冀中饶阳凹陷西柳10断块古近系沙三段-沙二段层序地层及沉积演化          下载免费PDF全文

王旭旭  张廷山  张喜  孙文钊 《沉积与特提斯地质》2019,39(4):27-37

为了探讨饶阳凹陷蠡县斜坡北东缘西柳10断块古近系沙河街组沙三段-沙二段(Es~3-Es~2)层序地层特征及其沉积特征,依据高分辨率层序地层学理论,结合岩心、测井等资料,对研究区沙三段-沙二段层序地层进行划分,对其沉积特征、相带展布及其演化规律进行研究。研究结果表明,沙河街组沙三段-沙二段可划分为4个III级旋回,11个IV级旋回,32个V级旋回。沉积物岩性以细砂岩、粉砂岩及泥岩为主,沉积环境主要为辫状河三角洲平原和三角洲前缘,划分出7种沉积微相。结合研究区区域构造演化及沉积背景,认为沙三段-沙二段沉积时期,主要经历湖退到湖进的演变过程。  相似文献   

长白山新生代火山岩之下新太古代基底年代学及地球化学特征     

张宏涛  张兴洲  曾振  刘洋  崔维龙 《世界地质》2017,36(3):763-776

对长白山第四系玄武岩覆盖区零星出露的花岗质岩石和片麻岩进行LA-ICPMS锆石U-Pb年龄测定及地球化学分析,结果显示花岗质岩石的年龄为2 509~2 558 Ma;斜长角闪片麻岩的年龄为2 475~2 553 Ma。地球化学特征上,这些岩石均属奥长花岗岩-英云闪长岩-石英闪长岩系列(TTG),稀土元素配分模式图呈右倾型,轻重稀土元素分馏明显(LREE/HREE=3.85~34.48),白云母二长花岗岩具有铕的负异常(δEu=0.41~0.54),富集Rb、K、Th等元素,亏损Nb、Sr、P、Ti等元素;黑云斜长角闪石片麻岩具有铕负异常(δEu=0.67~0.76),富集Rb、K、La、Nd等元素,亏损Th、Nb、Sr、P、Yb等元素;花岗质片麻岩和黑云斜长片麻岩具有铕的弱负-正异常(δEu=0.87~3.3),富集Rb、K、Sr等元素,亏损Nb、Th、P等元素。年代学和地球化学特征与白山地块和和龙地块中的同类岩石基本一致,表明白山地块与和龙地块在晚太古代是同一个陆块(龙岗陆块),二者目前的分布格局是后期北东向左行断裂构造改造的结果。  相似文献   

阿尔金断裂带东段古生代花岗岩浆作用及其大陆动力学意义   总被引：1，自引：0，他引：1  

王楠  吴才来  马昌前 《地球学报》2017,38(S1):33-37

造山带花岗岩浆作用一直是地学的重要研究方向, 它记录了地球动力学深部过程的信息, 开展深入的研究工作可以更好的了解板块汇聚环境的陆壳生长和再造以及壳幔之间的相互作用。北祁连造山带是一典型的早古生代造山带, 先后经历了洋盆的打开到闭合, 敦煌地块则是主要由前寒武纪TTG片麻岩和变质表壳岩组成。北祁连造山带和敦煌地块分别位于阿尔金断裂带东段的东南侧和西北侧, 且均出露有大面积的古生代花岗岩体。本文以阿尔金主断裂两侧产出的花岗岩类为研究对象, 涉及北祁连造山带中的赵家庄二长花岗岩, 石包城复式岩体(花岗岩、正长花岗岩和花岗闪长岩)和红柳河花岗岩, 敦煌地块中的党河水库花岗闪长岩、沙枣园二长花岗岩、安盆沟复式岩体(正长花岗岩和花岗岩)以及小草湖似斑状花岗岩。通过对上述花岗岩体的岩相学、锆石U-Pb年代学、地球化学和锆石Hf同位素的研究, 取得了新的认识:  相似文献   

2017年四川九寨沟M_s7.0地震InSAR同震形变场及发震构造探讨     

姚鑫  周振凯  李凌婧  刘星洪  姚佳明 《地质力学学报》2017,23(4):507-514

2017年8月8日四川省九寨沟县发生M_s7.0级地震,构造部位处于青藏高原东缘的巴颜喀拉地块东北角,震中位置是岷江断裂、塔藏断裂、虎牙断裂和雪山梁子断裂围闭的空震区。哪条断裂发震,如何界定其与周边活动断裂的关系,与青藏高原东缘近年来发生的大地震是否有成因联系等问题对于理解该区域现今构造活动模式、预判地震发展趋势和部署地震地质灾害防控等工作具有重要意义。利用地震前后两期Sentinel-1合成孔径雷达数据对地表同震形变场进行了InSAR测量,获取了极震区约2000 km²范围内的雷达视线向变形（-13~28 cm）和运动方向,呈现为主动盘单侧走滑兼逆冲的变形模式,结合震源机制、断裂展布、构造背景和近年地震迁移的分析,揭示了控震构造是巴颜喀拉地块北缘边界断裂弧形旋转体系的尾端构造,发震断层是该断裂系中塔藏断裂的南段,并有与虎牙断裂贯通的趋势,因此,应重视本次地震与虎牙断裂之间的空震区未来的强震危险性问题;从区域上看,此次九寨沟地震可能与汶川地震具有一定的时空成因联系,因在巴颜喀拉地块南北边界断裂破裂基本贯通的条件下,2008年汶川地震诱发的东缘中部锁固破裂导致块体加速向东挤出,2013年鲁甸地震又释放了东缘南段挤压构造应力,从而进一步加剧了东北角的应力集中,促使九寨沟地震的发生。  相似文献   

扬子板块北缘下志留统龙马溪组重晶石结核特征及其成因机制分析          下载免费PDF全文

昝博文  刘树根  冉波  叶豪  杨迪  黄瑞  夏国栋  焦堃 《岩石矿物学杂志》2017,36(2):213-226

在扬子板块北缘城口明中剖面及巫溪徐家坝剖面下志留统龙马溪组底部的硅质岩、泥岩中发现椭球状重晶石结核。其矿物组成主要为重晶石颗粒与作为"基质"的黄铁矿、粘土矿物和石英。通过重晶石岩石学、矿物学及锶同位素分析表明,重晶石结核形成于早期成岩阶段松软沉积物的孔隙水中。上升洋流带来丰富的营养及富钡物质,表层海水的高初始生产力促使生物繁盛,海水中的钡通过生物作用富集形成生物钡,生物钡(bio-barite)在埋藏过程中的硫酸盐耗竭区(sulfate depleted zones)通过硫酸盐细菌作用(BSR)溶解被激活提供了钡的来源。围岩岩性(黑色泥岩和硅质泥岩)表明重晶石结核形成于缺氧的环境中。上述研究对深入理解早志留世时期扬子板块北缘古海洋环境有一定的启示作用。  相似文献   

滇西镇康水头山Pb-Zn矿床成矿流体及矿质来源探讨——H、O、S、Pb同位素地球化学证据   总被引：2，自引：1，他引：1  

邓明国  赵剑星  刘凤祥  余海军  孙柏东  刘飞  李仕斌 《岩石学报》2017,33(7):2001-2017

滇西镇康水头山Pb-Zn矿床是保山地块镇康Pb-Zn-Fe-Cu多金属矿集区内又一重要找矿成果。矿体呈似层状、透镜状产于上寒武统保山组大理岩化灰岩中,呈NEE向顺层产出,矿石矿物主要为闪锌矿和方铅矿,偶见黄铜矿和黄铁矿等;脉石矿物主要有白云石、绿泥石、方解石、石英和绢云母等。本文基于对矿床地质特征的详细研究,结合矿床H、O、S、Pb同位素组成,对其成矿流体和矿质来源进行了探讨,同时与毗邻的芦子园超大型Pb-Zn-Fe-Cu多金属矿床进行了对比。研究表明:该矿床石英的δD值介于-101.1‰~-93.3‰之间,均值为-96.85‰(n=4),δ~(18)O_(H_2O)值为3.37‰~3.77‰之间,均值为3.57‰(n=4),表明成矿流体早期以原生岩浆水为主,有大气降水的混入。矿床金属硫化物的δ~(34)S值均为正值,介于4.1‰~12.2‰,均值为8.23‰(n=10),与旁侧的芦子园矿床δ~(34)S值(8.9‰~12‰)较为接近。该矿床可划分出三个成矿阶段,阶段Ⅱ为以闪锌矿和方铅矿为主的主要成矿阶段(δ~(34)S主要集中在4.1‰~6.2‰之间),其δ~(34)S均值可近似代表成矿热液中的δ~(34)S∑S值,即δ~(34)S∑S≈δ~(34)S均值=6.56‰(n=7),闪锌矿和方铅矿δ~(34)S值有部分重叠,但总体上具有δ~(34)S闪锌矿δ~(34)S方铅矿以及不同颜色闪锌矿之间δ~(34)S深棕色闪锌矿δ~(34)S棕褐色闪锌矿δ~(34)S浅棕色闪锌矿的分布特征,暗示硫同位素在硫化物间的分馏达到平衡,表明S同位素组成较为稳定,显示水头山矿床具有深部壳源岩浆成因的特征。矿床金属硫化物的Pb同位素分析显示,Pb同位素组成非常集中(~(206)Pb/~(204)Pb=18.3408~18.4483,均值为18.3815,~(207)Pb/~(204)Pb=15.8337~15.9440,均值为15.8745,~(208)Pb/~(204)Pb=38.8224~39.4391,均值为38.9941,n=10),投点主要分布在上地壳演化线上方,表明其Pb主要来自于以岩浆作用为主的上地壳物质。本文认为矿区深部壳源岩浆热液是水头山矿床最重要的成矿流体与矿质来源,流体的混合作用是矿床金属元素沉淀和富集的重要机制,矿床具有低温、后生成矿特征,推测矿床的形成与燕山晚期的岩浆热液作用有关。  相似文献   

Sedimentary control on the formation of a multi-superimposed gas system in the development of key layers in the sequence framework     

《Marine and Petroleum Geology》2017

Based on core observations, well logs and test results of siderite-bearing mudstone from the Benxi Formation to the Member 2 of the Shanxi Formations in the Linxing block, northeastern Ordos Basin, a logging identification model for siderite-bearing mudstone (key layer) was established. The porosity characteristics and sealing property were quantitatively evaluated by logging data. Sedimentary control on the formation of multi-superimposed gas-bearing system in the development of key layers in the sequence framework was also discussed. The results showed that the siderite-bearing mudstone has obvious logging response characteristics, e.g., high photoelectric absorption cross-section index (PE), high density (DEN), high amplitude natural gamma ray (GR), low acoustic (AC), low resistivity (M2RX) and low neutron porosity (CNCF). The quantitatively evaluated results of the porosity characteristics and sealing property for the key layer showed that the key layer has the characteristics of low porosity (with an average of 1.20 percent), low permeability (with an average of 2.29 × 10⁻⁸μm²), and high breakthrough pressure (with an average of 12.32 MPa) in the study area. This layer acts as an impermeable gas barrier in a multi-superimposed gas system. The results also indicated that the material composition of the multi-superimposed gas-bearing system can be established by the sequence stratigraphic framework. The sedimentary evolution results in a cyclic rhythm of material composition vertically. The spatial distribution of the corresponding transgressive event layer near the maximum flooding surface (MFS) in the sequence framework restricts the spatial distribution of the key layer with high breakthrough pressure and low porosity, which constitutes the gas-bearing system boundary. The siderite-bearing mudstone formed near the MFS in the second-order sequence and constitutes a stable comparison of the first-order gas-bearing system boundary, which has a wide range of regional distribution and stable thickness. The siderite-bearing mudstone formed near the MFS in the third-order sequence is often incompletely preserved due to the late (underwater) diversion channel erosion and cutting. This layer forms the coal-bearing reservoirs, which we termed as a second-order gas-bearing system in adjacent third-order sequences to form a uniform gas-bearing system.  相似文献   

Simulation of paleotectonic stress fields and quantitative prediction of multi-period fractures in shale reservoirs: A case study of the Niutitang Formation in the Lower Cambrian in the Cen'gong block,South China     

《Marine and Petroleum Geology》2017

Reservoirs where tectonic fractures significantly impact fluid flow are widespread. Industrial-level shale gas production has been established from the Lower Cambrian Niutitang Formation in the Cen'gong block, South China; the practice of exploration and development of shale gas in the Cen'gong block shows that the abundance of gas in different layers and wells is closely related to the degree of development of fractures. In this study, the data obtained from outcrop, cores, and logs were used to determine the developmental characteristics of such tectonic fractures. By doing an analysis of structural evolution, acoustic emission, burial history, logging evaluation, seismic inversion, and rock mechanics tests, 3-D heterogeneous geomechanical models were established by using a finite element method (FEM) stress analysis approach to simulate paleotectonic stress fields during the Late Hercynian—Early Indo-Chinese and Middle-Late Yanshanian periods. The effects of faulting, folding, and variations of mechanical parameters on the development of fractures could then be identified. A fracture density calculation model was established to determine the quantitative development of fractures in different stages and layers. Favorable areas for shale gas exploration were determined by examining the relationship between fracture density and gas content of three wells. The simulation results indicate the magnitude of minimum principal stress during the Late Hercynian — Early Indo-Chinese period within the Cen'gong block is −100 ∼ −110 MPa with a direction of SE-NW (140°–320°), and the magnitude of the maximum principal stress during the Middle-Late Yanshanian period within the Cen'gong block is 150–170 MPa with a direction of NNW-SSE (345°–165°). During the Late Hercynian — Early Indo-Chinese period, the mechanical parameters and faults play an important role in the development of fractures, and fractures at the downthrown side of the fault are more developed than those at the uplifted side; folding plays an important role in the development of fractures in the Middle-Late Yanshanian period, and faulting is a secondary control. This 3-D heterogeneous geomechanical modelling method and fracture density calculation modelling are not only significant for prediction of shale fractures in complex structural areas, but also have a practical significance for the prediction of other reservoir fractures.  相似文献   

Experimental analysis of breakwater stability with antifer concrete block     

S. Hooman Mousavi  M. R. Kavianpour  O. Aminoroayaie Yamini 《Marine Georesources & Geotechnology》2017,35(3):426-434

Armor is a pavement made of erosion-resistant materials like a stone or concrete that is constructed to protect breakwater, coasts, and other coastal line features against erosion. These armors are a kind of protective layer made of stone or concrete, used in breakwater constructions or coastal lines, arrayed with specific regular or irregular pattern on the breakwater or the coast. The antifer concrete blocks have almost cubic form, often changed into frustum by adding inclined plates to their sides. One of the most important advantages of these armors is their diversified regular and irregular placement patterns. In this study, using the physical modeling and different tests, the stability level of antifer concrete blocks was evaluated considering the decrease of the armor weight. Results of this study show that by a 10% decrease in the block weight, the failure graph slope is increased and the damage is intensified.  相似文献   

滇西兰坪盆地白秧坪Pb-Zn-Cu-Ag多金属矿床东矿带成矿年代学探讨     

冯彩霞  刘燊  毕献武  胡瑞忠  池国祥  陈俊瑾  冯强  郭晓磊 《矿床地质》2017,36(3):691-704

白秧坪Pb-Zn-Cu-Ag多金属矿集区夹持于金沙江和澜沧江断裂之间,隶属兰坪盆地北部,分为东、西2个矿带。文章采用闪锌矿、方铅矿的Rb-Sr法和成矿阶段方解石的Sm-Nd法,对白秧坪Pb-Zn-Cu-Ag多金属矿床东矿带华昌山和下区五矿段进行了成矿年代厘定,获得方铅矿以及闪锌矿和方铅矿的矿物组合Rb-Sr等时线年龄为(32.8±1.5)Ma,方解石的Sm-Nd等时线年龄为(33.32±0.43)Ma。研究表明,通过对特定矿床的主要矿石矿物采用Rb-Sr法和Sm-Nd法获得的年龄在误差范围内是一致的,从而起到了相互验证的作用,并对矿床的成矿背景具有一定的指示性。通过成矿年龄的探讨,认为东矿带铅锌为主的矿化期主要产生于青藏高原东缘晚碰撞阶段(40~26)Ma,伴随印度-亚洲大陆碰撞造山,形成逆冲推覆构造和赋矿地层,控制了Pb-Zn矿床的形成和发育。该期Pb-Zn矿床与兰坪盆地金顶和西矿带Pb-Zn矿床、囊谦盆地Pb-Zn矿床和沱沱河盆地Pb-Zn矿床具有一定的可比性。  相似文献