PRELIMINARY ANALYSIS ON THE ORE-CONTROLLING CONDITIONS OF GOLD (SILVER)DEPOSITS IN NORTHERN HEBEI(BEIJING-TIANJIN)REGION

The metallogenesis of the gold (silver) deposits in Northern Hebei (Beijing-Tianjin) region is mainly controlled by old domes and long-lasting active E-W-trending deep faults. Quite a few gold-silver-polymetal mineralization concentrating areas are formed in the intersections of the E-W-trending and NE-trending deep faults, which are developed inside and on the rims of the domes. The metallogenesis of the gold (silver) deposits is closely related to Yanshanian magmatism, followed by Hercynian magmatism. The gold (silver) mineralization commonly occurs around or between the acid-intermediate intrusive bodies. The Au (Ag) background values are generally high in the amphibolitic rocks of the Archean metamorphic series, which is the main source bed of the region. Amphibolite facies is the major Au (-Ag)-bearing lithofacies. The gold metallogenesis are superimposed in multiple epochs, mainly Hercynian and Yanshanian. The latter is more important, as the major regional Au, Ag, Cu, Pb and Zn metallogenic period.