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内蒙古西乌旗南部石炭纪石英闪长岩地球化学特征及其构造意义 总被引：40，自引：1，他引：39
内蒙古西乌旗地区位于贺根山蛇缘岩带和西拉木伦缝合带之间,区内岩浆岩分布广泛。本文对达其浑迪和金星石英闪长岩进行了锆石LAICPMS UPb定年,结果表明两个岩体分别形成于325±3Ma和322±3Ma。岩石学和地球化学分析结果显示岩石属于低钾拉斑系列和钙碱性系列,相对富集Rb、Ba、K等大离子亲石元素（LILE）,亏损Nb、Ta、Ti、P等高场强元素化学。地球化学成分表明岩体具有俯冲带成因的特征。通过区域对比分析,苏左旗和西乌旗地区均发育一套角闪闪长岩、石英闪长岩、英云闪长岩及花岗闪长岩组合,与岛弧和活动大陆边缘岩浆岩组合相似,共同构成早石炭世晚期到晚石炭世的岩浆弧,该岩浆弧的出现与古亚洲洋板片向北俯冲有关。 相似文献
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龙新岩体和夏郢岩体位于扬子地块与华夏地块拼合带的西南端,岩体中的Ⅰ型花岗岩成因研究对揭示桂东南地区早古生代的地球动力学背景及其构造演化具有重要的地质意义.对龙新岩体的寄主岩和其暗色微粒包体,以及夏郢岩体岩石进行了LA-ICP-MS锆石U-Pb定年、Lu-Hf同位素和全岩地球化学研究.锆石U-Pb定年结果显示,龙新岩体的寄主岩（花岗闪长岩）的年龄为440±2 Ma;龙新岩体的暗色包体（闪长岩）的年龄为441±1 Ma,寄主岩与暗色包体为同期岩浆作用的产物.夏郢岩体花岗闪长岩和二长花岗岩年龄分别为447±3 Ma和436±3 Ma,说明夏郢岩体至少发生了2期岩浆侵入事件.Hf同位素研究表明,龙新岩体寄主岩和暗色微粒包体的锆石εHf（t）值分别为-3.32~-5.83和-17.89~-1.82,二阶段模式年龄（TDM2）分别为1.62~1.76 Ga和1.57~2.54 Ga;夏郢岩体早期花岗岩闪长岩和晚期二长花岗岩的锆石εHf（t）值分别为-15.43~3.03和-4.79~6.82,TDM2分别为1.59~1.99 Ga和0.97~1.70 Ga,指示物源主要来自古-中元古代的地壳物质.地球化学特征表明龙新岩体寄主岩为准铝质高钾钙碱性Ⅰ型花岗岩,寄主岩和暗色微粒包体均富集轻稀土元素和大离子亲石元素,亏损重稀土元素及高场强元素;夏郢岩体早期的花岗闪长岩为弱过铝质高钾钙碱性Ⅰ型花岗岩,晚期的二长花岗岩则为强过铝质高钾钙碱性Ⅰ型花岗岩,主微量元素特征均与龙新岩体寄主岩相似.根据研究区花岗岩和镁铁质包体的岩相学、年代学、地球化学及Hf同位素组成特征,表明龙新岩体的暗色包体（闪长岩）为岩浆混合成因,而龙新岩体寄主岩（花岗闪长岩）和夏郢岩体（早期花岗岩闪长岩和晚期二长花岗岩）具有一致的岩石源区和岩石成因,但在后期的成岩过程中存在岩浆混合和结晶分异程度的差异.综合以往对华南地区构造背景的研究,认为龙新和夏郢岩体是在扬子地块和华夏地块陆内造山期后,岩石圈伸展减薄,热的幔源岩浆上涌底侵,中-下地壳受到地幔热影响发生部分熔融,形成的酸性岩浆在源区和基性岩浆经历了不均一且不强烈的壳-幔混合作用形成的. 相似文献
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《地质通报》2019,(Z1)
内蒙古乌拉特中旗中蒙边境地区的扎嘎乌苏岩体主要由闪长岩、石英闪长岩、花岗闪长岩和黑云母二长花岗岩组成,岩体及围岩普遍发育面理南倾的糜棱岩带。通过LA-ICP-MS锆石U-Pb测年,获得扎嘎乌苏岩体中黑云母二长花岗岩的结晶年龄为450.3±3.7Ma(MSWD=2.8),表明扎嘎乌苏岩体的形成时代为晚奥陶世。扎嘎乌苏岩体中不同类型岩石全岩微量和稀土元素组成总体相似,均呈现轻稀土元素相对于重稀土元素强烈富集,大离子亲石元素Ba、Sr等富集,高场强元素Nb、Ta、Ti相对亏损,高Sr,低Y、Yb,高Sr/Y、La/Yb值等特征,具有埃达克岩和岛弧岩浆岩的地球化学特征。这些新的年代学和岩石地球化学数据,为索伦山地区晚奥陶世古亚洲洋俯冲消减提供了可靠的证据。 相似文献
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北京大庄科花岗杂岩普遍含有微粒—细粒暗色包体,其中石英闪长岩和石英二长岩含包体较多,二长花岗岩含少量包体,淡色花岗岩和闪长岩含包体甚少。在含包体较多的岩体内,包体在岩体中部的分布量较多。计算结果表明,包体越小沉浮半径愈大、参数F值愈小的岩体,含包体愈多;岩体内岩浆上升速度大、包体下沉速度小以及F值小的部位,包体滞留量大。各岩体包体分布的多少,是由包体在寄主岩浆内的扩散系数、混合程度、岩浆携带力和基性岩浆混入量等因素综合决定的。 相似文献
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青藏高原大同西侧石英二长岩体地球化学及岩石系列 总被引：6，自引：1，他引：5
大同西侧石英二长岩体位于青藏高原西北缘、西昆仑山主峰地带,形成于早古生代。其地质、地球化学研究表明,岩体岩石组合类型为（石英）二长闪长岩－（石英）二长岩－石英正长岩。岩石主要由斜长石、微斜长石、石英、角闪石、辉少量黑云母组成。岩石化学成分富碱、富钾、Ｋ２Ｏ／ＮａＯ比值大而贫铁,微量元素富集Ｒｂ、Ｓｒ、Ｂａ特闫离子亲石元素和轻稀土元素,属于钾玄岩系列。 相似文献
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鄂城岩体位于鄂东南地区的最北部,是鄂东南地区的六大岩体之一.在该岩体的南缘接触带上产出了长江中下游地区最大的矽卡岩型铁矿床——程潮铁矿床.众多研究表明,程潮铁矿化与鄂城杂岩体的岩浆演化密切相关,然而目前对于成矿作用究竟是与花岗质岩还是闪长质岩有关仍存在争议.通过对鄂城杂岩体开展系统的锆石U-Pb年代学、元素地球化学和Sr-Nd-Hf同位素研究,结果表明该岩体主要由花岗岩、石英二长岩、花岗斑岩以及小面积的闪长岩组成,最早侵位于140±1 Ma（中粒闪长岩）,之后依次侵位形成了细粒闪长岩（132±2 Ma）、花岗斑岩（130±2 Ma）、花岗岩（中细粒花岗岩129±2 Ma,中粒花岗岩129±1 Ma）和石英二长岩（129±1 Ma）.根据全岩地球化学特征,鄂城杂岩体的岩石组成大致可以分为两组:（1）花岗岩类,包括花岗岩、花岗斑岩和角闪石英二长岩,钾质,具有高SiO2,低TiO2、FeOt、MnO、MgO含量等特征;（2）闪长岩类,包括中、细粒闪长岩,钠质,具有低SiO2,高TiO2、FeOt、MnO、MgO含量等特征.这些岩石均富集轻稀土元素（LREE）和大离子亲石元素（LILE,如Rb、Th等）,亏损高场强元素（HFSE,如Nb、P、Ti）等,且花岗岩类具明显的负Eu异常,而闪长岩类则无此特征.在同位素组成方面,鄂城花岗岩类具有较负的全岩εNd（t）值（-11.7~-10.1）和锆石εHf（t）值（-22.91~-9.83）,闪长岩类则具有稍高的全岩εNd（t）值（-7.6）和锆石εHf（t）值（-12.04~-4.69）.元素和同位素地球化学特征共同表明,鄂城花岗岩类属于高分异Ⅰ型花岗岩,且主要来源于古元古代基底物质的部分熔融作用,源区可能有少量幔源物质的加入;闪长岩类主要来源于富集岩石圈地幔,且经历了一定的分离结晶作用.年代学结果显示,鄂城花岗岩类和细粒闪长岩的侵位时间均与程潮铁矿床的主成矿期吻合.结合野外接触关系以及前人的研究,程潮铁矿化可能与上述两类岩石均密切相关.从整个鄂东南地区的成矿作用来看,随着岩浆源区壳源物质贡献的增大以及岩浆分异程度的增加,岩浆作用与铁矿化的关系也更加密切. 相似文献
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贵池铜山岩体岩石化学与地球化学特征 总被引：4，自引：0，他引：4
通过岩石化学、微量元素地球化学、稀土元素地球化学、铅同位素地球化学特征研究表明， 铜山石英闪长岩、花岗闪长岩、二长花岗岩是同一岩浆源同一时期（ 燕山早期） 三个侵入阶段的产物， 铜山岩体幔壳同熔型的复式岩体， 属太平洋钙碱性岩石系列。铜山铜矿床的形成与铜山复式岩体的岩浆充分演化分异有关。 相似文献
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大宁岩体是一个多期次侵入的复式岩体,主要由石英闪长岩、花岗闪长岩和二长花岗岩等花岗质岩石组成,其中富含镁铁质微粒包体（MME）,MME主要出露在花岗闪长岩中。花岗闪长岩中部和边部MME个数与单位测量面积的特征值（直径）之间均存在对数线性关系（p〉0．75）,表明MME一花岗质侵入岩体系为分形体。结合MME的形态、结构特征,认为大宁岩体中MME为岩浆混合成因。花岗闪长岩中部和边部MME的分维数分别是1．293和0．991,表明混合程度在空间上具有不均一性。MME长轴展布方向与寄主岩体的原生流动线理方向一致,暗示着在镁铁质岩浆注入之前,长英质岩浆已部分结晶。对流作用可能是MME分布、变形和岩浆混合程度差异的主要驱动力。 相似文献
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阿翁错- 盐湖复式岩体位于狮泉河- 纳木错蛇绿混杂岩带北缘，为狮泉河- 纳木错特提斯洋俯冲消减、碰撞造山过程中岩浆响应的重要组成部分，其研究对认识狮泉河- 纳木错特提斯洋盆的演化具有重要意义。本文以阿翁错- 盐湖复式岩体为研究对象，开展了系统的地质学、地球化学和锆石U- Pb年代学研究，总结了复式岩体的时空分布规律，探讨了复式岩体的成因类型、源区特征和构造背景。复式岩体主要由石英闪长（玢）岩、二长闪长岩、花岗闪长岩、黑云母正长花岗岩、（黑云母）二长花岗岩等组成，为一套岛弧岩浆岩组合，成岩年龄集中在120~104 Ma，属于早白垩世末期，空间分布上具从南到北，由早到晚的趋势。岩石地球化学特征显示从石英闪长岩到二长花岗岩具有由钙碱性系列岩石向钾玄岩系列演化的趋势，主体属于准铝质—弱过铝质I型花岗岩，轻稀土元素分馏程度较高，而重稀土近于平坦，具有弱的负铕异常；富集Rb、K等大离子亲石元素，Ta、Zr、Hf等高场强元素和轻稀土元素，相对亏损Nb、P、Ti等高场强元素和重稀土元素，具有岛弧岩浆岩的特征。基于本次研究结果，结合区域构造背景认为，阿翁错- 盐湖复式岩体形成于狮泉河- 纳木错特提斯洋盆北向俯冲的背景，来自俯冲板片的流体上升，引起上覆地幔楔物质发生部分熔融，形成幔源岩浆，在密度差的作用下幔源岩浆向上运移，底侵至新生下地壳，致其发生部分熔融，并与之发生混合作用，形成了阿翁错- 盐湖复式岩体的母源岩浆，早白垩世末期（104.8±1.4 Ma）狮泉河- 纳木错特提斯洋壳仍持续向北俯冲，下白垩统竟柱山组磨拉石建造的沉积才意味着洋盆彻底关闭。 相似文献
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J. E. Smith 《Mathematical Geology》1971,3(2):183-192
A substantial fraction of sandstones containing commercial quantities of oil are proposed to be in contact with source rocks which produce oil. For these situations the quantity of oil collected in a sandstone is proportional to the area of contact with a source rock of relatively low permeability, rather than to the total thickness of the potential source rock. It is inferred that source rocks along the upper or lower faces of a sandstone should produce more oil into the sandstone than source rocks lateral to the sandstone. Semiquantitative estimates of the thickness or width of required source rock are obtained. The arguments and results are based on published statistical studies and the assumption that a degree of geometrical similarity exists among sandstones. 相似文献
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KREEP Rocks 总被引：2，自引：1，他引：2
KREEP rocks with high contents of K, REE and P were first recognized in Apollo-12 samples, and it was confirmed later that there were KREEP rock fragments in all of the Apollo samples, particularly in Apollo-12 and -14 samples. The KREEP rocks distributed on the lunar surface are the very important objects of study on the evolution of the moon, as well as to evaluate the utilization prospect of REE in KREEP rocks. Based on previous studies and lunar exploration data, the authors analyzed the chemical and mineral characteristics of KREEP rocks, the abundance of Th on the lunar surface materials, the correlation between Th and REE of KREEP rocks in abundance, studied the distribution regions of KREEP rocks on the lunar surface, and further evaluated the utilization prospect of REE in KREEP rocks. 相似文献
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碳酸盐岩地区古风化壳岩溶储层 总被引：30，自引：0，他引：30
世界整装大油气田均以海相盆地为主,储集类型首推碳酸盐岩岩溶孔洞＋裂缝.岩溶发育的程度除相控外,层序不整合界面与区域性地层不整合面的复合面,在表生成岩作用环境下可形成碳酸盐岩古风化壳型岩溶.塔里木盆地和鄂尔多斯盆地奥陶系古喀斯特油气藏的重大突破,佐证了碳酸盐岩岩溶储层的特殊意义.我国海相盆地碳酸盐岩风化壳岩溶的形成和演化,均与加里东构造旋回中的幕次古隆起和海平面下降共耦,埋藏期和热水溶蚀的叠加可改善岩溶的储集性能.在大面积覆盖的油气田区预测古风化壳型的岩溶储层,可通过地震剖面追踪区域性地层不整合面和层序界面,圈出古岩溶的时空展布、推测古岩溶地貌以及与不同层位岩性相的关系.孔洞充填方解石与碳酸盐围岩的氧碳同位素有别,前者的Z值小于120,是反馈淡水岩溶环境的重要标志之一. 相似文献
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K. S. W. Campbell Convener 《Australian Journal of Earth Sciences》2013,60(4):423-425
The Mount Black lead‐zinc deposit at Cooleman Plains, southern New South Wales, occurs in the uppermost part of the moderately folded, weakly metamorphosed, Upper Silurian Cooleman Limestone. A joint‐controlled collapse‐breccia zone interpreted as a palaeokarst structure has been partly replaced by quartz, sphalerite, galena, and a little chalcopyrite, pyrite, marcasite, tetrahedrite, arseno‐pyrite, and mackinawite. These minerals show evidence of having encrusted and replaced limestone fragments in the breccia. Oxidic Zn, Pb, Cu, and Fe minerals have formed by the near‐surface oxidation of the sulphides. Petrographic and field evidence indicates that the quartz and sulphides were deposited mainly by encrustation and precipitation from saline solutions (possibly diagenetically expelled connate brines) in cavities, probably at low temperature at shallow depth. The deposit has many similarities to Mississippi Valley‐type lead‐zinc deposits. 相似文献
15.
碳酸盐岩与泥质烃源岩生气规律对比研究 总被引：10，自引：1，他引：10
配制了两套成熟度相近的碳酸盐岩和泥质岩丰度系列样品。采用半封闭外加温加压式热压模拟装置对碳酸盐岩的生烃情况进行了热模拟实验，研究了碳酸盐岩生气量随成熟度和温度变化的趋势，探讨了碳酸盐岩生气的变化规律。碳酸盐岩与泥质岩的生烃潜力是有机质质量和有机质丰度的函数，与岩性无关；碳酸盐岩的产气规律与泥质岩相似，而且两者产烃的量级也相当，并不存在碳酸盐岩生排烃效率高的现象；碳酸盐岩和泥质岩总有机碳(TOC)含量在热模拟过程中基本上不发生变化；不同岩性的有机质的产烃效率主要受温度和有机质类型决定。 相似文献
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Textural characteristics are a major factor in determining the mechanical behaviour of rocks and in the prediction of performance of rock cutting and drilling equipment. The principal textural characteristics of rocks are grain size, grain shape, grain orientation, relative proportion of grains and matrix material which were herein quantitatively measured using a modern image analysis system. These features resulted in a texture coefficient represented by a single number for each rock specimen. In this study a range of both textural and mechanical data for a range of rock types are given with some of the textural determination methodology. Correlation between textural and physical properties are also highlighted. The results of drilling tests using polycrystalline diamond compact (pin and hybrid) and impregnated diamond core bits in the rocks are presented which demonstrate the influence of rock texture on drillability. The rock texture can be used as a predictive factor for assessing the drillability and cuttability, mechanical and wear performance of rocks. 相似文献
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18.
Alan Spry A. H. Blissett K. Bubns I. B. Jennings B. Scott 《Australian Journal of Earth Sciences》2013,60(2):107-126
Bauxite deposits in Gippsland are small, low in grade, and buried under a thick cover of Tertiary sands. Occurring at various stratigraphic levels in the Thorpdale volcanic sequence, they are also texturally and compositionally primitive and hence now presumably fossilised. Although broadly comparable with deposits in Tasmania and New England, they show few obvious analogies with other Australian bauxites. Profile studies reveal a somewhat erratic vertical mineralogical zonation which can, at least in part, be accounted for by assuming a degree of post‐bauxitisation planation so that some profiles are now truncated. Some profiles show gibbsite increasing with depth and at least in the Boolarra profile this has significant genetic implications. Here, during submergence of the lateritic surface, rising carbonated connate waters precipitated scarbroite and this, with subsequent renewed leaching, decomposed initially to form nordstrandite, and finally gibbsite. 相似文献
19.
Twenty different rocks have been analyzed for tellurium by atomic absorption. The average tellurium content of 12 igneous rocks is 82 p.p.b., with a range, 3.4 p.p.b. ≥ Te = 210 p.p.b. In ultrabasic rocks, the tellurium content is ? 10 p.p.b. Of the rocks analyzed, carbonates showed the highest Te content, 1–2 p.p.m., and the tellurium concentrations in 6 sedimentary rocks decrease in the following order: carbonates > shales > sandstones. 相似文献
20.
HUGH ROLLINSON 《Geology Today》1997,13(5):185-190
In August 1994, Britain's top science journal, Nature, announced that a team of scientists working at the University of Cambridge had found Europe's oldest rocks at a remote location near to Gruinard Bay in the Scottish Highlands. They reported ancient volcanic rocks with an age of 3300 million years. This was more than 300 million years older than any age previously measured on rocks in the British Isles and between 100 and 200 million years older than any rocks known in Europe. The discovery of itself is in many ways unremarkable, for much older rocks are known from ancient continental shield areas in Canada, Australia and Greenland. What was important was that the reported age did not agree with any of the other measured ages known within the British Isles. This was highlighted in a comment in the same issue of Nature, which suggested that the new data were so important that they require a massive revision of our views on the earliest history of the British Isles. For other scientists, however, the conflict between these new data and previously reported ages began to raise questions about the methods employed in dating the 'oldest rocks'. 相似文献