AN INTRACONTINENTAL EXTENSIONAL TECTONIC SETTING FOR THE ORIGIN OF YULONG PORPHYRY COPPER DEPOSIT IN EAST TIBET

AN INTRACONTINENTAL EXTENSIONAL TECTONIC SETTING FOR THE ORIGIN OF YULONG PORPHYRY COPPER DEPOSIT IN EAST TIBET     

A DISCUSSION ON FORMATION AND EVOLUTION OF THE LANCANGJIANG PLATE JUNCTION WITH ANALOGY: WHETHER OR NOT THE LANCANGJIANG OCEAN EXISTED IN LATE PALEOZOIC

A DISCUSSION ON FORMATION AND EVOLUTION OF THE LANCANGJIANG PLATE JUNCTION WITH ANALOGY: WHETHER OR NOT THE LANCANGJIANG OCEAN EXISTED IN LATE PALEOZOIC     

Discussion on Relationship Between Western Margin of Yangtze Block and Southwestern Sanjiang Region in Proterozoic

DISCUSSION ON RELATIONSHIP BETWEEN WESTERN MARGIN OF YANGTZE BLOCK AND SOUTHWESTERN SANJIANG REGION IN PROTEROZOIC     

北黄海盆地东部前中生界基底特征

北黄海盆地是中国近海唯一未获得油气突破及勘探程度最低的含油气盆地（朝鲜已在该盆地东部实现了工业性油气突破）,朝鲜在东部凹陷的3口钻井证实北黄海盆地东部凹陷主体前中生界基底是下古生界(Pz₁)地层,与上覆以砂泥岩为主的中-新生界地层在地球物理特征上有很大差异,该特征提供了以地球物理资料推断和确定中-新生界盆地基底特征的可靠性。通过重力、磁力及大量多道地震资料解释认为,北黄海盆地前中生界基底最大埋深约5.5 km,凹陷主体部位前中生界基底以下古生界碳酸盐岩为主,其东北角可能存在上古生界碎屑岩基底,而凹陷南部可能是元古界浅变质岩基底。     

滇西漕涧地区崇山变质杂岩中崇山岩群的时代与构造属性

滇西崇山变质杂岩带位于三江造山带"峰腰"的北段,带内构造挤压变质作用强烈,主体由一套中-深变质岩系(崇山岩群)和晚期花岗岩组成.其中崇山岩群历来被认为是元古代的结晶基底,但至今无精确的年龄依据,其形成时代和构造属性存在较大争议,严重制约了对区域构造演化的认识.对滇西漕涧地区崇山岩群中的岩石组分开展了碎屑锆石U-Pb年代学及岩石地球化学研究,结果显示副变质岩中的锆石均具明显的磨圆特征和较大的岩浆核,其中3件样品的最小一组碎屑锆石年龄分别为366～412 Ma(平均值为395 Ma)、435～508 Ma(平均值为473 Ma)和673～704 Ma(平均值为689 Ma),指示了其原始沉积时代应不早于395 Ma;岩石地球化学表明,副变质岩是一套活动大陆边缘或被动大陆边缘构造背景有关的大陆岛弧碎屑岩,变质基性岩和变质中性岩为同源异相,均具活动大陆边缘的弧火山岩特征.结合副变质岩和两类正变质岩的构造属性相同以及普遍具相互伴生关系的特点,该3类岩石应属同一套地层系统的不同物质组分,崇山岩群主体为一套成岩于晚古生代(236～395 Ma)和形成于陆缘弧环境的火山-沉积地层单元;并与南东侧澜沧增...     

TECTONIC CHARACTERISTICS AND EVOLUTION OF THE QIANGTANG BASIN IN NORTHERN TIBET PLATEAU

TECTONIC CHARACTERISTICS AND EVOLUTION OF THE QIANGTANG BASIN IN NORTHERN TIBET PLATEAU     

BASIN-RANGE TRANSITION AND GENETIC TYPES OF SEQUENCE BOUNDARY OF THE QIANGTANG BASIN IN NORTHERN TIBET

BASIN-RANGE TRANSITION AND GENETIC TYPES OF SEQUENCE BOUNDARY OF THE QIANGTANG BASIN IN NORTHERN TIBET     

青藏高原中南部前寒武系及古生界岩石地层组成和时代特征

对青藏高原中南部北羌塘、南羌塘、冈底斯、仲巴、喜马拉雅和昌都6个地区前寒武系及古生界岩石地层的组成和时代特征进行分析,总结了117个群组级岩石地层单位的岩性组合和时代特征,梳理地层划分对比中存在的相关问题。通过调查认为,前人划定的前寒武纪基底大多不再具有典型的变质或结晶基底特征,北羌塘可能具有相对稳定的基底,下古生界包括部分奥陶系和志留系,上古生界不整合在下古生界之上,发育早泥盆世晚期地层及中—上泥盆统、上石炭统和二叠系。南羌塘地区基底性质不明,下古生界以“残块”形式出露在玛依岗日一带,上古生界在南羌塘地区西部和东部一带表现样式不同,在西部日土一带具稳定沉积特点,东部双湖一带为“基质+块体”的俯冲增生杂岩。冈底斯地区,拉萨地块(中部)和聂荣微地体具前寒武纪基底,新元古代末—寒武纪发育一套“双峰式”火山岩,奥陶系可能不整合在前奥陶系之上,奥陶纪—二叠纪均为海相(或海陆过渡相)沉积。仲巴微地体自下而上可由上震旦系—寒武系片岩构造层、奥陶系—泥盆系变质碳酸盐岩构造层、石炭系—二叠系构造层组成。喜马拉雅地区具有较稳定的前寒武系结晶基底,中奥陶世—晚二叠世均沉积一套海相地层。昌都地区可能存在前寒武系基底,下古生界仅零星出露下奥陶统和志留系,上古生界除乐平统与瓜德鲁普统之间为假整合接触外,其余均为较连续的海相沉积地层。     

PRINCIPLES IN DIFFERENTIATING STRUCTURAL-TECTONIC ZONES IN ORE-PETROGRAPHIC PROVINCES AND ORE DISTRICTS

The Zeya-Bureya plain and its mountain fringe are components of the Mongolo-Okhotsk folded belt, a northern segment of the East Asia Hercynian structure located between the ancient Siberian and Chinese platforms. The basement is a complex combination of Proterozoic, Sinian-lower Paleozoic and middle Paleozoic folded structures. In the Tomesk synclinorial zone, what appear to be parageosynclinal middle to upper Paleozoic structures, rest directly on Proterozoic crystalline foundation, and are correlative with similar formations in the western slope of the ancient Bureya-Girin massif. Structural trends in the southern half are north-northeasterly and north of latitude 52°; the trend is sublatitudinal. Deep rifts have been particularly important in the tectonics of the region. Regional Mesozoic structure shows inherent features from earlier stages, expressed in Paleozoic structural trends and faults. The largest and deepest of the Mesozoic troughs are associated with Paleozoic synclinoria and uplifts; swells are associated with pre-Sinian basement highs and Paleozoic anticlinoria. Maps showing geophysical anomalies and fields and tectonic features are included.—C. E. Sears.     

秦岭造山带主要大地构造单元的新划分

根据近年来的地层、沉积、岩浆-火山和构造变形及岩石地球化学等方面研究新进展,结合前人的成果,按照大地构造相单元划分原则,将秦岭造山带分为13个主要构造单元: ①华北南缘陆坡带,包括第一层序的青白口系大庄组、震旦系罗圈组和寒武系,与之对应的豫西栾川群;第二层序的奥陶纪陶湾群;②北秦岭弧后杂岩带,以宽坪群和部分二郎坪群中的基性火山岩与碳酸盐岩的构造块体与变质的古生代深海碎屑岩混杂为特征;③秦岭岛弧杂岩带,由丹凤群不同的古洋隆块体、富水幔源岛弧基性岩浆杂岩、云架山群、斜峪关群和草滩沟群的岛弧钙碱性岩浆岩和火山岩及深海沉积物及秦岭群弧基底杂岩等构成,时间跨度为奥陶纪-石炭纪;④秦岭弧前盆地系,泥盆系及其它晚古生代地层是其主要充填物,同沉积断裂控制了一系列的次级盆地;⑤秦岭增生混杂带,由泥、砂岩组成的基质和基性、超基性岩、火山岩、灰岩、硅质岩等岩块构成,最终形成于二叠纪末-三叠纪初;⑥南秦岭岛弧杂岩带,碧口群的基性-中酸性火山岩和岩浆岩组成,称碧口弧;由三花石群的中基性火山岩以及西乡群的中酸性火山岩共同构成,称西乡弧;由耀岭河群和郧西群中基性熔岩和中酸性火山岩组成,称安康弧;⑦南秦岭弧前盆地系,碧口弧前盆地充填物是以碎屑岩为主的横丹群和关家沟群;西乡弧前沉积主要由三花岩群包括王家坝组砂岩以及由泥岩、砂岩和中酸性火山岩变质而成的片岩、片麻岩和石英岩组成.安康弧前盆地具有明显的深海扇沉积特征梅子垭群和大贵坪组;⑧南秦岭弧后盆地系,包括后龙门山的茂县群和上古生界及三叠系,大巴山的洞河群和部分耀岭河群的火山岩;⑨南秦岭弧后陆坡带,只保留大巴山弧后陆缘,是高川-毛坝以南的下古生界;⑩南秦岭前陆褶冲带,包括龙门山北段、米仓山和大巴山前陆褶冲带.三带形成于印支-燕山期,但构造线不同,且在出现的时间上,由西到东由早到晚;(11)三叠纪残余海盆;(12)中-新生代走滑拉分和断陷盆地;(13)基底断块.     

松辽地块大地构造属性: 古生界碎屑锆石年代学的制约

对松辽地块南部上古生界哲斯组的碎屑锆石应用LA--ICP --MS U --Pb 测试的结果显示了4 个主要的年龄段: 263 ～ 378 Ma ( 峰值年龄274 Ma) ; 405 ～ 547 Ma ( 峰值515 Ma) ; 660 ～ 974 Ma ( 峰值为 923 Ma) ; 其余均为中元古代年龄1 165 Ma、1 369 Ma、1 476 Ma、1 517 Ma。其中最年轻一组锆石年龄263 ± 2 Ma 代表了哲斯组主体沉积的下限年龄; ～ 274 Ma 的峰期年龄与附近地区的大石寨组火山岩和岛弧岩浆岩的年龄一致; ～ 515 Ma 的峰期年龄与东北地区泛非期基底变质杂岩的年龄一致; 其余的古老年龄均反映了松辽地块基底的信息。结合松辽地块的北部上古生界土门岭组、西部本巴图组和东缘黑龙宫组的碎屑锆石年龄,显示松辽地块应存在太古代和元古代的变质基底,为古生界地层提供了丰富的物源。松辽地块应为一个稳定的微地块,而不是长期活动的造山带。     

LARGEST ALTYN TAGH LITHOSPHERIC SHEAR FAULT IN CENTRAL ASIA

LARGEST ALTYN TAGH LITHOSPHERIC SHEAR FAULT IN CENTRAL ASIA     

鄂尔多斯盆地乌审旗地区上古生界砂岩碎屑锆石U-Pb年龄及其地质意义

通过LA-ICP-MS碎屑锆石的U-Pb测年和U、Th元素含量分析,结合邻区年龄数据和岩性特征,对鄂尔多斯盆地乌审旗地区上古生界山西组1段和下石盒子组8段砂岩进行了同位素定年物源示踪研究。研究揭示,盒8段和山1段源区母岩形成年龄属于太古代、古元古代、中元古代、晚古生代,分别与华北块体的形成、增生和克拉通化相关,是华北克拉通演化多阶段地质事件作用下的产物。沉积物源区主要为华北克拉通内部或盆地北缘,物源主要来自华北地台东部的早太古代基底古老变质岩系和新太古代的变质岩系、乌拉山和东部集宁地区的新太古代晚期的片麻状花岗岩、早元古代早期的古老的TTG片麻岩及麻粒岩和早元古代晚期的孔兹岩带,此外,阴山地块390～310 Ma岩浆岩也是重要物源之一。该项成果不仅查明了乌审旗地区上古生界山西组1段和下石盒子组8段碎屑锆石年龄与华北克拉通地质事件在时间上的对应关系,指明了年龄区间碎屑物质成分来源的归属性,而且对研究区可能存在的华北克拉通地质事件首次从岩性上提供了重要信息。     

TECTONIC SIGNIFICANCE OF THE WEST KUNLUN FOLD-THRUST-BELT AND THE TARIM SOUTHWEST DEPRESSION

TECTONIC SIGNIFICANCE OF THE WEST KUNLUN FOLD-THRUST-BELT AND THE TARIM SOUTHWEST DEPRESSION     

Groundwater Systems and Resources in the Ordos Basin, China

The Ordos Basin is a large-scale sedimentary basin in northwestern China.The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks,Lower Paleozoic carbonate rocks,Upper Paleozoic to Mesozoic clastic rocks and Cenozoic deposits.The total thickness is up to 6000 m.Three groundwater systems are present in the Ordos Basin,based on the geological settings,i.e.the karst groundwater system,the Cretaceous clastic groundwater system and the Quaternary groundwater system.This paper describes systematically the groundwater flow patterns of each system and overall assessment of groundwater resources.     

Applying sandstone petrofacies to unravel the Upper Carboniferous evolution of the Paganzo Basin, northwest Argentina

A compositional study of sandstones belonging to the lower section of the Paganzo Group (Middle Carboniferous–Early Permian) in the Paganzo Basin (northwestern Argentina) helps unravel the stratigraphic and paleogeographic evolution of the basin. Three morphotectonic units constitute the complex basement of the basin: (1) to the east, the igneous–metamorphic basement of the Sierras Pampeanas and Famatina systems; (2) to the west, the Precordillera, made up of Early and Middle Paleozoic sedimentary rocks; and (3) the Upper Paleozoic volcanic arc along the western boundary with the Río Blanco Basin. On the basis of sandstone detrital modes of the Lagares, Malanzán, Loma Larga, Guandacol, Tupe, Punta del Agua, and Río del Peñón formations, seven petrofacies are distinguished: quartzofeldespathic (QF), quartzofeldespathic-metamorphic enriched (QF-Lm), quartzofeldespathic-sedimentary enriched (QF-Ls), mixed quartzolithic (QL), quartzolithic-volcanic (QLv), volcanolithic-quartzose (LvQ), and volcanolithic (Lv). The spatial and temporal distribution of these petrofacies suggest an evolutive model for the Upper Paleozoic sedimentary filling of the basin that includes three “petrosomes”: (1) the basement petrosome, a clastic wedge of arkosic composition that diachronically prograded and thinned from east to west; (2) the recycled orogen petrosome, revealing the Protoprecordillera as a positive element in the western Paganzo Basin during the Namurian; and (3) the volcanic arc petrosome, recording volcanic activity along the western margin of Gondwana during the Westphalian.     

Petrological and chronological characteristics of medium-high grade metamorphic rocks in Gonjo area,southeastern margin of Qamdo block,eastern Tibet.SCIEI北大核心CSCD

青藏高原东缘的昌都地块是连接青藏高原腹地和藏东南三江-印支地区的关键区域,发育有较完整的晚古生界,以三叠系、侏罗系-白垩系广泛分布为特色;但其前寒武纪基底岩系出露较少,主要以宁多岩群(Pt_(1-2)Nd.)和草曲群(Pt_(3)C)为代表。本文针对昌都地块东南缘贡觉地区出露的一套被前人称为“宁多岩群”的中深变质岩系,开展了系统的野外地质调查、显微薄片分析、锆石U-Pb年代学等研究工作,认为该套中深变质岩系属于一套变质杂岩,其岩石组合既包括了原岩沉积时代不早于奥陶纪的片麻岩、变粒岩和大理岩等副变质岩,又包含了原岩时代分别为中二叠世的斜长角闪岩和中三叠世花岗质片麻岩等正变质岩。其原岩时代特征与昌都地块北缘的宁多岩群有较大差别,不应当归属为昌都地块的前寒武纪结晶基底。结合片麻岩的变质新生云母类矿物Ar-Ar测年数据和变质后期侵入的闪长玢岩脉锆石U-Pb年龄,认为贡觉地区出露的中深变质岩的变质时代为ca.260~244Ma(P_(2)-T_(2))。该期发生在昌都地块东南缘的角闪岩相变质作用,是金沙江古特提斯洋向西俯冲-碰撞的构造响应。     

MULTIPLE ISLAND ARC-BASIN SYSTEM AND ITS EVOLUTION IN GANGDISE TECTONIC BELT,TIBET

MULTIPLE ISLAND ARC-BASIN SYSTEM AND ITS EVOLUTION IN GANGDISE TECTONIC BELT,TIBET     

Groundwater Systems and Resources in the Ordos Basin,China

The Ordos Basin is a large-scale sedimentary basin in northwestern China. The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks, Lower Paleozoic carbonate rocks, Upper Paleozoic to Mesozoic clastic rocks and Cenozoic deposits. The total thickness is up to 6000 m. Three groundwater systems are present in the Ordos Basin, based on the geological settings, i.e. the karst groundwater system, the Cretaceous clastic groundwater system and the Quaternary groundwater system. This paper describes systematically the groundwater flow patterns of each system and overall assessment of groundwater resources.     

THE EVOLUTION OF LANPING RIFT BASIN FROM LADINIAN IN MIDDLE TRIASSIC EPOCH TO EARLY JURASSIC EPOCH

THE EVOLUTION OF LANPING RIFT BASIN FROM LADINIAN IN MIDDLE TRIASSIC EPOCH TO EARLY JURASSIC EPOCH