哥伦比亚超大陆在扬子陆块西缘的探秘   总被引：4，自引：0，他引：4       下载免费PDF全文

尹福光  王冬兵  孙志明  任光明  庞维华 《沉积与特提斯地质》2012,(3):31-40

在扬子陆块西缘的拉拉、小关河-东川、大红山等地区出露了3套古元古代Statherian期（1.6～1.8Ga）的浅变质岩系,被分别命名为河口群、通安组-汤丹群-东川群、大红山群。从2.0Ga至1.4Ga期间,其地质历史演化经历：（1）约2.2～1.8Ga的造山运动;（2）约1.7～1.5Ga发生的非造山裂解事件群;（3）约1.7～1.5Ga侵入到古元古代地层的基性岩墙群、层状侵入体事件;（4）因民、落雪地区,约1.5～1.2Ga发生的陆架裂陷事件;（5）上扬子古陆块西缘,约1.0Ga发生的碰撞造山事件。本文重点阐述了扬子陆块西缘1.8～1.6Ga时期大规模裂解事件群的性质、特点和同位素年龄数据,认为上扬子陆块裂解事件群的性质、特点和时代等特征与华北、北美、西伯利亚和西北欧有很大的相似性,并提出了古元古代扬子陆块与其它陆块曾经联合的证据。  相似文献   

The East Side Story – The Transylvanian latest Cretaceous continental vertebrate record and its implications for understanding Cretaceous–Paleogene boundary events     

《Cretaceous Research》2016

The latest Cretaceous continental vertebrate faunas of the wider Transylvanian area figured prominently in discussions concerning the Cretaceous–Paleogene Boundary (K-Pg) events when they were first described by Nopcsa between 1897 and 1929, because they were assumed to be late Maastrichtian in age. Subsequently their age was reconsidered as early Maastrichtian, and were thus regarded of lesser importance in understanding the K-Pg boundary events in Europe and worldwide. Moreover, Transylvanian continental vertebrate assemblages (the so-called ‘Haţeg Island’ faunas) were often lumped together as a temporally restricted assemblage with a homogenous taxonomic composition. Recent fossil discoveries and more precise dating techniques have considerably expanded knowledge of the Transylvanian vertebrate assemblages, their ages, and their evolution. A synthesis of the available stratigraphic data allows development of the first comprehensive chronostratigraphic framework of the latest Cretaceous Transylvanian vertebrates. According to these new data, expansion of continental habitats and emergence of their vertebrate faunas started locally during the latter part of the late Campanian, and these faunas continued up to the second half of the Maastrichtian. During this time, long-term faunal stasis appears to have characterized the Transylvanian vertebrate assemblages, which is different from the striking turnovers recorded in western Europe during the same time interval. This suggests that there was no single ‘Europe-wide’ pattern of latest Cretaceous continental vertebrate evolution. Together, the available data shows that dinosaurs and other vertebrates were relatively abundant and diverse until at least ca. 1 million years before the K-Pg boundary, and is therefore consistent with the hypothesis of a sudden extinction, although this must be tested with future discoveries and better age constraints and correlations.  相似文献   

华北陆块南、北缘铅锌矿床成矿特征对比   总被引：6，自引：1，他引：5       下载免费PDF全文

段士刚  薛春纪  燕长海  刘国印  宋要武  张德会 《矿床地质》2008,27(3)

华北陆块北缘是中国重要铅锌成矿带,对其南缘地区铅锌矿的勘查近年进展明显,对比南、北缘成矿地质环境和矿床地质特征,有助于南缘地区铅锌找矿方向的进一步明确。对比分析表明,华北陆块南、北缘地质特征相似:南、北缘印支期铅锌成矿作用都不太发育,均在燕山期铅锌成矿明显;以与岩浆作用有关的接触交代、热液充填和变质热液成矿以及对早先形成的矿床或矿源层的变质改造作用为主,出现斑岩型、矽卡岩型、热液脉型及蚀变岩型等矿床类型;南、北缘铅锌矿都有由"层控"向"岩控"变化的趋势,成矿元素组合也由简单变得复杂。但华北陆块南、北缘不同的地质时代成矿的主导作用有所不同:北缘有太古宙VMS型矿床,而南缘发现的都是中元古代以来的矿床;北缘主要是元古宙和燕山期成矿作用,特别是中元古代Sedex型成矿作用更为显著,形成多个大型-超大型铅锌矿床,而南缘的成矿作用主要发生在古生代和燕山晚期,矿床规模多为中、小型,研究程度相对较低。栾川断裂以北的裂谷系中碳酸盐岩台地沉积有寻找MVT矿床的前景,宽坪岩群分布区可以作为今后寻找Sedex型铅锌矿床的重要地区。  相似文献   

Assessment and zonation of regional crustal stability in and around the dam region of the Three Gorges Project on the Yangtze River   总被引：5，自引：0，他引：5  

Tan Chengxuan  Sun Ye  Wang Reijiang  Hu Daogong 《Environmental Geology》1997,32(4):285-295

 The scale of the Three Georges Project (TGP) on the Yangtze River ensures that it will have enormous social and economic consequences. Determining the safety of the TGP is an essential consideration, and conducting the assessment and zonation of regional crustal stability has a crucial role in determining the success or failure of the TGP in the future. In this paper, the assessment of regional crustal stability, places much emphasis on tectonic stability and the stability of partial foundations (rock and soil masses) and surface slopes (which include landslides, collapses, etc.) related to fracture activity is also taken into consideration. The evaluation and zonation of regional crustal stability was conducted on two scales and scopes: the dam region and the vicinity of the TGP (about 310 000 km²), and the dam region of the TGP (about 30 000 km²). On the basis of tectonic zonation and present crustal stress field analysis, fuzzy mathematics was used to perform quantitative and comprehensive evaluations of crustal stability, and then the zonation of crustal stability in the study region, combined with a theoretical geological study, was made. The results of the assessment and zonation of the crustal stability can be summarized as follows: (1) the general crustal stability of the dam region is in a less stable-stable state and the Sandouping dam site is on a relatively stable landmass; and (2) the Sandouping dam site is on an ancient integrated granite body belonging to a stable (I) landmass. Therefore, from the view of assessment and zonation of regional crustal stability, a large-scale hydropower station can be constructed at Sandouping. Received: 8 September 1995 · Accepted: 25 February 1997  相似文献   

成岩地层学与层序地层学   总被引：14，自引：1，他引：14  

贾振远  蔡忠贤 《地球科学》1997,22(5):538-543

层序地怪学研究是通过对露头、测井的地震反射剖面研究进行的，是属宏观研究，但大量实践证明，在不少层序界面，宏观上是难于辨别的，这就有碍于正确划分层序，开展层序地层学的研究工作，任何一个层序都过成岩作用的改进，因此成岩地层学与层序地层学有密切的关系，特别是与有生成岩作用有非常密切的关系，在许多不整合面上形成区域性的成岩标志，如溶蚀作用、硅化作用、白云岩化作用、土化作用、交代作用等标志，因此，可以通过成  相似文献   

昌都地区三叠纪事件沉积及其成因     

彭勇民  汪名杰  陈明 《四川地质学报》1999,(4)

事件沉积是指偏离正常过程的地质作用（事件） 所形成的沉积物。昌都地区的事件沉积很发育,尤以风暴沉积与火山堆积为典型例子。本文对区内事件沉积作了较系统的总结与分析,阐述了风暴沉积事件与火山事件的时空分布,探讨了其成因及其作用过程。  相似文献   

西藏羌北—昌都地区三叠纪岩石地层及印支运动   总被引：1，自引：0，他引：1  

刘世坤  徐开锋 《地质通报》1998,(1)

西藏羌北—昌都地区地处阿尔卑斯—喜马拉雅构造域东段弧形转弯部分,位于“劳亚大陆”与“冈瓦纳大陆”之间,是一个具有过渡性质的中间陆块,即常被称为“三江褶皱系”。羌北—昌都地区属于“褶皱系”的北段,其岩石地层、生物地层、岩浆活动、火山作用、构造运动、地壳变形变质作用等方面都具有独立的特征,但与周围也具有诸多的联系。从现代地层学、沉积学的观点研究认为,羌塘—昌都地区的印支运动主要受到３个区域性构造运动界面的控制,形成两个主要的构造层,属于印支运动的主幕有两期。印支期的海水进退、岩石地层沉积、岩浆火山活动、变形变质作用与成矿作用等都可分属这两期构造运动的产物。  相似文献   

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

Wang Mingjie  Wang GaomingWT  ”BX 《地学前缘》2000,(Z1)

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

Discussion on rotational tectonic stress field and the genesis of circum-Ordos landmass fault system   总被引：1，自引：0，他引：1  

谢新生 《地震学报(英文版)》2004,17(4):464-472

Introduction Rotation is a universal form of the motion of matter, such as the rotation of cyclones in the air, eddies in streams and spiral nebulas in the universe. Rotational structure is a commonly seen structure in the crust, such as broom-shaped structure, S-shaped or reverse S-shaped structure, lo-tus-like structure, and turbine-like structure. They are the result of non-uniform motion of matter and dissymmetrical force actions in the nature. Turbine-like structure is the most complete …  相似文献   

旋卷构造应力场与鄂尔多斯地块周缘断裂系成因探讨   总被引：3，自引：0，他引：3       下载免费PDF全文

谢新生 《地震学报》2004,26(4):419-425

当外力的合力不通过活动地块的质量中心时，该地块将产生旋扭运动，运动的结果在其周边形成旋卷构造应力场．在该应力场作用下，与主应力作用面方向一致的断裂将由作用面的力学性质决定其活动方式．与主张应力作用面一致的断裂将产生张破裂，长期作用下将形成断陷盆地；与主压应力作用面一致的断裂将产生逆冲或逆掩活动，或形成褶皱．地质资料表明，长期稳定的华北地块在早第三纪初期解体，其中晋冀陕地块发生过逆时针转动，形成其周缘断陷系；上新世时晋冀陕地块解体，地块东边界西移，出现山西地堑系，形成鄂尔多斯地块．晋冀陕地块周缘的一些主要断裂的构造形迹及力学性质可用旋转构造应力场的主应力作用面解释．   相似文献