The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is si...The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.展开更多
The Yarlung Zangbo Suture Zone(YZSZ)on the southern margin of the Lhasa block and the Tangjia-Sumdo ultrahigh-pressure metamorphic belt(TSMB)within the block represent natural laboratories for the study of plate tecto...The Yarlung Zangbo Suture Zone(YZSZ)on the southern margin of the Lhasa block and the Tangjia-Sumdo ultrahigh-pressure metamorphic belt(TSMB)within the block represent natural laboratories for the study of plate tectonics and oceanic slab subduction.It is generally believed that these two zones represent the remnants of the ancient oceanic crust and upper mantle of the Yarlung Zangbo Neo-Tethys(YZNT)and the Tangjia-Sumdo Paleo-Tethys(TSPT).However,the evolutionary patterns and spatiotemporal relationships of the TSPT and the YZNT have been debated.展开更多
The Late Paleozoic-Early Mesozoic sedimentary system of the Luang Prabang Paleotethyan back-arc basin in northern Laos is important for investigating sedimentary provenance,paleogeographic patterns,and the tectonic ev...The Late Paleozoic-Early Mesozoic sedimentary system of the Luang Prabang Paleotethyan back-arc basin in northern Laos is important for investigating sedimentary provenance,paleogeographic patterns,and the tectonic evolution of the eastern Paleotethyan Ocean.This study presents systematic stratigraphy,petrology,geochemistry,and detrital zircon U-Pb-Hf isotopic analyses for the Late Carboniferous-Jurassic sedimentary strata on both sides of the Luang Prabang Basin.Based on distinct stratigraphic ages and provenance characteristics,the clastic rock samples can be divided into four groups.The Group 1 Late Carboniferous-Early Permian samples from the western part of the basin yield detrital zircon age-peaks of~348 and~1425 Ma,with correspondingεHf(t)values ranging from-2.0 to+15.5 and+1.5 to+14,respectively.The age spectrum of Group 2 Late Carboniferous-Early Permian samples from the eastern part of the basin shows major age-peaks of~287 and~1860 Ma,withεHf(t)values of-5.9--0.9 and-3.6-+4.2,respectively.Group 3 Late Permian-Triassic samples exhibit age-peaks of~242 and~1853 Ma,along withεHf(t)values of-0.7-+14.4 and-5.4--1.8,respectively.Group 4 Middle-Late Jurassic samples yield agepeaks of~237,~431,~813,~1833,and~2460 Ma,lacking Late Devonian(413-345 Ma)detrital zircons.All these data collectively suggest that the Group 1 sample primarily originated from the Sukhothai arc in western Indochina,Group 2 was from the Kontum and Truong Son in eastern Indochina,and Group 3 has a combined provenance of the Sukhothai,Kontum,and Truong Son.Regional comparisons suggest that the Jurassic provenance was mainly derived from South China,which was imported through the northern river system.Our data,combined with the regional angular unconformities between the Jurassic continental strata and pre-Jurassic marine strata,suggest that the Luang Prabang Basin transformed into a superimposed collisional retroforeland basin during the Jurassic,and the closure of the Luang Prabang BAB occurred before the Late Triassic.展开更多
The Zongwulong Shan-Qinghai Nanshan tectonic belt of the northern Xizang Plateau experienced a protracted tectonica history,including the openings and closures of the Proto-and Paleo-Tethyan Oceans.Although the tecton...The Zongwulong Shan-Qinghai Nanshan tectonic belt of the northern Xizang Plateau experienced a protracted tectonica history,including the openings and closures of the Proto-and Paleo-Tethyan Oceans.Although the tectonic belt has been extensively studied,details regarding the tectonic processes involved in its development remain controversial.To better constrain the tectonic processes of this tectonic belt,we conducted detailed field geological mapping,zircon U-Pb geochronology,and whole-rock geochemical and Sr-Nd isotopic analyses.Our results show that intrusive rocks in the tectonic belt crystallized in ca.292-233 Ma,perhaps in an arc/subduction setting.Geochemical and Sr-Nd isotopic data suggest that Early Permian-Late Triassic ultramaficintermediate intrusions were sourced from the enriched mantle,whereas intermediate-acidic rocks were sourced from mixed crust-mantle.We present the tectonic model that involves:(1)Early Devonian-Early Permian intracontinental extension occurred in the northern margin of the Qaidam continent(ca.416-292 Ma);(2)Early Permian-Late Triassic northward subduction of the Paleo-Tethyan Ocean resulted in arc magmatism(ca.292-233 Ma);and(3)subsequent Late Triassic intracontinental extension(ca.233-215 Ma).Our results suggest that the Late Paleozoic-Early Mesozoic development of the Zongwulong Shan-Qinghai Nanshan was related to the opening,subduction,and slab retreat of the Paleo-Tethyan Ocean,which has key implications for the tectonic evolution of the northern Tibetan Plateau.展开更多
The Indosinian and Yanshanian orogenic movements are both important Mesozoic orogenies in eastern China.The resulted tectonic belts are neither products of the third stage of crustal evolution,as proposed by Chen Guod...The Indosinian and Yanshanian orogenic movements are both important Mesozoic orogenies in eastern China.The resulted tectonic belts are neither products of the third stage of crustal evolution,as proposed by Chen Guoda,nor intra-continental(or intraplate)orogenic belts generated by intraplate dynamics,as argued by some scholars-rather,they are superposed orogenic belts formed on the pre-existing continental crust in eastern China due to Mesozoic Paleo-Pacific dynamic system.In the past,these orogenic belts were called the marginal Pacific epicontinental activation belts of eastern China.In the Mesozoic,under the effect of Paleo-Pacific dynamic system,the East Asia margin orogenic system formed along Northeast Russia-Sikhote Alin(Russia)-Japan-Ryukyu-Taiwan(China)-Palawan(Philippines)regions,while simultaneously the Mesozoic superposed orogenic system formed in the pre-existing continental crust in eastern China adjacent to the East Asia continental margin.The two orogenic systems,both driven by Mesozoic Paleo-Pacific dynamic system,developed synchronously to form the giant Mesozoic orogenic system in the Pacific tectonic domain in eastern Asia,radically changing the pre-Indosian tectonic framework of the area.展开更多
Indicating the tectonic features of the Hanshan-Wuwei basin can reconstruct the framework of the basins formed in Mesozoic and further understand the Mesozoic tectonic evolution of the South China Block.Studies on sur...Indicating the tectonic features of the Hanshan-Wuwei basin can reconstruct the framework of the basins formed in Mesozoic and further understand the Mesozoic tectonic evolution of the South China Block.Studies on surface structure,regional stress field and deep geophysical characteristics of the Mesozoic Hanshan-Wuwei basin in Lower Yangtze region were carried out.NE-NNE trending folds and faults developed in the northern margin of the basins.The reconstruction of tectonic stress fields indicates four stress stages dominating the basins'evolution including NW-SE compression,N-S compression,NW-SE extension and NWW-SEE compression.2D seismic profiles reveal coexistence of thrust,strike-slip and normal faults in the basin.Combined with regional geological studies,the geodynamic processes for the formation of the Hanshan-Wuwei basin can be divided into five stages:1)During the Late Triassic,EW trending foreland basin was formed by N-S compression;2)From Mid-Jurassic to Late Jurassic,continuous compression strengthened the foreland deformation and formed thrust nappes.In this stage,the integrated foreland basin was compartmentalized or fragmented,and transferred to the broken foreland basin;3)NE-trending sinistral strike-slip movement at the beginning of the Early Cretaceous;4)Regional extension resulted in normal faults and rift basins developing in the Late Cretaceous;5)The NWW-SEE compression at the end of the Late Cretaceous caused NW sinistral strike-slip faults to form,which partly transformed the rift basin.展开更多
The magma sources,origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain.New results reveal that,miarolites from the Qishan and Kuiqi intrusions yield crystallization ag...The magma sources,origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain.New results reveal that,miarolites from the Qishan and Kuiqi intrusions yield crystallization ages of~101 and~98 Ma,and they have a high formation temperature(~910℃)and low oxygen fugacity value,indicating crystallization condition at low pressure in the upper crust with temperature of 678℃.The Qishan and Kuiqi miarolites are characterized by enrichment in SiO_(2) and high-K alkali,depletion in Ca and Mg,and belong to the high-K weak peraluminous rock series.The samples are enriched in HFSEs(i.e.,Ta,Zr and Hf)and LILEs(i.e.,Ba,P and Sr),depleted in Ba and Sr with the negative anomaly of Eu.In the primitive mantle normalized trace element spider diagram,the samples show a right-inclined‘seagull-type’pattern,combined the ratios of(La/Yb)_(N),10000×Al/Ga,Rb/Nb and Nb/Ta etc.,they were proved to be alkaline A-type granite.Combined the characterize of the trace elements,they were derived from clay-rich source accompanied pelite melting,and subjected to K-feldspar crystallization fractional.The values of ε_(Hf)(t)and tDM2 are distributed in the range of-2.8 to 3.3 with~1.2 Ga,and-6.0 to 4.0 with~1.2 Ga,revealing that they were generated from the Mesoproterozoic Cathaysia basement rocks.The comprehensive research reveals the Kuiqi and Qishan intrusions derived from crust-mantle mixing and partial melting of the crust,respectively,resulting from lithospheric extension generated by the Paleo-Pacific Plate subducted into the European-Asian Plate.展开更多
The Shangdan suture zone(SDZ)in the Qinling orogenic belt(QOB)is a key to understanding the East Asia tectonic evolution.The SDZ gives information about convergent processes between the North China Block(NCB)and South...The Shangdan suture zone(SDZ)in the Qinling orogenic belt(QOB)is a key to understanding the East Asia tectonic evolution.The SDZ gives information about convergent processes between the North China Block(NCB)and South China Block(SCB).In the Late Mesozoic,several shear zones evolved along the SDZ boundary that helps us comprehend the collisional deformation between the NCB and SCB,which was neglected in previous studies.These shear zones play an essential role in the tectonic evolution of the East Asia continents.This study focuses on the deformation and geochronology of two shear zones distributed along the SDZ,identified in the Shaliangzi and Maanqiao areas.The shear sense indicators and kinematic vorticity numbers(0.54–0.90)suggest these shear zones have sinistral shear and sub-simple shear deformation kinematics.The quartz’s dynamic recrystallization and c-axis fabric analysis in the Maanqiao shear zone(MSZ)revealed that the MSZ experienced deformation under green-schist facies conditions at∼400–500℃.The Shaliangzi shear zone deformed under amphibolite facies at∼500–700℃.The^(40)Ar/^(39)Ar(muscovite-biotite)dating of samples provided a plateau age of 121–123 Ma.Together with previously published data,our results concluded that QOB was dominated by compressional tectonics during the Late Early Cretaceous.Moreover,we suggested that the Siberian Block moved back to the south and Lhasa-Qiantang-Indochina Block to the north,which promoted intra-continental compressional tectonics.展开更多
? The intensive extensional deformation in the eastern part of the Chinese continent in Late Mesozoic time (J3-K1) caused the formation of largescale fault basin system in Northeastern China block, metamorphic core ...? The intensive extensional deformation in the eastern part of the Chinese continent in Late Mesozoic time (J3-K1) caused the formation of largescale fault basin system in Northeastern China block, metamorphic core complexes in North China block and widespread volcanic eruption and granitic intrusive in eastern China. Generally, the deformation has been interpreted as subduction tectonics along the eastern continental margin. We suggest that the combination effect of the subduction and collision in Tethys domain and the subduction from Pacific side and the mantle upwelling beneath the lithosphere. This event controlled the Late Jurassic to Early Cretaceous tectonic history in eastern China.展开更多
Since the Paleozoic,the tectonic evolution of northeastern Eurasia has been primarily influenced by the Paleo-Asian Ocean and the Paleo-Pacific tectonic domains.However,the spatial and temporal frameworks,as well as t...Since the Paleozoic,the tectonic evolution of northeastern Eurasia has been primarily influenced by the Paleo-Asian Ocean and the Paleo-Pacific tectonic domains.However,the spatial and temporal frameworks,as well as the timing of the tectonic transition between these two oceanic domains,remain unclear.For addressing these issues,we present petrological,geochronological,and geochemical data for andesite and sandstone samples from the Seluohe Group along the Jilin-Yanji Suture between the Jiamusi-Khanka Block and the North China Craton.The geochemical results indicate that the andesite sample is high-Mg andesite.Its magma source was generated by the metasomatized mantle wedge influenced by fluids derived from the subducted slab in a continental island arc setting.The high-Mg andesite gives the crystallization ages of Early Triassic(249±3 Ma).The sandstone is immature greywacke with a maximum depositional age of Early Triassic(247±1 Ma),and its sediments primarily originate from concurrent magmatic rocks within a juvenile continental arc.Based on our new findings,we propose that the Seluohe Group represents an Early Triassic volcanic-sedimentary association with continental island arc characteristics associated with the southwestward subduction of the Heilongjiang Ocean.We identified a sedimentary basin intimately associated with one or more continental arcs along the northeastern edge of the North China Craton.We suggest that the southwestward subduction of the Jilin-Heilongjiang Ocean in the Early Mesozoic accounts for this continental arc setting.There is a distinct temporal gap between the closure of the Paleo-Asian Ocean(ca.260 Ma)and the onset of Paleo-Pacific plate subduction(234–220 Ma),which is essentially coeval with the southwestward subduction of the Jilin-Heilongjiang Ocean between 255 Ma and 239 Ma.展开更多
1.Objective,The Luang Prabang(Laos)-Loei(Thailand)metallogenetic belt,located along the northwestern margin of the Indochina Block(Fig.1a)and endowed nearly 200 t of gold and more than 106 t of copper,is one of the mo...1.Objective,The Luang Prabang(Laos)-Loei(Thailand)metallogenetic belt,located along the northwestern margin of the Indochina Block(Fig.1a)and endowed nearly 200 t of gold and more than 106 t of copper,is one of the most important gold-copper metallogenic belts in Indo-China Peninsula.It has undergone tectonic changes during the Early Paleozoic to Mesozoic Proto-Paleo Tethys tectonic evolution,recorded by the Luang Prabang tectonic belt,the Nan-Uttaradit suture,and the Dien Bien Phu-Loei suture.展开更多
SHRIMP zircon U-Pb dating in the Liguo and Jiagou intrusives indicates that they were formed at -130 Ma in the Early Cretaceous. Most inherited zircons in the Liguo intrusive were formed at 2509±43 Ma. Most inher...SHRIMP zircon U-Pb dating in the Liguo and Jiagou intrusives indicates that they were formed at -130 Ma in the Early Cretaceous. Most inherited zircons in the Liguo intrusive were formed at 2509±43 Ma. Most inherited and detrital zircons in the Jiagou intrusive were formed at -2500 Ma, -2000 Ma and -1800 Ma. The SHRIMP zircon U-Pb dating in two gneiss xenoliths from the Jiagou intrusive yields the ages of 2461±22 Ma and 2508±15 Ma, respectively. The dating results from inherited and detrital zircons in the intrusives and the gneiss xenoliths imply that the magmas could be derived from the partial melting of the basement of the North China Block (NCB). The magmatism is strong and extensive in the periods from 115 to 132 Ma, which is of typical bimodal characteristics. It is suggested that the lithospheric thinning in the eastern North China Block reached its peak in 115-132 Ma.展开更多
Based on the new data of isotopic ages and geochemical analyses, three types of Mesozoic granites have been identified for the Xiong＇ershan-Waifangshan region in western Henan Province： high-Ba-Sr I-type granite emp...Based on the new data of isotopic ages and geochemical analyses, three types of Mesozoic granites have been identified for the Xiong＇ershan-Waifangshan region in western Henan Province： high-Ba-Sr I-type granite emplaced in the early stage （-160 Ma）, I-type granite in the middle stage （-130 Ma） and anorogenic A-type granite in the late stage （-115 Ma）. Geochemical characteristics of the high-Ba-Sr I-type granite suggest that it may have been generated from the thickened lower crust by partial melting with primary residues of amphibole and garnet. Gradual increase of negative Eu anomaly and Sr content variations reflect progressive shallowing of the source regions of these granites from the early to late stage. New ^40Ar/^39Ar plateau ages of the early-stage Wuzhangshan granite （156.0±1.1 Ma, amphibole） and middle-stage Heyu granite （131.8±0.7 Ma, biotite） are indistinguishable from their SHRIMP U-Pb ages previous published, indicating a rapid uplift and erosion in this region. The representative anorogenic A- type granite, Taishanmiao pluton, was emplaced at -115 Ma. The evolution of the granites in this region reveals a tectonic regime change from post-collisional to anorogenic between -160 Ma and -115 Ma. The genesis of the early- and middle-stage I-type granites could be linked to delamination of subducted lithosphere of the Qinling orogenic belt, while the late-stage A-type granites represent the onset of extension and the end of orogenic process. In fact, along the Qiniing -Dabie-Sulu belt, the Mesozoic granitoids in western Henan, Dabieshan and Jiaodong regions are comparable on the basis of these temporal evolutionary stages and their initial ^87Sr/^86Sr ratios, which may suggest a similar geodynamic process related to the collision between the North China and Yangtze cratous.展开更多
During the Late Mesozoic Middle Jurassic--Late Cretaceous, basin and range tectonics and associated magmatism representative of an extensional tectonic setting was widespread in southeastern China as a result of Pacif...During the Late Mesozoic Middle Jurassic--Late Cretaceous, basin and range tectonics and associated magmatism representative of an extensional tectonic setting was widespread in southeastern China as a result of Pacific Plate subduction. Basin tectonics consists of post-orogenic （Type I） and intra-continental extensional basins （Type II）. Type I basins developed in the piedmont and intraland during the Late Triassic to Early Jurassic, in which coarse-grained terrestrial clastic sediments were deposited. Type II basins formed during intra-continental crustal thinning and were characterized by the development of grabens and half-grabens. Graben basins were mainly generated during the Middle Jurassic and were associated with bimodal volcanism. Sediments in half-grabens are intercalated with rhyolitic tufts and lavas and are Early Cretaceous in age with a dominance of Late Cretaceous-Paleogene red beds. Ranges are composed of granitoids and bimodal volcanic rocks, A-type granites and dome-type metamorphic core complexes. The authors analyzed lithological, geochemical and geochronological features of the Late Mesozoic igneous rock assemblages and proposed some geodynamical constraints on forming the basin and range tectonics of South China. A comparison of the similarities and differences of basin and range tectonics between the eastern and western shores of the Pacific is made, and the geo- dynamical evolution model of the Southeast China Block during Late Mesozoic is discussed. Studied results suggest that the basin and range terrane within South China developed on a pre-Mesozoic folded belt was derived from a polyphase tectonic evolution mainly constrained by subduction of the western Pacific Plate since the Late Mesozoic, leading to formation of various magmatism in a back-arc exten- sional setting. Its geodynamic mechanism can compare with that of basin and range tectonics in the eastern shore of the Pacific. Differences of basin and range tectonics between both shores of the Pacific, such as mantle plume formation, scales of extensional and igneous rock assemblages and the age of basin and range tectonics, were caused mainly by the Yellowstone mantle plume in the eastern shore of the Pacific.展开更多
A synthesis is given in this paper on late Mesozoic deformation pattern in the zones around the Ordos Basin based on lithostratigraphic and structural analyses. A relative chronology of the late Mesozoic tectonic stre...A synthesis is given in this paper on late Mesozoic deformation pattern in the zones around the Ordos Basin based on lithostratigraphic and structural analyses. A relative chronology of the late Mesozoic tectonic stress evolution was established from the field analyses of fault kinematics and constrained by stratigraphic contact relationships. The results show alternation of tectonic compressional and extensional regimes. The Ordos Basin and its surroundings were in weak N-S to NNE-SSW extension during the Early to Middle Jurassic, which reactivated E-W-trending basement fractures. The tectonic regime changed to a multi-directional compressional one during the Late Jurassic, which resulted in crustal shortening deformation along the marginal zones of the Ordos Basin. Then it changed to an extensional one during the Early Cretaceous, which rifted the western, northwestern and southeastern margins of the Ordos Basin. A NW-SE compression occurred during the Late Cretaceous and caused the termination of sedimentation and uplift of the Ordos Basin. This phased evolution of the late Mesozoic tectonic stress regimes and associated deformation pattern around the Ordos Basin best records the changes in regional geodynamic settings in East Asia, from the Early to Middle Jurassic post-orogenic extension following the Triassic collision between the North and South China Blocks, to the Late Jurassic multi-directional compressions produced by synchronous convergence of the three plates （the Siberian Plate to the north, Paleo-Pacific Plate to the east and Lhasa Block to the west） towards the East Asian continent. Early Cretaceous extension might be the response to collapse and lithospheric thinning of the North China Craton.展开更多
In the Langshan region, northwestern China, marked multi-stage intraplate deformation events have occurred since the Mesozoic, including（1） northeast-striking ductile left-lateral strike slip during the Middle-Late ...In the Langshan region, northwestern China, marked multi-stage intraplate deformation events have occurred since the Mesozoic, including（1） northeast-striking ductile left-lateral strike slip during the Middle-Late Triassic, which is closely related to the collision between the North China and the Yangtze plates;（2） top-to-the-southeast thrust with northwest-southeast trending maximum compression during the Late Jurassic;（3） nearly eastward detachment during the Early Cretaceous;（4） top-to-the-northwest thrust with northwest-southeast trending maximum compression during the Late Cretaceous and Early Cenozoic;（5） northeast-striking brittle left-lateral strike slip with nearly north-south trending maximum compression; and（6） northwest-southeast extension during the Middle-Late Cenozoic. All these deformation events belong to the intraplate deformation across the entire Central Asian region and respond to the tectonic events along the plate boundaries or deep tectonics. The structures developed in early events in the crust were the most important factors controlling the later deformation styles, and few new structures have later developed. Based on previous research and our results, the paleostress inversion in the Langshan region shows that the Mesozoic intraplate deformations in the study region mainly resulted from the tectonic events from the Paleo-Pacific region and have no or a weak relation to the Tethys region. During the Late Jurassic, the maximum compression from the Mongolia-Okhotsk region cannot be excluded. The Langshan region is the bridge between southern Mongolia and the western Ordos tectonic belt and is thus important to understand the nature and relationship between both regions.展开更多
The Cambrian to Cretaceous paleomagnetic data from Chinese continental and adjacent blocks were collected using principles to obtain reliable and high-precision paleomagnetic data and to pay attention to the similarit...The Cambrian to Cretaceous paleomagnetic data from Chinese continental and adjacent blocks were collected using principles to obtain reliable and high-precision paleomagnetic data and to pay attention to the similarity of paleobiogeography and the coordination of tectonic evolution.The Chinese continental blocks were laid up on the reconstruction of proposed global paleocontinents with almost the same scale.Thus,it can be clearly recognized that the global continents,including Chinese continental blocks,range along latitudes on the southern side of the equator during the Early Paleozoic. In the Paleozoic,Chinese continental blocks were still located among the Laurentia,Siberia and Gondwana plates,following the fast moving of the Siberia Plate northwards,the amalgamation in a north-south direction at the western parts of the Laurentia and Gondwana plates,and the Iapetus and Rheic Oceans were subducted,eventually to form a uniform Pangea in the Late Paleozoic.The Australian and Indian plates of Eastern Gondwana moved and dispersed gradually southwards, continued to extend the Paleo-Tethys Ocean.The Chinese continental and adjacent blocks were still located in the Paleo-Tethys Ocean,preserved the status of dispersion,gradually moving northwards, showing characteristics of ranging along a north-south orientation until the Permian.In addition,a series of local collisions happened during the Triassic,and consequently most of the Chinese continental blocks were amalgamated into the Pangea,except for the Gangdise and Himalayan blocks. There was a counter-clockwise rotation of the Eastern Asian continent in the Jurassic and northwards migration of the Chinese continent in varying degrees during the Cretaceous,but the Himalayan and Indian plates did not collide into the Chinese continent during this period.展开更多
South China is the most important polymetallic （tungsten, tin, bismuth, copper, silver, antimony, mercury, rare metals, heavy rare earth elements, gold and lead-zinc） province in China. This paper describes the basi...South China is the most important polymetallic （tungsten, tin, bismuth, copper, silver, antimony, mercury, rare metals, heavy rare earth elements, gold and lead-zinc） province in China. This paper describes the basic characteristics of Mesozoic large-scale mineralization in South China. The large-scale mineralization mainly took place in three intervals： 170-150 Ma, 140-126 Ma and 110-80 Ma. Among these the first stage is mainly marked by copper, lead-zinc and tungsten mineralization and the third stage is mainly characterized by tin, gold, silver and uranium mineralization. The stage of 140-126 Ma mainly characterized by tungsten and tin mineralization is a transitional interval from the first to the third stage. In fight of the current research results of the regional tectonic evolution it is proposed that the large-scale mineralization in the three stages is related to post-collision between the South China block and the North China block, transfer of the principal stress-field of tectonic regimes from N-S to E-W direction, and multiple back-arc lithospheric extensions caused by subduction of the Paleo-Pacific plate.展开更多
The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area ...The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian （493.1±4.9 Ma）, the Silurian （422.9±8.0 Ma-420.4±4.6 Ma） and the Late Permian-Middle Triassic （257.8±4.0 Ma-228.8＋1.5 Ma）, respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma （main）, 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic （P-T） granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism （293.6-270 Ma） occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basement thrust system developed in the eastern Qaidam Basin, the nearly N-S-trending shortening and deformation in the basement of the basin tended to intensify from west to east, which went contrary to the distribution trend of N-S-trending shortening and deformation in the Cenozoic cover of the basin, reflecting that there was a transformation of shortening and thickening of Cenozoic crust between the eastern and western parts of the Qaidam Basin, i.e., the crustal shortening of eastern Qaidam was dominated by the basement deformation （triggered at the middle and lower crust）, whereas that of western Qaidam was mainly by folding and thrusting of the sedimentary cover （the upper crust）.展开更多
基金This study was jointly supported by the Science&Technology Fundamental Resources Investigation Program(2022FY101800)National Science Foundation(92162212)+1 种基金the project from the Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences,Wuhan)(TPR-2022-22)the International Geoscience Programme(IGCP-675)。
文摘The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.
基金supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202404310,KJQN202304302)National Natural Science Foundation of China(41972118).
文摘The Yarlung Zangbo Suture Zone(YZSZ)on the southern margin of the Lhasa block and the Tangjia-Sumdo ultrahigh-pressure metamorphic belt(TSMB)within the block represent natural laboratories for the study of plate tectonics and oceanic slab subduction.It is generally believed that these two zones represent the remnants of the ancient oceanic crust and upper mantle of the Yarlung Zangbo Neo-Tethys(YZNT)and the Tangjia-Sumdo Paleo-Tethys(TSPT).However,the evolutionary patterns and spatiotemporal relationships of the TSPT and the YZNT have been debated.
基金supported by the National Key Research and Development Program of China(No.2023YFF0803701)the National Natural Science Foundation of China(Nos.42330302 and 42472265)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2023SP239)。
文摘The Late Paleozoic-Early Mesozoic sedimentary system of the Luang Prabang Paleotethyan back-arc basin in northern Laos is important for investigating sedimentary provenance,paleogeographic patterns,and the tectonic evolution of the eastern Paleotethyan Ocean.This study presents systematic stratigraphy,petrology,geochemistry,and detrital zircon U-Pb-Hf isotopic analyses for the Late Carboniferous-Jurassic sedimentary strata on both sides of the Luang Prabang Basin.Based on distinct stratigraphic ages and provenance characteristics,the clastic rock samples can be divided into four groups.The Group 1 Late Carboniferous-Early Permian samples from the western part of the basin yield detrital zircon age-peaks of~348 and~1425 Ma,with correspondingεHf(t)values ranging from-2.0 to+15.5 and+1.5 to+14,respectively.The age spectrum of Group 2 Late Carboniferous-Early Permian samples from the eastern part of the basin shows major age-peaks of~287 and~1860 Ma,withεHf(t)values of-5.9--0.9 and-3.6-+4.2,respectively.Group 3 Late Permian-Triassic samples exhibit age-peaks of~242 and~1853 Ma,along withεHf(t)values of-0.7-+14.4 and-5.4--1.8,respectively.Group 4 Middle-Late Jurassic samples yield agepeaks of~237,~431,~813,~1833,and~2460 Ma,lacking Late Devonian(413-345 Ma)detrital zircons.All these data collectively suggest that the Group 1 sample primarily originated from the Sukhothai arc in western Indochina,Group 2 was from the Kontum and Truong Son in eastern Indochina,and Group 3 has a combined provenance of the Sukhothai,Kontum,and Truong Son.Regional comparisons suggest that the Jurassic provenance was mainly derived from South China,which was imported through the northern river system.Our data,combined with the regional angular unconformities between the Jurassic continental strata and pre-Jurassic marine strata,suggest that the Luang Prabang Basin transformed into a superimposed collisional retroforeland basin during the Jurassic,and the closure of the Luang Prabang BAB occurred before the Late Triassic.
基金supported by the National Natural Science Foundation of China(No.42372256)the Basic Science Center for Tibetan Plateau Earth System(No.41988101)the Second Tibetan Plateau Scientific Expedition and Research Program(No.2019QZKK0708)。
文摘The Zongwulong Shan-Qinghai Nanshan tectonic belt of the northern Xizang Plateau experienced a protracted tectonica history,including the openings and closures of the Proto-and Paleo-Tethyan Oceans.Although the tectonic belt has been extensively studied,details regarding the tectonic processes involved in its development remain controversial.To better constrain the tectonic processes of this tectonic belt,we conducted detailed field geological mapping,zircon U-Pb geochronology,and whole-rock geochemical and Sr-Nd isotopic analyses.Our results show that intrusive rocks in the tectonic belt crystallized in ca.292-233 Ma,perhaps in an arc/subduction setting.Geochemical and Sr-Nd isotopic data suggest that Early Permian-Late Triassic ultramaficintermediate intrusions were sourced from the enriched mantle,whereas intermediate-acidic rocks were sourced from mixed crust-mantle.We present the tectonic model that involves:(1)Early Devonian-Early Permian intracontinental extension occurred in the northern margin of the Qaidam continent(ca.416-292 Ma);(2)Early Permian-Late Triassic northward subduction of the Paleo-Tethyan Ocean resulted in arc magmatism(ca.292-233 Ma);and(3)subsequent Late Triassic intracontinental extension(ca.233-215 Ma).Our results suggest that the Late Paleozoic-Early Mesozoic development of the Zongwulong Shan-Qinghai Nanshan was related to the opening,subduction,and slab retreat of the Paleo-Tethyan Ocean,which has key implications for the tectonic evolution of the northern Tibetan Plateau.
基金funded by the Regional Geological Survey Project of the China Geological Survey(DD20221646)the National Natural Science Foundation of China(42172218).
文摘The Indosinian and Yanshanian orogenic movements are both important Mesozoic orogenies in eastern China.The resulted tectonic belts are neither products of the third stage of crustal evolution,as proposed by Chen Guoda,nor intra-continental(or intraplate)orogenic belts generated by intraplate dynamics,as argued by some scholars-rather,they are superposed orogenic belts formed on the pre-existing continental crust in eastern China due to Mesozoic Paleo-Pacific dynamic system.In the past,these orogenic belts were called the marginal Pacific epicontinental activation belts of eastern China.In the Mesozoic,under the effect of Paleo-Pacific dynamic system,the East Asia margin orogenic system formed along Northeast Russia-Sikhote Alin(Russia)-Japan-Ryukyu-Taiwan(China)-Palawan(Philippines)regions,while simultaneously the Mesozoic superposed orogenic system formed in the pre-existing continental crust in eastern China adjacent to the East Asia continental margin.The two orogenic systems,both driven by Mesozoic Paleo-Pacific dynamic system,developed synchronously to form the giant Mesozoic orogenic system in the Pacific tectonic domain in eastern Asia,radically changing the pre-Indosian tectonic framework of the area.
基金supported by National Natural Science Foundation of China(Grant Nos.42372239,41872237 and 41573023)the projects of China Geological Survey(Grant Nos.DD20160180,DD20190083,DD20190043,DD20221633)。
文摘Indicating the tectonic features of the Hanshan-Wuwei basin can reconstruct the framework of the basins formed in Mesozoic and further understand the Mesozoic tectonic evolution of the South China Block.Studies on surface structure,regional stress field and deep geophysical characteristics of the Mesozoic Hanshan-Wuwei basin in Lower Yangtze region were carried out.NE-NNE trending folds and faults developed in the northern margin of the basins.The reconstruction of tectonic stress fields indicates four stress stages dominating the basins'evolution including NW-SE compression,N-S compression,NW-SE extension and NWW-SEE compression.2D seismic profiles reveal coexistence of thrust,strike-slip and normal faults in the basin.Combined with regional geological studies,the geodynamic processes for the formation of the Hanshan-Wuwei basin can be divided into five stages:1)During the Late Triassic,EW trending foreland basin was formed by N-S compression;2)From Mid-Jurassic to Late Jurassic,continuous compression strengthened the foreland deformation and formed thrust nappes.In this stage,the integrated foreland basin was compartmentalized or fragmented,and transferred to the broken foreland basin;3)NE-trending sinistral strike-slip movement at the beginning of the Early Cretaceous;4)Regional extension resulted in normal faults and rift basins developing in the Late Cretaceous;5)The NWW-SEE compression at the end of the Late Cretaceous caused NW sinistral strike-slip faults to form,which partly transformed the rift basin.
基金granted by Opening Foundation of State Key Laboratory of Continental Dynamics(Grant No.21LCD08),Northwest University。
文摘The magma sources,origins and precise forming ages of the miarolite from Qishan and Kuiqi intrusions are still uncertain.New results reveal that,miarolites from the Qishan and Kuiqi intrusions yield crystallization ages of~101 and~98 Ma,and they have a high formation temperature(~910℃)and low oxygen fugacity value,indicating crystallization condition at low pressure in the upper crust with temperature of 678℃.The Qishan and Kuiqi miarolites are characterized by enrichment in SiO_(2) and high-K alkali,depletion in Ca and Mg,and belong to the high-K weak peraluminous rock series.The samples are enriched in HFSEs(i.e.,Ta,Zr and Hf)and LILEs(i.e.,Ba,P and Sr),depleted in Ba and Sr with the negative anomaly of Eu.In the primitive mantle normalized trace element spider diagram,the samples show a right-inclined‘seagull-type’pattern,combined the ratios of(La/Yb)_(N),10000×Al/Ga,Rb/Nb and Nb/Ta etc.,they were proved to be alkaline A-type granite.Combined the characterize of the trace elements,they were derived from clay-rich source accompanied pelite melting,and subjected to K-feldspar crystallization fractional.The values of ε_(Hf)(t)and tDM2 are distributed in the range of-2.8 to 3.3 with~1.2 Ga,and-6.0 to 4.0 with~1.2 Ga,revealing that they were generated from the Mesoproterozoic Cathaysia basement rocks.The comprehensive research reveals the Kuiqi and Qishan intrusions derived from crust-mantle mixing and partial melting of the crust,respectively,resulting from lithospheric extension generated by the Paleo-Pacific Plate subducted into the European-Asian Plate.
基金the National Natural Science Foundation of China who provided necessary financial support for this study(Nos.41872218,41572179,and 41372204)the State Key Laboratory of Continental Dynamics,Northwest University,Xi’an for providing a special fund to accomplish this study.
文摘The Shangdan suture zone(SDZ)in the Qinling orogenic belt(QOB)is a key to understanding the East Asia tectonic evolution.The SDZ gives information about convergent processes between the North China Block(NCB)and South China Block(SCB).In the Late Mesozoic,several shear zones evolved along the SDZ boundary that helps us comprehend the collisional deformation between the NCB and SCB,which was neglected in previous studies.These shear zones play an essential role in the tectonic evolution of the East Asia continents.This study focuses on the deformation and geochronology of two shear zones distributed along the SDZ,identified in the Shaliangzi and Maanqiao areas.The shear sense indicators and kinematic vorticity numbers(0.54–0.90)suggest these shear zones have sinistral shear and sub-simple shear deformation kinematics.The quartz’s dynamic recrystallization and c-axis fabric analysis in the Maanqiao shear zone(MSZ)revealed that the MSZ experienced deformation under green-schist facies conditions at∼400–500℃.The Shaliangzi shear zone deformed under amphibolite facies at∼500–700℃.The^(40)Ar/^(39)Ar(muscovite-biotite)dating of samples provided a plateau age of 121–123 Ma.Together with previously published data,our results concluded that QOB was dominated by compressional tectonics during the Late Early Cretaceous.Moreover,we suggested that the Siberian Block moved back to the south and Lhasa-Qiantang-Indochina Block to the north,which promoted intra-continental compressional tectonics.
文摘? The intensive extensional deformation in the eastern part of the Chinese continent in Late Mesozoic time (J3-K1) caused the formation of largescale fault basin system in Northeastern China block, metamorphic core complexes in North China block and widespread volcanic eruption and granitic intrusive in eastern China. Generally, the deformation has been interpreted as subduction tectonics along the eastern continental margin. We suggest that the combination effect of the subduction and collision in Tethys domain and the subduction from Pacific side and the mantle upwelling beneath the lithosphere. This event controlled the Late Jurassic to Early Cretaceous tectonic history in eastern China.
基金Supported by the National Natural Science Foundation of China Nos.42230303,42430305 and 42302236Graduate Innovation Fund of Jilin University Number:2024CX109.
文摘Since the Paleozoic,the tectonic evolution of northeastern Eurasia has been primarily influenced by the Paleo-Asian Ocean and the Paleo-Pacific tectonic domains.However,the spatial and temporal frameworks,as well as the timing of the tectonic transition between these two oceanic domains,remain unclear.For addressing these issues,we present petrological,geochronological,and geochemical data for andesite and sandstone samples from the Seluohe Group along the Jilin-Yanji Suture between the Jiamusi-Khanka Block and the North China Craton.The geochemical results indicate that the andesite sample is high-Mg andesite.Its magma source was generated by the metasomatized mantle wedge influenced by fluids derived from the subducted slab in a continental island arc setting.The high-Mg andesite gives the crystallization ages of Early Triassic(249±3 Ma).The sandstone is immature greywacke with a maximum depositional age of Early Triassic(247±1 Ma),and its sediments primarily originate from concurrent magmatic rocks within a juvenile continental arc.Based on our new findings,we propose that the Seluohe Group represents an Early Triassic volcanic-sedimentary association with continental island arc characteristics associated with the southwestward subduction of the Heilongjiang Ocean.We identified a sedimentary basin intimately associated with one or more continental arcs along the northeastern edge of the North China Craton.We suggest that the southwestward subduction of the Jilin-Heilongjiang Ocean in the Early Mesozoic accounts for this continental arc setting.There is a distinct temporal gap between the closure of the Paleo-Asian Ocean(ca.260 Ma)and the onset of Paleo-Pacific plate subduction(234–220 Ma),which is essentially coeval with the southwestward subduction of the Jilin-Heilongjiang Ocean between 255 Ma and 239 Ma.
基金supported by the National Natural Science Foundation of China(Grant No.42102113)the National Key Research and Development Program of China(Grant No.2021YFC2901803)+1 种基金the China Geological Survey Project(Grant No.DD20230579)China Scholarship Council(File No.202108575008).
文摘1.Objective,The Luang Prabang(Laos)-Loei(Thailand)metallogenetic belt,located along the northwestern margin of the Indochina Block(Fig.1a)and endowed nearly 200 t of gold and more than 106 t of copper,is one of the most important gold-copper metallogenic belts in Indo-China Peninsula.It has undergone tectonic changes during the Early Paleozoic to Mesozoic Proto-Paleo Tethys tectonic evolution,recorded by the Luang Prabang tectonic belt,the Nan-Uttaradit suture,and the Dien Bien Phu-Loei suture.
基金research grants No.40172030 from the NSFC and No.TG1999075502 from the Ministryof Science and Technology of China.
文摘SHRIMP zircon U-Pb dating in the Liguo and Jiagou intrusives indicates that they were formed at -130 Ma in the Early Cretaceous. Most inherited zircons in the Liguo intrusive were formed at 2509±43 Ma. Most inherited and detrital zircons in the Jiagou intrusive were formed at -2500 Ma, -2000 Ma and -1800 Ma. The SHRIMP zircon U-Pb dating in two gneiss xenoliths from the Jiagou intrusive yields the ages of 2461±22 Ma and 2508±15 Ma, respectively. The dating results from inherited and detrital zircons in the intrusives and the gneiss xenoliths imply that the magmas could be derived from the partial melting of the basement of the North China Block (NCB). The magmatism is strong and extensive in the periods from 115 to 132 Ma, which is of typical bimodal characteristics. It is suggested that the lithospheric thinning in the eastern North China Block reached its peak in 115-132 Ma.
基金the National Natural Science Foundation of China （grant No. 40032010B）.
文摘Based on the new data of isotopic ages and geochemical analyses, three types of Mesozoic granites have been identified for the Xiong＇ershan-Waifangshan region in western Henan Province： high-Ba-Sr I-type granite emplaced in the early stage （-160 Ma）, I-type granite in the middle stage （-130 Ma） and anorogenic A-type granite in the late stage （-115 Ma）. Geochemical characteristics of the high-Ba-Sr I-type granite suggest that it may have been generated from the thickened lower crust by partial melting with primary residues of amphibole and garnet. Gradual increase of negative Eu anomaly and Sr content variations reflect progressive shallowing of the source regions of these granites from the early to late stage. New ^40Ar/^39Ar plateau ages of the early-stage Wuzhangshan granite （156.0±1.1 Ma, amphibole） and middle-stage Heyu granite （131.8±0.7 Ma, biotite） are indistinguishable from their SHRIMP U-Pb ages previous published, indicating a rapid uplift and erosion in this region. The representative anorogenic A- type granite, Taishanmiao pluton, was emplaced at -115 Ma. The evolution of the granites in this region reveals a tectonic regime change from post-collisional to anorogenic between -160 Ma and -115 Ma. The genesis of the early- and middle-stage I-type granites could be linked to delamination of subducted lithosphere of the Qinling orogenic belt, while the late-stage A-type granites represent the onset of extension and the end of orogenic process. In fact, along the Qiniing -Dabie-Sulu belt, the Mesozoic granitoids in western Henan, Dabieshan and Jiaodong regions are comparable on the basis of these temporal evolutionary stages and their initial ^87Sr/^86Sr ratios, which may suggest a similar geodynamic process related to the collision between the North China and Yangtze cratous.
基金funded by the National Basic Research Program of China(973 Program,No.2012CB416701)National Natural Science Foundation of China(Grant 40972132)was partly supported by the State Key Laboratory for Mineral Deposits Research of Nanjing University(No.2008-Ⅰ-01)
文摘During the Late Mesozoic Middle Jurassic--Late Cretaceous, basin and range tectonics and associated magmatism representative of an extensional tectonic setting was widespread in southeastern China as a result of Pacific Plate subduction. Basin tectonics consists of post-orogenic （Type I） and intra-continental extensional basins （Type II）. Type I basins developed in the piedmont and intraland during the Late Triassic to Early Jurassic, in which coarse-grained terrestrial clastic sediments were deposited. Type II basins formed during intra-continental crustal thinning and were characterized by the development of grabens and half-grabens. Graben basins were mainly generated during the Middle Jurassic and were associated with bimodal volcanism. Sediments in half-grabens are intercalated with rhyolitic tufts and lavas and are Early Cretaceous in age with a dominance of Late Cretaceous-Paleogene red beds. Ranges are composed of granitoids and bimodal volcanic rocks, A-type granites and dome-type metamorphic core complexes. The authors analyzed lithological, geochemical and geochronological features of the Late Mesozoic igneous rock assemblages and proposed some geodynamical constraints on forming the basin and range tectonics of South China. A comparison of the similarities and differences of basin and range tectonics between the eastern and western shores of the Pacific is made, and the geo- dynamical evolution model of the Southeast China Block during Late Mesozoic is discussed. Studied results suggest that the basin and range terrane within South China developed on a pre-Mesozoic folded belt was derived from a polyphase tectonic evolution mainly constrained by subduction of the western Pacific Plate since the Late Mesozoic, leading to formation of various magmatism in a back-arc exten- sional setting. Its geodynamic mechanism can compare with that of basin and range tectonics in the eastern shore of the Pacific. Differences of basin and range tectonics between both shores of the Pacific, such as mantle plume formation, scales of extensional and igneous rock assemblages and the age of basin and range tectonics, were caused mainly by the Yellowstone mantle plume in the eastern shore of the Pacific.
基金funded by Sino-Probe 08-01the National Natural Science Foundation of China(grant No40572120)
文摘A synthesis is given in this paper on late Mesozoic deformation pattern in the zones around the Ordos Basin based on lithostratigraphic and structural analyses. A relative chronology of the late Mesozoic tectonic stress evolution was established from the field analyses of fault kinematics and constrained by stratigraphic contact relationships. The results show alternation of tectonic compressional and extensional regimes. The Ordos Basin and its surroundings were in weak N-S to NNE-SSW extension during the Early to Middle Jurassic, which reactivated E-W-trending basement fractures. The tectonic regime changed to a multi-directional compressional one during the Late Jurassic, which resulted in crustal shortening deformation along the marginal zones of the Ordos Basin. Then it changed to an extensional one during the Early Cretaceous, which rifted the western, northwestern and southeastern margins of the Ordos Basin. A NW-SE compression occurred during the Late Cretaceous and caused the termination of sedimentation and uplift of the Ordos Basin. This phased evolution of the late Mesozoic tectonic stress regimes and associated deformation pattern around the Ordos Basin best records the changes in regional geodynamic settings in East Asia, from the Early to Middle Jurassic post-orogenic extension following the Triassic collision between the North and South China Blocks, to the Late Jurassic multi-directional compressions produced by synchronous convergence of the three plates （the Siberian Plate to the north, Paleo-Pacific Plate to the east and Lhasa Block to the west） towards the East Asian continent. Early Cretaceous extension might be the response to collapse and lithospheric thinning of the North China Craton.
基金funded by the National Science Foundation of China (Nos. 41172198, 40702032)China Geological Survey Project (Nos. 12120113096400, 1212011121064)
文摘In the Langshan region, northwestern China, marked multi-stage intraplate deformation events have occurred since the Mesozoic, including（1） northeast-striking ductile left-lateral strike slip during the Middle-Late Triassic, which is closely related to the collision between the North China and the Yangtze plates;（2） top-to-the-southeast thrust with northwest-southeast trending maximum compression during the Late Jurassic;（3） nearly eastward detachment during the Early Cretaceous;（4） top-to-the-northwest thrust with northwest-southeast trending maximum compression during the Late Cretaceous and Early Cenozoic;（5） northeast-striking brittle left-lateral strike slip with nearly north-south trending maximum compression; and（6） northwest-southeast extension during the Middle-Late Cenozoic. All these deformation events belong to the intraplate deformation across the entire Central Asian region and respond to the tectonic events along the plate boundaries or deep tectonics. The structures developed in early events in the crust were the most important factors controlling the later deformation styles, and few new structures have later developed. Based on previous research and our results, the paleostress inversion in the Langshan region shows that the Mesozoic intraplate deformations in the study region mainly resulted from the tectonic events from the Paleo-Pacific region and have no or a weak relation to the Tethys region. During the Late Jurassic, the maximum compression from the Mongolia-Okhotsk region cannot be excluded. The Langshan region is the bridge between southern Mongolia and the western Ordos tectonic belt and is thus important to understand the nature and relationship between both regions.
基金supported in part by a grant from the National Science Foundation of China(No40674046)
文摘The Cambrian to Cretaceous paleomagnetic data from Chinese continental and adjacent blocks were collected using principles to obtain reliable and high-precision paleomagnetic data and to pay attention to the similarity of paleobiogeography and the coordination of tectonic evolution.The Chinese continental blocks were laid up on the reconstruction of proposed global paleocontinents with almost the same scale.Thus,it can be clearly recognized that the global continents,including Chinese continental blocks,range along latitudes on the southern side of the equator during the Early Paleozoic. In the Paleozoic,Chinese continental blocks were still located among the Laurentia,Siberia and Gondwana plates,following the fast moving of the Siberia Plate northwards,the amalgamation in a north-south direction at the western parts of the Laurentia and Gondwana plates,and the Iapetus and Rheic Oceans were subducted,eventually to form a uniform Pangea in the Late Paleozoic.The Australian and Indian plates of Eastern Gondwana moved and dispersed gradually southwards, continued to extend the Paleo-Tethys Ocean.The Chinese continental and adjacent blocks were still located in the Paleo-Tethys Ocean,preserved the status of dispersion,gradually moving northwards, showing characteristics of ranging along a north-south orientation until the Permian.In addition,a series of local collisions happened during the Triassic,and consequently most of the Chinese continental blocks were amalgamated into the Pangea,except for the Gangdise and Himalayan blocks. There was a counter-clockwise rotation of the Eastern Asian continent in the Jurassic and northwards migration of the Chinese continent in varying degrees during the Cretaceous,but the Himalayan and Indian plates did not collide into the Chinese continent during this period.
文摘South China is the most important polymetallic （tungsten, tin, bismuth, copper, silver, antimony, mercury, rare metals, heavy rare earth elements, gold and lead-zinc） province in China. This paper describes the basic characteristics of Mesozoic large-scale mineralization in South China. The large-scale mineralization mainly took place in three intervals： 170-150 Ma, 140-126 Ma and 110-80 Ma. Among these the first stage is mainly marked by copper, lead-zinc and tungsten mineralization and the third stage is mainly characterized by tin, gold, silver and uranium mineralization. The stage of 140-126 Ma mainly characterized by tungsten and tin mineralization is a transitional interval from the first to the third stage. In fight of the current research results of the regional tectonic evolution it is proposed that the large-scale mineralization in the three stages is related to post-collision between the South China block and the North China block, transfer of the principal stress-field of tectonic regimes from N-S to E-W direction, and multiple back-arc lithospheric extensions caused by subduction of the Paleo-Pacific plate.
基金supports by the Basic Research Foundation of the Institute of Geomechanics,CAGS,China (DZLXJK200703)the National Natural Science Foundation of China(40342015)+1 种基金SinoProbe-Deep Exploration in China(SinoProbe-08)the National Science Foundation(USA) Instrumentation and Facilities Program (EAR-0443387)
文摘The eastern margin of the Qaidam Basin lies in the key tectonic location connecting the Qinling, Qilian and East Kunlun orogens. The paper presents an investigation and analysis of the geologic structures of the area and LA-ICP MS zircon U-Pb dating of Paleozoic and Mesozoic magmatisms of granitoids in the basement of the eastern Qaidam Basin on the basis of 16 granitoid samples collected from the South Qilian Mountains, the Qaidam Basin basement and the East Kunlun Mountains. According to the results in this paper, the basement of the basin, from the northern margin of the Qaidam Basin to the East Kunlun Mountains, has experienced at least three periods of intrusive activities of granitoids since the Early Paleozoic, i.e. the magmatisms occurring in the Late Cambrian （493.1±4.9 Ma）, the Silurian （422.9±8.0 Ma-420.4±4.6 Ma） and the Late Permian-Middle Triassic （257.8±4.0 Ma-228.8＋1.5 Ma）, respectively. Among them, the Late Permian - Middle Triassic granitoids form the main components of the basement of the basin. The statistics of dated zircons in this paper shows the intrusive magmatic activities in the basement of the basin have three peak ages of 244 Ma （main）, 418 Ma, and 493 Ma respectively. The dating results reveal that the Early Paleozoic magmatism of granitoids mainly occurred on the northern margin of the Qaidam Basin and the southern margin of the Qilian Mountains, with only weak indications in the East Kunlun Mountains. However, the distribution of Permo-Triassic （P-T） granitoids occupied across the whole basement of the eastern Qaidam Basin from the southern margin of the Qilian Mountains to the East Kunlun Mountains. An integrated analysis of the age distribution of P-T granitoids in the Qaidam Basin and its surrounding mountains shows that the earliest P-T magmatism （293.6-270 Ma） occurred in the northwestern part of the basin and expanded eastwards and southwards, resulting in the P-T intrusive magmatism that ran through the whole basin basement. As the Cenozoic basement thrust system developed in the eastern Qaidam Basin, the nearly N-S-trending shortening and deformation in the basement of the basin tended to intensify from west to east, which went contrary to the distribution trend of N-S-trending shortening and deformation in the Cenozoic cover of the basin, reflecting that there was a transformation of shortening and thickening of Cenozoic crust between the eastern and western parts of the Qaidam Basin, i.e., the crustal shortening of eastern Qaidam was dominated by the basement deformation （triggered at the middle and lower crust）, whereas that of western Qaidam was mainly by folding and thrusting of the sedimentary cover （the upper crust）.
