熊耳群火山岩形成的构造环境探讨     

张子敏  范光 《铀矿地质》1996,12(6):347-352

熊耳群中基－中酸性火山岩系是熊耳山区最为重要的产金层，其形成时代大致相当于华北地区的长城系，为华北地台南缘结晶基底之上的第一套盖层沉积。多年来，中元古代早期华北地台南缘构造框架颇有争议。本文从熊耳群火山岩系的分布形态、与基底的接触关系、常量、微量元素特征、稀土之素特征诸方面证实了熊耳群火山岩系为典型大陆裂谷喷发的产物，并非陆缘火山岛弧成因。  相似文献   

塔里木北缘及邻区海西期碱性岩岩石化学特征及其大地构造意义   总被引：30，自引：1，他引：30  

刘楚雄  许保良  邹天人  路凤香  童英  蔡剑辉 《新疆地质》2004,22(1):43-49

塔里木地台北缘及邻区发育一套以正长岩、石英正长岩、霓辉正长岩、霓霞正长岩、碱性花岗岩类为代表，包括碱性辉长岩、碱长花岗岩、霓辉花岗岩、角闪正长岩、碱性辉石闪长岩、煌斑岩等类岩石在内的碱性侵入岩体．它们具有近东西向的带状分布特征．主体形成于海西期．相当于泥盆-二叠纪．钾钠含量较高，具有碱性岩类的岩石化学特征．构成一条碱性侵入岩带．其时空分布与北山-阿拉善地区的碱性岩带基本一致．该碱性岩带反映出在泥盆-二叠纪期间．塔里木地台北缘及邻区处于造山期后的拉张构造环境．  相似文献   

扬子地台灯影组碳酸盐岩中的硫和碳同位素记录   总被引：17，自引：3，他引：17  

张同钢储雪蕾  张启锐冯连君 霍卫国 《岩石学报》2004,20(3):717-724

扬子地区灯影组的海相碳酸盐岩地层不仅记录了当时海水的碳同位素变化，也保存了海水的硫同位素记录，能够通过测定所提取的微量硫酸盐的硫同位素组成来获得。灯影组碳酸盐岩中微量硫酸盐的δ^34S值大部分在 20.0‰～ 38．7‰之间变化，碳酸盐岩的δ^13C值变化在 0．5‰～ 5．0‰之间。除灯影组顶、底界线处外，δ^34S和δ^13C值总体上变化幅度较小，大体上呈逐渐降低的变化趋势。灯影组碳酸盐岩中连续的硫、碳同位素记录分别反映了同期海水中溶解硫酸盐和碳酸盐的硫、碳同位素的变化特征。灯影组微量硫酸盐和碳酸盐岩的同位素特征，意味着灯影期海洋中具有高的生物产率和有机碳埋藏速率；除了顶底界线处，具有相对稳定的古气候条件和古海洋环境。灯影期海水的δ^34S值和δ^13C值同时呈逐渐降低的变化趋势，可能是由海洋深部水体逐渐氧化所致。  相似文献   

Re-Os and Nd isotopes of black shales at the bottom of the Lower Cambrian from the northern Tarim Platform and their comparison with those from the Yangtze Platform   总被引：1，自引：0，他引：1  

Yu Bingsong  Dong Hailiang  E.Widom  CHENG Jianqiang  Lin Changsong 《中国科学D辑(英文版)》2004,47(Z2)

This paper reports Re-Os and Nd isotopes of black shales at the bottom of Lower Cambrian from the northern Tarim Basin and traces source materials of the black shales through isotopes. The average Re/Os, 187Re/188Os, and 187Os/188Os ratios of the black shales at the bottom of Lower Cambrian from the Tarim Basin are 7.18, 5.6438, and 1.9616, respectively. These isotopic ratios suggest the crustal sources of the black shales. The εNd(0) value is -13.17, the εNd(540 Ma) value is -7.32 and the Nd model ages are 1.535 Ga. These parameters in the black shales are quite consistent with those from the basement rocks. Based on the Re-Os and Nd isotopic characteristics of the black shales, we conclude that the continental crust mainly composed of basement rocks is the source material of the black shales. Through comparison of these isotopic parameters with those from the Yangtze Platform, it is clear that the Re-Os isotopic characteristics in the black shales from the Tarim and Yangtze platforms are quite different, which maybe indicates the differences in depositional settings between two platforms. These Re-Os isotopic data provide us with constraints to analyze the genetic relation between the two platforms.  相似文献   

华南上扬子区早-中奥陶世疑源类古环境意义   总被引：1，自引：2，他引：1  

李军  T.Servais  燕夔 《地层学杂志》2003,27(4):298-305

对上扬子区 7个剖面早—中奥陶世疑源类研究表明 ,这些疑源类组合在分异度及属种组成上呈现有规律的变化 ,这种变化是上扬子区古环境变化的反映。在上扬子区西部 ,近岸碎屑岩相沉积的滇东红石崖组所产疑源类组合分异度低 ,为个体较小、壳饰较简单的分子 ;上扬子区中部 ,以黔北湄潭组为代表的浅海相碎屑岩和灰岩沉积中 ,疑源类分异度较高 ,并出现许多个体较大、壳饰较复杂的分子 ;而在上扬子区东部鄂西宜昌大湾组陆棚相灰岩与泥岩中 ,疑源类分异度继续增高 ,其中个体大、具粗大、长而复杂突起的分子占优势。  相似文献   

滚石在平台上的运动特征分析   总被引：6，自引：0，他引：6  

黄润秋  刘卫华 《地球科学进展》2008,23(5):517-523

危岩体;滚石;平台;运动距离;现场试验;滚动摩擦系数  相似文献   

华北地台类的演化与煤层生成   总被引：2，自引：0，他引：2  

汪增荫  尚冠雄  毛邦倬 《地学前缘》1999,6(Z1):73-79

以华北地台59处创面全涵盖式研究为基础,建立了华北石炭、二叠纪类生物群演化系列,并划分为6带13亚带,从中抽取4个与煤层生成关系密切的阶段加以详细讨论,分别称为：（1）Pr阶段;（2）T阶段;（3）Ps阶段和（4）S阶段。其中第1阶段反映煤盆地的构造启动,另外3个阶段分别代表太原组底部厚煤层、山西组主煤层、南华北区大风口组煤层的生成机制。  相似文献   

Information theory measures for the engineering validation of ground‐motion simulations     

《地震工程与结构动力学》2018,47(4):1095-1104

This short communication introduces a quantitative approach for the engineering validation of ground‐motion simulations based on information theory concepts and statistical hypothesis testing. Specifically, we use the Kullback‐Leibler divergence to measure the similarity of the probability distributions of recorded and simulated ground‐motion intensity measures (IMs). We demonstrate the application of the proposed validation approach to ground‐motion simulations computed by using a variety of methods, including Graves and Pitarka hybrid broadband, the deterministic composite source model, and a stochastic white noise finite‐fault model. Ground‐motion IMs, acting as proxies for the (nonlinear) seismic response of more complex engineered systems, are considered herein to validate the considered ground‐motion simulation methods. The list of considered IMs includes both spectral‐shape and duration‐related proxies, shown to be the optimal IMs in several probabilistic seismic demand models of different structural types, within the framework of performance‐based earthquake engineering. The proposed validation exercise (1) can highlight the similarities and differences between simulated and recorded ground motions for a given simulation method and/or (2) allow the ranking of the performance of alternative simulation methods. The similarities between records and simulations should provide confidence in using the simulation method for engineering applications, while the discrepancies should help in improving the tested method for the generation of synthetic records.  相似文献   

Multi-component seismic response analysis of offshore platform by wavelet energy principle     

Hong-Nan Li  Xiao-Yu He  Ting-Hua Yi 《Coastal Engineering》2009

A wavelet energy method is presented to search the critical incidence of earthquake excitation in a multi-dimensional seismic response of offshore platforms. The total effective energy and the instantaneous effective energy input rate of an earthquake can be obtained by wavelet transformation to predict the critical incidence of the earthquake and then the maximum dynamic response of the platform can be calculated. The critical incidence is determined using this method for an actual platform and a group of single degree-of-freedom systems. Numerical results show that the application of wavelet transform in a multi-dimensional seismic response of structures is convenient and reliable.  相似文献   

内蒙古狼山-渣尔泰山中元古代被动陆缘裂陷槽裂解过程中的火山活动及其示踪意义   总被引：3，自引：3，他引：3  

彭润民翟裕生  韩雪峰王志刚王建平  刘家军 《岩石学报》2007,23(5):1007-1017

狼山-渣尔泰山中元古代被动陆缘裂陷槽内产有炭窑口、东升庙、霍各乞和甲生盘等海底喷流-沉积铅锌铜铁硫化物矿床。它在裂解过程中产生了明显的间歇性海底火山喷发。已分别在霍各乞、东升庙和炭窑口矿床容矿岩组中已找到岩性不同、并具有变余斑状或聚斑状或显微球粒结构、变余杏仁构造的海相火山岩与凝灰岩层,它们是确认该裂陷槽裂解过程的有效标志。依据(1)西部炭窑口矿区容矿岩组中发育钾质"双峰式"火山岩,其基性火山岩的K_2O(4.23～5.93%)>Na_2O (2.15～3.14%)、Na_2O K_2O=6.51～8.08%、长石斑晶为钠长石(No.=2.8～7.2),酸性火山岩的K_2O(6.22～4.83%)>Na_2O(2.78～3.87%)、Na_2O K_2O=8.63～9.00%、长石斑晶为钠长石(No.=0.2～0.7)、长石微晶主要为钾长石;(2)东升庙矿区则发育钠质"双峰式"火山岩,其基性火山岩的Na_2O(3.84～4.30%)>K_2O(2.49～3.80%)、Na_2O K_2O=6.44～7.92%、长石斑晶为更长石(No.=11～25),酸性火山岩的Na_2O(3.64～5.31%)>K_2O(1.19～2.75%)、Na_2O K_2O=6.28～7.68%,长石斑晶与基质均为钠长石(No.=0～1.1);(3)霍各乞矿区发育基性火山岩,其Na_2O(1.36～3.78%)>K_2O (0.30～2.16%),Na_2O K_2O=2.03～4.09%;(4)炭窑口、东升庙与霍各乞矿床三矿区火山岩的稀土元素与微量元素蛛网图的标准化曲线有相似性和显著差别;(5)炭窑口、东各庙和霍各乞矿区基性火山岩的Sm-Nd模式年龄依次为1857～1877Ma和2006～2132Ma、1740～1867Ma、1486～1606Ma;(6)容矿岩组中有多层凝灰岩与火山碎屑及少量含火山碎屑的矿石,再结合该裂陷槽内各矿床的铅同位素模式年龄和甲生盘矿区只有少量凝灰质夹层,可以揭示该裂陷槽在中元古代的不均匀裂解过程,表现出从西部炭窑口→东升庙→东部的甲生盘一带先后裂解、狼山南侧早于北侧裂解以及从狼山→渣尔泰山同沉积期火山活动由明显→微弱的明显变化趋势。  相似文献