GEOCHEMISTRY AND GENESIS OF POSTMIGMATIZATION-REFORMED GOLD DEPOSITS IN CHINA

This paper deals with the geological, minoralogieal and geoehemical characteristies of anew type of strata-bound gold deposits of postmigmatization-reformed typo occurring in theArchean metamorphic rocks of North China Platform. The integrated results of geologic stud-ics, stable and radioactive isotopic compositions, constituents in minerals inclusions and traceelement data provide evidence to show that ore-forming materials and ore-fluids are mainlyfrom Archean gold source beds, and ore bodies are the products of tectonic-hydrothermal re-forming process at the Hercynian and the Yenshanian times. By a comparison of the natureof this type to the gold deposits in Archean greenstone belts abroad, it is suggested that theyare different in genesis. Postmigmatization-reformed gold deposits are formed under specialconditions. They are mainly developed in later activation zones of platform along the westcoast of ttie Pacific Ocean. This paper presents a model for the formation of this type ofgold deposits.