Giant Mesozoic gold provinces related to the destruction of the North China craton
Giant Mesozoic gold provinces related to the destruction of the North China craton
复制标题
与华北克拉通破坏有关的中生代巨型金省
DOI：
10.1016/j.epsl.2012.06.058
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发表时间：
2012-10-01
影响因子：
5.3
通讯作者：
Qiu, Hua-Ning
中科院分区：
文献类型：
--
作者：
Li, Jian-Wei;Bi, Shi-Jian;Qiu, Hua-Ning
前寒武纪古陆中的矿脉型金矿床是世界上主要的金矿源，主要形成于古陆的形成和稳定过程中。然而，在华北克拉通（NCC）有一个特殊的例外，那里的矿脉金矿床形成后，克拉通长期稳定。小秦岭地区主要金矿床的辉钼矿Re-Os、热液绢云母和黑云母40 Ar/39 Ar定年结果表明，金矿床的侵位年龄为154.1 ± 1.1 ~ 118.9 ± 1.2Ma（n=23），晚于克拉通形成17亿年。含金黄铁矿中流体包裹体的He-3/He-4比值（1.52-0.22 Ra）和类幔源Ne同位素（Ne-20/Ne-22=10.02-9.22和Ne-21/Ne-22=0.033-0.027）均升高，表明成矿系统中存在幔源流体。测得的黄铁矿δ S-34和含金石英中热液云母和流体包裹体沃茨的δ D和δ O-18进一步证实了硫和成矿流体的岩浆/地幔来源。在华北克拉通东部和北方边缘也广泛分布有类似时代的金矿床，它们与小秦岭地区的金矿床一起，总储量约为2500 t，构成了世界上已知的前寒武纪盆地中唯一的晚中生代巨型金省。这些矿床形成于广泛的长英质至镁铁质岩浆活动、陆内裂谷盆地的发育以及NCC东部变质核杂岩的折返，这些事件被解释为克拉通下岩石圈的减薄和破坏。软流圈的上升，加上岩石圈的破坏，产生了大量的镁铁质和长英质岩浆，提供了足够的流体，硫，并通过推理，其他矿石成分，形成巨大的金矿省。(C)2012爱思唯尔有限公司版权所有。
Lode gold deposits in Precambrian cratons represent the world's major gold source and were mostly generated during formation and stabilization of the cratons. However, there is an extraordinary exception in the North China craton (NCC), where lode gold deposits formed after prolonged stabilization of the craton. Molybdenite Re-Os and hydrothermal sericite and biotite 40Ar/39Ar dating of major gold deposits from the Xiaoqinling district, southern NCC, bracket their emplacement in the range of 154.1 +/- 1.1 to 118.9 +/- 1.2 Ma (n=23), postdating formation of the craton by more than 1.7 billion years. Fluid inclusions extracted from gold-bearing pyrite have elevated He-3/He-4 ratios (1.52-0.22 Ra) and mantle-like Ne isotopes (Ne-20/Ne-22=10.02-9.22 and Ne-21/Ne-22=0.033-0.027), indicating presence of mantle-derived fluids in the ore system. Measured delta S-34 of pyrite and delta D and delta O-18 of hydrothermal micas and fluid inclusion waters in auriferous quartz further confirm a magmatic/mantle source for sulfur and ore fluids. Gold deposits of similar ages also widely occur in the eastern and northern margins of the NCC, which, together with those in the Xiaoqinling district, have a total reserve of similar to 2500 t gold, forming the only known giant late Mesozoic gold province in the world's Precambrian cratons. These deposits formed coevally with extensive felsic to mafic magmatism, development of intracontinental rift basins, and exhumation of metamorphic core complexes across the eastern NCC, events interpreted as indicating thinning and destruction of the lithosphere beneath the craton. Rising of asthenosphere coupled with destruction of the lithosphere has generated voluminous mafic and felsic magmas that provided sufficient fluids, sulfur and, by inference, other ore components to form the giant gold provinces. (C) 2012 Elsevier B.V. All rights reserved.