排序方式： 共有23条查询结果，搜索用时 15 毫秒
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内蒙乌拉山群岩石的稀土地球化学特征及其所反映的成岩环境 总被引：1，自引：0，他引：1
18个乌拉山群片麻岩和麻粒岩样品的REE含量分析显示,乌拉山群岩石形成于古大陆边缘岛弧环境。碎屑沉积岩和火山碎屑沉积岩的沉积物来自邻近的火山岛弧。其中,138号标本(石英二长片麻岩)的ΣREE=62.3ppm,(La/Yb)_N=87.5,δEu=3.26,代表了太古代高级区的特征岩类。麻粒岩的ΣREE较低,显示在麻粒岩相变质过程中有REE的亏损。 相似文献
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冀东南堡凹陷高尚堡潜山深层花岗质基岩的特征及成因 总被引：1，自引：0，他引：1
通过对高参１井岩石化学、地球化学（含微量元素地球化学）及年代学的研究,确定本区花岗质基岩及其包体形成于地壳深部,并被上部地壳同化混杂。其原岩形成年代为２８．９Ｍａ,花岗质岩石为２５～２４Ｍａ;在２２～２０Ｍａ,１７～１５Ｍａ,１０～９Ｍａ间,由于受华北造台运动影响,本区花岗质岩石中发生过几次构造—热事件并遭受过强烈改造。 相似文献
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基于MRAS证据权重法的辽西锦州—阜新金矿化带金矿潜力评价 总被引：1，自引：0，他引：1
利用已有的地质、矿产、物探及化探等资料,建立锦州—阜新金矿化带基于GIS的空间数据库。在此基础上重新建立研究区金矿区域找矿模型,其中主要找矿标志包括太古宙变质岩系、北东向及东西向韧性剪切带、北东—北北东及北西向断裂、Au-Ag-Cu-Zn化探异常、金重砂异常、航磁磁感应强度-T异常在50 nT至150 nT区间内、已发现金矿床（点）。以上述找矿标志构置预测变量（证据因子）,采用MRAS（矿产资源评价系统）中的证据权重模型,对研究区首次进行基于GIS下的金矿产资源评价工作。以2 km×2 km网格为单元计算得到后验概率（P）,根据P将研究区成矿远景分级并确定A,B和C 3个级别预测远景区。根据远景区分布特征,将其最终划分为19个找矿靶区,其中,A级找矿靶区3处,B级找矿靶区6处,C级找矿靶区10处。 相似文献
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The LA-ICP-MS U-Pb dating of hundreds of detrital zircon grains from the Sinian sandstones of Liantuo formation and tillites of Nantuo formation at Sanxia area in Yichang identified 3319?3508 Ma zircon grains. Their 207Pb/206Pb and 206Pb/238U ages show excellent agreement (concordia degree 99%?100%). Their CL images exhibit well-developed oscillatory zoning and the Th/U ratios are within 0.46?0.76, implying that they are igneous zircons which formed during middle-early Archean. These zircons are the oldest ones discovered in Yangtze craton until now. However, the detrital zircons with ages older than 3.3 Ga in the metamorphic rocks of Kongling group were not found by further investigation, which suggests the presence of crust older than high-grade metamorphic Kongling terrain in Yangtze craton. 相似文献
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研究区位于坦桑尼亚地盾上的维多利亚湖金-金刚石成矿带上,通过对研究区的地质、化探、物探综合找矿工作,区内地表没有发现金及其他元素异常;但磁异常显示深部可能存在由基性、超基性岩浆活动引起南北向及近东西向深大断裂,预示深部可能有与基性、超基性岩有关的金属矿产,研究区深部具有较大找矿潜力. 相似文献
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Sm Nd isotopic compositions of associated amphibolites, TTG gneisses and granitic gneisses from the Archean Kongling Complex of the Yangtze Craton, South China are systematically analyzed. The results show that the amphibolites and TTG gneisses have a similar age of ca. 2 700 Ma, which well agrees with zircon U Pb dating of previous studies. However, their ε Nd ( t ) are different, suggestive of possible dissimilarity in source composition. 相似文献
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在出露地表的中、高压相麻粒岩地体代表下陆壳的认识基础上,建成全球麻粒岩相地体地球化学成分数据库（共１６８５套分析数据）。利用ＩＢＭ４３８１大型计算机对全部数据进行了多元变量统计分析,成功地建立了迄今为止精度最高的太古代、后太古代和全球大陆下地壳化学成分模型。 相似文献
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ZHENG YongFei ZHANG ShaoBing 《科学通报(英文版)》2007,52(1):1-12
The occurrence of zircons with U-Pb ages of ~3.8 Ga and Hf model ages of ~4.0 Ga in South China suggests the existence of the Hadean crustal remnants in South China. Furthermore, a detrital zircon with a U-Pb age as old as 4.1 Ga has been found in Tibet. This is the oldest zircon so far reported in China. These results imply that continental crust was more widespread than previously thought in the late Hadean, but its majority was efficiently reworked into Archean continental crust. On the basis of available zircon U-Pb age and Hf isotope data, it appears that the growth of continental crust in South China started since the early Archean, but a stable cratonic block through reworking did not occur until the Paleoproterozoic. Thus the operation of some form of plate tectonics may occur in China conti- nents since Eoarchean. The initial destruction of the South China craton was caused by intensive magmatic activity in association with the assembly and breakup of the supercontinent Rodinia during the Neoproterozoic. However, most of the Archean and Paleoproterozoic crustal materials in South China do not occur as surface rocks, but exist as sporadic crustal remnants. Nevertheless, the occur- rence of Neoproterozoic magmatism is still a signature to distinguish South China from North China. 相似文献
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辽西太古代“建平变质杂岩”的变质作用演化 总被引：6，自引：0，他引：6
“建平变质杂岩”是辽宁省西部太古代的最下部的地体,它由连续性很差的表壳岩、TTG岩石及其它深成侵入岩构成。基本岩石类型有镁铁质岩石(包括角闪岩、辉石岩、斜长角闪岩等)、麻粒岩、紫苏花岗岩、片麻岩及少量的超镁铁质岩和磁铁石英岩。常见且主要的矿物相是斜方辉石、单斜辉石、石榴石、角闪石、斜长石和石英。岩相学研究确定了指示变质作用不同阶段的三个变质反应的存在,并且它们与推测的矿物相的转化关系吻合,结合地质温压的限定,本文得出了本区太古代末期的强烈的变质热事件的反时针的P-T-t演化轨迹,并推测出此变质热事件与大量的岩浆增聚密切相关。 相似文献