Authigenetic K-feldspars and Their Relations to Sn-Polymetallic Mineralization in the Dachang Ore Field.

摘要

Sn-polymetallic ores at Dachang, Guangxi Autonomous Region, China, are hosted in Middle-Upper Devonian reef limestones, siliceous rocks, and banded and lenticular limestones. Two types of orebodies can be distinguished according to their relations to the bedding. One is distributed along the bedding and the other cuts across the bedding. Sn and sulfide orebodies associated with K-feldspars are mostly characterized by laminated ore structure. Microscopic examinations of K-feldspar-bearing rocks, in conjunction with X-ray diffraction, chemical composition and cathodoluminescence data for K-feldspars, as well as their relations to mineralization, the authors consider that the K-feldspars are of authigenic origin, subordinate to the epigenetic stage of diagenesis. They resulted from the reaction of mixed, deep-seated, circulating underground hot waters rich in K, Al and Si with argillaceous carbonates during the Indonesian orogenic movement.