Mineralogy of the Rincón Blanco selenide occurrence, La Rioja, Argentina

[摘要] Rincón Blanco is a small selenide occurrence situated to the WNW of Jagüé, a small town of the General Sarmientodepartment, La Rioja province, Argentina. This occurrence, also called El Chire in recent years, is located (28°35'46.10"S,68°44'35.78"W, 3120 m. a. s. l.) in the Precordillera environment, to the furthermost southwestern corner of the seleniumore district of Los Llantenes, defined as one of the representative metallogenic belts of the Gondwanic episodes. Theselenide minerals occur as veinlets up to few centimeters or as patches or fine inclusions, widespread in calcite. We haveidentified eleven hypogene Se-bearing minerals (naumannite, tiemannite, chrisstanleyite, jagüéite, eucairite, clausthalite,fischesserite, umangite, athabascaite, berzelianite and bellidoite) mainly associated with gold, silver, hematite and varioussupergene minerals, including malachite, chalcomenite, and molybdomenite. The paragenesis should have formed fromlow temperature (< 133°C), neutral to mildly alkaline pH and highly oxidizing fluids with increasing sulfur fugacity. Thecountry-rock, rich in graptolite-fauna, could be considered, at least in part, the source for the Se and associated metalsforming the minerals of this paragenesis, although this hypothesis has yet to be tested.

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[关键词] selenide mineralization;chrisstanleyite;jagüéite;fischesserite;gold;Rincón Blanco;La Rioja;Argentina