Process-facies Types and Sequences of Devonian Volcanic Sedimentary Successions in Northern Xinjiang and Their Relation to Plate Tectonics

The process-facies types of the Devonian volcanic sedimentary successions in northern Xinjiang include explosive facies, effusive facies, pyroclastic-calcareous-terrigenous tempestite facies, and coarse~-, medium~- and fine-grained pyroclastic turbidite facies, volcanic eruption tsunamite facies, syndepositional and soft-deformed seismite facies, sandy and silt-muddy contourite facies. This paper presents their characteristics and diagnostic indicators, and discusses the temporal and spatial structures of both the process-facies and the environment-facies of the Zhifang section, east Junggar, and the Mount Sarburti section, west Junggar, and their relation to plate tectonism. The author holds that the facies analysis dominated by process-facies is the facies analysis' nucleus in an orogenic belt and active continental margin.     

STABILITY ANALYSIS OF COFFERDAM SLUMP AND ITS APPLICATION IN THE CLOSURE OPERATION OF THREE GORGES PROJECT

I.INTRODUCTIONTheclosureoperationofThreeGorgesprojectisfamousintheworldforitslargedischarge,deepwater,lowvelocityinclosuregaps,largequantitiesandhighintensityforfillingmaterials.Thus,thedikeconstT'Uctionintheclosureoperationprocessisverydifficult.Sothedesign,researchandconstrUctiongroupshavepaidmuchenergyinthedesignprinciplesandoptimalitymeasuresofthegrandriverclosureoperation.FromtheexperimentsofhydraulicsanddikeslumpinthesecondperiodofclosureoperationattheResearchinstitUteofYangtZeR…     

The First Hadrosaurid Dinosaur from Southern China

A new hadrosaurid dinosaur,Nanningosaurus dashiensis gen.et sp.nov.,is described based on an incomplete skeleton from the Late Cretaceous red beds of the Nalong Basin,Guangxi,southern China.Diagnostic features for the new taxon include the presence of a tall and sharply peaked dorsal process of the maxilla with reduced process of the jugai and a distinct lacrimal facet,gracile humerus with low,rounded deltopectoral crest,mandibular condyle of the quadrate transversly broad with reduced paraquadrate notch,dentary tooth with sinuous median carina and subsidiary ridge,relatively few tooth positions,ischial shaft straight along most of its distance,but to curve dorsally and expand at the distal end before the ischial foot begins.Phylogenetic analysis suggests that Nanningosaurus dashiensis is a basal member of Lambeosanrinae.     

"罗田穹隆"中的下地壳俯冲成因榴辉岩及其地质意义

在“罗田穹隆”中发现了下地壳俯冲成因榴辉岩．榴辉岩呈透镜状或板状产于含石榴子石条带状片麻岩中．新鲜的榴辉岩主要由石榴子石、绿辉石、金红石等组成．含少量退变质的角闪石、斜长石、紫苏辉石、透辉石、(钛)磁铁矿和石英等．研究区榴辉岩以保留早期麻粒岩相变质矿物残留体以及经受晚期麻粒岩相和角闪岩相退变为特征．指示它们由扬子镁铁质下地壳麻粒岩相岩石俯冲到深部发生变质并形成榴辉岩．然后折返至下地壳发生麻粒岩相退变，由于麻粒岩相退变质阶段仅以后成合晶形式出现．因而它们可能在下地壳停留时间不长．就又进一步被构造抬升至中上地壳而发生角闪岩相退变．大别山造山带乃至扬子板块北缘现今缺乏厚层镁铁质下地壳．它们也很少出露地表．推测这些俯冲的镁铁质下地壳可能已拆离再循环进人地幔．从而为“罗田穹隆”的形成和演化以及大别山高压-超高压岩石的形成与折返机制等研究提供了关键性的岩石学证据。     

鄂尔多斯盆地合水地区长8储层孔隙结构及物性特征研究

储集层岩石的孔隙结构不仅对油气储量,而且对油气井产能和最终采收率都有影响,在研究中根据实验得出的孔隙结构参数用来表征孔隙结构的优劣程度,便于在油气勘探与开发中应用[1]。通过对合水地区长8储层的研究认为,长8储层砂岩类型以长石砂岩、岩屑长石砂岩为主,为近源沉积体系,是典型的低孔低渗储集岩。油组内不同小层的物性存在着差异,相比之下,长81小层储层物性最好,含油面积较大,长82小层储层物性较差,局部发育含油富集区。     

Hydrogen and Oxygen Isotope Study on the Water-Rock Interaction of the Yinshan (Cu-) Pb-Zn-Ag Ore Deposit, Jiangxi Province

The δ18O values of vein quartz of different stages from the Yinshan ore deposit are constant around 16‰ and the calculated δ18OH2O values attain 8‰± ; the δDH2O values of fluid inclu-sions in vein quartz are constant at about-60‰. From the surface down to 1200 m below the δ18O values of altered rocks gradually decrease from 15‰± to 11‰± . Various water-rock inversion calculations indicate that the ore fluids were formed by the interaction between meteoric water and phyllite at 350℃ and the effective W/ R value of around 0.1. When the water-rock exchange in the upper mineralization system took place, the effective W / R value increased to 5.0 or more. As a result, an evolution and mineralization model of a buffered open system with two-stage water-rock interactions is proposed in this study.     

The Background of Regional Lead Isotopic Compositions and Its Application in the Lower and Middle Reaches of the Yangtze River and Neighbouring Areas

The paper systematically deals with the background of regional isotopic compo-sitions in the lower and middle reaches of the Yangtze River and neighbouring areas. It isshown that the lead isotopic compositions of different geological formations and units are con-trolled by the primary mantle heterogeneity, dynamic process of crust-mantle interchange,abundances of uraninm, thorium and lead of various layers of the earth and timing. Studies onthe background of regional isotopic compositions may offer significant information forgeochemical regionalization, tracing of sources of ore-forming materials, and regionalprognosis of ore deposits.     

Free Vibration of Sagging Pipelines in Water

- Studied in this paper is free vibration of a long span pipeline with nonlinearities taken into account. The pipeline sags under gravity and takes the shape of a plane curve. Vibration in the plane and out of the plane is regarded as small motions about the large static deflection. Manifestations of nonlinearities such as amplitude-dependent frequencies and internal resonance are investigated.     

分叉波痕在广西上泥盆统钙质浊积岩中的发现及意义

小型不对称分叉波痕(简称分叉波痕)发现于桂林杨堤剖面上泥盆统弗拉斯阶linguiformis牙形石带，桂林碳酸盐台地东南缘斜坡相钙质浊积岩鲍马序列C段。波长7．5～8．0cm，波高0．5～0．8cm，波痕指数15～10；向流面长5．0～7．0cm，背流面长2．5～4．0cm，波痕对称指数2．0～1．8；背流面向东倾；波脊较圆滑、缓曲，且具明显的分叉现象。是浊流流速减缓，密度流转化为牵引流后在低流态条件下，并叠加有推进型风暴浪作用形成的复合成因波痕。根据该波痕和寄主地层特征，推断含分叉波痕的阳朔碳酸盐盆地的最大水深约100m，极限水深小于200m。这一估计值应能代表广西乃至华南板块泥盆纪广泛发育的含牙形石动物群和钙质浊积岩碳酸盐沉积盆地的定量水深，可能也代表了弗拉斯阶一法门阶之交受集群绝灭事件重创的浅水海相生物与基本未受影响的深水海相生物的水深分界线。     

青海拉鸡山早古生代“开”,“合”演化的地球化学证据及成矿

位于青藏高原北部的拉鸡山下古生界为典型的火山－复理石活动类型建造,并赋含有丰富的矿产,本文基于地质,地球化学的方法,对拉鸡山早古代火山盆地的“开”,“合”历史及“开”,“合”与铜,金等多金属矿产形成作用的关系进行了探索,认识到拉鸡山早古生代经历了３个旋回的“开”,“合”拉鸡山铜,金等多金属矿源层形成于“开”的阶段,而“合”的作用最终促使矿物质活化,迁移和富集,“开”“合”与成矿关系的认识,无疑会增