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91.
青藏高原南部冈底斯斑岩铜矿带的含矿斑岩具有埃达克岩的本质特征,是由俯冲到深部的新特提斯洋壳在榴辉岩相条件下部分熔融形成的.本文用冲江和拉抗俄两个矿区含矿斑岩的黑云母和斜长石斑晶测定了它们的40Ar/39Ar年龄,结果表明两个矿区虽然相隔百余千米,但形成时间非常一致.两个黑云母斑晶的坪年龄分别为13.5±1.0 Ma和13.42±0.10 Ma;两个斜长石斑晶分别给出了12.22±0.05 Ma和12.5±1.3 Ma的坪年龄.考虑到斜长石和黑云母对40Ar/39Ar系统较低的封闭温度,这些结果与辉钼矿给出的斑岩铜矿的Re-Os等时线成矿年龄(14 Ma±)是一致的.根据含矿斑岩的产出位置和形成时间推测,印度板块沿雅鲁藏布江缝合带可能以高角度向亚洲大陆下俯冲进入岩石圈地幔.含矿斑岩和矿(化)带近EW向产出指示着斑岩岩浆上升侵位和铜矿化过程与高原达到最大高度的隆升过程是同步的.在此之后,高原的应力体制转变为Ew向伸展,在重力作用下形成了一系列SN向塌陷构造-裂谷和正断层. 相似文献
92.
CHEN Xiaohong WANG XiaofengYichang Institute of Geology Mineral Resources CAGS Gangyao Rd. Yichang Hubei 《《地质学报》英文版》1998,72(4):432-440
A great amount of black rock series has been found in the Upper Sinian Members 2 and 4 of the Jinjiadong Formation, middle-upper Liuchapo Formation and the Lower Cambrian Xiaoyanxi Formation in West Hunan, which is associated with periodic sea-level changes. By the studies of relationships between the distribution and development of the biota and the abundance of Au, Ag, U, V, Ni, Mo and Cu in the Upper Sinian and Early Cambrian black rock series in Cili, Dayong, Yuanling, Xupu and Qianyang of West Hunan, central China, it has been revealed that the enrichment of Ag, V, and Mo is related with the development of multi-cell plants and vendotaenides, and that of Cu and Ni is related to flourishing of bacteria and shelly fossils. The black rock series in the study area contains abundant organic matter, among which the siliceous shale contains the highest TOC, amounting to 4.51-13.4%. All the values of the equivalent vitrinite reflectance (medium values) determinated with the IR-spectroscopic method in the a 相似文献
93.
The Younger Dryas Event and Holocene Climate Fluctuations Recorded in a Stalagmite from the Panlong Cave of Guilin 总被引：2，自引：1，他引：1
Stein-Erik LAURITZEN 《《地质学报》英文版》1998,72(4):455-465
Comprehensive studies on a stalagmite from the Panlong cave, Guilin, have shown that the isotopic records and sedimentary characteristics can reflect the changes of both palaeotemperatures and palaeorainfall, that is to say, it is possible to get some information about the changes in climate of the area from the speleothem. The results suggest that: (1) the Younger Dryas event might have persisted in the area from 11 300 to 10 800 a B.P.; (2) from 9000 to 7000 a B.P., the climate got warmer and wetter, and the summer monsoon was gradually enhanced; (3) from 7000 to 4500 a B.P., the climate was warm and wet, and the summer monsoon prevailed; and (4) from 4500 a B.P. on, the summer monsoon was weakened and the modern climate pattern appeared, but there were several cold and dry periods, namely, from 4000 to 2500 a B.P., ca. 2400 a B.P. and < 1000 a B.P. 相似文献
94.
新元古时期Rodinia超大陆研究进展述评 总被引：63，自引：7，他引：56
新元古时期Ｒｏｄｉｎｉａ超大陆的假说自１９９０年提出以来,引起国外许多地质学家的关注,其研究程度不断提高,本文在回顾Ｒｏｄｉｎｉａ超大陆研究历史的基础上,介绍了Ｒｏｄｉｎｉａ超大陆的古地理再造图,并着重介绍中国大陆古地块在超大陆中古地理位置的最新研究动向,文中对建立Ｒｏｄｉｎｉａ超大陆的标志,特别是中元古代晚期－新元古代早期的造山运动和新元古代晚期的裂谷作用进行了评述。同时对我国中－新元古代与Ｒｏ 相似文献
95.
应用高温显微镜和显微加热装置及自动录像等设备，对广东凡口铅锌矿区的铅锌矿石进行退火生长实验。退火实验条件为：500℃，12h；540℃，132h；600℃，12h。样品仓通氩气保护试样表面、电炉加热、循环水冷却。实验表明闪锌矿在540℃退火静态重结晶过程中，有些颗粒长大，有些颗粒则缩小甚至消失，颗粒的凸界面趋于退缩，凹界面趋于变凸，向球状闪锌矿方向演化。虽然总体积基本保持不变，但ZnS组分在局部得到明显富集，类似于自然界的成矿过程。退火实验后的球状闪锌矿颗粒，与实验前样品的主成分对比，Zn、Fe含量明显增加，S含量却明显降低，证明退火重结晶作用直接导致Zn元素的进一步富集。600℃时方铅矿和部分闪锌矿矿物出现蒸发现象。凡口矿区中生代晚期热事件的加热和保温层的覆盖，使得早期贫矿体经历退火静态重结晶作用，使贫矿体向内部收缩和圆化呈截然边界，总体演变成为高品位的超大型铅锌矿床。 相似文献
96.
WU Cailai Jone WOODEN YANG Jingsui LI Haibing Trevor IRELAND LIOU June Guang Wan Yusheng Shi Rendeng Institute of Geology CAGS Beijing Department of Geology Stanford University Stanfor CA - USA 《《地质学报》英文版》2002,76(1):118-125
Zircon SHRIMP ages of the Aolaoshan granite on the south margin of the Qilian Mts. range from 445±15.3 to 496±7.6 Ma (averaging 473 Ma), belonging to the Early Ordovician. Geochemically, the granite is similar to I-type granite and, tectonically, was formed in an island-arc environment based on relevant diagrams for structural discriminations. Considering also the regional geology, the authors suggest that the granite is part of an ultrahigh-pressure belt on the south margin of the Qilian Mts. and that its formation bears a close relationship to this belt. 相似文献
97.
本文在前人零星的遥感图象信息基础上,于“七、五”期间在太行—冀辽区(河北—辽宁)开展了野外实地考察和研究,发现等距相间的大量NNW向主干压性或压扭性构造带,以及彼此有成生联系的、力学性质不同的各向配套构造,如朝阳、滦河和紫荆关—怀安等三大构造带比较突出,它们共同显示了EWE—WSW或近EW向的构造应力场特征,由此将新第三纪以来,第四纪达到顶峰而形成的NNW向构造体系厘定为“华北系”。“华北系”的建立,目前在我国东部尚属首次。 相似文献