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矿床地质:1988,Vol.>>Issue(4):16-26

古老地壳内部脉状金矿床的形成模式——以冀东地区金矿为例
长春地质学院
A genetic model for veinlike gold deposits in paleocrust with gold deposits in Palecrust —with gold deposits in eastern Hebei cration as examples
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中文摘要:本文以冀东地区为例,从太古宙区域地质背景研究出发,根据已知金矿床的通性,从同位素角度系统讨论了古老地壳内部含矿流体的性质、来源和可能的成因,并建立了金矿成因 模式。指出该区具有花岗岩一绿岩构造体制,在空间上可以分为紫苏花岗岩系、TTG杂岩系和构造置换一复合岩系三个构造亚区。建立了区域地质事件年表,阐述了金矿分布与地质背景的空间关系。金矿化与地质事件的时间关系。文中将冀东地区金矿分为金厂峪、都山和峪耳崖三种类型,总结了该区近三十多个矿床(点)的八点通性。通过氢、氧、铅同位素的讨论,论证了含矿热液是一种与围岩近似处于氧同位素平衡的特殊流体。中文强调了区域性地壳隆起对金矿形成的重要控制作用,提出太古宙末期伴随着变质作用结束和中生代中期伴随着太平洋板块俯冲而发生的两次大规模地壳迅速隆起是冀东地区金矿形成的重要机制。
中文关键词:太古宙地壳  液态矿源  隆起  金矿床  冀东
Abstract:A large quantity of field geological investigation shows that, just like other Archean craton in the world. The Achean craton i n the eastern Hebei is of granite-greenstone structural system. In space, it can be divided into three structural subazeas: high grade area, TTG complex area and struetttral transposition—compounding series area, The first two areas corrsespond to different levels of granitic complex associations and the third, to the root of a greenstone belt.The gold deposits in the craton aa-e mainly distributed in the last two areas and might be classified into three types:Jinchangyu, Dushan and Yuerya.There exists on metallogenic specianzatjon of host rocks and structures (faults)for different types of gold deposits.The H, O and Pb isotope data and the composition of fluid inclusions in quartz suggest that the ore-forming fluids responsible for all types of gold deposits are rather similar in chemical composition and other geochemical features and belong to a kind of special solution from the deep crust which has reached iso tope equilibrium with mits surrounding rocks.Two periods of gold mineralizations in the craton took place at the end of the.Archean and in the Mesozoic respectively, the former probably related to the continental uplifting at the end of metamorphism and the latter, to the other continental uplifting during subduction of the Pacific Plate. The ubiquitously existent mafic to ultramafic inclusions in the deep part of the granite-greenstone association contain large quantities of easily-released gold and thus serve as the sources for gold mineralization. When these inclusions were in a zone saturated by water and other volatiles as a result of devolatilization at the depth of the crust, gold was first extracted from.The mafic to ultramafic inclusions into the fluids, forming a horizontal liquid source bed which had nothing to do with the bedding or foliation of their surrounding rocks. When the crust was uplifted, the static pressure of the overlying rocks fell so rapidly that the fluids in the liquid source bed would cause the country rocks to form hydraulic fissures and would migrate along these fissures to form gold deposits in favorable sites. The multi-stage-mineralization of many veinlike gold deposits might be at tributed to the variation in rate of the crust. The Mesozoic magmatic activities in the eastern Hebei craton must have played a certain role in gold mineralization: they either raised the temperature of the liquid source bed or acted as conduits and/or favorable sites for the migration or precipitation of gold-bearing fluids.
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引用文本:
王安建.1988.古老地壳内部脉状金矿床的形成模式——以冀东地区金矿为例[J].矿床地质,7(4):16~26
.1988.A genetic model for veinlike gold deposits in paleocrust with gold deposits in Palecrust —with gold deposits in eastern Hebei cration as examples[J].Mineral Deposits7(4):16~26
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