阿勒吞昆多蛇绿混杂岩斜长花岗岩锆石SHRIMP测年及时限

在大量查阅分析和研究前人资料基础上,提出阿勒吞昆多蛇绿混杂岩是卡拉麦里蛇绿岩带的向东延伸部分。卡拉麦里蛇绿岩带西起卡拉麦里—塔克扎勒—大黑山至伊吾县阿勒吞昆多一带,向东可能延伸至蒙古境内。该蛇绿混杂岩中斜长花岗岩产于辉长岩顶部,二者呈突变或渐变接触关系。应用SHRIMP方法对斜长花岗岩进行了锆石U-Pb定年,获得了(351±6Ma)的年龄,这一年龄反映阿勒吞昆多蛇绿岩形成于早石炭世。同时,该蛇绿混杂岩上覆岩系的时代为晚石炭世,表明阿勒吞昆多蛇绿混杂岩侵位时代不晚于晚石炭世。     

The study of Neo-Tethys Paleogeography in Marri-Asbkeshan area, north-northwest Doruneh–Kashmar subzone (Khartouran)

The study area is a small part of the Sabzevar structural zone, and is confined between Semnan and Khorasan provinces. The oldest sedimentary rocks of this region are Middle Jurassic in age with horizons of calc-alkaline rhyolitic-rhyodacitic lavas in between. First alkaline basaltic lavas accompanied by diabasic dikes in this region appeared along with Early Cretaceous lime-stone. Late Cretaceous rocks are composed of volu-minous calc-alkaline rhyodacitic-rhyolitic and trachy-andesitic lavas and dikes, and basaltic dikes. With abundance pinkish-cream plagic limestone this has been overlain by Paleocene rocks.     

新疆塔什库尔干县达布太尔地区二叠纪孢粉化石的发现及其地质意义

新疆维吾尔自治区塔什库尔干县达布太尔地区位于印度板块与欧亚板块结合部的西昆仑造山带,是研究喀喇昆仑山-昆仑山地质演化的重要地区之一。由于西昆仑地区处于中亚腹地的高寒缺氧地带,自然条件差,交通不便,野外地质调查研究十分困难,区域地质研究程度较低,达布太尔地区沉积地层中一直没有获得可靠微体化石证据。经笔者的室内、外地质调查与研究,在达布太尔地区发现了内点囊三缝孢Endosporites punctatus Gao,雅致韦氏粉 Wilsonites delicatus (Kosanke) Kosanke,多孔柯达粉 Cordaitina spongiosa (Luber ) Samolovich,马什阿里粉 Alisporites mathalensis Clarke,卵形侧囊粉 Sulcatisporites ovatus (Balme and Hennelly) Balme,以及光面和点状孢子Leiotriletes 和Punctatisporites 等二叠纪孢子花粉化石。从上述化石组合特征看,这些孢子花粉化石基本属于华夏植物地理区类型。结合前人对该区生物地层和同位素年代学的研究,笔者认为塔什库尔干县达布太尔地区原划为二叠纪的碎屑岩沉积地层可能为包含了志留纪、二叠纪及其它时代岩层的混杂地层体。     

瑞士阿尔卑斯山地质考察纪实

本文概述了瑞士地质单元基本特征和地质演化过程。详细记述的内容为:汝拉山侏罗纪地层和构造;磨拉石盆地中海相和陆相磨拉石沉积;海尔微第带的推覆构造、复理石沉积、华力西地块;平宁带中的蛇绿混杂岩、闪光片岩、低温高压变质岩(蓝闪石片岩、榴辉岩),活化基底和盖层推覆体;奥地利阿尔卑斯—南阿尔卑斯仰冲叠覆体中的基底和未受变质的南大陆边缘的浅水碳酸盐岩及断陷盆地内较深水放射虫硅质岩。笔者提出,具有典型意义的瑞士阿尔卑斯碰撞造山带的研究成果对于深入研究我国西部造山带有着重要借鉴作用。     

论板溪群与板溪蛇绿混杂岩

华南大地构造问题已经引起了国内外地质界的普遍关注，板溪群的问题是其中的关键。本文从地层，构造，同位素年龄和古生物等方面对板溪群及有关问题做了讨论，认为按多重地层划分原则定义的板溪群是一套正常的沉积地层；原带状大“板溪群”中含蛇绿岩的变质系是前震旦纪的产物，板（中笔代）蛇绿混杂岩的概念难以成立。     

Relationships Between the North China Plate and the Tarim Plate

The relationships and boundary between the North China and Tarim plates have been unclear for a long time ; however, the two plates occupy a prominent position in the formation and evolution of the continental lithosphere of China. It is proposed that the Engger Us ophiolitic melange zone discovered recently north of Alaxa is a typical suture between the two plates. The ophiolitic melange zone is composed mainly of a mixture of fragments of ancient oceanic crust and sedimentary rocks of active and passive continental margins. The melange may be divided into tectonic inclusions and matrix. The suture extends northeastwards into the Republic of Mongolia and probably westwards to meet the Altun fault. With the Engger Us ophiolitic melange zone as the boundary the Alaxa area may be divided into two parts: the northern part (AN ) belongs to the Tarim plate, while the southern part (AS) the North China plate. Geological evidence shows that the two plates were amalgamated in the Late Permian or a bit later.     

西昆仑于田南部阿羌蛇绿构造混杂岩地质特征及意义

近年的区调工作在西昆仑于田南部阿羌一带新填绘出一套具有蛇绿岩特征的变质橄榄岩、蛇纹岩、变辉长岩、辉绿岩和玄武岩等岩石组合.其中,变质橄榄岩、蛇纹岩具有低SiO2、高MgO、低稀土特征;辉长岩、辉绿岩和玄武岩绝大多数样品岩石化学具有低K2O＜1％,TiO2含量为1.5％等特征;稀土元素及微量元素特征与N-MORB及E-M...     

The age of the lateritized summit surface on Kangaroo Island and adjacent areas of South Australia

Stratigraphic, geomorphological, and radiometric evidence shows that the laterite of the high plains and plateau of Kangaroo Island is older than the Middle Jurassic but younger than the Early Permian. Palaeoclimatic and palaeontological considerations suggest the Triassic as the most likely age of both the laterite and the surface on which it is developed. High‐level lateritized surfaces in the adjacent Mount Lofty Ranges and southern Eyre Peninsula are of similar age.     

青海拉脊山东段峡门蛇绿混杂岩带的物质确定及其构造意义

在拉脊山东段青海省民和县峡门镇以南地区新识别出一条蛇绿混杂岩带,其物质组成复杂,构造岩块主要由蛇绿岩岩块、外来岩块、火山岩岩块以及变沉积岩岩块组成. 基性火山熔岩和辉绿岩具轻稀土富集的"右倾"配分模式,大离子亲石元素Ba、Th、Sr相对富集,高场强元素P、Ti、Nb相对亏损,总体岩石地球化学特征与岛弧拉斑玄武岩类似. 岩石学、岩石地球化学、同位素年代学特征及区域资料综合研究认为,峡门蛇绿岩属与俯冲有关的SSZ型蛇绿岩,很可能是早古生代原特提斯洋俯冲消减的弧后小洋盆,属于弧后盆地扩张型蛇绿岩.     

托莫尔日特蛇绿混杂岩带地质特征及其构造意义

托莫尔日特蛇绿混杂岩带是柴北缘早古生代蛇绿混杂岩带东段的重要组成部分,亦是整个柴北缘地区各蛇绿混杂单元组合、出露较为齐全的地段之一,其中放射虫硅质岩在蛇绿混杂岩带中首次发现。托莫尔日特蛇绿混杂岩岩石学、岩石化学、地球化学等特征表明,其具有大洋中脊向岛弧蛇绿岩过渡的特点。