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Abstract
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The Takab-Angouran gold province, with more than 500 t of proven gold resources, is unique in that its Cenozoic gold deposits are hosted in a Precambrian-Miocene volcano- sedimentary rocks. 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 Takab-Angouran 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 Cenozoic magmatic systems show that Late Paleocene breakoff of the subduction slab and rollback of the Afro-Arabian Plate caused asthenosphere upwelling and lithosphere extension and thinning. Robust geochronological studies demonstrate that the Takab-Angouran gold deposits formed at ca. 14 Ma during a change of subduction direction of the Afro-Arabian 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. The Takab-Angouran gold deposits, although commonly hosted in Precambrian Chaldagh limestone, clearly post-date them on the basis of robust and reliable geochronology. The spatial but non-temporal relationships of gold deposits with Precambrian limestone, their strong structural control, and their other characteristics clearly place them in the distal disseminated gold class. It is suggested, because of their uniqueness, that they be termed "Zarshuran-type" distal disseminated gold system (DDGS).
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