闽西-赣南早-中侏罗世盆地及其火成岩特征   总被引：22，自引：3，他引：22  

邓平舒良树  余心起王彬  谭正中孙岩 《岩石学报》2004,20(3):521-532

闽西-赣南地区早、中侏罗世陆相盆地带东起福建永定,经江西寻乌到龙南,断续延伸约250km,宽60～80km.受后期构造破坏和花岗岩浆侵入影响,现呈肢解散碎的残留盆地面貌.盆地边界特征和盆区岩层节理测量统计结果反映该区自晚三叠世以来,先后经历了近S-N向水平挤压(T3-J1E),S-N向垂向挤压、近E-W向水平伸展(J1L-J2),SE-NW向挤压(K1)和近E-W向挤压、S-N向伸展(K2)等复杂的演化过程.早-中侏罗世强烈的拉张-断陷作用导致盆区大量双峰式火山岩的喷发,其基性端员玄武岩的颗粒锆石U-Pb年龄值为170±1Ma,酸性端员流纹岩Rb-Sr等时线年龄为179Ma～165±2Ma.流纹岩具有高的SiO2、Al2O3、K2O含量,ANKC值＞1.1;轻稀土富集、稀土总量高,铕亏损,具明显Eu负异常;富集Rb、Th,贫化Ba、Ti、P、Nb、Zr等特点,属富钾过铝火山岩类.与之共生的玄武岩则以富硅贫碱为特征,轻稀土轻度富集,铕异常不明显;弱富集Rb、Ba、Th、Ce,贫Nb、Zr、Y,配分样式呈上凸型,属拉斑系列玄武岩类,反映一种后造山的陆内裂谷环境.闽西-赣南地区盆山格局的形成经历过多期地球动力学演化前中生代近E-W向古亚洲构造域的基底阶段,晚三叠世-早侏罗世早期挤压造山阶段,早侏罗世晚期-中侏罗世裂谷盆地阶段,早白垩世太平洋构造域对本区的置换和改造阶段,包括早期的火山-岩浆活动和晚期的伸展断陷盆地作用.  相似文献   

议京西大台地区的燕山运动   总被引：3，自引：1，他引：3  

邵济安  张履桥 《岩石学报》2004,20(3):647-654

作者研究了京西大台地区的燕山运动，初步研究表明：这里不存在强烈的挤压变形迹象和显著的角度不整合．缺乏磨拉石建造。龙门组是厚度有限的河流相沉积，九龙山组是具有弱火山活动的湖相一滨湖相沉积。在隆起带和沉降带之间侏罗系地层显著的厚度变化率、大安山一斋堂滑覆构造及其派生的髫髻山断陷盆和大量高角度滑动面理，都显示了伸展构造背景下基底断块的差异升降。髫髻山组与壳幔相互作用有关的一套火山岩显示了上述运动的深部背景。  相似文献   

沉积盆地中的流体包裹体：理论基础、图解与分析方法     

JeanDUBESSY 《岩石学报》2004,20(6):1301-1318

本文主要介绍如何利用流体包裹体来获得合理的数据。首先对H2O-体系进行总结，着重介绍利用显微测温法和其他新的分析技术来确定流体的组成，并举例说明流体混合在流体包裹体研究中的应用。介绍了H2O-(气)-盐体系特别是CO2-CH4体系的图解，探讨了在低温下由于笼舍物的形成H2O-(气)-盐体系的复杂相变。重点介绍显微激光拉曼光谱仪在含甲烷水溶液流体中的应用，并根据相图详细讨论了如何确定流体的不混溶。  相似文献   

江苏西南部晚侏罗世西横山组沉积特征及成因     

夏嘉生黄建平  谢有才 《江苏地质》2004,28(3):134-139

江苏西南部晚侏罗世西横山组为一套粗碎屑岩—细碎屑岩及泥灰岩组成的陆相沉积岩，普遍含有火山物质。从地层分布、岩性特征、碎屑岩粒度统计分析表明，天生桥盆地和西横山盆地基本上是连续、贯通的，自东向西，由冲积扇相—河流相—湖泊相逐渐过渡，属于同一水中盆地中不同沉积相的产物。沉积物主要来自盆地东部，可能与“古茅山”隆起带有关。  相似文献   

沉积有机相的研究现状及其应用   总被引：5，自引：0，他引：5       下载免费PDF全文

李君文  陈洪德  田景春  侯中健 《沉积与特提斯地质》2004,24(2):96-100

沉积有机相是近年来国内外广泛运用于油气勘探的一种有效的研究方法。本文介绍了沉积有机相的概念、划分方案，及其在油气勘探、盆地分析和层序地层学中的应用，指出了沉积有机相与层序地层分析相结合对油气资源评价和预测烃源岩有广阔的发展前景。  相似文献   

U-Pb Zircon Calendar for Namaquan (Grenville) Crustal Events in the Granulite-facies Terrane of the O'okiep Copper District of South Africa     

CLIFFORD  TOM N.; BARTON  ERIKA S.; STERN  RICHARD A.; DUCHESNE  JEAN-CLAIR 《Journal of Petrology》2004,45(4):669-691

The O'okiep Copper District is underlain by voluminous 1035–1210Ma granite gneiss and granite with remnants of metamorphosedsupracrustal rocks. This assemblage was intruded by the 1030Ma copper-bearing Koperberg Suite that includes jotunite, anorthosite,biotite diorite and hypersthene-bearing rocks ranging from leuconoriteto hypersthenite. New sensitive high-resolution ion microprobeage data demonstrate the presence of 1700–2000 Ma zirconas xenocrysts in all of the intrusive rocks, and as detritalzircon in the metasediments of the Khurisberg Subgroup. Thesedata are consistent with published Sm–Nd model ages ofc. 1700 Ma (T_CHUR) and c. 2000 Ma (T_DM) of many of the intrusivesthat support a major crust-forming event in Eburnian (Hudsonian)times. In addition, U–Th–Pb analyses of zirconsfrom all major rock units define two tectono-magmatic episodesof the Namaquan Orogeny: (1) the O'okiepian Episode (1180–1210Ma), represented by regional granite plutonism, notably theNababeep and Modderfontein Granite Gneisses and the Concordiaand Kweekfontein Granites that accompanied and outlasted (e.g.Kweekfontein Granite) regional tectonism [F₂(D₂)] and granulite-faciesmetamorphism (M₂); (2) the Klondikean Episode (1020–1040Ma), which includes the intrusion of the porphyritic RietbergGranite and of the Koperberg Suite that are devoid of regionalplanar or linear fabrics. Klondikean tectonism (D₃) is reflectedby major east–west-trending open folds [F₃(D_3a)], andby localized east–west-trending near-vertical ductilefolds [‘steep structures’; F₄(D_3b)] whose formationwas broadly coeval with the intrusion of the Koperberg Suite.A regional, largely thermal, amphibolite- to granulite-faciesmetamorphism (M₃) accompanied D₃. This study demonstrates, interalia, that the complete spectrum of rock-types of the KoperbergSuite, together with the Rietberg Granite, was intruded in ashort time-interval (<10 Myr) at c. 1030 Ma, and that therewere lengthy periods of about 150 Myr of tectonic quiescencewithin the Namaquan Orogeny: (1) between the O'okiepian andKlondikean Episodes; (2) from the end of the latter to the formalend of Namaquan Orogenesis 800–850 Ma ago. KEY WORDS: U–Pb, zircon; O'okiep, Namaqualand; granite plutonism; granulite facies; Koperberg Suite; Namaquan (Grenville) Orogeny  相似文献   

Transformation of garnet epidote amphibolite to eclogite, western Dabie Mountains, China   总被引：8，自引：0，他引：8  

J. Liu  K. Ye 《Journal of Metamorphic Geology》2004,22(5):383-394

Omphacite and garnet coronas around amphibole occur in amphibolites in the Hong'an area, western Dabie Mountains, China. These amphibolites consist of an epidote–amphibolite facies assemblage of amphibole, garnet, albite, clinozoisite, paragonite, ilmenite and quartz, which is incompletely overprinted by an eclogite facies assemblage of garnet, omphacite and rutile. Coronas around amphibole can be divided into three types: an omphacite corona; a garnet–omphacite–rutile corona; and, a garnet–omphacite corona with less rutile. Chemographic analysis for local reaction domains in combination with petrographical observations show that reactions Amp + Ab + Pg = Omp +Czo + Qtz + H₂O, and Amp + Ab = Omp ± Czo + Qtz + H₂O may lead to the development of omphacite coronas. The garnet–omphacite–rutile corona was formed from the reaction Amp + Ab + Czo + Ilm ± Qtz = Omp + Grt + Rt + H₂O. In garnet–omphacite coronas, the garnet corona grew during an early stage of epidote amphibolite facies metamorphism, whereas omphacite probably formed by the reactions forming the omphacite corona during the eclogite facies stage. It is estimated that these reactions occurred at 0.8–1.4 GPa and 480–610 °C using the garnet–clinopyroxene thermometer and omphacite barometer in the presence of albite.  相似文献   

Late Pleistocene-Holocene Paleoclimatic History of the Southern Kerala Basin, Southwest India     

K. Jayalakshmi  K.M. Nair  Hisao Kumai  M. Santosh 《Gondwana Research》2004,7(2):585-594

The South Kerala Sedimentary Basin (SKSB) constitutes one of the most significant landward extensions of the southwest offshore sedimentary basins of India, and is situated between 8^o45^' and 10^o15^' N latitudes. With a maximum width of about 20 km and incorporating a 700 m thick sedimentary succession ranging in age from Early Miocene to Holocene, this belt lies almost entirely under water or alluvium-covered coastal plains. In this study, we use two continuously cored bore holes at Eruva (7.25m deep) and Muthukulam (3m deep) separated by a distance of about 7km to investigate the depositional environment as well as paleo ecology of the depocentre and climatic aspects during the Late Pleistocene and Holocene. Results from C¹⁴ dating of shell fragments from Eruva (depth zone: 2.10–6.64m) yielded ages in the range of 36.2 to 42.5 kyBP corresponding to the late Pleistocene. Wood fragments in the Muthukulam core sample (depth zone: 1.27–3.00m) gave C¹⁴ ages in the range of 3.7 to 7.2 kyBP indicating a Holocene history. The lower half of the Eruva bore hole indicates a marginal marine environment with an abundant supply of terrestrial carbonaceous debris probably corresponding to a period of abnormally high rainfall recorded in many parts of the globe covered by the Asian summer monsoon. The sediments in the upper part of this bore hole indicate a continuation of this environment but with much less input of terrestrial organic carbon. The lower part of the bore hole from this locality, corresponding to the Holocene transgression, is similar to the lower part of Eruva bore hole in the case of TOC. Deposition took place in water bodies with considerable marine influence but receiving high amounts of terrestrial plant debris-mostly in the form of finely divided particles mixed with mud. This transgressive sequence was also deposited during a time when the Asian summer monsoon was abnormally high in intensity as indicated by many examples in India, Africa, Madagascar and elsewhere. It is significant that during the deposition of this part, the sea level was probably the same as present or higher suggesting possible lowering of the stream velocities and resultant deposition of only muddy sediments laden with terrestrial organic material along the coast. The upper part of the section shows a progressively reduced rainfall pattern culminating in a period of very low precipitation with the development of a paleosol, which is traceable all over the SKSB where Late Holocene sediments are available. This period also witnessed aeolian activity modifying the sand ridges in the ridge-runnel systems formed by the Holocene regression.  相似文献   

Le Silurien de la région d'Oulad Abbou (Meseta occidentale,Maroc) : une sédimentation péritidale sous contrôle tectonique     

Ahmed Attou  Naima Hamoumi 《Comptes Rendus Geoscience》2004,336(9):767-774

In the Oulad Abbou syncline, western coastal Meseta, the Silurian deposits exhibit siliciclastic or mixed siliciclastic/carbonate tidal facies that recorded alkaline basalt flows and syn-sedimentary deformations. These facies are staked into peritidal shallowing upward sequences reflecting the evolution from an infratidal to a supratidal environment. These sequences recorded low-amplitude and high-frequency sea-level variations. The built-up of these rhythmic sequences is related to distensive tectonic that allowed the development of isolated platform from extensive siliciclastic influx. This tectonic event is well recorded in the palaeogeographic evolution of the northern Gondwana platform during the Lower Palaeozoic time. To cite this article: A. Attou, N. Hamoumi, C. R. Geoscience 336 (2004).  相似文献   

顺义地裂缝成因与顺义-良乡断裂北段第四纪活动性讨论   总被引：3，自引：0，他引：3  

张世民  刘旭东  任俊杰  刘光勋  Liu Guangxun 《中国地震》2005,21(1):84-92

本文通过钻孔地层对比方法研究了顺义一良乡断裂北段的第四纪活动性，资料显示该断裂在第四纪期间呈现强弱交替的分期活动特征，距今315万年以来有3个较强活动期和3个较弱活动期，前三者分别距今266～315、171～228、73～147万年，后三者距今分别为228．266、147～171、0～73万年。中更新世晚期以来断裂活动不明显。超量开采地下水导致地面不均匀沉降是造成顺义地裂缝现今活动的主要原因。  相似文献