The Archipelagic Ocean System of the Eastern Eurasian Tethys

Unlike typical oceans such as the wide and "clean" Atlantic, the Tethys has been showing an archipelagic pattern during all its evolutionary stages. Compared with the traditional, wedge-shaped and relatively "clean" ocean model, the archipelagic model is more suitable for the Tethys, especially the eastern Tethys. This paper demonstrates the eastern Tethys archipelagic system in terms of the subdivision, characteristics and evolutionary history of the Qinling-Qilian-Kunlun, South China and Xizang (Tibet)-Yunnan Regions of the eastern Eurasian Tethys.     

库车坳陷东部断裂特征与构造演化

山前逆冲褶皱带的几何学和运动学研究属于构造地质学前沿课题,也是全球山前盆地油气勘探开发所关注的问题.综合二维地震剖面、钻测井数据、地质填图资料,建立了库车坳陷东部两类断层几何学和运动学模型,绘制了吐孜洛克断层和东秋里塔格断层断距分布图以及东秋里塔格背斜位移缩短量分布图.研究资料表明库车坳陷东部发育两种类型断层,古近纪发育高角度逆冲断层,造成山前基底抬升,白垩系-古近系被剥蚀;上新世发育低角度逆冲断层,引发库车坳陷中生界-新生界变形,形成盆地腹部隐伏的叠瓦状逆冲构造.      

Eastern Ancient Terrane of the North China Craton

Based on the spatial distribution of ancient rocks and zircons, three ancient terranes older than ca. 2.6 Ga have recently been identified in the North China Craton, namely the Eastern, Southern, and Central Ancient Terranes. The Eastern Ancient Terrane is the best studied and understood of the three ancient terranes. It has a long geological history back to ca. 3.8 Ga ago and includes the areas of Anshan-Benxi, eastern Hebei, eastern Shandong and western Shandong. In Anshan-Benxi, several different types of 3.8 Ga rocks were discovered together with 3.1-3.7 Ga rocks, whereas 2.9-3.0 Ga K-rich granites and 2.5 Ga syenogranite occur on larger scales. In eastern Hebei, 3.0-3.4 Ga rocks and older detrital and xenocrystic zircons were identified. In eastern Shandong, there are a large volumes of 2.7 Ga and 2.9 Ga rocks. In western Shandong, early Neoarchean(2.6-2.7 Ga) intrusive and supracrustal rocks are widely distributed. Whole-rock Nd and zircon Hf isotope data suggest that both mantle additions and crustal recycling played important roles within the Eastern Ancient Terrane during almost every tectono-magmatic event. Most BIFs in the North China Craton are late Neoarchean in age and are distributed on continental crust along the western margin of the Eastern Ancient Terrane, probably suggesting that a stable environment was one of the key factors for the formation of large-scale BIFs.     

Seismic Velocity Structure and Composition of the Continental Crust of Eastern China

On the basis of a one-by-one latitude-longitude grid three-dimensional seismic velocity model, the crustal P-wave velocity structure in eastern China (105-125°E and 18-41°N) is obtained, and a set of geotherms for each grid is established for P-T correction on P-wave velocities. The average depths of sub-crustal layers and their average P-wave velocities of 18 tectonic units in eastern China are exhibited. Our result presents a 32-34 km thick crust beneath eastern China, which is thinner than previous studies, with an average velocity of 6.54 km/s, corresponding to a 5 kg/m3 variation in crustal mean density. The thicker upper but thinner middle and lower crust results in a lower average seismic velocity of eastern China. An intermediate crustal composition with a SiO2 content of 59.7 wt% has been estimated. However, there exists a significant lateral variation in the crustal structures among the tectonic units of eastern China. The structure and composition features of some regions in eastern China in     

Vertical Diastrophic Movement of the Continental Blocks in Eastern China

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东喜马拉雅构造结东、西边界断裂对比及其构造演化过程

为了查明东喜马拉雅构造结东、西边界断裂的关系,及其印度与欧亚板块碰撞以来东喜马拉雅构造结的构造演化过程.在综合野外填图、构造观察、代表性岩石的锆石LA-ICP-MS U-Pb测年分析及前人研究的基础上,对东构造结两条边界断裂的几何学、运动学特征进行对比,讨论了两条断裂的多期次、多阶段的变形特征,还探讨了在东构造结地区自印度板块-欧亚板块碰撞以来的演化历史.结果显示,东构造结两条边界断裂几何学和运动学非常相似,构造变形具有明显的同时代、同期次特点,共同经历从碰撞、持续俯冲-折返、直到后期垮塌-隆升等一系列重要的地质事件.      

冀东下营坊金矿成矿年代学研究

冀东下营坊金矿地处华北地台北缘燕山造山带东段,是该区一个重要的岩浆期后热液型金矿。该金矿产于大铜山杂岩体及外接触带中,有三种矿化类型,即斑岩型、角砾岩型、矽卡岩型,构成了典型的斑岩型金矿成矿系统。为精确厘定下营坊金矿的成矿年代,更好的理解该矿与区内其他金矿的关系,本文采用锆石U-Pb和辉钼矿Re-Os同位素定年,获得赋矿斑岩(花岗斑岩)的结晶年龄为163.32±0.90Ma,切穿矿体的煌斑岩脉结晶年龄为159.0±1.5Ma,由此限定成矿年龄可能在163.32Ma~159.0Ma之间;而由辉钼矿获得的Re-Os同位素模式年龄为164.2±2.3Ma。在误差范围内,Re-Os同位素模式年龄与U-Pb同位素年龄是一致的,表明下营坊金矿成矿年龄为164.2±2.3Ma,属于中侏罗世岩浆热液事件。结合前人研究结果,认为下营坊金矿以及冀东中侏罗世金矿的成岩成矿构造背景与区内该时期的岩浆事件一样,可能受古太平洋板块俯冲的影响而处于挤压的构造环境。     

Thermal History since the Paleozoic in the Eastern Qaidam Basin,Northwest China

The Qaidam Basin is the one of the three major petroliferous basins in northeastern Tibetan Plateau, which has experienced multiphase superimposition and transformation. The study of thermal history not only plays an important role on revealing the tectonic origin of the Qaidam Basin and the forming mechanism and uplift history of the Tibetan Plateau,but also can provide scientific evidence for the assessment of oil and gas resources. This work used balanced cross-section technique and apatite fission track ages with modeling of fission track length distribution to infer that the eastern Qaidam Basin has experienced significant tectonic movement in the Early Jurassic movement(～200 Ma), which caused the carboniferous uplift and denudation, the geological movement in the Late Cretaceous, characterized by early stretching and late northeast-southwest extrusion; the Himalayan movement in multi-stage development in eastern Qaidam Basin, which can be divided into the early Himalayan movement(41.1–33.6 Ma) and the late Himalayan movement(9.6–7.1 Ma, 2.9–1.8 Ma), and large-scale orogeny caused pre-existing faults reactivated in late Himalayan movement. On the basis of burial history reconstruction, the thermal history of eastern Qaidam Basin was restored. The result shows that the thermal history in eastern Qaidam Basin shows slow cooling characteristics; the paleo-geothermal gradient of eastern Qaidam Basin was 38–41.5℃/km, with an average value of 39.0℃/km in the Late Paleozoic, 29–35.2℃/km, with an average value of 33.0℃/km in the Early Paleogene; the geothermal gradient of the Qaidam Basin increased in the Late Paleogene, which was similar to the present geothermal gradient in the Late Neogene. The characteristics of the tectono-thermal evolution since Paleozoic in the eastern Qaidam Basin are mainly controlled by magmatic thermal events in the study area.     

喜马拉雅造山带东、西构造结的地质特征与对比

喜马拉雅造山带的东、西两端分别有一个构造急剧转向的地区——构造结, 这里是探讨喜马拉雅造山带构造演化的重要场所.区域地质调查资料对比显示这2个构造结有: (1)相似的地貌景观; (2)相似的地质特征和演化历史, 即都缺失喜马拉雅沉积岩(寒武纪—第三纪); (3)结晶岩系中都有高压变质岩, 且在10 Ma以来均发生过深熔与混合岩化作用; (4)25 Ma以来, 特别是10 Ma以来两地都经历了快速剥露和隆升作用; (5)印度板块-欧亚板块的碰撞时间接近, 分别为75 Ma和65 Ma, 均早于喜马拉雅造山带的其他地区.这些相似性表明: 伸展拆离和以河流作用为主的地表过程是喜马拉雅造山带的东、西构造结快速剥露的主导因素; 因强烈剥露减压所致的地壳部分熔融作用形成的岩浆向地表减压处的流动在构造结的演化过程中起着重要作用.      

青藏东缘新生代高钾岩浆活动的热年代学制约

热年代学研究表明 ,青藏东缘存在两期新生代高钾岩浆活动 ,其活动时限分别为 40～ 2 8Ma和 16～ 0Ma。两期高钾岩石在地质背景、岩石类型和地球化学特征上明显不同 ,表明早期高钾岩石是在转换压缩过程中产生的 ,起源于富集地幔的部分熔融 ,而晚期高钾岩石则与东亚和青藏地区构造伸展有关 ,起源于新近交代富集的亏损地幔。     

Trace Elements in Coals of Eastern Donbas

Peculiarities of trace element (TE) distribution in coals of the eastern Donets Basin (Donbas) are discussed. The correlation of TE distribution with specific features of the geological setting of the region can testify to the hydrothermal introduction of trace elements or their redistribution in fluid-active zones. The geochemical regionalization of eastern Donbas is based on TE distribution. Strontium–gold–base metal, tungsten, and selenium geochemical belts and a rare metal geochemical block are outlined.     

中国东部新生代沉积盆地演化

新生代, 中国东部大陆边缘系统总体受到来自印度、澳大利亚、菲律宾和太平洋板块向欧亚板块下部俯冲碰撞的作用, 在大陆边缘形成一系列边缘海盆地和断陷-坳陷盆地, 主要发育松辽、渤海湾、江汉、苏北、东海、珠江口和北部湾等盆地.基于中国东部沉积盆地的中生代构造背景分析和新生代盆地的分布特征, 对其中的7个主要沉积盆地进行了详细的沉积序列和构造演化分析.通过周缘板块和郯庐断裂的构造演化、火山活动、低温热年代学、气候演变等对比分析, 中国东部沉积盆地的演化可划分为3个阶段: 古新世-始新世、渐新世-早中新世和晚中新世-第四纪.      

Karst Hazard Assessment of Eastern Saudi Arabia

Karst phenomena exist in areas in the eastern part of Saudi Arabia, forming solution features such as sinkholes, collapsed dolines and solution caverns, as a result of the chemical leaching of the carbonate and evaporite formations by percolating water. The instability of these karst phenomena could produce land subsidence problems. This paper reviews the geology of documented karstic rock units in Saudi Arabia and proposes a simple engineering classification of the solution features characteristic of limestone. Two case histories in the Dhahran area, eastern Saudi Arabia, will be used as examples for the application of a modified engineering classification.     

邢台市东部平原地热开发远景初探

在简述邢台市东部平原地质构造、地层、地热地质模型、地质变异常区分布特征基础上,对邢台市东部平原地热开发远景进行了分析探讨,并提出了在邢台市东部平原进行地热资源开发的合理化建议。指出地热异常区内的远景开发区应优先开发;准地热异常区的地热资源开发应引起足够重视;在不具备完整地热地质模型的地热异常区内也有地热资源存在的可能。     

太平洋板块俯冲与中国东部中生代地质事件

中国东部至少自侏罗纪开始就一直处于俯冲大洋板块之上,但是有关俯冲板块对其影响程度一直有不同的认识。最近的研究表明,太平洋海山岛链的时空分布显示太平洋板块的漂移方向曾发生多次转折,这些转折与白垩纪中国东部的构造演化和岩浆事件有着密切的时空耦合关系。从时代和力学性质上看,太平洋板块俯冲方向的改变在很大程度上控制着中国东部中生代的盆地演化和郯庐断裂活动等重要地质事件。这些认识为理解中国东部构造演化提供了新的视角,包括岩石圈减薄的机制、郯庐断裂的演化,以及燕山期大规模岩浆活动等。本文重点分析了太平洋板块俯冲与中国东部中生代岩浆活动的对应关系。在125～140Ma太平洋板块向南西方向俯冲,造成中国东部岩石圈减薄,软流圈卸载上涌,发生减压部分熔融;约125Ma,太平洋板块漂移方向发生了大幅度转折,形成安第斯式的俯冲挤压,岩石圈停止减薄和减压部分熔融,出现岩浆宁静期。随着俯冲的深入,到110Ma前后俯冲板块后撤,形成弧后拉张,岩浆活动又重新开始。     

Structure and Evolution of the Eastern Part of the Southwest Indian Ridge

Geotectonics - The structure and evolution of the eastern part of the Southwest Indian Ridge are discussed. Based on geological-geophysical data and cartographic materials, analysis of spatial and...     

珠江口盆地阳江凹陷东部地区断控成藏条件

阳江凹陷东部地区是近年来珠江口盆地(东部)的热点探区,过去四十余年受限于钻井数量、地震资料品质和覆盖范围,缺少对断裂特征及控藏作用的系统解剖.本文在覆盖全区的高品质三维地震资料基础上,对阳江凹陷东部的断裂系统进行解剖,并探讨断裂对沉积充填、烃源展布、圈闭发育、油气运聚与保存的控制作用.研究表明,阳江凹陷东部的断陷格局具...     

Upper mantle heterogeneities beneath Eastern Europe

P-wave travel-time residuals for seismograph stations in eastern Europe as reported by ISC for the years 1964–1977 were used for constructing a seismic image of upper mantle heterogeneities in the network region. For the depth range 0–100 km, dominant tectonic features like the Pannonian Basin and the Aegean Sea and western Turkey correlate well with pronounced velocity lows which a ppear to extenddown to a 300 km depth. The velocity anomaly patterns in the depth intervals 300–500 km and 500–600 km are broadly similar but quite different from those of shallower depths. The observed seismic heterogeneities are briefly discussed in terms of large-scale tectonic and geophysical (heat-flow) characteristics of eastern Europe.     

四川盆地东部黄龙组碳酸盐岩储层沉积-成岩系统

四川盆地东部上石炭统黄龙组是天然气藏的主力产层.在岩心观察、野外剖面实测和室内薄片鉴定分析的基础上, 结合钻井、测井、物性分析和X-衍射分析资料, 对川东黄龙组碳酸盐岩储层沉积-成岩系统进行了深入研究.认为川东黄龙组主要发育萨勃哈、有障壁海岸和陆棚3个相带以及特殊的古喀斯特相, 储集岩类型以白云质岩溶角砾岩及颗粒白云岩为主, 有效的储集空间类型主要为晶间孔、晶间溶孔, 最重要的储层类型为孔洞缝型, 最有利储层发育部位为岩溶上斜坡中的坡地和残丘微地貌单元.综合分析认为, 沉积-成岩系统与储层在时空上具有良好的耦合关系, 粒屑滩沉积微相控制了黄龙组储层的区域分布, 早-中成岩阶段压实卤水成岩系统、古表生期大气水成岩系统以及埋藏成岩阶段的温压水成岩系统对优质储层发育贡献最大.      

大别山北淮阳带东段石榴斜长角闪岩石炭纪变质作用的测定

北淮阳带位于大别碰撞造山带北部,相对于南部三叠纪超高压变质带来说,通常被认为是一个相对低级变质的构造岩石单位.以商(城)-麻(城)为界,分为西段和东段.其中,东段未发现与西段相对应的古生代大洋俯冲记录,也缺乏相关的古生代岩浆作用和变质作用方面报道.因而严重地阻碍了对大别造山带形成和演化的深刻理解和准确认识.北淮阳带东段岩石类型丰富,主要包括3类(套)岩石:(1)变质岩,如变质花岗岩(花岗片麻岩)、(石榴)斜长角闪岩、大理岩、云母石英片岩和变质复理石等;(2)岩浆岩,主要为中生代花岗岩、正长岩和火山岩等;(3)盆地沉积岩,主要为中新生代沉积及少量石炭纪沉积.然而,该区一直未发现古生代变质作用的岩石学记录.为此,对北淮阳带东段金寨县铁冲一带与大理岩相共生的石榴斜长角闪岩开展了锆石SHRIMP U-Pb定年和初步的岩石学研究.结果表明,该区石榴斜长角闪岩经历了355±5 Ma变质作用,因而首次发现研究区经历了石炭纪变质作用,为秦岭-桐柏造山带的东延以及大别山碰撞造山带的古生代构造演化过程提供了新的制约.