The Metallogenic Characteristics And Evolution Of Gold Deposits In Jidong Region, Hebei Province, China

Jidong region is one of the important concentrating area of gold deposits in ourcountry. Based on a lot of works for field investigation, laboratory analysis and comprehensivestudy, some new achievements have been acquired: (1) studied systematically on the Archeanmetamorphic complex rocks and divided the supracrustal rocks at the upper subgroup of Qian' xiGroup into two rock formations: Jinchangyu-Malanyu femic-felsic silicate formation and Long-wan silicon-iron formation. Jinchangyu-Malanyu femic-felsie silicate formation is the main gold-bearing formation. (2) Divided the granitoid intrusive rocks into three genetic series for thefirst time, the author thinks that the gold deposits are related to the crustal remelting grani-told. (3) Classified 147 gold deposits (occurrences) into three main types: quartz-vein-typegold deposit, altered-rock-type gold deposit and placer gold deposit. Two new deposit-styles,Dauliushui-style and Maoshan-style have been established. The characteristics of each type golddeposit has been summarized. (4) After researching into the problems such as provenance ofore-forming substance, controlling factor of gold mineralization, migrating and precipitatingmechanism of gold, the author can reach the conclusion that the various primary gold depositsin this region have the same ore-forming environments and similar genesis, and put forward anew cognition that the formation of the primary gold deposits in this region results from space-time coupling of gold-bearing formation, structure, granite and ore-forming fluid. (5) Themetallogenic chronology of gold deposits in this region have being researched systematically forthe first time. The main period of gold mineralization is Yanshanian of Mesozoic (200. 280Ma) and the high-tide period of it is 90～133Ma. (6) The evolutional law of the gold de-posits in this region has been discussed on the basis of the comprehension of the evolution ofArchean geological structure, granite and mineralization and so on.