内蒙古固阳渣尔泰山群层序地层学及其控制因素

渣尔泰山群是华北地台北缘中元古代裂陷槽沉积,主要为一套遭受绿片岩相区域变质的碎屑岩-碳酸盐岩建造。根据岩性、岩相、相序和不整合界面的综合研究,对这套地层进行了详细的层序界面分析和层序划分,识别出Ⅰ型、Ⅱ型和暴露-淹没复合型(Ⅲ型)3种类型层序界面,共划分出1个超层序、2个大层序和7个层序。总结了渣尔泰山群在碎屑滨岸、台缘碳酸盐岩与碎屑岩混积、碳酸盐台地、台前斜坡和陆棚盆地等不同古地理背景下的层序发育模式及其内部构成特征,并探讨了复合海平面变化、构造活动、沉积物供给、古地形等因素对层序形成和演化的控制作用。     

新疆普鲁一带下古生界地层岩石组合及构造环境

西昆仑地块是西昆仑造山带的重要组成部分，南北边界分别为康西瓦—苏巴什华力西期缝合带和库地—其曼于特加里东期缝合带。新疆普鲁一带下古生界地层，分布于西昆仑地块东部，主要由一套海相火山岩和浅海陆棚相细碎屑岩组成，并遭受了绿片岩相的变质作用。通过1：25万《于田一伯力克幅)区调工作，将新疆普鲁一带下古生界地层厘定为下古生界奥陶—志留系，认为形成的大地构造环境为大陆活动边缘。     

Practical VTI approximations: a systematic anatomy

Transverse isotropy (TI) with a vertical symmetry axis (VTI) often provides an appropriate earth model for prestack imaging of steep-dip reflection seismic data. Exact P-wave and SV-wave phase velocities in VTI media are described by complicated equations requiring four independent parameters. Estimating appropriate multiparameter earth models can be difficult and time-consuming, so it is often useful to replace the exact VTI equations with simpler approximations requiring fewer parameters. The accuracy limits of different previously published VTI approximations are not always clear, nor is it always obvious how these different approximations relate to each other. Here I present a systematic framework for deriving a variety of useful VTI approximations. I develop first a sequence of well-defined approximations to the exact P-wave and SV-wave phase velocities. In doing so, I show how the useful but physically questionable heuristic of setting shear velocities identically to zero can be replaced with a more precise and quantifiable approximation. The key here to deriving accurate approximations is to replace the stiffness a₁₃ with an appropriate factorization in terms of velocity parameters. Two different specific parameter choices lead to the P-wave approximations of Alkhalifah (Geophysics 63 (1998) 623) and Schoenberg and de Hoop (Geophysics 65 (2000) 919), but there are actually an infinite number of reasonable parametrizations possible. Further approximations then lead to a variety of other useful phase velocity expressions, including those of Thomsen (Geophysics 51 (1986) 1954), Dellinger et al. (Journal of Seismic Exploration 2 (1993) 23), Harlan (Stanford Exploration Project Report 89 (1995) 145), and Stopin (Stopin, A., 2001. Comparison of v(θ) equations in TI medium. 9th International Workshop on Seismic Anisotropy). Each P-wave phase velocity approximation derived this way can be paired naturally with a corresponding SV-wave approximation. Each P-wave or SV-wave phase velocity approximation can then be converted into an equivalent dispersion relation in terms of horizontal and vertical slownesses. A simple heuristic substitution also allows each phase velocity approximation to be converted into an explicit group velocity approximation. From these, in turn, travel time or moveout approximations can also be derived. The group velocity and travel time approximations derived this way include ones previously used by Byun et al. (Geophysics 54 (1989) 1564), Dellinger et al. (Journal of Seismic Exploration 2 (1993) 23), Tsvankin and Thomsen (Geophysics 59 (1994) 1290), Harlan (89 (1995) 145), and Zhang and Uren (Zhang, F. and Uren, N., 2001. Approximate explicit ray velocity functions and travel times for P-waves in TI media. 71st Annual International Meeting, Society of Exploration Geophysicists, Expanded Abstracts, 106–109).     

西藏南部郎杰学群碎屑物质来源的古水流证据

新近对西藏山南琼果和贡嘎地区(特提斯喜马拉雅北亚带)弱变质的上三叠统深海—半深海沉积地层——郎杰学群地质填图调查,在出露槽模沉积构造的37个古水流点获得了43组数据。赤平投影数据恢复后发现,这一地区主力古水流有南东140°～160°和南西190°～210°两个方向。这一分析结果为郎杰学群沉积物来自北边(未知块体)而非印度次大陆的观点提供了有力证据。     

Application of visual,statistical and artificial neural network methods in the differentiation of water from the exploited aquifers in Kuwait

The ability of artificial neural network to differentiate water samples from the two aquifers of Kuwait on the basis of their major ion chemistry has been demonstrated. The major ion concentration distribution in the groundwater of the Kuwait Group and the Dammam Formation aquifers of Kuwait appears very similar. Cross-plots, supported by the discriminant function analysis of the data, however, suggest that there are some subtle differences in the overall composition of the water from the two aquifers that make it possible to differentiate the water from the two aquifers in almost 80% of the cases. An artificial neural network improved the differentiation capability to 90% of the cases. It is also possible to estimate the fraction of Kuwait Group water in the flow stream of dually completed wells with the help of an artificial neural network developed for this purpose. Electronic Publication     

华北板块南缘栾川群研究

栾川群出露于东秦岭北部。在栾川群分布区域，古华北板块不同时代的地层往南逆冲，构成北秦岭的太华推覆体。栾川群存在于该推覆体内部的特定逆冲岩席之中，沿这一逆冲岩席追索，确定古华北板块南缘的栾川群是连续沉积的，而受后期推覆构造的改造，栾川群在推覆体前缘的分布是断续相连的。根据地层之间的接触关系、岩浆活动、沉积作用的研究，对栾川群的划分提出了新的看法，认为栾川群由三川组、南泥湖组、煤窑沟组及大红口组构成。栾川群形成于震旦纪晚期，由湖坪及潮下斜坡等滨浅海沉积物构成。栾川群的岩浆岩为具双众数特征的岩套，具典型的大陆裂谷岩浆岩特征。并认为中元古代以来，古华北板块南缘处于裂陷拉张环境。早期的裂陷形成了熊耳群、汝阳群、官道口群及竞坪群，晚期裂陷的过程形成了栾川群、陶湾群，其进一步发育导致以二郎坪群为代表的洋壳生成。     

拉尔玛金矿矿源层──太阳顶群硅质岩的有机地球化学研究

拉尔玛金矿矿源层──太阳顶群硅质岩的有机地球化学研究林丽（成都理工学院，成都６１００５９）关键词有机地球化学，硅质岩，太阳顶群，拉尔玛金矿床拉尔玛金矿床赋存于寒武系太阳顶群中，该群的硅质岩是矿源层。本文探讨矿源层形成过程中与金关系密切的有机质的生物先...     

滇西南澜沧群多硅白云母的多型和化学成分特征及其意义

从理论、实验及实际观察的结果都表明，随着压力的增加白云母中绿鳞石的含量显著地增加，可以认为在多期变质作用过程中，尤其是在变质压力不同的多期变质作用下，形成的多硅白云母，其化学成分就会打上不同的烙印。７７个多硅白云母化学成分的统计结果表明，澜沧群低级变质岩中的多硅白云母有两种成因。在Ｎａ－Ｍｇ相关图上，反映了高压和中压变质特征，高压变质的多硅白云母约占７０％。这与用多硅白云母ｂ０值鉴别的高压和中压变质是相吻合的。多硅白云母的多型为３Ｔ和２Ｍ１型，以２Ｍ１型为主     

黑龙江省东部跃进山群中绿片岩的地球化学特征及地质意义

跃进山群出露位于佳木斯地块和那丹哈达地体之间，是完达山造山带的组成部分。它由大陆斜坡相沉积物、大洋中脊型玄武岩和洋岛型玄武岩组成，其中有镁铁－超镁铁质岩块体。它不是一个地层单位，而是与活动大陆边缘板块俯冲作用有关的蛇绿混杂岩     

论江西双桥山群的底界问题

１∶５万庐山地区区域地质调查和专题研究，在星子县黄岭一带发现一套巨厚层状复成分的变质砾岩。根据该变质砾岩的砾石成分、变形组构及区域分布特点，以及上部（双桥山群）与下部（星子岩群）地层在变质与变形方面存在明显差别，认为变质砾岩应属于双桥山群的底部层位，是中元古界双桥山群与下伏下元古界星子岩群不整合关系的佐证。由于受后期构造叠加改造的影响，现今二者呈断层或隐蔽不整合接触关系。