SPACE-TIME TEXTURE AND TECTONIC EVOLUTION OF QAMDO BLOCK IN EAST TIBET

SPACE-TIME TEXTURE AND TECTONIC EVOLUTION OF QAMDO BLOCK IN EAST TIBET     

Geologic structure of Lesser Khingan and its position in structure of Far East

The Lesser Khingan has been variously assigned to, 1) a zone of Mesozoic folding at the western margin of the East Asian Mesozoic-Cenozoic folded belt; 2) the Mongol-Okhotsk folded belt. 3) the marginal zone of the northeast side of the Chinese platform as altered by very late folding, hi order to establish its tectonic affinity, the geologic and especially tectonic history is considered from Proterozoic rime to the present. Tectonic maps give details of structures within Proterozoic. Mesozoic, and Cenozoic sadimentary and associated igneous rock complexes. Major anticlinoria and synclinoria are discussed and the role of ancient deep faults is noted. From a consideration of the several stages in the history of the Lesser Khingan it is concluded that its geosynclinal. development within the southern (Paleozoic) branch of the Mongol-Okhotsk belt has been completed by the end of Paleozoic time, This means that the area has no direct affinity with the younger East Asia geosynclinal belt. However, it seems logical that the lesser Khingan should have exerted a dynamic action on the adjacent young platform to the west, as shown by extensive dislocation of Mesozoic strata in its eastern structures.—W.D. Lowry     

Boron-polymetallic metallogeny of the north and northeast of the Sino-Korean Craton

Based on published data and original investigations, it has been shown that the combination of widely known Ag, Fe, and Fe-Mn ore deposits, as well as boron and Pb-Zn world-class deposits, is typical for metallogenic zones in the north and northeast of the Sino-Korean Craton. The ore genesis was spatially inherited and lasted from the Archean to Mesozoic. The Archean metallogenic zones are related to the protocontinental margin terranes of the craton basement and they comprise banded iron ore and Cu-Zn sulfide deposits. The proterozoic-Early Paleozoic metallogenic zones are related to rift basins, where the ore-bearing Archean folded basement is overlain by volcanic and sedimentary complexes. The Proterozoic metallogenic zones host quartz veins and schistosity zone-related Au deposits, banded iron and Cu-Zn ore deposits, large sedimentary-metamorphogenic borate and magnesite deposits, Cu-W deposits in tourmalinites, exhalation-sedimentary Pb-Zn ore deposits, and large polygenic REE-Fe-Nb ore deposits. The Riphean-Cambrian terrigenous-carbonate strata are represented by stratiform Pb-Zn and fluorite deposits. Mesozoic metallogenic zones related to volcano-plutonic complexes of intraplate series coincide with zones where the folded basement is made of Precambrian ore-bearing series. Gold deposits are typical of all the metallogenic zones, but most of them are related to Mesozoic volcano-plutonic complexes.     

MONTMORILLONITIZATION OF HYDROMICAS AS A CRITERION OF TERTIARY 0IL-BEARING FORMATIONS IN DAGESTAN

Sinitsin's approach to the mercury-antimony mineralization of the Tien Shan and Alay was through a systematic study of the tectonics and geomorphological evolution of the area. In affirming an upper Paleozoic age for the mercury mineralization, Sinitsin stressed the study of Paleozoic structure and sedimentation. The principal factors controlling the origin, nature and distribution of ore deposits such as the combination of facies, folding, and the position of mineralization channels are determined by the tectonic development of the housing structure, beginning with the sedimentation period. Sinitsin believed that the historical approach is the only Way to attack the most intricate and controversial problems in geology, including those of mineralization and ore deposits distribution. Chapter I gives a brief survey of the Precambrian outcrops and the influence of pre-Paleozoic trends on Paleozoic and younger structures., Chapter II contains the bulk of the data on tectonic development on the Paleozoic of West Tien Shan and Alay and shows that the ore zones are located along the junction of older and younger major structures, largely within the first. Chapter III deals with Mesozoic structures of the Fergana Mountains. Chapter V, “Arrangement of the Principal Structural Elements,” considers first the problem of the relationship among Paleozoic structures of the Tien Shan and Alay; second, the problem posed by the Talas -Fergana fault: and third, relations between Alay and the Pamirs. Chapter VI presents a summary and conclusions and opens with an original genetic classification of folded structure in the province under study. First order folds, represented by anticlinoria tens of kilometers across, usually coincide with troughs of the later geosynclinal stages. First order structures have deep plutonic roots. Second order folds are anticlines and synclines measuring a few kilometers across. Third order folds, fen to hundreds of meters across, usually are local features. First order folded structures often are separated by marginal faults which are of prime importance in mineralization control. — C. E. Sears.     

陕西南秦岭地质组成及其演化

综合分析南秦岭地质组成与构造特征，显示出区内经历了太古－早、中元古代基底形成阶段，晚元古－早古生代统一扬子大陆北缘演化阶段，古生代勉略－石泉海槽的形成、闭合造山阶段和燕山以来的陆内造山4个大的演化阶段，并形成了相应的岩石建造与构造变形组合。     

中国东北地区主要地质特征和地壳构造格架

中国东北地区位于亚洲大陆东缘,发育中国乃至地球上最古老的地质记录、多个时代的古洋岩石圈残片和活动陆缘及陆间碰撞岩浆岩带,具有独特的盆山-山脉相间地貌特征,蕴藏着丰富的自然资源。迄今为止,对于该区古生代构造单元如何划分,一直存在截然不同的认识;对于该区中生代以来的构造格架,缺乏系统的论述。本文在简要介绍现今不同山脉和盆地等地理单元地质特征的基础上,基于断裂构造和地貌特征等方面的资料,把该区新生代构造单元划分为大兴安岭、小兴安岭、阴山-燕山和长白山等4个隆起带,海拉尔-锡林浩特、松辽、三江-兴凯湖和下辽河等4个断陷带。基于岩浆活动和沉积盆地分布,结合区域地球动力学背景,提出了该区晚三叠世至中侏罗世、晚侏罗世、早白垩世早期和早白垩世晚期至古新世等不同阶段构造单元划分的初步方案。基于对已有资料的综合研究,对该区古生代构造单元的特征、松辽盆地的基底组成、早古生代和晚古生代华北克拉通北部边界的位置以及古生代洋盆演化及结束时间等重大地质构造问题,进行了初步探讨,提出了阴山-燕山地区在古生代晚期由克拉通转化为陆缘活化造山带;松辽盆地基底具有与周缘造山系相同的地质组成;该区古生代构造单元是陆缘造山带与碰撞造山带的复合而不是地块拼贴;该区在二叠纪晚期遭受了碰撞造山并在华北北缘形成了高耸的近东西走向的碰撞造山带等新认识。根据洋岩石圈残片和古陆缘岩浆岩的分布,把该区古生代构造单元划分为大兴安岭、阴山-燕山、小兴安岭、张广才岭和老爷岭等5个造山系及华北克拉通,简要介绍了不同造山系的地质特征。     

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     

论河北省兴隆一带东西向走滑断裂系统

河北省兴隆县一带地处燕山造山带的中段，是中生代构造变形的典型地区。该区广泛发育了东西向和北东向联合构造，东西向主走滑断裂呈右行右阶式（Ｐ断裂），北东向次级构造由北盘的雁列式褶皱、分枝断裂及南盘次级断裂等组成。燕山台褶带变形是由尚义─平泉断裂和密云─洪山口断裂在侏罗纪时发生右行走滑形成的，其间的剪切变形带，总体特征类似于一个大型Ｓ─Ｃ构造或平面对冲构造。区内古基底断裂不仅控制中晚元古代的沉积地层和岩浆活动，而且对中生代的构造变形方式也产生重要作用。主走滑断裂与古基底断裂的复活有直接的关系     

Tectonics of the northern part of the Lena-Yenisey oil-bearing region

This article discusses the historical tectonic development of the portion of Siberia lying within the Arctic Circle. The exposed rocks are referred to seven tectonic or geotectonic stages: Archean, Proterozoic, Sinian, lower to middle Paleozoic, upper Paleozoic to lower Mesozoic, and Mesozoic-Cenozoic. Locally on the Shorikka and Kamennaya, the nearly horizontal Lower Cambrian beds overlie the Sinian with angular unconformity. In contrast, isolated areas on the west side of the Yenisey show a gradational relationship between the Late Sinian and Early Cambrian beds in a dominantly carbonate succession. The present tectonic elements of the Siberian platform were developed in Mesozoic-Cenozoic time, and differential movements in the basement have continued into Neogene time. The sedimentary platform cover was enlarged by sedimentary overlap from Sinian to mid-Paleozoic time. The sediment came from the older fold systems. The major structures are measured in terms of variations in stratigraphic thickness, but details are unfortunately omitted. The main features are delineated on a geotectonic map embracing 42 map units and symbols. The map lacks basic reference data, geographic designations, scale, and other essential information. — B. N. Cooper.     

Spatial patterns of Mesozoic facies relationships and the age of the Rhenish Lineament: a compilation

The age and the southern continuation of the Rhenish Lineament, and its relation to the Bressegraben has been an elusive problem for a long time. Sedimentological data are presented in this paper, which show that a major fault zone associated with the Rhenish Lineament extends southwards underneath the Jura Mountains of northern Switzerland. Mesozoic facies boundaries occur along this lineament and indicate that the Tertiary Upper Rhinegraben may be an ancient inherited structure, which was repeatedly reactivated during Mesozoic time. While reactivated Paleozoic faults seated in the basement are now known to play an important role in defining east–west trending facies boundaries and depocenters, north–south facies boundaries were attributed to autocyclic effects. This north–south component found in facies boundaries is now attributed to subsidence variations, which took place along the Rhenish Lineament. To distinguish increased local subsidence from eustatic sea level rise (i.e. development of accommodation space) it is necessary to reinterpret the sedimentary record accordingly. This study demonstrates that some sedimentary facies boundaries follow the Rhenish Lineament over the Paleozoic basins of northern Switzerland into the Bressegraben, thereby indicating an ancient structure, which had been reactivated during Mesozoic time. Sedimentological analysis shows that there is a relationship between facies boundaries, isopach anomalies, and basement structure.     

安徽的地壳演化:Sr,Nd同位素证据

在地壳(幔)演化和板块构遣的框架内，评述了有关安徽南部(扬子地块东部，包括大别遣山带和江南遣山带)的同位素地质年代学和Nd，Sr同位素地球化学示踪研究的成果。该地区出露地表的中元古界溪口群浅变质岩代表皖南的基底，沿江地区和大别山区的基底包舍太古宇或／和古元古界古老岩石。此格局还影响到从震旦纪到古生代沉积岩的物源区，江南深断裂以北的沉积岩中有古老岩石的贡献，而以南的物源主要来自出露的中元古界岩石。扬子陆块南北缘(大别和江南遣山带)的晋宁期演化可能与罗迪尼亚超大陆演化有密切关系，但有关研究开展很少。三叠纪大陆深俯冲和超高压变质作用研究已成为国际地球科学的热点。晚中生代(120-140Ma)本区发生强烈的岩浆活动，并伴有重要矿床的形成。中酸性岩的形成是一种壳幔物质混合的过程。沿江地区陆下地幔具有富集特征，为扬子型岩石圈地幔与软流圈地幔混合的产物。从晚中生代到第四纪，基性岩指示其源区的地球化学性质有随时间变得越来越亏损的趋势。     

闽西南—粤东北地区大地构造演化与铜、（伴生）银的成矿作用

本文论述了闽西南—粤东北地区大地构造演化及其特征、铜、（伴生）银矿床的成矿作用及与大地构造演化的关系。指出本区地壳经历了从太古代陆核阶段→中元古代—早元古代地槽裂谷阶段→晚古生代地台断拉谷阶段→中生代地洼陆相火山岩阶段的多阶段演化，形成了结晶基底、褶皱基底、地台盖层和地洼盖层的四层结构。铜、（伴生）银矿床赋在于三个构造层七个层泣中，与一定的沉积建造有关。成矿作用与各大地构造阶段发生的主要构造热事件有关。矿床具有明显的多因复成特点。     

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。     

FACTORS DETERMINING COMPACTION IN SEDIMENTARY ROCKS

A complex of variously metamorphosed sedimentary and volcanic rocks, migmatites, and plutonic intrusives are exposed in long fault blocks at different structural and metamorphic levels in the Main Range Region of the West Caucasus. A Proterozoic and lower Paleozoic suite is largely comprised of amphibolite foliates and biotite schist and gneiss. A middle Paleozoic suite consists of metasedimentary and metavolcanic rocks mostly in the green schist facies. Intrusive and extrusive magmatic products are classified as middle Paleozoic, upper Paleozoic, and Mesozoic. Petrography and mineralogy of the major metamorphic and igneous units are described in detail. Complex isoclinal to open folds occur in long blocks bounded by subvertical longitudinal faults. Major deformation is Hercynian. Modern strike-slip faulting is briefly described. The region is subdivided tectonically and described in detail. — L.T. Grose.     

河北省铁矿分布与重磁场特征的关系

在河北省铁矿资源潜力评价及成矿预测中,对重力场、磁场特征进行了总结和归纳,认为规模较大的航磁正异常主要是出露或隐伏侵入岩基的反映;大面积分布的低缓正磁异常区则主要反映了太古宙变质岩系或基底隆起的边缘,沉积变质型铁矿主要密集分布在此区域;负磁场区主要出现在中上元古界、古生界碳酸盐岩和中生界酸性火山—沉积岩系;强度高、梯度大、或有明显负值伴生的局部磁异常则可能是磁性铁矿的反映。从重力场特征看,磁性铁矿主要分布在布格重力异常的梯级带或异常扭曲处,以及正、负异常的交界处,这些地方多与地质构造强烈变形密切相关。只有对重磁场进行深入地质剖析,结合典型矿床上建立的识别标志进行对比分析,才能得出一个符合客观实际的地质解释。     

中国东南部花岗岩类Nd—Sr同位素研究

根据本文测定的５８个数据以已发表的１２７个数据讨论了中国东南部不同时代花岗岩类的Ｎｄ－Ｓｒ同位素特征,工通过与基底变质岩Ｓｍ－Ｎｄ同位素组成的对比,研究了这些花岗岩类的物质来源与成因。仅分布于浙西南的古元古代花岗岩娄是由成分上类似干被其侵入的八都群片麻岩经部分熔融形成的。沿江绍断裂带分布的新元古代花岗岩类是由地幔来源岩浆或初生地壳形成的;浙西－皖南－赣北地区的新元古代花岗岩类可能是由中元古代地层中的低成熟度组分形成的。古生代和大部分中生代花岗岩类主要是由所在区域内出露的中元古代变质沉积岩的相当物衍生的。沿浙闽沿海地区分布的大多数晚中生代花岗岩娄含有较多的地幔组分．两种来诹岩浆混台可能是其一种重要的成岩方式。     

天山早古生代花岗岩锆石U-Pb定年、岩石地球化学特征及其大地构造意义

天山早古生代花岗岩普遍发育片麻状构造或者发生糜棱岩化，主要是由于受到后来构造——变形热事件影响的结果．锆石U-Pb定年结果显示．天山早古生代花岗岩形成于380-490Ma,目前主要产出在具有元古代基底的中天山构造带中，在霍拉山一带也应该具有一定的规模．它们的岩石地球化学不显示活动大陆边缘花岗岩的特点，而是具有铝质A型花岗岩的特征．它们的形成可能与南天山洋南支的扩张过程有关，或者与早古生代的一次造山过程的晚期伸展阶段有关．     

北京地质大厦景观石的地质特征

北京地貌呈现"北京湾"特征,北山产铁,西山产煤,平原产地热。地质大厦院内东侧花坛摆放代表地球从老到新5个代(宙)的岩石,西侧花坛摆放阳坊花岗岩,体现了地质学为首都城市发展的贡献。太古代密云岩群表壳岩铁矿曾为首钢铁矿的主要原料,元古代雾迷山组汉白玉大理岩曾用于古都北京的建设,古生代马家沟组石灰岩中流出了优质饮用水,中生代窑坡组煤矿使西山成为中国地质工作的摇篮,新生代马兰黄土是中国最早研究的黄土,中生代形成的阳坊花岗岩曾用于北京1959年十大建筑的基石。     

甘肃西秦岭区域成矿模式

通过对西秦岭区域成矿特点和区域构造演化阶段的讨论,选择区内主要矿床就控矿地质因素、成矿时代、物质来源等特征进行对比,根据矿床成矿模式概括区域成矿模式。提出新元古代、晚古生代、晚中生代是本区大规模成矿期,对甘肃西秦岭地区成矿环境的分析认识进一步深化,对指导区域矿产评价和预测具有指导意义。     

淮北夹沟—桃山集地区推覆构造研究

本区存在大型中生代推覆构造,所有震旦纪—古生代的沉积岩层都卷入了褶皱和断裂,构造推覆发生在较高构造部位,属脆性变形域,以台阶状逆断层和断层相关褶皱为特征。区内存在若干推覆构造,每个岩片均可分为上盘、下盘和滑动层系三部分,共查明8个滑动岩系。是一种发生在早中生代的盖层推覆,无根褶皱,也是徐宿地区最重要的控煤构造。最后对推覆构造的地球动力学机制进行了讨论。