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1.
苏北青龙山超高压变质榴辉岩流体包裹体特征与流体演化 总被引：3，自引：7，他引：3
根据青龙山超高压变质榴辉岩中流体包裹体的化学成分、矿物中的分布特征将岩石中的流体包裹体分为五类,即富N2包裹体、高盐度(22.4-略大于23.2wt%NaCl)的NaCl CaCl2 H2O体系流体包裹体、中高盐度(12.6-16.0wt%NaCl)的含Mg2 或Fe2 的NaCl H2O体系流体包裹体、中等盐度(6.4-10.5wt%NaCl)水溶液包裹体和低盐度(3.3-0.2wt%NaCl)的水溶液包裹体。富N2包裹体形成于超高压变质峰期阶段,高盐度的流体包裹体形成于超高压变质岩折返早期固体出溶体出溶阶段,中高盐度的流体包裹体形成于高压变质重结晶作用阶段,中等盐度的流体包裹体形成于角闪岩相变质重结晶作用阶段,低盐度的流体包裹体形成于折返晚期的绿片岩退变质作用阶段。超高压变质峰期阶段和折返早期的高盐度流体和中高盐度的流体主要来自继承原岩中的流体(如含NH4 矿物分解或片麻岩原岩中的有机质分解,名义上无水矿物中羧基水的出溶),晚期角闪岩相退变质阶段的中等盐度的流体除名义上无水矿物中羟基水的出溶外还有外来流体的加入,绿片岩相退变质作用阶段的流体主要为外来流体。 相似文献
2.
中国大陆科学钻探（CCSD）高压超高压变质岩中石英脉流体包裹体初步研究 总被引：2，自引：15，他引：2
初步的岩相学和冷热台显微测温表明，CCSDHP—UHP岩石中石英脉和后期碳酸盐脉中含有3种流体包裹体：盐水溶液(NaCl-H2O)包裹体(Ⅰ类)、NaCl-CaCl2-H20(Ⅱ类)和N2-CH4纯气相(Ⅲ类)包裹体，其中Ⅰ类盐水溶液包裹体可进一步分为中高盐度盐水溶液包裹体(Ia)、中等盐度盐水溶液包裹体(Ib)和低盐度盐水溶液包裹体(Ic)，而Ⅲ类为CCSD中首次发现：Ia、Ib和Ⅱ型流体包裹体主要以原生或假次生形式赋存在榴辉岩的石英脉或石英颗粒中，在角闪岩相的片麻岩及其石英脉中均未观察到，显示它们可能主要被捕获于榴辉岩的减压重结晶或退变质阶段，而Ic型包裹体分布广泛，表明其主体可能是在超高压变质岩折返过程的最晚阶段捕获的；N2-CH4纯气相包裹体均为原生包裹体，主要呈孤立和小群状与Ia和Ib类包裹体分布于榴辉岩中条带状石英脉中，可能主要是在高压-超高压榴辉岩相变质条件下被捕获的；CCSD榴辉岩中石英脉的主体形成于板块折返有关的减压重结晶和退变质，而片麻岩中石英脉则主要来源于角闪岩相及其后期退变质作用；榴辉岩和片麻岩中石英脉流体包裹体的组成和地球化学特征存在明显区别，但它们各自相似于其寄主岩石中的石英颗粒中包裹体，说明CCSD中HP—UHP岩石在板块折返过程中释放出的变质流体没有经过大规模的迁移。 相似文献
3.
江苏东海水晶矿床成因初探：流体包裹体和硅氧同位素证据 总被引：5，自引：0，他引：5
东海水晶矿床位于苏鲁超高压变质带中，它的成因机制及其与超高压变质作用的关系一直是大家关注的问题。本文运用流体包裹体、硅氧同位素地球化学以及微量元素地球化学，对东海水晶矿床的成因进行了初步研究。结果显示，含晶石英脉中流体包裹体主要有单液相、气液两相以及H2O-CO2流体包裹体，其中以气液两相流体包裹体为主，大小在5～50μm，但在含金红石发晶的水晶中气液两相流体包裹体最大可达300μm。其形成温度可以分为3个区间，即100℃～120℃，160℃～220℃和240℃～260℃；而其盐度也集中于0～2wt％NaCl，4～12wt％NaCl和14～16wt％NaCl三个区间，反映了多期流体的叠加作用。激光拉曼和流体包裹体群成分分析可知，流体包裹体中除了H2O和CO2外，还有N2、CH4、H2S和C2H6等，并且在不同的爆裂温度情况下，流体包裹体所释放的成分有所差别。东海水晶矿床中不合金红石发晶的石英的δ^18O变化范围在-5．6～＋4．6‰，δ^34Si变化范围在-0．2～＋0．2‰之间；而含金红石发晶的石英的δ^18O变化范围在10．5～14．9‰，δ^34Si变化范围在～0．2～＋0．1‰之间。相对来说，与水晶热液作用有关的鳞片状黑云母比斜绿泥石更加富集Nb、Cr、Fe、V、W、Ti和Zr等。本文认为东海水晶矿床的形成在富舍石英的榴辉岩在大陆板块俯冲折返过程中及其以后，由不同时期、不同性质、不同成分流体叠加作用下的结果，而舍金红石发晶的形成则是叠加富Nb、Fe流体的结果。 相似文献
4.
桃行榴辉岩是苏鲁超高压变质带中段主要榴辉岩体密集分布区之一。流体包裹体研究表明,榴辉岩矿物及高压脉体石英中捕获有五种类型的流体包裹体：在超高压-高压榴辉岩相条件下捕获的N2±CH4包裹体;在榴辉岩发生麻粒岩相叠加变质作用期间被捕获的B型纯CO2液相包裹体;在高压榴辉岩重结晶阶段被捕获的C型CO2-H2O包裹体和D型高盐度水溶液包裹体;超高压岩石折返过程中的最晚阶段（角闪岩相退变质甚至更晚）捕获的E型低盐度水溶液包裹体。利用榴辉岩矿物及高压脉体石英中捕获的流体包裹体类型及期次可以重建超高压变质作用板片折返过程中的流体性状与演化,而石榴石中捕获的纯CO2包裹体为本区榴辉岩相岩石遭受了麻粒岩相叠加提供了佐证。 相似文献
5.
鲁东南岚山头含柯石英榴辉岩主要产于花岗质片麻岩内,是苏鲁超高压变质带主要榴辉岩体密集分布区之一。流体包裹体研究表明,榴辉岩矿物及细脉石英中捕获有四种类型包裹体:在超高压-高压榴辉岩相条件下捕获的 N_2±CO_2包裹体;在高压榴辉宕重结晶阶段被捕获的 CO_2-H_2O 包裹体和含子矿物高盐度 H_2O 溶液包裹体:在超高压岩石折返过程中的最晚(角闪岩相退变质甚至更晚)阶段捕获的低盐度 H_2O 溶液包裹体。利用榴辉岩矿物及脉体石英中捕获的流体包裹体相互期次关系,可以对本区超高压变质作用板片折返过程中的流体演化史进行重建。 相似文献
6.
东海超高压榴辉岩中绿帘石、褐帘石、磷灰石和钍石集合体的电子探针成分和化学定年研究 总被引：2，自引：4，他引：2
中国大陆超深钻(CCSD)主孔从100米到3000米切穿含柯石英榴辉岩,为系统研究大陆深俯冲过程中含稀土元素副矿物提供了机会。本文报道了该钻孔榴辉岩存在发现的绿帘石、褐帘石、磷灰石和钍石复合颗粒。它们以同心环带结构为特征,从边部向中心依次为绿帘石、褐帘石和磷灰石;钍石既可包裹再磷灰石中,也可见于褐帘石中。电子探针分析显示,褐帘石不仅含有较高的轻稀土元素(LREE2O3=23．36wt％),而且可含有2．6wt％ThO2。根据绿帘石和褐帘石的电子探针高分辨U、Th、Pb成分计算得到绿帘石边部的形成年龄为738±88Ma,该年龄与大别-苏鲁地体榴辉岩的元古代源岩的年龄相当,因此,绿帘石可能为残留相。相反,褐帘石的年龄为220±41Ma,与大别-苏鲁超高压变质年龄相近。因此,褐帘石与磷灰石和钍石一起应该为超高压变质事件的产物。根据绿帘石、褐帘石及其共生的磷灰石和钍石的结构、成分特征和化学定年结果,我们推测绿帘石与可能已完全消耗的独居石很可能为变质副矿物组合的先驱矿物。独居石-绿帘石复合颗粒在榴辉岩相高压／超高压变质过程中反应形成磷灰石+钍石+褐帘石组合。 相似文献
7.
河南洛宁段河金矿流体包裹体研究和矿床成因 总被引：2，自引：1，他引：1
河南省洛宁县段河石英脉型金矿主要包括石寨沟和岭东两个矿区,分别由3～4条含金石英脉构成。矿化过程从早到晚包括石英-黄铁矿、石英-多金属硫化物和石英-碳酸盐等3个阶段．其中中阶段金矿化最强,次为早阶段。各阶段石英中流体包裹体以气液两相包裹体为主．次为纯液体包裹体。激光拉曼测试表明,气液两相包裹体的液相为H2O,气相主要为Ho和CO2混合、纯H2O,次为纯CO2;纯液体包裹体为纯H2O。石寨沟矿区包裹体均一温度从早到晚依次为240．9～315．9℃．188．7～304．5℃,137．3～259．3℃：流体盐度变化依次为（6．74～12．85）wt%NaCl．eq,（2．41～8．68）wt％NaCl．eq,（2．24-7．86）wt%NaCl．eq。岭东矿区均一温度从早到晚依次为303．7-343．1℃,251．8-325．4℃,305．7～355．0℃：流体盐度变化依次为（5．11～11．70）wt％NaCl．eq,（2．74-10．11）wt％NaCl．eq,（0．53-6．74）wt％NaCl．eq。两矿区主成矿期流体均为中温、低盐度,早阶段流体为改造热液和变质热液的混合体,含一定量CO2,且流体CO2含量和盐度从早到晚逐渐降低。石寨沟矿区包裹体均一温度逐渐降低,而岭东矿区包裹体均一温度先降后升,加之岭东矿区各阶段成矿温度均高于石寨沟矿区．表明成矿流体系统主要受岩浆热驱动,岭东矿区更靠近岩体,且在晚阶段又有脉动性的岩浆加热．段河金矿区南部存在隐伏岩体。 相似文献
8.
北秦岭官坡地区柯石英榴辉岩变质作用的P—T—t轨迹 总被引：2，自引：0，他引：2
赵东林 《西安地质学院学报》1997,19(2):28-33
根据矿物包裹和替代关系以及共生组合规律，北秦岭官坡地区柯石英榴辉岩的变质作用演化可划分为５个阶段，即前榴岩相的绿帘角闪岩相，榴辉岩相，后榴辉岩相的角闪岩相，绿帘角闪岩相和绿片岩相。 相似文献
9.
超高压变质流体的组成与演化：中国大陆科学钻探工程主孔岩心的流体包裹体研究 总被引：6，自引：15，他引：6
中国大陆科学钻探工程主孔位于大别-苏鲁超高压变质带东段的江苏东海县,孔深为5100m,其上部2050m钻遇的岩石主要为榴辉岩,其次是正、副片麻岩、石榴橄榄(辉石)岩以及少量片岩和石英岩。它们经历了超高压变质作用和随后的角闪岩相退变质作用。通过对上述各种岩石的详细流体包体观察和RAMAN光谱分析,发现了五种不同成分的流体包裹体:(1)中-低盐度水溶液包裹体(Ⅰ型),呈原生的孤立和小群存在于榴辉岩和片麻岩锆石的岩浆核和超高压变质边缘,或存在于绿辉石、黝帘石和被绿辉石包裹的方解石和石英中,偶尔呈出溶包裹体产于磷灰石中,而主要沿绿辉石、石榴石、蓝晶石、黝帘石和石英等矿物的穿颗粒裂隙分布;也呈孤立和小群产于切穿榴辉岩的方解石脉和片麻岩重结晶石榴石和绿帘石中;(2)CO2(±CH4)-H2O包裹体(Ⅱ型),存在于锆石的岩浆核和变质边缘,或沿石英裂隙分布;(3)含石盐±SiO2±CaCO3的复杂盐水包裹体(Ⅲ型),呈原生流体包裹体产在榴辉岩的绿辉石中,与石英出溶棒一起平行于绿辉石的C轴分布,或产在石榴辉石岩透辉石的晶内裂隙中;(4)富CO2包裹体(Ⅳ型),在榴辉岩的石英中随机分布;(5)单气相包裹体(Ⅴ型),沿各种矿物穿颗粒裂隙分布。流体包裹体产状及其与捕获时代关系表明,Ⅰ型和Ⅱ型包裹体可以出现在超高压变质岩原岩、峰期变质和退变质各阶段。Ⅲ型包裹体出现在超高压变质岩的早期减压退变质阶段。而Ⅳ型和Ⅴ型包裹体主要形成于角闪岩相及更晚的退变质阶段。本研究的主要认识是:(1)低盐度H2O和CO2流体在进变质、超高压变质和退变质作用各阶段均有存在,这表明在整个超高压变质演化过程中流体具有继承性。(2)超高压变质岩原岩和角闪岩相退变质岩中存在较丰富的流体包裹体,但在超高压峰期捕获的流体包裹体却很少见,这表明丰富的原岩流体或在超高压进变质过程中被排出岩石体系,或进入含水超高压矿物和结合进名义无水矿物。(3)复杂成分原生流体包裹体的发现证明在超高压变质峰期后的早期减压退变质阶段存在一种高盐度似熔体流体,名义上的无水矿物在超高压条件下可以保存相当量的流体,并在退变质过程中分离出来,产生流体-岩石相互作用。(4)角闪岩阶段的流体包裹体具有各种不同的化学组成,且在局部富集,推测可能有部分外部加入的流体。(5)流体包裹体类型、丰度和成分在不同岩石类型中和不同钻孔深度都存在明显差异,表明超高压变质作用过程中没有大规模的透入性流体活动。(6)根据超高压变质峰期包裹体等容线得到的压力值大大低于根据矿物温压计获得的近峰期变质压力,这表明包裹体的密度在捕获后发生了改变。这些改变是由于流体渗漏、部分爆裂和流体-岩石相互作用所引起。 相似文献
10.
CCSD(0～5158m)HP-UHP变质岩中石英脉流体包裹体研究 总被引：1，自引：1，他引：1
本文对中国大陆科学钻探(CCSD)0～5158m HP-UHP变质岩石英脉中流体包裹体进行了研究,通过冷热台与拉曼光谱测定发现其中含有4种流体包裹体:(Ⅰ型)盐水溶液包裹体,并进一步分为高盐度盐水溶液包裹体(Ⅰa型)、中高盐度盐水溶液包襄体(Ⅰb型)、中等盐度盐水溶液包裹体(Ⅰc型)和低盐度盐水溶液包裹体;(Ⅱ型)N2-CH4纯气相包襄体;(Ⅲ型)含方解石子矿物的流体包裹体;(Ⅳ型)CO2-NaCl-H2O包裹体及纯CO2包裹体.其中Ⅲ和Ⅳ型流体包裹体是CCSD石英脉中首次发现.Ⅰa、Ⅰb型流体包裹体主要以原生的形式赋存在榴辉岩及片麻岩的石英脉或石英颗粒当中,它们主要是被捕获于折返早期高压变质重结晶阶段;Ⅰc和Ⅰd两类包裹体则主要以次生的形式赋存于榴辉岩及片麻岩的石英脉或石英颗粒当中.说明它们是在超高压变质岩折返过程的较晚阶段捕获的.以原生形式出现的含方解石子晶及CO2包裹体,指示部分石英脉及其围岩可能经历过超高压变质作用甚至麻粒岩相阶段.CCSD中的石英脉可能主要形成于折返早期高压变质重结晶阶段,其中的HP-UHP岩石在板决折返及其以后退变质过程中释放出的变质流体活动范围有限,没有经历大规模的流动或迁移. 相似文献
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S. Viswanathan K. Surya Prakash Rao B. Mahabaleswar 《Journal of the Geological Society of India》2013,82(6):621-627
Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours. 相似文献
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E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others. 相似文献
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奥地利安东帕有限公司 《岩矿测试》2009,28(3):306-306
最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提 相似文献
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Mining induced subsidence can significantly affect mining costs where major surface facilities and natural environment need to be protected. Overburden grout injection is a technology used to control coal mine subsidence by injecting the mine waste material extracted from the coal back into the inter-burden rock during longwall mining. The flowing slurry is here categorised as a nonlinear viscous cohesive (Bingham plastic) fluid. During longwall mining the grout slurry is pumped into the separated beds of the rock mass through a central vertical borehole, which is drilled deep into the inter-burden rock strata above the coal seam. However, a blockage can occur in the injection system when the slurry velocity falls below a certain critical threshold velocity, indicating a material phase change from cohesive-viscous to cohesive-frictional. In situ field injection tests through boreholes have been simulated at a smaller scale at the CSIRO laboratory in Brisbane by pumping the slurry through a radial disk (gap = 4 mm) from its centre. Laboratory experiments indicate a general, nonlinear, cohesive, viscous, frictional model for shear behaviour of the slurry, in which the material shear parameters are functions of the disk radial distance. Complete dimensional and dimensionless analytical solutions have been developed based on an approach related to Bingham–Herschel–Bulkley fluid mechanics. The derived formulae include relations for minimum pump pressure, local pressure and pressure gradient, wall shear stress, volume rate, velocity and velocity gradient. The theoretical results match the experimental measurements. The experiments covered slurries with maximum particle sizes of 0.5 to 2 mm with about 50% being larger than 100 µm. The viscosities at the various solids concentrations were measured with a standard torsion viscometer. This study differs from the previous research in several distinct aspects, namely, consideration of the variable shear parameters rather than fixed values, inclusion of total nonlinear behaviour, and implementation of a friction function to mimic behaviour of the deposited and consolidating stiff slurry, which can cause a significant pressure rise as a result of the increased shear resistance. 相似文献
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Alexander E. C. Broberg J. S. Kehren A. R. Graziani M. M. Turri W. L. 《Environmental Geology》1993,22(4):353-361
Bellechester, Minnesota, is a small community of approximately 155 residents located on the county line between Goodhue and Wabasha counties in southeast Minnesota's karst region. Bellechester is served by a 21-year-old wastewater treatment facility (WWTF) consisting of three waste-stabilization ponds. On 28 April 1992 six sinkholes were discovered to have drained cell 2 of the WWTF resulting in the loss of approximately 8.7×106 1 of partially treated effluent and about 600 m3 of soil into previously undetected subsurface voids of unknown dimensions. In the week following the collapse, approximately 200 water wells located within a 5-km radius of the WWTF were sampled in an after-the-fact, emergency sampling program. Twelve samples with elevated fecal coliform levels, 18 samples with nitrate-nitrogen greater than the 10 mg/1 standard, and no samples with elevated chlorides were found. However, the elevated levels could not be unambiguously attributed to the WWTF collapse. This is the third WWTF to fail by sinkhole collapse in southeast Minnesota since 1974. All three collapsed lagoons have been located in similar geomorphic and stratigraphic settings. However, at least two lagoons have collapsed in the adjacent area in northeast Iowa, and these lagoons are located at different stratigraphic positions. Twenty-two WWTFs constructed in southeast Minnesota's karst region in the last 25 years have been identified as subject to potential sinkhole collapse. An unknown but significant number of manure storage lagoons, flood control structures, etc., have also been constructed in the karst region and are at risk. Public agencies are beginning to develop plans to deal with the risk associated with existing and future waste lagoons in this environment. The critical hydrogeologic parameters that can be used to prioritize the risk of collapse at existing facilities include: (1) the lithology of the first bedrock beneath each lagoon, (2) the thickness of surficial materials between the lagoon and the bedrock surface, (3) the presence and construction of liners (seepage rate), and (4) the proximity to existing sinkholes. 相似文献
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岩石密度和超高压岩石折返速率 总被引：1，自引：3，他引：1
在常温常压条件下对中国大陆科学钻CCSD主孔100-3000米岩心样品进行了密度测量,建立了密度连续剖面,并界定了不同超高压岩石的密度值。通过对比高温高压物性实验资料,岩石密度随着退变程度增强而降低,榴辉岩密度变化序列为3.52g/cm3→3.49g/cm3→3.07g/cm3→2.93g/cm3。超高压长英质岩石密度变化序列为3.00g/cm→2.80g/cm3→2.65g/cm3。上述实验资料是讨论不同折返阶段岩石所受浮力的基础,为研究折返速率大小提供了基本参数。本文通过折返板块运动平衡时,上浮力与粘滞力平衡这一关系式,定量研究了大陆俯冲板块的折返速率,认为密度差产生上浮力从而引起折返,温度对板块折返速率的影响最为显著;密度差大小、折返角度、折返板块大小对折返速率也有直接的影响。定量模拟分析表明,在温度高于850℃时,板块的折返速率可以超过100mm/a;当温度降至700℃时,折返速率则低于1.5mm/a。作者认为在折返早期,温度较高,板块快速折返至60-70km榴辉岩相深度;随着传导散热,温度降低,板块以较慢的速率折返至中下地壳。折返速率的估算表明,浮力是板块折返第一阶段(从>100km深部折返至<40km的中下地壳)的主要驱动力。 相似文献
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滇东南锡、银、铅、锌多金属矿床主要分布在个旧、白牛厂、都龙3个矿区,而滇东南较大的3个花岗岩体又分别出露在3个矿区或附近.花岗岩体均形成于燕山晚期,岩石化学、矿物成分相似,富含锡、银、铅、锌、钨、铜等成矿元素.矿床主金属元素组合与岩体之间的距离由远而近出现由锡、钨、(铍、铌、钽)→锡、钨、(铁)、铜、铟→锡、铅、锌、银、铟、(锑)有规律的变化.花岗岩浆是成矿物质来源和成矿热源.岩浆侵入初期使上覆地层隆起产生背斜(凹陷部位成向斜);同时使地层产生一系列裂隙、压性断层或层间断裂;岩浆侵入晚期,这些断层再次活动,表现为张性,岩浆产生的含矿热液沿由其活动所造成的断裂迁移、充填、交代、沉淀而形成矿床. 相似文献