraint from the zircon U-Pb dating of the Linxi Formation,Inner Mongolia

The Linxi Formation occupies an extensive area in the eastern Inner Mongolia in the Central Asian Orogenic Belt （CAOB）. The Linxi Formation is composed of slate, siltstone, sandstone and plant, lamellibranch microfossils in the associated strata. Major and trace element data （including REE） for sandstones from the formation indicate that these rocks have a greywacke protolith and have been deposited during a strong tectonic activity. LA-ICPMS U-Pb dating of detrital zircons yield ages of 1801 to 238 Ma for four samples from the Linxi Formation. 425-585 Ma, together with the ~500 Ma age for the metamorphism event previously determined for Northeast China, indicates that their provenance is the metamorphic rocks of Pan-African age that have a tectonic affinity to NE China. A few older zircons with U-Pb ages at 1689-1801 Ma, 1307 1414 Ma, 593-978 Ma are also present, revealing the Neoproterozoic history of NE China. The youngest population shows a peak at ca. 252 Ma, suggesting that the main deposition of the Linxi Formation was at late Permain. Moreover, the ca. 250 Ma zircon grains of all four samples yield weighted mean ^206pb/^238U ages of 250 ± 3 Ma, 248 ± 3 Ma, 249 ± 3 Ma, and 250 ± 2 Ma, respectively. These ages, together with the youngest zircon age in the sample ZJB-28 （ca. 238 Ma）, suggest that the deposition of the Linxi Formation extended to the early Triassic. Combining with previous results, we suggest that the final collision of the Central Asian Orogenic Belt （CAOB） in the southern of Linxi Formation, which located in the Solonker-Xra Moron-Changchun suture, and the timing for final collision should be at early Triassic.

THE CENTRAL PAMIR—AN ALPINE COLLISION ZONE

The Alpine zone of Central Pamir is elongated in sublatitudinal direction between the Hercynians of Northern Pamir and the Cimmerians of Southern Pamir south of the Vanch\|Akbaital thrust. Its western continuation is overthrusted by the Herat fault and its eastern continuation is cut by the Karakoram strike\|slip fault.. The Central Pamir is a mainly S\|vergent (at the southern part N\|vergent) Alpine nappe stack then folding in antiform. It comprises deposits from Vendian to Neogene which have a thickness of 10km. Paleozoic and Mesozoic tectonic activity was poorly displaied in its limits. Rifting took place in Early and probably Upper Paleozoic. Pre\|Upper Cretaceous unconformity is known only in southern (autochthonous) part of the Zone as a result of closing of Bangong\|Nu Jiang ocean. In northern (allochthonous) part of the zone the sequence of Mesozoic and Paleogene rocks has no unconformities. Alpine endogenous processes were developed very intensively. They implied nappes and imbricate structures, linear folding, different igneous activity, zonal metamorphism. Slices of pyroxenites and gabbroids occured. Calc\|alkaline lavas and tuffs constitutes the major part of Paleocene to Miocene sequence (andesites\|ryolites\|in Paleogene, alkaline basalts in Oligocene—Miocene). Oligocene—Miocene zonal metamorphic belt of the intermediate type of high pressure including series of granitegneiss domes can be traced along the Central Pamir. Cores of domes include migmatites and remobilized bodies of the Early Paleozoic gneissic granites. The decompression took place at a later stage and rocks were overprinted by the andalusite\|sillimanite type metamorphism.. Syenite and leucogranite bodies, pegmatite and aplite veins were emplaced.

Isotopic Ages of the Penglai Group in the Jiaobei Belt and Their Geotectonic Implications

The Penglai Group in the Jiaobei Belt is the only remaining cover of the Archaean to Early Proterozoic crystalline basement in eastern Shandong. The ages of deposition of the Penglai Group and of its deformation and metamorphism have long been a subject of speculation. Whole-rock Rb-Sr ages, illite-whole-rock pair Rb-Sr ages and illite K-Ar ages recently obtained from the Penglai Group slates are reported and interpreted in this paper. On the basis of structural and metamorphic studies coupled with analyses of illite crystallinity, XRD and SEM , a whole-rock age of 473±32 Ma (Ordovician) is interpreted as the time of termination of burial metamorphism experienced by the Penglai Group. Therefore, the age of the Penghai Group is older than Ordovician. The first-phase folding and syntectonic low greenschist facies metamorphism in the Penglai Group, i.e. the Penglai Movement, took place before 299±4 Ma B.P., i.e in the Late Carboniferous. The Penglai Movement that occurred in the Jiaobei Belt on the southern margin of the North China Plate is attributed to collision between the North China and Yangtze plates along the Jiaonan Collision Belt. This demonstrates that the continent-continent collision between the North China and Yangtze plates east of the Tan-Lu Fault Zone took place in the Late Carboniferous. The collision caused N-S compression and deformation in the southern margin belt of the North China Plate north of the Qinling-Dabieshan-Jiaonan Collision Belt.

Transpressive Deformation across Tongbo-Dabie Orogenic Belt

Deformation characteristics of the dextral Dashankou ductile shear zone , parallel to the Tongbo-Dabie Orogenic Belt and regional stretching lineation patterns within the blueschist belt in Northern Hubei , China , are examined at various scales , respectively . The new data , combined with those obtained in the Wudangshan area , indicate a transpressive deformation involving a WNW directed nearly horizontal shearing accompanied by shortening across the orogenic belt . A kinematic model is proposed for development of the deformation within the Tongboshan segment . Based on these findings it can be seen that the convergence and collision between the North China Craton and the Yangtze Craton may locally be oblique during the Proterozoic Jinningian Orogeny . This oblique collision is probably related to a certain extent to the shapes of the older craton margins .

The Influence of an Interdependent Structures on the Post-Mesozoic Evolution of the Eastern Flank of the Mongol-Okhotsk Orogenic Belt

Based on the analysis of known geodynamic models that explain the processes in various geodynamic settings of the Meso-Cenozoic stages of the development of continental margins and the tectonic-magmatic events accompanying these processes, as well as on the basis of our own data obtained as a result of many years of research on the axial structure of the Central Asian Fold Belt-Mongol-Okhotsk orogenic belt and the influence of interdependent structures on the post-Mesozoic evolution of the eastern flank of the Mongol-Okhotsk orogenic belt was substantiated by us. The closure of the Mongol-Okhotsk basin due to the approach of the Siberian and North China cratons was accompanied by a change in geodynamic conditions: subduction, collision, intraplate-rift and was reflected in the formation of synchronous igneous complexes in the frame of the Mongol-Okhotsk orogenic belt. In the northern frame of the belt, the distribution of magmatites is cut off by the structure of the Selenga-Stanovoy superterrane in the west. The northern boundary of the superterrane is the zone of the Dzheltulak fault. In the south, it borders on the Mongol-Okhotsk orogenic belt along the zone of tectonic melange. We believe that evolutionary processes within the orogenic belt and its framing continued into the post-Mesozoic time after the final formation of the belt as an orogen. The position of the Selenga-Stanovoy superterrane in the late Mesozoic did not correspond to the modern one. The structures of the Central Asian fold belt located between the Mongol-Okhotsk orogenic belt and the Siberian craton in the Cenozoic were influenced by collisional processes occurring between the Indian and Eurasian plates. And these processes were not only the “driving force” for the movement of the Selenga-Stanovoy superterrane in the post-Mesozoic time, but also changed the structure of the Mongol-Okhotsk orogen, dividing it into two flanks.