New geochronological data provide evidence for Permo-Triassic low-sulfidation epithermal gold-silver mineralization in the Cordillera Frontal, Argentina. The U-Pb sensitive high-resolution ion microprobe (SHRIMP) analyses on zircons and titanite gave the following results: (1) andesite and rhyolite volcanic host rocks of the Casposo Au-Ag deposit yielded a range of ages between 267.1 ± 0.7 and 241.7 ± 2.2 Ma; (2) two composite plutons located near Casposo yielded ages of 268.2 ± 1.5 and 265.1 ± 1.5 Ma for the Colorado syenogranite-granite pluton and 266.6 ± 1.4 and 254.0 ± 2.4 Ma for the Casposo granodiorite-tonalite pluton; (3) a trachyandesite dike emplaced at 265.7 ± 1.2 Ma that is crosscut by mineralized quartz-adularia-calcite-gold veins in the Kamila East area; (4) felsite intrusions, interpreted to be temporally related to the emplacement of mineralized veins at 261.1 ± 3.5 Ma; and (5) composite rhyolite/andesite dikes that crosscut all other lithostratigraphic units and mineralized veins at 238.4 ± 1.6 Ma. The ⁴⁰Ar/³⁹Ar dates on hydrothermal adularia within quartz-adularia-calcite-gold veins of the Casposo deposit revealed at least three, likely discreet, hydro-thermal fluid pulses and associated periods of vein formation during extensional events between 280–274, 262–258, and 250–246 Ma.Relative and absolute timing of volcanic host rocks, plutons, postmineralization felsic dikes, and gold-bearing veins of the Casposo epithermal vein system suggest the presence of significant Permian (Cisuralian)-Lower Triassic low-sulfidation epithermal-style gold-silver mineralization at the eastern flank of the Cordillera Principal in Argentina. The existence of this epithermal Au-Ag system opens the potential for a significant magmatic-hydrothermal system in a part of the Andes that previously was considered to be of low prospectivity.

中文翻译：

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CASPOSO金银矿床：阿根廷圣胡安省科尔迪拉拉山地二叠系低硫表皮成矿作用的证据

新的年代学数据为阿根廷Cordillera Frontal的Permo-Triassic低硫化超热金银矿化提供了证据。U-Pb敏感的高分辨率离子微探针（SHRIMP）对锆石和钛矿的分析得出以下结果：（1）Casposo Au-Ag矿床的安山岩和流纹岩火山岩主岩的年龄范围为267.1±0.7至241.7 ±2.2毫安; （2）位于卡斯波索附近的两个复合体俯冲的年龄为：科罗拉多正长花岗岩-花岗岩体的年龄为268.2±1.5和265.1±1.5 Ma，而卡斯波索花岗闪长岩-tonalite岩体的年龄为266.6±1.4和254.0±2.4 Ma；（3）位于卡米拉东部地区的一条砂砾岩型堤坝，位于矿化的石英-阿杜利亚-方解石-金矿脉中，横穿位置为265.7±1.2 Ma；（4）恶魔入侵，解释为在时间上与261.1±3.5 Ma的矿化脉的位置有关；（5）流纹岩/安山岩复合堤防在238.4±1.6 Ma处横切了所有其他岩石地层单元和矿化脉。这⁴⁰氩/ ³⁹在卡斯波索矿床的石英-阿达拉斯-方解石-金矿脉中的热液阿德里亚上的Ar日期揭示了在280-274、262-258和280-240之间的扩张事件期间，至少有三个可能的离散的热液脉动和相关的静脉形成时期。 250–246 Ma.Casposo超热脉系统的火山岩，岩体，矿化后的长笛岩和含金脉的相对和绝对时间表明存在显着的二叠纪（Cisuralian）-下三叠统低硫化低热型金-阿根廷科尔迪勒拉校长东部侧面的银矿化。这种超热金-银系统的存在为安第斯山脉的一部分以前被认为是低前景的重要岩浆-热液系统打开了潜力。