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An integrated mineral system model for the gold deposits of the giant Jiaodong province, eastern China
Earth-Science Reviews ( IF 12.1 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.earscirev.2020.103274 Jun Deng , Li-Qiang Yang , David I. Groves , Liang Zhang , Kun-Feng Qiu , Qing-Fei Wang
Earth-Science Reviews ( IF 12.1 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.earscirev.2020.103274 Jun Deng , Li-Qiang Yang , David I. Groves , Liang Zhang , Kun-Feng Qiu , Qing-Fei Wang
Abstract The giant Jiaodong gold province, with more than 5000 t of proven gold resources, is unique in that its Mesozoic gold deposits are hosted in a Precambrian basement block. There has long been debate on the source of gold, the mechanism for its extreme enrichment, and a holistic genetic model for these spectacular deposits. In order to improve understanding of these factors, a mineral-system model is proposed for the Jiaodong gold deposits for the first time. It is based on a detailed review of the architecture and composition of the underlying mantle lithosphere, the geodynamic setting at the time of gold mineralization, the geological and geochemical features of the deposits themselves, and mechanisms of their preservation. Regional geodynamic reconstructions, combined with the nature of Mesozoic magmatic systems show that Late Mesozoic breakoff of the subduction slab and rollback of the paleo-Pacific Plate caused asthenosphere upwelling and lithosphere extension and thinning. Robust geochronological studies demonstrate that the Jiaodong gold deposits formed at ca. 120 Ma during a change of subduction direction of the paleo-Pacific Plate and the synchronous transition of tectonic regime from regional compression to transpression or transtension prior to peak extension caused by thinning of the lithosphere. Geophysical exploration data and Hf-Nd isotope mapping of the Jiaodong Peninsula reveal a relatively simple ancient crustal structure cut by near-vertical shear or fault zones, including the lithosphere-scale Tan-Lu and Wulian-Yantai Faults, that provided the first-order architecture for emplacement of mantle magmas and sub-crustal fluids. In terms of fertility, the significant older pre-mineralization crustal metamorphism, combined with sulfur, lead and strontium isotope ratios, indicate a dominant sub-crustal source for the ore components for the Jiaodong gold deposits, consistent with evidence for volatile- and gold-fertilized metasomatized mantle lithosphere beneath the North China Block. Helium-Ar and C-O isotope ratios implicate mantle sources of ore fluids with contamination by crustal components en-route to crustal depositional sites. In terms of crustal architecture, combined geophysical, structural, mineralogical, fluid inclusion, and geochemical studies show that the deeply-sourced ore-fluids and metals advected upwards through lithosphere-scale faults to deposit gold via sulfidation and phase separation in crustal-scale NNE-NE-trending fault systems at mid- to upper-crustal levels. Preservation of disseminated- to stockwork-style deposits and auriferous quartz-pyrite vein deposits was enhanced by deep crustal formation combined with limited uplift and exhumation of the province. The Jiaodong gold deposits, although commonly hosted in granite intrusions, clearly post-date them on the basis of robust and reliable geochronology. The spatial but non-temporal relationships of gold deposits with granites, their strong structural control, and their other characteristics clearly place them in the orogenic gold group. It is suggested, because of their uniqueness, that they be termed ‘Jiaodong-type’ orogenic gold deposits.
更新日期：2020-09-01
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