GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF GOLD IN THE GREENSTONE BELT OF XINTAI AREA,SHANDONG

The principal characteristics, structures and their evolution regularity of the greenstone belt of Xintai area are summerised. It is considered that the granitoid rocks were formed as mantle materials were upwelling and the greenstone belt were partially remelted. Coefficient K is got as 0.37 and used as a standard for correlating komatiites in Archean greenstone belts. Initial abundance of gold in the komatiite is 5.79 ppb in western belt and 2.37 ppb in eastern belt, suggesting inequality of gold content in the primitive mantle of this area in Archean. The atatistics of various rock types, stratigraphic units, granitoid rocks and their dikes in the greenstone belt witharithmetic and geometric mean show that increasing of variation coefficient of some rocks is favorable to dispersion and concentration of gold. Geological and geoc-hemical characteristics of gold-mineralization and halo mechanism is discu-ssed.It is recognized that in surficial gold mineralization zone the elements in passitive correlation with gold are Ag, As, Sb, Pb, Zn and in negative correlation with gold are Cu and Hg; in deep gold mineralization zone only element Sb is of passitive correlation with gold while the gold correlation coefficient of elements Ag, As, Hg, Cu, Pb, Zn is tending towards zero. Discussing genesis of greenstone type gold deposits in this area, the author proposes a metamorphic-magmatic-hydrothermal filling alterating minerogenetic mo-del and outlines preliminarily the ore-searching area.