Sedimentary Characteristics of the Pleistocene Outwash Accumulation and their Implications for Paleoclimate Change in the Midstream of Dadu River,Southwestern China   总被引：1，自引：0，他引：1  

TU Guoxiang  HUANG Runqiu  DENG Hui  LI Yanrong 《《地质学报》英文版》2012,86(4):924-931

Ancient outwash accumulations, deposited in Pleistocene with complicated sedimentary characteristics, are discovered in the midstream valley of Dadu River, Southwestern China. Their sedimentation characteristics are investigated for gaining a deep insight into the dependency of Paleoclimate changes in this area. This is achieved by means of detailed site investigation, sampling and laboratory tests (grain size distribution and Electron Spin Resonance dating tests) for two representative outwash accumulations. Based on the present study, several main conclusions are drown out as follows: 1) The accumulations are composed mainly of coarse soils (coarse fraction is over 50%) and very coarse soils (coarse fraction is about 20%–35%, and very coarse fraction is over 55%); 2) The coarse soils are sub-rounded well-sorted and sub-stratified to well-stratified, while the very coarse soils exhibit sub-rounded to sub-angular and poorly-sorted; 3) The accumulations are postulated to have been intermittently deposited in three time periods. This is evidenced by two layers of weathered/residual clay, purple to brick red in color; and 4) It is inferred that the temperature in the study area increased over three time periods, i.e., 280 ka B.P. to 120 ka B.P., 110 ka B.P. to 80 ka B.P. and 70 ka B.P. to 25 ka B.P., and declined twice at 120 ka B.P. and 77 ka B.P. respectively.  相似文献   

四川盆地东北部海、陆相储层沥青组成特征及来源     

朱扬明  李颖  郝芳  邹华耀  郭彤楼 《岩石学报》2012,28(3):870-878

本研究系统采集了四川盆地东北部大普光、元坝地区上三叠统须家河组、下三叠统飞仙关组、上二叠统长兴组和鄂西渝东地区中石炭统黄龙组储层固体沥青样品,进行了岩石热解、有机元素、碳同位素和饱和烃、芳烃组分GC/MS的分析,以确定其成因、性质和来源。这些沥青总体上具有低溶性(多数氯仿抽提物/TOC<8%)、高反射率(换算的Ro>1.4%)、低H/C原子比(<0.6)的性质,属焦沥青类,是古油藏原油或运移烃经热裂解成气的残留物。其中,飞仙关组、长兴组碳酸岩储层沥青的S/C原子比值普遍较高(主要在0.025~0.085范围),且硫同位素δ³⁴S值(主要在12‰~24‰)接近硬石膏,说明可能包含有部分TSR成因的沥青。这些高热演化沥青中饱和烃生物标志物的组成和分布出现了异常变化,基本失去了其常规应用意义。芳烃中2,6-/2,10-DMP(二甲基菲)、1,7-/1,9-DMP和4-/1-MDBT(甲基二苯并噻吩)比值,可用来指示沥青烃源岩的有机质生源构成和沉积环境性质。须家河组陆相沥青中这些芳烃比值较高,表征其烃源母质中陆源有机质占优势,且形成于氧化性的环境;而飞仙关组、长兴组及黄龙组海相沥青中这些参数值低得多,意味着其烃源岩有机质生源应以水生生物为主,并沉积于还原性环境。经沥青/烃源岩的碳同位素和二苯并噻吩系列组成对比,认为须家河组储层沥青来源于本层位烃源岩,飞仙关组和长兴组沥青同源于二叠系烃源层。鄂西渝东地区的黄龙组沥青碳同位素偏重(δ¹³C值为-23.2‰~-26.4‰),原始烃源可能主要来自中、下志留统韩家店组及小河坝组地层。  相似文献   

新疆于田阿什库勒火山群若干新的野外地质证据   总被引：4，自引：1，他引：3  

冯民  黄杰  涂勇  黄少鹏 《岩石学报》2014,30(12):3512-3520

位于青藏高原北缘的新疆于田阿什库勒火山群地区是中国大陆现代火山和地震活动最活跃的构造区之一,是研究青藏高原演化的重要窗口,但由于地处高海拔(4700~5600m.a.s.l.)无人区,研究程度还很低,甚至还不曾开展过系统详细的野外地质调查。本文报道最近在这一地区的一次野外考察结果,在前人鲜为涉足的阿什库勒盆地北部发现了苏贝稀1号、苏贝稀2号和托甫热三个火山口,并且在前人有争议的盆地南部高台山地区找到确凿的证据,重新认定高台山火山的存在。我们还在高台山和椅子山火山之间考察了前人未曾报道的小黑沟火山。由小黑沟流向乌鲁克库勒湖的火山熔岩流动和冷却过程中形成的熔岩冢等火山地质景观在严酷的荒漠环境中迄今仍然保存完好,表明小黑山火山很可能是一座全新世的火山,是本次考察到的最年轻的火山。  相似文献   

四川雅安绿色软玉的宝石矿物学特征     

金晓婷  ;丘志力  ;戴苏兰  ;易建华  ;李榴芬  ;张跃峰 《地质科学译丛》2014,(5):1-8

四川雅安地区新近发现一处颇具特色的绿色 浅绿色软玉矿产资源,该软玉在产出状态、外观特征、玉石结构、构造及成矿特点等方面明显有别于国内外同类型软玉矿床.采用X射线粉末衍射仪、扫描电子显微镜、傅里叶变换红外光谱仪及电子探针等测试方法,重点就该类软玉的物相、微组构、振动光谱、微区化学成分等特征进行了分析.观察与测试结果表明,雅安软玉具致密块状构造和典型的纤柱状交织结构,其主要矿物组成为透闪石（95％～98％）,还含少量钙铬榴石、铬铁矿及石英等次要矿物;红外吸收光谱显示其吸收谱带数目、峰位均与透闪石标准图谱相吻合;透闪石微区化学成分分析结果显示,雅安软玉相对贫Mg,富Fe,含Cr,其中w（FeOT）=1.810％～2.365％,w（Cr2O3）=0.019％～0.152％,Mg/（Mg＋Fe）在0.944～0.957区间内变化,其中Fe、Cr元素可能是导致雅安绿色软玉致色的主要因素.  相似文献   

川西九龙黄牛坪铍矿床地质特征及找矿潜力          下载免费PDF全文

王伟  刘图强  袁蔺平  刘善宝  于扬  刘丽君  吕秉廷  郑小刚  代鸿章 《中国地质调查》2014,6(6):72-78

通过在川西九龙三岔河地区开展综合地质调查工作,发现该区桥棚子花岗岩体与三叠系围岩接触带及其附近具有较好的铍矿化,初步圈定了4条铍矿体,主要沿岩体接触带呈NNW向延伸,BeO品位最高可达0.698%,初步预测BeO资源量可达大型规模,矿石矿物主要为绿柱石,围岩蚀变以电气石化为主。花岗岩体顶部是含铍伟晶岩的重要成矿部位,野外可采用遥感先行的技术手段查找异常,再对遥感异常开展大比例尺追索,进一步采用工程手段进行验证。结果表明,九龙地区具有明显锂、铍异常,且与地质体套合度高。研究区外围东部发现稀有金属矿化显著的打枪沟锂铍矿床,南部乌拉溪地区追索到大量含锂辉石矿化伟晶岩转石,表明该区具有良好的稀有金属成矿条件及找矿潜力。  相似文献   

大渡河巴拉水电站坝区外围日部断裂活动性研究     

黄晨  吴德超  王道永  孙东 《云南地质》2011,30(1):107-111

研究表明：断层通过处无动态构造地貌发育,断裂构造中的石英颗粒形态以深度溶蚀的桔皮状-苔藓状为主,认为日部断裂不具活动性。  相似文献   

安徽天井山金矿成矿流体特征及成矿过程初探   总被引：6，自引：0，他引：6  

姜妍岑  谢玉玲  唐燕文  李应栩  王爱国  曾献育  李媛  刘保顺 《岩石矿物学杂志》2013,32(3):329-340

本文在矿床地质调研的基础上,通过主要矿石和蚀变岩石的岩矿相、SEM/EDS、流体包裹体岩相学、显微测温和成分分析,对天井山金矿成矿流体特征、流体来源及成矿过程进行了研究.结果表明,金矿化主要发育于石英脉中,少数产于蚀变围岩中,矿区蚀变以硅化、绢云母化最为发育,另发育含铁碳酸盐化、绿泥石化、黄铁矿化、黄铜矿化、方铅矿化、闪锌矿化等.金矿化发生于石英脉形成后的脆性变形阶段,与之相关的蚀变以绢云母化为主,其次为含铁碳酸盐化和硫化物矿化.金主要以自然金的形式与绢云母共生于石英脉的裂隙中或蚀变围岩中.通过与绢云母同期的流体包裹体研究表明,与金矿化有关的成矿流体为富水、含CO2的中高温(286～380℃)、低盐度流体(3.0％～5.1％,NaCleq,质量分数),单个流体包裹体的LA-ICP-MS成分分析表明,成矿流体中富含Pb、Zn、Cu、Bi、Mo、Sb等金属元素.综合流体包裹体中水的H同位素组成和流体成分特征,成矿流体主要为岩浆水的贡献.含CO2的岩浆流体沿活化的先期断裂上升并发生流体沸腾,在流体沸腾过程中CO2进入气相而改变了流体的pH值,造成金和其它金属硫化物的沉淀,同时形成石英裂隙中和围岩中的绢云母化、含铁碳酸盐化等蚀变.  相似文献   

燃气管道地震紧急处置装置设计和示范应用     

崔建文  王暾  樊荣  高东  徐硕  张潜  段建新 《中国地震》2012,28(4):425-433

震后火灾是破坏性地震发生后城市面对的主要危害之一。对于城市中燃气管网,建立地震紧急处置系统尤为重要。在日本、美国和我国的台湾地区,均因城市天然气管网建立了紧急处置系统而取得了减轻地震次生火灾的实效。我国是多地震的国家,随着管道燃气的日益普及,地震紧急处置设施非常重要。本文采用美国Northridge2000小型地震燃气阀,结合所设计的一种燃气管道地震紧急处置装置,在昆明市区,分别用于4户民居小管径燃气管道和一个大管径燃气管道,开展燃气管道的地震紧急处置示范应用。进行的人工触发试验显示,紧急处置装置响应与预期的一致,但还需实际地震的检验。本文介绍了燃气管道地震紧急处置的设计和示范应用情况,并对我国开展相关工作需要解决的问题进行了讨论。  相似文献   

DISCUSSION ON ATTENUATION CHARACTERISTICS,SITE RESPONSE AND MAGNITUDE DETERMINATION IN SICHUAN          下载免费PDF全文

WU Wei-wei  SU Jin-rong  WEI Ya-ling  WU Peng  LI Jun  SUN Wei 《地震地质》2016,38(4):1005-1018

The attenuation characteristics and site response are calculated respectively for each individual tectonic unit in Sichuan (Sichuan Basin,west Sichuan plateau and Panzhihua-Xichang area),using digital waveform data recorded by regional seismic networks and relevant seismic phase data collected from China Seismograph Network.The frequency dependent Q(f) is obtained by the iterative grid-search technique described by Atkinson and Mereu based on trilinear geometrical spreading model.The source spectra are determined by the model of Brune and the site responses of seismic stations are derived by Moya's method using genetic algorithms.Comparison to conventional M_L estimates shows that the network local magnitude bias is quite significant at low and intermediate magnitudes.The bias at the j^th station for the i^th event is defined as ΔM_ij=M_ij-M_i, where ΔM_ij is the station magnitude and M_i the network-average value.For comparison,we mapped the spatial distribution of biases by digital seismograms recorded from 10535 earthquakes of magnitude 2.5≤M_L≤4.9 that occurred in Sichuan from January 1,2009 to June 30,2015.Based on the above data,the attenuation characteristics,site response and their effects on magnitude determination in Sichuan are analyzed.Our results demonstrate that the associated model for regional quality factor for frequencies can be expressed as Q₁(f)=450.6f^{0.513 4} for Sichuan Basin,Q₂(f)=136.6f^{0.581 3} for west Sichuan Plateau and Q₃(f)=101.9f^{0.666 3} for Panzhihua-Xichang area.Site response results indicate that different stations show different amplifications.Maps of biases appear to be different,but with similar dominant spatial distribution.For stations in Sichuan Basin,their greater magnitudes are functions of low attenuation in structure and amplification effects of both seismic stations and basin effects.For stations in west Sichuan Plateau,the possible causes of these lower magnitudes are severe dependence upon source region due to extreme lateral variations in either structure or path effect attenuation.For stations in Panzhihua-Xichang area,broken medium caused by strong tectonic activity or large earthquakes and heat flow up-welling along active faults may be the main reasons of low magnitude values when earthquakes occur in western Sichuan and eastern Tibetan region.And the greater magnitudes for earthquakes along the Longmen Mountains appear to be well correlated with edge effect of sedimentary basin on strong ground motion.In our study,stations magnitude biases appear to be extremely correlated with tectonic structures and different regions when seismic rays passing through,magnitudes are affected significantly by lateral variations in attenuation characters rather than site responses.  相似文献   

基于经验模态分解(EMD)的小波熵阈值地震信号去噪   总被引：1，自引：0，他引：1  

刘霞  黄阳  黄敬  段志伟 《吉林大学学报(地球科学版)》2016,46(1):262-269

针对EMD阈值去噪算法中阈值由经验选取以及无法有效区分各固有模态函数上有用信息的不足,本文对各固有模态函数进行小波变换,对各层小波系数进行相关处理,以突出有效信息,抑制噪声;将细节系数的有效信号和突变点置零并等分为若干区间,选取小波熵最大子区间的高频小波系数平均值作为噪声方差计算得到阈值。该阈值选取方法依据小波熵的特点,自适应地根据对应尺度上信号自身的能量特征确定该尺度阈值。将该算法应用于仿真信号和实际地震信号去噪,结果表明该方法优于基于EMD的小波阈值去噪,在提高去噪效果的同时,也更好地保护有效信号。  相似文献