西天山艾肯达坂组火山岩系同位素定年及其构造意义   总被引：10，自引：1，他引：10  

陈衍景  刘玉琳  鲍景新  张增杰  陈华勇  蔡文俊  Herb Helmstaedt 《矿物岩石》2004,24(1):52-55

西天山艾肯达坂地区较好发育了艾肯达坂纽红色陆相火山岩建造．它不整合在下石炭统大哈拉军山组之上,未经变形和变质，属于陆陆碰撞晚期的橄榄安粗岩系，其年龄确定是厘定从碰撞造山向陆内构造演化的关键。因此,通过16件新获得的钾氩年龄测值，确定艾肯达坂组火山岩系形成在260Ma～270Ma之间，属早二叠世，而不是过去认为的石炭纪；西天山的陆陆碰撞应在二叠纪末结束,此后进入陆内造山阶段。  相似文献   

新疆天山表壳元素地球化学特征     

汪洋  杜佩轩 《矿物岩石地球化学通报》2004,23(1):5-9

根据天山地区(42～44^oN，81～89^oE)1：20万，七探采集的900余个岩石样品的分析结果，基于全样本统计和迭代剔除方法，得到新疆天山地区表壳(出露地壳)的39种元素丰度值；对其中的SiO2、TiO2、Al2O3、TFe2O3、MgO、MnO、CaO、Na2O、K2O、P2O5 10种常量元素，按氧化物之和为100％进行归算。与全球大陆上地壳元素丰度值相比，天山地区表壳元素丰度富集SiO2、MnO和Ag、As、Hj、Sb元素，明显亏损CaO和。Be、Co、Cr、Ni、Mo、Sn，V、W等元素。从元素比值来看，该区表壳的Ba/La、K／La、K／Th、Nb/La、Th/La、Y／La值与全球大陆上地壳相应元素值相当；而K／Na、La／As、La／Sb值明显低于全球大陆上地壳。该区表壳化学成分相当于花岗闪长岩，同时表现出相对富钠和As、Sb元素的特征；这一地球化学特征与区内出露的表壳岩石主要是加里东期和海西期岛弧造山作用的产物有关，相对富钠的成分特征与岛弧岩浆活动中的Adakite质岩浆作用有关。  相似文献   

Genesis of Kanggur Gold Deposit in Eastern Tianshan Orogenic Belt, NW China: Fluid Inclusion and Oxygen and Hydrogen Isotope Constraints   总被引：3，自引：0，他引：3  

Zhiliang Wang    Neng Jiang  Yitian Wang    Jingwen Mao  Jianmin Yang 《Resource Geology》2004,54(2):177-185

Abstract. Primary fluid inclusions in quartz and carbonates from the Kanggur gold deposit are dominated by aqueous inclusions, with subsidiary CO₂-H₂O inclusions that have a constant range in CO₂ content (10–20 vol %). Microthermometric results indicate that total homogenization temperatures have a wide but similar range for both aqueous inclusions (120 to 310C) and CO₂-H₂O inclusions (140 to 340C). Estimates of fluid salinity for CO₂-H₂O inclusions are quite restricted (5.9∼10.3 equiv. wt% NaCl), whereas aqueous inclusions show much wider salinity ranging from 2.2 to 15.6 equivalent wt %NaCl.
The 6D values of fluid inclusions in carbonates vary from -45 to -61 %, in well accord with the published δD values of fluid inclusions in quartz (-46 to -66 %). Most of the δ¹⁸O and δD values of the ore-forming fluids can be achieved by exchanged meteoric water after isotopic equilibration with wall rock by fluid/rock interaction at a low water/rock ratio. However, the exchanged meteoric water alone cannot explain the full range of δ¹⁸O and δD values, magmatic and/or meta-morphic water should also be involved. The wide salinity in aqueous inclusions may also result from mixing of meteoric water and magmatic and/or metamorphic water.  相似文献   

塔里木盆地南缘历史时期气候环境变化的过程与特征   总被引：2，自引：9，他引：2  

钟巍  塔西甫拉提·特依甫  王立国  李偲 《中国沙漠》2004,24(3):261-267

根据塔里木盆地南缘具较高分辨率的湖沼相沉积物碳酸盐δ^13C和粒度等记录，恢复出2162-850BC期间为一相对稳定的温暖干旱时期，之后迅速转冷湿，湿润程度呈持续、阶段式增加，50 BC至500 AD期间呈现的显著冷湿特征于550 AD之后突变转暖干而结束。550 AD和1000 AD前后的具突变性质的气候事件在南疆地区近2．0ka的气候变化中具有重要意义，反映气候状况有过重大调整。850—1300AD期间(相当于中世纪温暖期)冷暖、干湿多变，但温暖特征并不明显。特别是1100—1200AD期间气候快速、频繁变化之后，奠定了本地区现代稳定干旱环境特征。区域对比表明，尼雅剖面记录的气候变化具有广泛的区域一致性。  相似文献   

Mesozoic-Cenozoic tectonic transition in Kuqa Depression-Tianshan, Northwest China: Evidence from sandstone detrital and geochemical records   总被引：2，自引：0，他引：2  

LI Zhong  GUO Hong  WANG Daoxuan & LIN Wei . Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  China . Tarim Oilfield Branch  CNPC  Korla  China  . Hefei University of Industry  Tunxilu  Hefei  China 《中国科学D辑(英文版)》2005,48(9):1387-1402

Succeeding to multiply collisions of different blocks in Late Paleozoic[1―5], complex intracontinental structural deformation occurred in the Tianshan area during Mesozoic-Cenozoic[6―16], which controlled coeval basin-range evolution and resulted in intensive modi- fication and adjustment of the Paleozoic oil-gas reser- voirs[17―19]. The Kuqa Depression is a secendary struc- tural unit of the Tarim basin, in which Mesozoic- Ce- nozoic deposits occur in thickness of 6000―7000 m. The Kuq…  相似文献   

Geochemical characteristics of the metapelites from the Xingxingxia group in the Eastern Segment of the Central Tianshan: Implications for the provenance and paleoweathering     

LI Qiugen  LIU Shuwen  HAN Baofu  WANG Yueran & DANG Qingning The Key Laboratory of Orogenic Belts  Crustal Evolution  Ministry of Education  School of Earth  Space Sciences  Peking University  Beijing  China 《中国科学D辑(英文版)》2005,48(10)

Clastic sedimentary rocks record a number of in-formation about the compositions and paleoweathering conditions of the source areas, and the tectonic setting of the depositional basin[1―6]. The traditionallypetrological study commonly utilizes the major com-ponents (Quartz, Feldspar and Lithics) of the silici-clastic sedimentary rocks to investigate the source rock composition and tectonic setting[7]. However, thepetrological method is somewhat limited, because many of the mafic components f…  相似文献   

Study on the Source Parameters of Earthquakes in the Middle Eastern Area of North Tianshan in Xinjiang     

Zhao Cuiping 《中国地震研究》2005,19(4):381-390

INTRODUCTIONThe study of source parameters is usually based oninversionfromobservational seismic waveformdata.Seismic wave affected bygeometric spreading,inelastic attenuation,scatteringandsite effects ofthe mediumontheir way fromsource to station.Therefo…  相似文献   

Characteristics of Energy Accumulation and Release of Seismogenic Tectonics and Seismic Risk Analysis in Some Areas in the Tianshan Mountains, Xinjiang1     

Shen Jun 《中国地震研究》2005,19(1):1-11

INTRODUCTIONHowtocombinethestudyofseismogenictectonicswithearthquakepredictionisanurgentscientificdifficulty .Thereexistbiggapsbetweenstudymethodsandcurrentknowledgeonseismogenitectonics ,earthquakeprediction ,seismogenesisandthephysicsofearthquakeoccurre…  相似文献   

Permo-Carboniferous Radiolarians from the Wupata''''erkan Group,Western South Tianshan, Xinjiang, China   总被引：3，自引：0，他引：3  

LI Yuejun  SUN Longde  WU Haoruo  ZHANG Guangya  WANG Guolin  HUANG Zhibin Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  Tarim Oilfield Company  PetroChina  Korla  Xinjiang 《《地质学报》英文版》2005,(1)

1 IntroductionThe Wupata'erkan Group, also called Wupata'erkanFormation (Wang et al., 1990), in the western SouthTianshan, China (Fig. 1), mainly comprises gray and darkgray fine-grained clastic rocks, interlayered with medium-acidic volcanic rocks (andesite and quartz porphyry),carbonates, cherts and variegated tuffaceousconglomerates. The chert in the formation was firstly foundin our field trip along sections of the Qiqi'erjianakesu Riverand Kekebiele Daban. Deformation of the group is…  相似文献   

Saprolite Remnants as Indicators of Pre-Glacial Landform Genesis in Southeast Sweden   总被引：3，自引：0，他引：3  

Mats Olvmo  Karna Lidmar-Bergström  Kerstin Ericson  Johan M. Bonow 《Geografiska Annaler: Series A, Physical Geography》2005,87(3):447-460

Twenty‐six sites with remnants of gravelly saprolites (grus) have been located in southeast Sweden. Joint block hills (castle kopjes) and steep rock walls with weathered joints as well as rounded boulders are documented to have an origin in deep weathering and subsequent stripping of saprolites. The saprolite remnants and landforms result from the fragmentation of the re‐exposed sub‐Cambrian peneplain along fracture systems. Only shallow saprolites occur on the elevated intact parts of the sub‐Cambrian peneplain, while saprolites up to 20 m thick are encountered in areas where the sub‐Cambrian peneplain is fractured and dissected. Neogene uplift with reactivation of the weathering system is thought to be the main cause of saprolite formation. Deep weathering is thus judged to have been the major agent of landform formation in the study area, while glacial and glaciofluvial erosion has contributed mainly by stripping saprolites, detaching corestones, and plucking joint blocks along weathered joints.  相似文献