2011 Vol. 17, No. 3

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STUDY ON TECTONIC BACKGROUND, EVOLUTION AND TECTONIC DOMAIN DIVISION OF EASTERN ASIA
SHANG Yue-nan, KANG Yong-shang, YUE Lai-qun, WEI Yan-zhi, QI Xue-feng, MA Su-min
2011, 17(3): 211-222.
Abstract (330) HTML (101) PDF (1213KB)(29)
Abstract:
Eastern Asia continent is a compound continent composed of some blocks, numerous micro-landblocks and fold belts or orogenic belts. In this article, the tectonic background and evolution of Eastern Asia as a whole are studied from the results of numerous authors relative to different sub-regions. Our synthetic study shows that the tectonic evolution of Eastern Asia can be divided into three stages: the generation stage of Precambrian epeirocratons, divergence and convergence stage of continental and oceanic crusts during the Paleozoic and basin-mountain development stage in the Meso-Cenozoic, with the tectonic evolution since Meso-Cenozoic particularly significant for the formation of most petroliferous basins in Eastern Asia. According to the geodynamical background since Yanshan of Eastern Asia experienced and the distinction among the different areas, Eastern Asia can be divided into 7 tectonic domains: western compressive tectonic domain, western pediocratic tectonic domain, Qingzang-Qiangtang tectonic domain, centeral cratonic tectonic domain, subducted margin tectonic domain, eastern clroum-Pacific tectonic domain and Xing'an-Mengolia tectonic domain. This division is meaningful for understanding basins forming mechanism as well as for analogue analysis between basins for prediction of petroleum resources.
A NUMERICAL SIMULATING RESEARCH ON NEOTECTONICS IN THE LOP NUR BASIN
SHI Wei, TIAN Mi, MA Yin-sheng, GONG Ming-quan, DU Jian-jun, LIU Yuan
2011, 17(3): 223-231.
Abstract (147) HTML (65) PDF (1216KB)(8)
Abstract:
Based on analysis of previous researches on neotectonic in Lop Nur Basin, two types of numerical simulation models have been built in this paper: ~N-S trending compression in first stage and NE-SW striking compression in the later stage. Combining with the previous studies, our numerical simulation shows the two main episodes of tectonic evolution occurred in the Lop Nur Basin since Late Cenozoic: (1) the ~N-S trending compression, the extension and rifting from late Oligocene to Early Pleistocene, and (2) the NE-SW striking compression and the shearing deformation since Early Pleistocene. Furthermore, the research shows the stress condition of the geological units is controlled both by lithology and faults; moreover, the low stress appears inside of the basin, and extensional direction is perpendicular to maximum principle compressive stress. The two main faults to the south of the basin are dominated by high shearing stress, whereas the minimal shearing stress distributes both in the basin and to its east. Furthermore, obviously controlled by faults, the displacement decreases from southwest to northeast, indicating the pore fluid migrates from southwest to northeast. This study provides some structural evidences for the research on sylvite forming and oil storage and transformation.
THE SPLIT AND REARRANGED OF ORIGINAL XINGXINGXIA GROUP OF EAST TIANSHAN IN XINJIANG
XU Sheng-li, WANG Jie
2011, 17(3): 232-242.
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The original Xingxing Xia group of Xingxing Xia in Xinjiang is a set of metamorphite system of complex lithology and obviously different metamorphic grade.According to Baishidu 1:50000 regional geological survey and rocl assemblage metamorphic degree and the combination of stromatolite, strata sequences of this region are rearranged.They include TianHu rock suite of Archean-Proterozoic ear, Xingxing Xia rock suite of Changchengian system.At the same time, wa did the regional contrast research on rock assemblage, metamorphite and deformation of every rock suite.
CRETACEOUS DEFORMATION HISTORY DETERMINED BY RESTORATION OF THE BALANCED SECTION ACROSS THE LANPING-JINDING REGION, YUNNAN, CHINA
LIU Li-jie, GUO Fu-sheng, JIANG Yong-biao, ZHU Zhi-jun
2011, 17(3): 243-248,261.
Abstract (198) HTML (130) PDF (1318KB)(6)
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The Nanping Basin, located between the India and Eurasian plates, was a large Mesozoic-Cenozoic basin and deposited huge thick continuous Cretaceous strata, which recorded well the regional tectonic movement characteristics. Based on field survey and indoor data sorting, a technique of balanced section across the Lanping-Jinding region was applied to a NW-SN geological profile to reconstruct the crust shortening history from Cretaceous and to understand the nature of the basin and to check up its geological structure explained correctly and to make a digital analysis. The results showed that the total length about the Cretaceous crust shortening was 2.938 km from the under section of Jingxing Formation to Nanxin Formation, and Nanxin Formation had the most strongest tectonic movement.
IN-SITU STRESS MEASUREMENT BY DIFFERENTIAL STRAIN ANALYSIS METHOD IN WFSD-1
PENG Hua, MA Xiu-min, JIANG Jing-jie
2011, 17(3): 249-261.
Abstract (170) HTML (87) PDF (1111KB)(14)
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Core differential strain analysis method is one of the primary means of in-situ stress measurement in WFSD. Through the pressure vessel, the experimental samples taken from different depths are pressured. And it is observed that the produced cracks are re-closed due to the previously loss stratum stress. The technology is that the size and direction of principal stress are determined by differential stain analysis in the process of crack closure. This article describes the principle and data processing method of in-situ stress measurement by differential strain analysis (DSA) in WFSD-1. And the stress profile is established with depth in the hole. Test results show that the stress states of the upper and lower plate in the Yingxiu-Beichuan fault are significant differences. Regional in-situ stress not only increases with depth, but also concerns with the geological structure, rock physical properties and other factors.
STUDY ON STRUCTURAL STRESS FIELDS SINCE PERMIAN, BACHU AREA, TARIM BASIN
LI Le, HOU Gui-ting, PAN Wen-qing, JU Yan, ZHANG Qing-lian, SHU Wu-lin, XIAO Fang-feng, JU Wei
2011, 17(3): 262-273.
Abstract (205) HTML (102) PDF (1155KB)(9)
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Three periods of structural stress fields can be recognized since Permian in northwest of Tarim Basin and adjacent areas based on structural evolution analysis, which is the end of Permian, the Triassic to paleogene and Neogene. Based on the research of stress-response structures of dykes, joints, slickensides, folds and faults, and analysis of the comparison characters of field of stress, it is found that the direction of the maximum principal stress formed by the collision of middle Tianshan island arc and Tarim basin was NW. The direction of maximum principal stress Triassic to paleogene was NNE, which developed by repression of dextrorotary of Tarim basin. And it was N-S direction since Neogene in Bachu area as a result of the collision of Indian plate with Eurasian plate. Furthermore, the authors simulated the stress field since Neogene based on 2D finite-element method, to deeply analyze the distribution and direction of stresses in the research area.
GEOCHEMICAL CHARACTERISTICS OF UPPER JURASSIC INTERMEDIATE-GRANITIC VOLCANIC ROCKS FROM NORTHERN CHIFENG, INNER MONGOLIA
HAO Bin, YANG Xin-de, ZHANG Ming-yang, XIE Cheng-fei
2011, 17(3): 274-285.
Abstract (208) HTML (89) PDF (978KB)(3)
Abstract:
Upper Jurassic intermediate-granitic volcanic rocks from northern Chifeng lie in Mongolia Paleo-uplift, the northern margin of the North China Craton.The lava mainly consists of rhyolite, andesite and augite andesite.The geochemical study for intermediate-granitic volcanic rocks suggests that the SiO2 is in 50.74% ~58.82%, Al2O3 and K2O+Na2O range from 15.32% ~ 17.17% and 4.89%~7.05%, Mg# changes from 0.13 to 0.39, which belong to Sodium and Calc-alkaline series.Geochemical results for rhyolite indicate that the SiO2 are in 74.68%~74.86%, Al2O3 and K2O+Na2O range from 12.09%~13.13%, Mg# changes from 0.13 to 0.39 and they belong to Calc-alkaline series or Shoshonitic series.The trace elements analysis for intermediate volcanic rocks demonstrate the insignificantly Eu anomalies (Eu*/Eu=0.94~1.12) and intense fractionation between LREE and HREE, [(La/Yb)N=9.6~16.09].The primitive mantle-normalized spider diagrams are characterized by LILE enrichment and HFSE depletion, especially an obviously negative Nb-Ta anomalies, and obviously positive Pb anomalies.Rhyolite has the similar characteristics and is characterized by a significantly negative Eu anomalies, [(La/Yb)N=7.86~10.05].Based on the previous studies, we infer that intermediate volcanic rocks formed under the stretching and thinning environment.With geothermal gradient increasing and atmosphere upwelling, andesitic magma resulted from partial melting of enriched lithospheric mantle.
GEOCHEMICAL CHARACTERISTICS AND TECTONIC SETTING OF UPPER JURASSIC GRANITE FROM NORTHERN CHIFENG, INNER MONGOLIA
LIU Hao, YANG Xin-de, HAO Bin, LIU Gui-quan, LI Yong-feng
2011, 17(3): 286-294.
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:Comparison geochemical characteristics of granite from northern Chifeng, Inner Mongolia with various type of granite at home and abroad and the discrimination show that most of the Chifeng granite belongs to Ⅰ-type granite, and a small number of A-type with.It is with the characteristic of high-K and alkali.The trace elements is rich in Ba, Th, K and other large ion lithophile elements (LILE), while the high field strength elements (HFSE) Nb, Ti, etc.are relatively depleted, which appear strongly depleted in Sr and P.LREE fractionation significantly, no significant fractionation of heavy rare earth.Significant negative Eu anomalies (δ Eu between the 0.3-0.843), REE patterns show significant Eu anomalies for the right-wing pedigree.Integrating the outcome of this paper and previous studies, we infer that the granite formed under the stretching and thinning environment.In this process, reducing the pressure and the upwelling of asthenosphere partial melting of the crust plays a role, so as to provide the conditions for the formation of granite.
GEOCHEMICAL CHARACTERISTICS OF CLASTIC SEDIMENTARY ROCKS FROM LOWER PERMIAN YUJIABEIGOU FORMATION IN NORTHERN CHIFENG, INNER MONGOLIA
GUO Wei, YANG Xinde, ZHANG Juan, HAO Bin
2011, 17(3): 295-302.
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Located in northern Chifeng, Inner Mongolia, the clastic sedimentary rocks of Lower Permian Yujiabeigou Formation is mainly distributed at the Inner Mongolia uplift in the northern margin of North China craton.These clastic sedimentary rocks are dominated by graywackes, and their source rocks have not been fully handling and sorting, with relatively low maturity.The studying results have shown that light and heavy rare earth elements differentiate distinctly, and that light rare earth elements are obvious enrichment while the heavy rare earth elements stay stable.The values of δEu vary from 0.72 to 0.99, show negative Eu anomalies particularly and are similar with NASC or PAAS distributing model, which suggest that these sediments are sourced from upper crust.Combining with the predecessors' achievements, it is obtained that the original rocks of these sediments' parent rocks mainly are consist of sedimentary rocks and granites, with a small amount of basalt; The geotectonic background of these sediments' source area is active continental margin or continent island arc, which may show that this studying area is in the suture stage between Siberia plate and North China craton in Lower Permian or earlier time.