Geological characteristics of the Sizhuang gold deposit in the region of Jiaodong, Shandong Province—A study on tectono-geochemical ore prospecting of ore deposits

Abstract

Tectono-geochemical samples were systematically collected from 5 drillcores along the No. 304 exploration line and at the −310 m level under the pit in the mining area, totalling 705 samples from the metamorphic rocks, granites, altered rocks and orebodies, and were determined for their contents of 20 kinds of elements including Au, Ag, As, Sb, Hg, Cu,-Pb, Zn, Sn, Bi, Mo, Co, Ni, Mn, Cr, V, Ti, Ba, Rb, Sr, etc. By using the Surfer software the geochemical exploration line profile maps for the 20 kinds of elements and the curves for the element geochemical contents of individual ore vein groups were established. In conbination with the geochemical map analytical method and Gregorian’s zoning index calculation method, the vertical, longitudinal and lateral zonation sequences of the elements were ascertained and the geochemical three-dimentional zonation model of the primary halos was established on the basis of the analysis of metallogenic structures and alteration zonation. Coupled with the results of analysis of the geology and geochemistry data, it may be concluded that the process of alteration of granites in the mining area is also accompanied with the process of gold enrichment and mineralization. With the intensification of alteration of granites from granite →potash feldspathization granite →sericite-quartz alteration granite, sericite-quartz rocks →beresitized granite, pyrite sericite-quartz rock, silicified granite →gold ore, the contents of thiophile ore-forming elements such as Au, Ag, As, Cu, Bi, Mo, Pb, Sb, Hg, and Sn tended to increase. Factor analysis of trace elements indicated: factor F2 (Au, Ag, Cu, Sn, As) represents the element association brought in at the main stage of hydrothermal metallogenesis; factor F4 (Bi, Sb) and factor F5 (Pb, Zn) represent the ore-forming element association supperposed during the late stage of Au-bearing sulfides. By using the Gregorian’s zoning index and map analysis method we have ascertained the primary halo axial zonation sequence (form frontal halo →tail halo): Pb, Zn, Mn, Ba, Sr, Rb, As, Sb, Ag, Cu, Sn, Mo, Au, Bi, Hg, Ti, Cr, V, Ni, and Co. The geochemical anomalies in the mining area display a tendency of lateral plunging to WS, which is consistent with the lateral plunging of orebodies and mineralization alteration zone. Comprehensive analysis of the results of investigations on ore-controlling structures, mineralization-alteration zonation and geochemical zonation of the primary halos indicates that the gold orebodies in this area are still of greater extension.