Dissertation > Astronomy,Earth Sciences > Geology > Structural Geology > Regional structural geology

Early Palaeozoic Tectonic Evolution in HongLiuGou, Altyn,Xinjiang

Author YangZiJiang
Tutor WangZongXiu
School Chinese Academy of Geological Sciences
Course Structural Geology
Keywords HongLiuGou early palaeozoic volcanic-sedimentary basin Ophiolite belt Magmatic activity Back-arc basin
CLC P548
Type PhD thesis
Year 2012
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Hongliugou was at the east section on the northern slope of Altun mountain which located in between the Tarim plate and Qaidam plate, preservated the remnants of the early Paleozoic limited ocean basin-the Hongliugou ophiolite belt, and magmatic rock belt of the Paleozoic collision and post-collision period in the southeast edge of Tarim plate, in which process appeared the diverse and complex tectonic deformation, is one of the most complex geological structure of the Altun orogenic belt.This paper focuses on the study of orogeny and its closely related to the volcanic sedimentary basins、ophiolitic melange(belt)、magmatic activity, etc. and discusses the early Paleozoic tectonic system, orogeny and period of Altun Mountain. Focused on the following aspects of key problems:(1) redefinite the early Paleozoic strata and its regional geological significance;(2) accurately determine the ophiolite (belt) and ophiolitic melange (belt) had been,and finely study the timing, qualitative, and positioning;(3) deeply syudy the spatial and temporal distribution of magmatism (magma intrusion and volcanism) and tectonic environmental tracer.The results as follows:1、The radiolarian microfossils information of middle-late Ordovician had been obtained from the former division of Precambrian Jixian System strata, and the early Silurian basalt’s zircon U-Pb isotopic age(439+18/-24Ma, laser Denudation method), on the basis of these, which had been redefinited middle-upper ordovician and lower silurian.2、Based on the analysis of formation lithology, sedimentary facies, sedimentary basin of volcano-sedimentary basin of Middle-Late Ordovician to early Silurian in the study area, it is clear that the basin had developed furtherly on the basis of intracontinental rift, formed the limited oceanic basin, having the nature of the back-arc basin.3、The characteristics of Temporal-spatial distribution、rock composition、lithochemistry of ophiolitic melange belt in the Hongliugou-binggou had been mainly researched,449.5±10.9Ma of the zircon U-Pb isotopic age was obtained in the dark-gray-green gabbro of the north of Binggou.4、Through the study of the early Paleozoic volcano rock and granite in the region, a large number of high-quality test data of rock chemistry、rare earth and trace elements had been obtained, and also gotten a number of accurate SHRIMP method U-Pb zircon age in the granite, for example,461.7±12.7Ma of the zircon U-Pb isotopic age was obtained in the pale red porphyritic K-feldspar granite of the the upstream of Qiashikansay、418.5±9.6Ma of the zircon U-Pb isotopic age was obtained in the light pale red porphyritic adamellite of Binggou、410.7±11.9Ma of the zircon U-Pb isotopic age was obtained in celandine green coarse-grained granodiorite of Binggou、419.9±7.9Ma of the zircon U-Pb isotopic age was obtained in ofwhite mediumgrained granodiorite of Binggou of Shansha boundary.6、The characteristics of the study area strata, volcanic rocks and intrusive rocks had been summarized through comprehensive analysis of sedimentary basin evolution and magmatism, the early Paleozoic tectonic system and the evolution model were proposed in the study area:the study region as part of the "Proto-Tethys" had formed the trench-arc-basin tectonic system of the edge of the Tarim plate in Early Paleozoic; Hongliugou area was the back-arc basin evolution stages in the late Ordovician to early the Silurian; the Limited Ocean basin of the back-arc basin had closed in the Late Silurian, and formed large-scale mitigation activities, eventually formed the early Paleozoic orogenic belt of Altun

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