Placer Gold Deposits

Abstract

Placer gold deposits are abundant in Mongolia and form through endogenic and exogenic processes. Deposits are classified into four major genetic types: (1) eluvial-weathering zone, (2) deluvial, (3) proluvial, and (4) alluvial. The most economic deposits are often sourced from upper Cretaceous rocks and formed in late Cenozoic alluvial fans (Liskun and Badamgarav, Kaynozoyskaya litologiya Mongolii (Cenozoic lithology of Mongolia). In: Proceedings of Joint Russian-Mongolian Geological Expedition. Nauka, p 160; 1977). Carboniferous, upper Permian, upper Jurassic, and lower to upper Cretaceous conglomeratic successions also act as an intermediate supply. Distribution of these deposits is reflected in comprehensive geomorphological studies and follows mountainous regions of Altai, Khangai, and Khentii ranges of Mongolia. Surrounding these mountains, proluvial-alluvial type placer gold deposits are formed and change to more proluvial type in dry and hot climate. In terms of primary gold mineralization zones, Mongolian territory is divided into (1) Khangai- Khentii, (2) Altai, (3) Gobi, Southern Mongolia, and (4) Eastern Tenger mountain zones. Representative primary gold mineralization types are gold-quartz, gold-quartz sulfide, gold-skarn, and gold-silver.