西藏恐弄拉地区中侏罗统桑卡拉佣组的厘定及其地质意义   总被引：2，自引：2，他引：0       下载免费PDF全文

白培荣  杨育慎  曾禹人  李月森  马德胜  樊洪富 《贵州地质》2016,33(4):289-294,299

贵州省地质调查院在开展西藏自治区1∶5万班戈县恐弄拉地区区域地质调查时,在马前乡恐弄拉西侧车尖西南一带前人划分的一套早白垩世桂牙岩组碳酸盐岩地层中采集了腕足类和腹足类化石,据采集的古生物化石时代确定此套碳酸盐岩地层为中侏罗世沉积(晚巴柔期—卡洛期),通过岩石组合特征、基本层序、沉积环境及生物化石时代对比,将该套地层重新厘定为桑卡拉佣组。这一地层的确定为冈底斯带地层区侏罗系地层划分对比、地层格架建立提供了重要的依据,并为中生代盆地的演化历史,古地理轮廓的确定提供了新的基础资料。  相似文献   

胶西北大尹格金矿床成矿机理:载金黄铁矿标型及硫同位素地球化学约束   总被引：4，自引：3，他引：1  

张瑞忠  王中亮  王偲瑞  刘育  秦文凯 《岩石学报》2016,32(8):2451-2464

胶东是我国最重要的金矿集中区,破碎带蚀变岩型金矿床是区内最主要的金矿床类型,该类型金矿床已探明金资源量占全区的90%以上,其巨量金的来源是引人瞩目的关键科学问题。招平断裂带是该区内规模最大的断裂-成矿带,位于招平金矿带中段的大尹格庄金矿床是该金矿带最具代表性的破碎带蚀变岩型金矿床之一,已探明金金属量约283t。大尹格庄金矿床严格受沿胶东群与玲珑花岗岩接触带发育的NNE向招平断裂带控制,矿体赋存在招平断裂下盘黄铁绢英岩化和碎裂岩化玲珑花岗岩中,主要由Ⅰ号和Ⅱ号矿体组成,其具有相似的矿物组成,矿石主要矿物是绢云母、石英、黄铁矿,次要矿物是钾长石、斜长石、黑云母、方解石、黄铜矿、方铅矿、闪锌矿、磁黄铁矿、黝铜矿和自然金、自然银、金银矿、碲银矿等;其中黄铁矿是最主要的载金矿物。根据穿插关系和矿物共生组合,大尹格庄金矿床内成矿作用可划分为4个成矿阶段,分别是黄铁矿-石英-绢云母阶段(I)、石英-黄铁矿阶段(Ⅱ)、石英-多金属硫化物阶段(Ⅲ)和石英-方解石-多金属硫化物阶段(Ⅳ)。各个成矿阶段的黄铁矿的晶体形态标型研究表明,成矿Ⅰ阶段黄铁矿以粗粒自形立方体为主,含有少量五角十二面体;成矿Ⅱ和Ⅲ阶段黄铁矿以细粒五角十二面体为主,且具有更多五角十二面体、八面体和立方体形成的聚形;成矿Ⅳ阶段主要为细粒立方体晶形。不同矿体各个成矿阶段的硫化物的δ~(34)S值集中在4.58‰~7.54‰,具有一定的塔式效应,正向偏离陨石硫,与胶东地区胶东群变质岩、围岩花岗岩类δ~(34)S比较接近,指示大尹格庄金矿床各个成矿阶段的矿石硫源总体一致,与胶东群变质岩和中生代花岗岩间具有继承演化关系。此外,从成矿Ⅰ阶段→Ⅱ阶段→Ⅲ阶段→Ⅳ阶段,大尹格庄金矿床矿石硫化物δ~(34)S呈现出逐渐降低的趋势,反映了成矿过程中物理化学条件的演化趋势:Ⅰ阶段为较高温度(330~350℃)、快速冷却、低过饱和度、低氧逸度和硫逸度的成矿环境;Ⅱ和Ⅲ阶段黄铁矿形成于中-低温(200~300℃)、成矿流体过饱和度高、高氧逸度和硫逸度、缓慢冷却同时物质供应充分的成矿环境;Ⅳ阶段处于较低温度(200℃)、热液流体过饱和度较低、低氧逸度和硫逸度、同时物质供应不足的成矿环境。  相似文献   

怀柔应急水源地地下水水质变化研究     

杨利锦  任宇  张景华  欧志亮 《城市地质》2016,(1):57-61

本文综合怀柔应急水源地开采期间开采量、水质等系列动态监测资料,对水源地地下水水质变化规律以及引起水质变化的主要因素进行了分析。随着地下水的开采,地下水中硬度、溶解性总固体、硝酸盐等含量呈现逐年增高的趋势,其中,浅层地下水年际增速较快,深层地下水年际增速较缓。另外,利用同位素分析技术识别地下水中NO3-污染的来源,分析结果表明,NO3-主要来源是人工化肥和中水/污水,经土壤微生物硝化作用转为硝酸盐。针对怀柔应急水源地水质变化情况,为保障供水安全,提出了改善地下水水质的对策。  相似文献   

怀柔应急水源地可持续供水与水源涵养研究     

袁庆亮  任宇  张景华 《城市地质》2016,(1):69-74

怀柔应急水源地自运行以来一直续采至今,由于连续干旱和多年的超设计规模运行,导致区内水文地质条件发生了较大变化,为保证其"应急供水"的能力,具备随时启动供水的功能,结合南水北调水源进京的机遇,从资源回补涵养和供水系统的热备运行两方面开展研究工作。在综合分析区域水文地质条件和研究多年地下水动态变化规律的基础上,利用地下水数值模型对怀柔应急水源地在不同开采条件下的回补方式和效果进行模拟,拟定了南水北调进京后区域水资源人工回补方案及应急水源地的热备运行方案,并模拟预测了水源地热备运行和地下水涵养效果,为怀柔应急水源地可持续供水提供科学依据。分析结果表明:南水北调水源进京后,怀柔应急水源地可采用夏季高峰集中供水与日常保压相结合的"集中开采"方案和日常"稳压开采"方案。  相似文献   

New data on sedimentation and pedogenesis in the Selenga Midland (western Transbaikalia) during Late Glacial and Holocene     

Yu. V. Ryzhov  V. A. Golubtsov  D. V. Kobylkin  V. A. Snytko 《Doklady Earth Sciences》2016,467(2):376-379

The investigation of soil-sedimentary sequences formed in different erosional and depositional environments in the central part of the Selenga Midland (western Transbaikalia region) during Late Glacial and Holocene made it possible to reveal nine periods of activation of exogenic processes and sedimentation and eight stages of intense pedogenesis, to define the specific features of these pedogenesis and sedimentation epochs, and to assess their duration. The data on the intensity of sedimentation and its influence on pedogenesis is demonstrated. Asynchronous development of exogenic processes and pedogenesis related to the landscapeâ “climate heterogeneity of the Selenga Midland have been revealed. The latter is reflected in more distinct epochs of intense exogenic processes in more arid southern areas of the midland and more durable periods of pedogenesis in humid climatic environments of its central part.  相似文献   

Paleoproterozoic anorogenic granitoids of the Zheltav sialic massif (Southern Kazakhstan): Structural position and geochronology     

A. A. Tretyakov  K. E. Degtyarev  E. B. Sal’nikova  K. N. Shatagin  A. B. Kotov  A. V. Ryazantsev  A. V. Pilitsyna  S. Z. Yakovleva  E. V. Tolmacheva  Yu. V. Plotkina 《Doklady Earth Sciences》2016,466(1):14-19

The basement of the Zheltav sialic massif (Southern Kazakhstan) is composed of different metamorphic rocks united into the Anrakhai Complex. In the southeastern part of the massif, these rocks form a large antiform with the core represented by amphibole and clinopyroxene gneissic granite varieties. By their chemical composition, dominant amphibole (hastingsite) gneissic granites correspond to subalkaline granites, while their petroand geochemical properties make them close to A-type granites. The U–Pb geochronological study of accessory zircons yielded an age of 1841 ± 6 Ma, which corresponds to the crystallization age of melts parental for protoliths of amphibole gneissic granites of the Zheltav Massif. Thus, the structural–geological and geochronological data make it possible to define the Paleoproterozoic (Staterian) stage of anorogenic magmatism in the Precambrian history of the Zheltav Massif. The combined Sm–Nd isotopic—geochronological data and age estimates obtained for detrital zircons indicate the significant role of the Paleoproterozoic tectono-magmatic stage in the formation of the Precambrian continental crust of sialic massifs in Kazakhstan and northern Tien Shan.  相似文献   

The formation of graphite upon the interaction of subducted carbonates and sulfur with metal-bearing rocks of the lithospheric mantle     

Yu. V. Bataleva  Yu. N. Palyanov  Yu. M. Borzdov  O. A. Bayukov  N. V. Sobolev 《Doklady Earth Sciences》2016,466(1):88-91

Experimental studies of the Fe⁰–(Mg, Ca)CO₃–S system were carried out during 18–20 h at 6.3 GPa, 900–1400°C. It is shown that the major processes resulting in the formation of free carbon include reduction of carbonates upon redox interaction with Fe⁰ (or Fe₃C), extraction of carbon from iron carbide upon interaction with a sulfur melt/fluid, and reduction of the carbonate melt by Fe–S and Fe?S–C melts. Reconstruction of the processes of graphite formation indicates that carbonates and iron carbide may be potential sources of carbon under the conditions of subduction, and participation of the sulfur melt/fluid may result in the formation of mantle sulfides.  相似文献   

Silurian U–Pb zircon age (LA-ICP-MS) of granitoids from the Zelenodol Cu–porphyry deposit,Southern Urals     

A. I. Grabezhev  Yu. L. Ronkin  V. N. Puchkov  G. Yu. Shardakova  O. B. Azovskova  A. Gerdes 《Doklady Earth Sciences》2016,466(1):92-95

The Zelenodol porphyry Cu-(Au, Mo) deposit located about 65 km SSW of the city of Chelyabinsk is confined to the western part of the West Uralian Volcanogenic Megazone. The concordant U-Pb age of zircons from ore-bearing island-arc diorite porphyryis 418.3 Â ± 2.9 Ma.  相似文献   

First results on determination of chlorophill <Emphasis Type="Italic">A</Emphasis> and its derivatives in the system of trapped sedimentary material–fluffy layer–bottom sediment of the Caspian Sea     

M. D. Kravchishina  A. P. Lisitzin  A. Yu. Lein  V. N. Lukashin  A. N. Novigatsky  A. A. Klyuvitkin 《Doklady Earth Sciences》2016,467(1):284-288

The first data were obtained on the vertical chlorin flux in the water column and its accumulation in the upper layer of sediments of the Caspian Sea. Seasonal variability of the chlorine concentration in sedimentary matter was evaluated. The tendency of decrease in the phytoplankton-synthesized (allochtonous) organic matter content was revealed over approximately the past 60 years.  相似文献   

Detachment folding in a Lower Cambrian–Upper Permian karst reservoir: 3D model of the Yubei 3D area (eastern Markit Slope,Tarim Basin,Northwest China)     

JiuMei Li  LiangJie Tang  Yong Yue  Meng Li  ShengLong Zhang  Yu Long  ShaoHui Luo 《Arabian Journal of Geosciences》2016,9(14):630

A three-dimensional (3D) structural modeling of the Lower Cambrian–Upper Permian Yubei 3D area was performed to understand its structural evolution. This model reproduces the present-day structure of the basin and comprises 11 horizons within Lower Cambrian to Upper Permian rocks. The analysis is based on 3D depth views and faults. The results image salt movements due to tectonics and/or burial. From these observations, this paper deduces that salt structures are correlated to the main faults and tectonic events. From the model analysis, we interpret the timing and geometry of Tarim Basin tectonics. The fault geometry can be resolved based on the strike of the fault, the morphology of hanging wall strata, and the stratigraphic distribution. Emphasis is placed on gypsum rock detachment, considering its movements during the Middle Caledonian event and decoupling effects during tectonic evolution. Moreover, we point to the structural control of the Paleozoic basement and the crustal architecture (Yubei 3D Zone) on the geometry of the Tarim Basin.  相似文献