Genesis and mining potential of kaolin deposits in Patagonia (Argentina)

Abstract

Kaolin occurs in Patagonia as residual (weathering or hydrothermal) deposits at the surface of an extended Jurassic rhyolite province or in the upper sedimentary Cretaceous or Danian–Paleocene layers. On the same paleogeographic surface, numerous epithermal Au–Ag lodes occur, making kaolin genesis a crucial point in mining exploration. The weathering or sedimentary genesis of some deposits (Puma, Súper, FPS, Espingarda and Marta) was confirmed through clay isotope results. The origin of some corrective clays (Bajo Grande and White Bentonite) was analyzed and compared with that of one sample from Ukraine and one from a hydrothermal deposit in Furtei, Sardinia, Italy. In Patagonia, the residual and sedimentary kaolin deposits have resources of over 12 million tons. The identified hydrothermal deposits have more limited resources, due to their strong mineralogical zonation, which requires their selective “pocket” kaolin exploitation. The Patagonian region is the southernmost part of a continent where a Gondwana paleosurface of Late Mesozoic age developed on Jurassic rhyolite volcanic units. This surface is exposed along tens of thousands square kilometers in the cratonic units of northern and southern Patagonia, having a strong potential for finding new kaolin or epithermal precious metal deposits.