Metallogeny of the southern Sierras Pampeanas, Argentina: geological, ⁴⁰Ar–³⁹Ar dating and stable isotope evidence for Devonian Au, Ag–Pb–Zn and W ore formation

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• 作者：Skirrow ; R.G. ; Camacho ; A. ; et. al.
• 关键词：metallogeny ; southern Sierras Pampeanas ; Argentina ; ⁴⁰Ar&ndash ; ³⁹Ar
• 刊名：Ore Geology Reviews
• 出版年：2000
• 出版时间：September, 2000
• 年：2000
• 卷：17
• 期：1-2
• 页码：39-81
• 全文大小：3.09 M

文摘

Early to mid-Paleozoic metamorphic and igneous rocks of the southern Sierras Pampeanas tectono-stratigraphic terrane, northwestern Argentina, host diverse metallic mineral deposits of Au, Ni–Cu, Ag–Pb–Zn, W, Li, Be, Nb, LREE and Th. Integration of deposit geology, ⁴⁰Ar–³⁹Ar geochronology and stable isotope studies with regional geological mapping and U–Pb zircon dating, has led to the resolution of three principal metallogenic epochs. Ordovician intrusion-hosted Ni–Cu sulfide deposits and rare-metal-enriched pegmatites were succeeded by a province-wide metallogenic epoch and concurrent tectonic processes during the Devonian. This epoch was characterized by mesothermal lode Au deposits, high-level Ag–Pb–Zn veins, W±Cu-bearing veins and replacements, and various pegmatite- and granite-related lithophile element deposits. Finally, Miocene–Pliocene epithermal Au–Ag mineralization developed during Andean tectonic events. Sericitic alteration associated with mesothermal lode Au (±Cu±Ag) in the Sierra de Las Minas and Sierras de Córdoba yields Devonian ⁴⁰Ar–³⁹Ar step heating ages in the ranges 382–393 and 351–378 Ma, respectively. These ages span the timing of Ag–Pb–Zn sulfide–quartz veining in the El Guaico district (386±4 Ma, sericite), and W-bearing quartz vein mineralization in the Aguas de Ramón and El Morro districts which yielded muscovite ages of 366±1 and 363±1 Ma, respectively. Oxygen isotope δ¹⁸O_SMOW compositions of the Au, Ag–Pb–Zn and W ore-forming fluids, calculated from quartz, white mica and chlorite isotope ratios, range from 5.2‰ to 10.8‰ (n