华南岩石圈三维结构   总被引：7，自引：1，他引：6       下载免费PDF全文

袁学诚  华九如 《中国地质》2011,38(1):1-19

从穿过华南陆块的6条P波地震层析剖面出发,综合引用海量出版物中部分成果,对华南岩石圈三维结构作了初步探讨。以川湘黔裂陷槽和钦杭断裂为界,可以将华南岩石圈分成三大部分。在钦杭断裂东南为华夏岩石圈。它是东南亚西太平洋低速带的一部分,它与东南亚西太平洋低速带的其他地区的共同特点是它们的岩石圈地幔都受到软流圈物质上升而被改造。部分地区幔源物质侵入地壳,形成丰富的矿藏。川湘黔裂陷槽以西的地区为上扬子岩石圈。它在地表是一个热块体,但在深部有延伸超过200 km的高速基底。上扬子岩石圈受到其西攀西地幔柱的改造,在壳幔过渡带产生峨眉山岩浆房,在古生代末曾引发玄武岩的大面积喷发,至今仍在滇西留有岩浆房,并产生丰富的热泉。在川湘黔裂陷槽与钦杭断裂之间的是中扬子岩石圈。中扬子在地表是一个冷块体,在湘中实测热流值低到小于20 mW m-2,根据热流值计算得到的岩石圈厚度达到300 km。具有低速、低电阻率特征。根据大地电磁测深得到的结果也与地热流计算得到的相似。  相似文献   

扬子地块北缘晚古生代-早中生代裂谷系统的分布及成因分析   总被引：5，自引：4，他引：1  

毛黎光  肖安成  魏国齐  沈中延  王亮  张林  钱俊锋 《岩石学报》2011,27(3):721-731

晚二叠世长兴期-早三叠世印度期,在扬子地块的西北缘发育了一系列北西向展布的深水盆地区。根据成因分析证实,它们为伸展背景下形成的裂谷系统或者裂谷盆地群。平面上各裂谷盆地彼此近于平行,与北侧的南秦岭造山带在走向上呈正交和大角度斜交的排列,自西向东依次为开江-梁平裂谷、城口-鄂西裂谷和荆门-当阳裂谷。其中的开江-梁平裂谷东西两侧发现了巨大的天然气田而引起石油勘探家和地质学家的关注。本文对于这些控制油气资源储备的裂谷体系的分布和形成机制进行研究后,认为它们形成于南秦岭洋闭合时的碰撞作用,是南秦岭造山带和扬子地块拼合时同生的巨型"碰撞裂谷系统"。  相似文献   

新疆坡十铜镍硫化物含矿岩体岩浆源区特征及构造背景探讨   总被引：7，自引：1，他引：6       下载免费PDF全文

颉炜  宋谢炎  聂晓勇  程松林 《地学前缘》2011,18(3):189-200

新疆坡北辉长岩体位于塔里木古陆东北缘的北山裂谷带中,坡一和坡十铜镍硫化物含矿超镁铁岩体位于坡北岩体内.尽管坡十超镁铁岩体与坡北辉长岩呈侵入接触,但两者的微量元素和同位素组成显示良好 的一致性,表明两岩相虽然分不同阶段侵入就位,但仍为同源岩浆的产物.MnO-TiO2-R2O5及Th-Hf-Ta判别图解显示坡北及坡十岩体的...  相似文献   

五台山地区古元古界滹沱群沉积环境:前陆盆地还是陆内裂谷盆地?   总被引：1，自引：0，他引：1       下载免费PDF全文

郭进京  任留东  白瑾 《地学前缘》2011,18(3):211-220

分布于五台山地区的古元古界滹沱群形成的大地构造环境和地质演化过程,对华北克拉通东、西部陆块之间的华北中部碰撞造山带的形成时代和演化具有关键性的地质约束.通过对滹沱群与下伏地质体之间的接触关系、滹沱群沉积岩石序列组合特征、构造变形样式和已有同位素年代学资料的综合分析,认为(1)滹沱群呈区域性角度不整合覆盖于新太古代五台群...  相似文献   

内蒙古西部额济纳旗及邻区上石炭统—下二叠统阿木山组火山岩的地球化学特征   总被引：2，自引：1，他引：1  

姜亭  李玉宏  陈高潮  魏建设  李金超 《地质通报》2011,30(6):932-942

分析了上石炭统小独山阶—下二叠统紫松阶阿木山组玄武岩地球化学特征,对玄武岩类型、岩石特征、构造环境等进行了探讨,结合前人的研究成果,阐述了石炭纪—二叠纪盆地的基本性质。Zr/TiO2-Nb/Y、SiO2-TFeO/MgO和Zr-Y-Nb图解显示,玄武岩类型主要为亚碱性的拉斑玄武岩;稀土元素球粒陨石配分模式为右倾曲线,(La/Yb）N值较高,轻重稀土元素分馏较强,(Gd/Lu）N值相对较低,重稀土元素分馏较弱,δEu在0.87~1.11之间,无明显Eu异常;N-MORB标准化的微量元素蛛网图显示,K2O、Rb、Ba、Th等不相容元素富集,Hf、Nb、Y等亏损。Zr-Zr/Y和Ta/Hf-Th/Hf构造环境图解表明,该玄武岩产于陆内裂谷,指示晚石炭世—早二叠世额济纳旗及其邻区已进入了陆内演化阶段,为拉张作用下的陆内裂谷（裂陷）盆地。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987111000594     

Victor D. Mats  Tatiana I. Perepelova 《地学前缘(英文版)》2011,2(3):349-365

A new model is suggested for the history of the Baikal Rift,in deviation from the classic two-stage evolution scenario,based on a synthesis of the available data from the Baikal Basin and revised correlation between tectonic-lithological-stratigraphic complexes(TLSC) in sedimentary sections around Lake Baikal and seismic stratigraphic sequences(SSS) in the lake sediments.Unlike the previous models,the revised model places the onset of rifting during Late Cretaceous and comprises three major stages which are subdivided into several substages.The stages and the substages are separated by events of tectonic activity and stress reversal when additional compression produced folds and shear structures.The events that mark the stage boundaries show up as gaps,unconformities,and deformation features in the deposition patterns. The earliest Late Cretaceous-Oligocene stage began long before the India-Eurasia collision in a setting of diffuse extension that acted over a large territory of Asia.The NW-SE far-field pure extension produced an NE-striking half-graben oriented along an old zone of weakness at the edge of the Siberian craton.That was already the onset of rift evolution recorded in weathered lacustrine deposits on the Baikal shore and in a wedge-shaped acoustically transparent seismic unit in the lake sediments.The second stage spanning Late Oligocene-Early Pliocene time began with a stress change when the effect from the Eocene India-Eurasia collision had reached the region and became a major control of its geodynamics.The EW and NE transpression and shear from the collisional front transformed the Late Cretaceous half-graben into a U-shaped one which accumulated a deformed layered sequence of sediments.Rifting at the latest stage was driven by extension from a local source associated with hot mantle material rising to the base of the rifted crust.The asthenospheric upwarp first induced the growth of the Baikal dome and the related change from finer to coarser molasse deposition.With time,the upwarp became a more powerful stress source than the collision,and the stress vector returned to the previous NW-SE extension that changed the rift geometry back to a half-graben. The layered Late Pliocene-Quaternary subaerial tectonic-lithological-stratigraphic and the Quaternary submarine seismic stratigraphic units filling the latest half-graben remained almost undeformed.The rifting mechanisms were thus passive during two earlier stages and active during the third stage. The three-stage model of the rift history does not rule out the previous division into two major stages but rather extends its limits back into time as far as the Maastrichtian.Our model is consistent with geological, stratigraphic,structural,and geophysical data and provides further insights into the understanding of rifting in the Baikal region in particular and continental rifting in general.  相似文献   

3D seismic analysis of the structure and evolution of a salt-influenced normal fault zone: A test of competing fault growth models     

《Journal of Structural Geology》2013

In this paper we determine the structure and evolution of a normal fault system by applying qualitative and quantitative fault analysis techniques to a 3D seismic reflection dataset from the Suez Rift, Egypt. Our analysis indicates that the October Fault Zone is composed of two fault systems that are locally decoupled across a salt-bearing interval of Late Miocene (Messinian) age. The sub-salt system offsets pre-rift crystalline basement, and was active during the Late Oligocene-early Middle Miocene. It is composed of four, planar, NW–SE-striking segments that are hard- linked by N–S-striking segments, and up to 2 km of displacement occurs at top basement, suggesting that this fault system nucleated at or, more likely, below this structural level. The supra-salt system was active during the Pliocene-Holocene, and is composed of four, NW–SE-striking, listric fault segments, which are soft-linked by unbreached relay zones. Segments in the supra-salt fault system nucleated within Pliocene strata and have maximum throws of up to 482 m. Locally, the segments of the supra-salt fault system breach the Messinian salt to hard-link downwards with the underlying, sub-salt fault system, thus forming the upper part of a fault zone composed of: (i) a single, amalgamated fault system below the salt and (ii) a fault system composed of multiple soft-linked segments above the salt. Analysis of throw-distance (T-x) and throw-depth (T-z) plots for the supra-salt fault system, isopach maps of the associated growth strata and backstripping of intervening relay zones indicates that these faults rapidly established their lengths during the early stages of their slip history. The fault tips were then effectively ‘pinned’ and the faults accumulated displacement via predominantly downward propagation. We interpret that the October Fault Zone had the following evolutionary trend; (i) growth of the sub-salt fault system during the Oligocene-to-early Middle Miocene; (ii) cessation of activity on the sub-salt fault system during the Middle Miocene-to-?Early Pliocene; (iii) stretching of the sub- and supra-salt intervals during Pliocene regional extension, which resulted in mild reactivation of the sub-salt fault system and nucleation of the segmented supra-salt fault system, which at this time was geometrically decoupled from the sub-salt fault system; and (iv) Pliocene-to-Holocene growth of the supra-salt fault system by downwards vertical tip line propagation, which resulted in downward breaching of the salt and dip-linkage with the sub-salt fault system. The structure of the October Fault Zone and the rapid establishment of supra-salt fault lengths are compatible with the predictions of the coherent fault model, although we note that individual segments in the supra-salt array grew in accordance with the isolated fault model. Our study thereby indicates that both coherent and isolated fault models may be applicable to the growth of kilometre-scale, basin-bounding faults. Furthermore, we highlight the role that fault reactivation and dip-linkage in mechanically layered sequences can play in controlling the three-dimensional geometry of normal faults.  相似文献   

会理菜子园镍矿床方辉橄榄岩铂族元素、Re-Os同位素及其地质意义     

王生伟  孙晓明  廖震文  屈文俊  杨波  蒋小芳  李超  李永灿 《矿床地质》2013,32(3):515-532

四川省会理菜子园红土型镍矿床中出露较多的基性-超基性岩体,文章系统报道了其中3个橄榄岩体的岩石化学、铂族元素及Re-Os同位素地球化学特征.岩石化学均显示为高MgO及高Mg#值,低SiO2、Al2O3、Na2O、K2O特征,计算显示出主要的标准矿物为橄榄石和紫苏辉石(体积百分数＞90％),表明菜子园属镁质方辉橄榄岩.铂族元素总量比世界上大多数地幔橄榄岩低,且Cu/Pd比值大于原始地幔,可能是早期地幔较高部分熔融出的基性岩浆中硫化物的萃取、抽提作用所致.PPGE相对IPGE强烈亏损,与正常蛇绿岩底部的地幔橄榄岩特征类似,向右倾斜的原始地幔标准化配分模式表明菜子园铂族元素体系主要受地幔部分熔融的控制.PPGE中,Pt相对于Pd富集,可能与后期强烈蚀变有关,此外还可能反映了少量Pt以合金形式残留于方辉橄榄岩中,Pd以不相容元素的形式更多被熔体带走.菜子园方辉橄榄岩的Re-Os同位素体系封闭性相对好,γ(Os)值较小.岩石化学、铂族元素及Re-Os同位素地球化学显示,菜子园橄榄岩直接来自地幔,属正常蛇绿岩套底部的方辉橄榄岩,为古小洋盆洋壳的残片.菜子园蛇绿岩反映了中元古代晚期昆阳裂谷在菜子园-踩马水-麻塘断裂带以北演化成小洋盆,于其中沉积会理群,并在中元古代末期与南侧的东川群、汤丹群碰撞、拼贴.菜子园橄榄岩的蛇绿岩属性进一步证明,扬子地台西南缘的基底由不同时代的小陆块碰撞、拼贴导致基底陆壳增生.  相似文献   

内蒙古银额盆地额济纳旗赛汉陶来地区石炭系 —二叠系煤层的发现及其意义     

卢进才  魏仙样  魏建设  姜亭  牛亚卓  陶继雄  徐永 《地质通报》2013,32(10):1653-1664

在对赛汉陶来地区19口石油及煤田钻井地层岩性组合特征分析的基础上,总结了中生代不同构造单元的地层分布特征、含煤层段岩性特征及煤岩物理化学特征。含煤层段岩性组合为沉火山碎屑岩或再搬运的沉火山岩、泥岩夹煤层,具有典型裂谷盆地沉积特征。该套地层横向分布稳定,不同构造单元之间可进行对比,单井平均可采煤层的厚度为4.77m。煤岩演化程度较低,为不粘煤。含煤层段沉火山角砾岩获得的锆石年龄为295.0Ma±1.3Ma~303.4Ma±2.8Ma,对应地层为上石炭统—下二叠统干泉组。银额盆地赛汉陶来地区石炭系—二叠系含煤地层的发现不仅指示了良好的煤炭资源前景,并且对石炭纪—二叠纪盆地构造演化、沉积体系,以及石炭系—二叠系沉积埋藏史等基础地质问题的研究具有重要意义。  相似文献   

渤海湾盆地东营凹陷碎屑流主控型深水体系沉积过程及模式          下载免费PDF全文

刘建平  鲜本忠  张莉  苏明  李宇志  闫海清  王震  陈鹏  吴千然  李晋  田荣恒  杨鑫  周欢焕  罗勋  陈龙 《中国地质》2022,49(6):1951-1969

【研究目的】碎屑流是深水环境沉积物搬运和分散的重要机制,其相关的砂岩储层是含油气盆地重要的勘探目标,然而,与经典浊流及浊积系统相比,对碎屑流主控型深水体系的发育规律目前仍知之甚少。【研究方法】本文基于岩心、测井及全三维地震资料,通过系统的岩心观察描述、测井及地震资料解释,对渤海湾盆地东营凹陷始新统沙三中亚段深水体系沉积过程及模式开展研究。【研究结果】结果表明,沙三中深水体系发育九种异地搬运岩相,可概括为四大成因类型,反映了块体及流体两种搬运过程。岩相定量统计表明,该深水体系主要由碎屑流沉积构成,浊流沉积很少,碎屑流中又以砂质碎屑流为主。重力流在搬运过程中经历了滑动、滑塌、砂质碎屑流、泥质碎屑流及浊流等5个阶段演变,发育5类主要的深水沉积单元,包括滑动体、滑塌体、碎屑流水道、碎屑流朵体及浊积薄层砂。从发育规模及储层物性上,砂质碎屑流水道、朵体及砂质滑动体构成了本区最重要的深水储层类型。【结论】认为沙三中时期充足的物源供给、三角洲前缘高沉积速率、断陷期频繁的断层活动以及较短的搬运距离是碎屑流主控型深水体系形成及演化的主控因素,最终基于沉积过程、沉积样式及盆地地貌特征综合建立了碎屑流主控型深水体系沉积模式。本研究将进一步丰富深水沉积理论,为陆相深水储层预测提供借鉴。  相似文献