基于GPS应变、地震应变率与震源应力场对帕米尔高原现今构造变形特征的分析          下载免费PDF全文

潘正洋  邵志刚  周云  王洵  解孟雨  艾萨·伊斯马伊力 《地球物理学报》2020,63(3):1143-1154

研究帕米尔高原的构造变形特征对于理解印度板块向北推挤过程中的应变分配方式以及应力转换模式具有重要的意义.本文利用区域GPS应变场、地震应变场与震源应力场分析帕米尔高原的构造形变特征.主要结论为:(1)该区域变形主要以NNW-SSE或近N-S向的挤压为主,在高原内部伴有明显的近ENE-WSW或E-W向拉张,应力方向在帕米尔高原与塔吉克盆地区域呈现逆时针旋转的趋势,而在塔里木盆地则显示几乎与帕米尔高原的一致的应力状态,这可能与两侧盆地块体的强度差异有关.(2)安德森断层参数A∅显示帕米尔高原北缘与西侧区域为逆断层应力状态,在高原内部为正断层应力状态,这与GPS应变的结果显示的应变主要集中在主帕米尔断裂与阿莱谷地附近而在高原内部应变较低是一致的,另外应力在喀喇昆仑断裂北段的方向基本平行于断层走向,以及断层北端较低的滑动速率,这说明了地壳挤压缩短可能是帕米尔高原主要的的构造变形特征,并不支持由于边界走滑断裂导致的应变分异或者块体挤出的模式.(3)综合考虑地震应变方向与SHmax从帕米尔北部NNW-SSE方向到天山北部的近N-S方向的转换,GPS应变方向在帕米尔高原两侧盆地都存在不同程度的旋转,应力场安德森参数A∅显示的应力状态以及SKS的结果显示的近ENE-WSW方向,我们认为印度板块向北推挤与天山造山带碰撞导致帕米尔高原不对称的径向逆冲是帕米尔高原现今构造变形的主要成因与构造模式.  相似文献   

帕米尔高原Rushan-Pshart古特提斯洋或中特提斯洋争论的岩石地球化学证据     

徐天德  王世锋  汤文坤  姚鑫 《地质科学》2020,(1):218-233

帕米尔高原上广泛分布的加里东期火山岩,印支期火山岩与燕山期火山岩被认为是块体依次向北俯冲拼贴到欧亚板块上的产物。特别是燕山期火山岩被认为是Rushan-Pshart中特提斯洋闭合的产物。但近年来地层古生物、火山岩证据不断表明Rushan-Pshart洋闭合时间在晚三叠一早侏罗世,由此限定Rushan-Pshart古特提斯洋性质,而帕米尔高原上广泛分布的燕山期火山岩是更南部的Shyok中特提斯洋闭合的产物。目前,中国境内Rushan-Pshart缝合带属性的研究工作展开较晚,研究程度较低。我们对塔什库尔干明铁盖沟一线燕山期火山岩带展开的工作发现零星分布的印支期花岗岩。印支期花岗岩错石U・Pb年龄显示岩体侵位时间在201 Ma左右。全岩主量元素特征表明岩石为I型高钾钙碱性闪长花岗岩;稀土元素在球粒陨石标准化图解中呈轻稀土元素相对富集,重稀土元素相对亏损的右倾海鸥型。明铁盖岩体的微量元素显示大离子亲石元素明显富集,而高场强元素明显亏损。稀土微量元素特征倾向花岗岩属性为岛弧型花岗岩,Sr-Nd-Hf同位素比值特征显示岩体形成于下地壳部分熔融环境。岩体的地化特征表明岩体形成的构造环境为板块汇聚的洋壳俯冲阶段,结合区域地质特征,我们将花岗岩体归为Rushan-Pshart古特提斯洋壳俯冲消减的产物。Rushan-Pshart缝合带传统上认为是中特提斯带,近年的研究进展认为其为古特提斯缝合带,本文的工作支持这种观点。Rushan-Pshart古特提斯缝合带的确立对帕米尔高原与青藏高原主体的块体对比提供了可信的对比方案,并对青藏高原新生代陆内变形方式的争论提供了可靠的证据。  相似文献   

Paleogene evolution and demise of the proto‐Paratethys Sea in Central Asia (Tarim and Tajik basins): Role of intensified tectonic activity at ca. 41 Ma     

Mustafa Y. Kaya  Guillaume Dupont‐Nivet  Jean‐Noël Proust  Pierrick Roperch  Laurie Bougeois  Niels Meijer  Joost Frieling  Chiara Fioroni  Sevin zkan Alt&#x;ner  Ezgi Vardar  Natasha Barbolini  Marius Stoica  Jovid Aminov  Mehmut Mamtimin  Guo Zhaojie 《Basin Research》2019,31(3):461-486

The proto‐Paratethys Sea covered a vast area extending from the Mediterranean Tethys to the Tarim Basin in western China during Cretaceous and early Paleogene. Climate modelling and proxy studies suggest that Asian aridification has been governed by westerly moisture modulated by fluctuations of the proto‐Paratethys Sea. Transgressive and regressive episodes of the proto‐Paratethys Sea have been previously recognized but their timing, extent and depositional environments remain poorly constrained. This hampers understanding of their driving mechanisms (tectonic and/or eustatic) and their contribution to Asian aridification. Here, we present a new chronostratigraphic framework based on biostratigraphy and magnetostratigraphy as well as a detailed palaeoenvironmental analysis for the Paleogene proto‐Paratethys Sea incursions in the Tajik and Tarim basins. This enables us to identify the major drivers of marine fluctuations and their potential consequences on Asian aridification. A major regional restriction event, marked by the exceptionally thick (≤ 400 m) shelf evaporites is assigned a Danian‐Selandian age (ca. 63–59 Ma) in the Aertashi Formation. This is followed by the largest recorded proto‐Paratethys Sea incursion with a transgression estimated as early Thanetian (ca. 59–57 Ma) and a regression within the Ypresian (ca. 53–52 Ma), both within the Qimugen Formation. The transgression of the next incursion in the Kalatar and Wulagen formations is now constrained as early Lutetian (ca. 47–46 Ma), whereas its regression in the Bashibulake Formation is constrained as late Lutetian (ca. 41 Ma) and is associated with a drastic increase in both tectonic subsidence and basin infilling. The age of the final and least pronounced sea incursion restricted to the westernmost margin of the Tarim Basin is assigned as Bartonian–Priabonian (ca. 39.7–36.7 Ma). We interpret the long‐term westward retreat of the proto‐Paratethys Sea starting at ca. 41 Ma to be associated with far‐field tectonic effects of the Indo‐Asia collision and Pamir/Tibetan plateau uplift. Short‐term eustatic sea level transgressions are superimposed on this long‐term regression and seem coeval with the transgression events in the other northern Peri‐Tethyan sedimentary provinces for the 1st and 2nd sea incursions. However, the 3rd sea incursion is interpreted as related to tectonism. The transgressive and regressive intervals of the proto‐Paratethys Sea correlate well with the reported humid and arid phases, respectively in the Qaidam and Xining basins, thus demonstrating the role of the proto‐Paratethys Sea as an important moisture source for the Asian interior and its regression as a contributor to Asian aridification.  相似文献   

帕米尔东北缘地壳结构的P波接收函数研究   总被引：6，自引：2，他引：4       下载免费PDF全文

唐明帅  郑勇  葛粲  王海涛  冀战波  孔祥艳  魏斌  李志海 《地球物理学报》2014,57(10):3176-3188

利用位于新疆帕米尔东北缘地带12个固定数字地震台和天山动力学Ⅱ期10个流动宽频带数字地震台记录的高质量远震波形数据,应用接收函数H_-κ叠加方法研究了帕米尔东北缘的地壳厚度-泊松比特征和部分台站下方的壳内界面深度.研究发现:(1) 帕米尔东北缘的Moho面起伏变化剧烈,其总体分布呈现东薄西厚、南厚北薄的特征,由塔里木盆地向天山延伸,地壳厚度约从45 km加深到55 km,从塔里木盆地向西昆仑山延伸,地壳厚度约从45 km加深到69 km;(2)沿着天山动力学Ⅱ期剖面,位于塔里木盆地北缘台站的壳内间断面的深度约为13~16 km,向北进入天山南麓加深到20 km左右,继续向北进入南天山山区壳内间断面不明显,可能暗示塔里木盆地基底向北俯冲,俯冲距离可能到达南天山的山前;(3)研究区地壳泊松比变化复杂(约从0.20到0.31),显示地壳物质组成的复杂性和显著的不均匀构造;(4)整个研究区的地壳厚度和泊松比之间没有明显的相关性,但天山动力学Ⅱ期剖面的结果表明,从塔里木盆地北缘到西南天山,地壳厚度和泊松比之间存在反相关关系,意味着天山地壳的增厚可能主要是通过以长英质岩石为主要组成成分的上地壳叠置而成;(5) 研究区全部地震台地壳厚度与海拔高程的线性回归方程表明地壳厚度与海拔的相关性相对较弱(相关系数为0.66),天山动力学Ⅱ期10个台站的地壳厚度与海拔具有很好的相关性(相关系数为0.85),可能表明沿该剖面地壳整体上处于相对均衡的状态.  相似文献   

滑脱褶皱陡坎的变形特征和运动学模型:以帕米尔-南天山前陆地区明尧勒背斜为例          下载免费PDF全文

李涛  陈杰  肖伟鹏 《地震地质》2014,36(3)

褶皱陡坎是褶皱变形过程中形成的地貌陡坎,是近期发现的一种不同于断层陡坎的构造作用形成的陡坎状地貌。在缺少地震反射剖面等深部资料时,利用褶皱陡坎可对活动褶皱的变形特征和生长演化历史进行限定,但迄今为止有关研究较少。位于帕米尔-南天山前陆地区的明尧勒背斜为第四纪活动的滑脱褶皱。在背斜南翼的河流阶地上发育了一系列褶皱陡坎:在T2和T3b阶地上,褶皱陡坎的高度/宽度/坡度分别为16m/40m/25°和20m/50m/26°,陡坎位置与下伏基岩中向斜枢纽位置对应。通过对这些褶皱陡坎的分析,得出:1)这些褶皱陡坎是滑脱褶皱通过膝折带迁移机制形成的。2)褶皱陡坎形成初期,陡坎高度、宽度和坡度逐渐增大;当陡坎宽度达到枢纽带宽度2倍时,陡坎坡度将达到最大值;之后尽管陡坎高度和宽度逐渐增大,其坡度将保持恒定。3)褶皱陡坎吸收的缩短增量与陡坎高度和下伏地层倾角间存在定量几何关系。根据T2阶地上褶皱陡坎的高度约16m和暴露年龄约8ka,估算T2阶地面暴露以来明尧勒背斜南翼的缩短速率为~1.3mm/a。在上述分析基础上,还对比总结了滑脱褶皱陡坎和断弯褶皱陡坎的异同点。  相似文献   

Early Cretaceous deformation in the southern Tashkorgan region: Implications for the tectonic evolution of the northeastern Pamir     

《China Geology》2021,4(1):67-76

The Pamir Plateau comprises a series of crustal fragments that successively accreted to the Eurasian margin preceded the India-Asia collision, is an ideal place to study the Mesozoic tectonics. The authors investigate the southern Tashkorgan area, northeastern Pamir Plateau, where Mesozoic metamorphic and igneous rocks are exposed. New structural and biotite ⁴⁰Ar-³⁹Ar age data are presented. Two stages of intense deformation in the metamorphic rocks are identified, which are unconformably covered by the Early Cretaceous sediment. Two high-grade metamorphic rocks yielding 128.4 ± 0.8 Ma and 144.5 ± 0.9 Ma ⁴⁰Ar-³⁹Ar ages indicate that the samples experienced an Early Cretaceous cooling event. Combined with previous studies, it is proposed that the Early Cretaceous tectonic records in the southern Tashkorgan region are associated with Andean-style orogenesis. They are the results of the flat/low-angle subduction of the Neotethyan oceanic lithosphere.©2021 China Geology Editorial Office.  相似文献   

中亚天山—帕米尔地区成矿地质背景   总被引：1，自引：0，他引：1  

李宝强  孟广路  曹新  曹积飞  范堡程  王斌 《地质通报》2015,34(4):686-695

中亚天山—帕米尔地区地处亚欧大陆腹地,跨古亚洲、特提斯两大全球性构造域,是哈萨克斯坦—准噶尔、卡拉库姆—塔里木、中伊朗—冈底斯、印度四大古板块的结合部位,地质构造复杂,矿产资源丰富。自中新太古代(或古元古代)以来分为5大演化阶段:1太古宙—古元古代演化阶段,本区古陆可能是组成Pangea-Ⅳ泛大陆的一部分;2长城纪—青白口纪泛大陆裂解事件导致了西昆仑地区第一次大规模的成矿作用,新元古代超大陆汇聚形成阶段,中天山地区广泛沉积了一套文德系含炭质岩系,形成金的矿源层,为后期大规模金的成矿作用提供了物质基础;3新元古代超大陆裂解及古亚洲洋—原特提斯洋演化阶段,岩浆活动强烈深部壳幔物质交换频繁,尤其是晚泥盆世—早中二叠世碰撞后伸展期,是区内最重要的成矿期;4研究区工作程度低(部分地区为空白区),特提斯洋演化阶段矿床发现较少,但找矿潜力巨大;5欧亚大陆形成后的后造山阶段,伴随着造山带强烈的挤压、褶皱、抬升、走滑、推覆等构造活动,岩浆作用十分发育,形成了一系列与韧性剪切构造有关的金矿化,以及与中酸性岩浆热液活动有关的铁、铜、多金属、锂铍(铌钽)、钨、锡、钼等矿产。  相似文献   

帕米尔弧形构造带的构造过程与地貌特征     

陈汉林  陈亚光  陈沈强  林秀斌  杨蓉  程晓敢  李康 《地球学报》2019,40(1):55-75

帕米尔弧形构造带是印度-欧亚板块碰撞变形最强烈的地区之一,是研究构造过程、地貌演化以及气候变化及其相互作用的理想场所。本文基于前人的研究成果,对帕米尔弧形构造带新生代构造单元、地貌特征和动力学演化模型进行了总结归纳,包括:主要构造单元的活动起止时间、活动量及活动速率;帕米尔弧形构造带现今的地貌特征(水系和冰川的分布);帕米尔弧形构造带6种主要的地球动力学演化模型的主要样式、优点及限制。论文提出了帕米尔弧形构造带晚新生代构造研究的三个重要的科学问题:精细厘定构造带内部的不同断裂带运动学特征和相互关系;深部地质过程与浅部响应相结合,探讨构造带形成的深部地质过程控制;将构造过程、气候特征与地貌演化作为一个耦合系统开展研究。  相似文献   

COSEISMIC SURFACE RUPTURES AND SEISMOGENIC MUJI FAULT OF THE 25 NOVEMBER 2016 ARKETAO M_W6.6 EARTHQUAKE IN NORTHERN PAMIR          下载免费PDF全文

CHEN Jie  LI Tao  SUN Jian-bao  FANG Li-hua  YAO Yuan  Li Yue-hua  WANG Hao-ran  FU Bo 《地震地质》2016,38(4):1160-1174

The M_W6.6 Arketao earthquake,which occurred at 14:24:30 UTC 25 November 2016 was the largest earthquake to strike the sparsely inhabited Muji Basin of the Kongur extension system in the eastern Pamir since the M 7 1895 Tashkurgan earthquake.The preliminary field work,sentinel-1A radar interferometry,and relocated hypocenters of earthquake sequences show that the earthquake consists of at least two sub-events and ruptured at least 77km long of the active Muji dextral-slip fault,and the rupture from this right-lateral earthquake propagated mostly unilaterally to the east and up-dip.Tectonic surface rupture with dextral slip of up to 20cm was observed on two tens-meter long segments near the CENC epicenter and 32.6km to the east along the Muji Fault,the later was along a previously existing strand of the Holocene Muji fault scarps.Focal mechanisms are consistent with right-lateral motion along a plane striking 107°,dipping 76° to the south,with a rake of 174°.This plane is compatible with the observed tectonic surface rupture.More than 388 aftershocks were detected and located using a double-difference technique.The mainshock is relocated at the Muji Fault with a depth of 9.3km.The relocated hypocenters of the 2016 Arketao earthquake sequence showed a more than 85km long,less than 8km wide,and 5~13km deep,NWW trending streak of seismicity to the south of the Muji Fault.The focal mechanism and mapping of the surface rupture helped to document the south-dipping fault plane of the mainshock.The listric Muji Fault is outlined by the well-resolved south-dipping streak of seismicity.The 2016 Arketao M_W6.6 and 2015 Murghob M_W7.2 earthquakes highlight the importance role of strike-slip faulting in accommodating both east-west extensional and north-south compressional forces in the Pamir interior,and demonstrate that the present-day stress and deformation patterns in the northern Pamir plateau are dominant by east-west extension in the shallow upper crust.  相似文献   

DETRITAL ZIRCON U-PB DATING OF MODERN RIVERS' DEPOSITS IN PAMIR,SOUTH TIAN SHAN AND THEIR CONVERGENCE ZONE          下载免费PDF全文

LIU Lang-tao  CHEN Jie  LI Tao 《地震地质》2017,39(3):497-516

By dating detrital zircon U-Pb ages of deposition sequence in foreland basins, we can analyze the provenance of these zircons and further infer the tectonic history of the mountain belts. This is a new direction of the zircon U-Pb chronology. The precondition of using this method is that we have to have all-around understanding to the U-Pb ages of the rocks of the orogenic belts, while the varied topography, high altitude of the zircon U-Pb ages of the orogenic belts are very rare and uneven. This restricts the application of this method. Modern river deposits contain abundant geologic information of their provenances, so we can probe the zircon U-Pb ages of the geological bodies in the provenances by dating the detrital zircon U-Pb ages of modern rivers' deposits. We collected modern river deposits of 14 main rivers draining from Pamir, South Tian Shan and their convergence zone and conducted detrital zircon U-Pb dating. Combining with the massive bed rock zircon U-Pb ages of the magmatic rocks and the detrital zircon U-Pb ages of the modern fluvial deposit of other authors, we obtained the distribution characteristics of zircon U-Pb ages of different tectonic blocks of Pamir and South Tian Shan. Overlaying on the regional geological map, we pointed out the specific provenance geological bodies of different U-Pb age populations and speculated the existence of some new geological bodies. The results show that different tectonic blocks have different age peaks. The main age peaks of South Tian Shan are 270~289Ma and 428~449Ma, that of North Pamir are 205~224Ma and 448~477Ma, Central Pamir 36~40Ma, and South Pamir 80~82Ma and 102~106Ma. The Pamir syntaxis locates at the west end of the India-Eurasia collision zone. The northern boundary of the Pamir is the Main Pamir Thrust(MPT)and the Pamir Front Thrust(PFT). In the Cenozoic, because of the squeezing action of the India Plate, the Pamir thrust a lot toward the north and the internal terranes of the Pamir strongly uplifted. For the far-field effect of the India-Eurasia collision, the Tian Shan on the north margin of the Tarim Basin also uplifted intensely during this period. Extensive exhumation went along with these upliftings. The material of the exhumation was transported to the foreland basin by rivers, which formed the very thick Cenozoic deposition sequence. These age peaks can be used as characteristic ages to recognize these tectonic blocks. These results lay a solid foundation for tracing the convergence process of Pamir and South Tian Shan in Cenozoic with the help of detrital zircon U-Pb ages of sediments in the foreland basin.  相似文献