Stratigraphic geochemistry of Upper-Middle Proterozoic Suberathem in northern Guangxi, China

Abstract

The Upper-Middle Proterozoic epimetamorphic rock series in northern Guangxi is a suite of volcanic-terrigenous clastic formations transforming in fades from mobile to stable, which is similar to Eparchean normal argillo-arenaceous sediments both in petrochemistry and in REE geochemistry. The Upper-Middle Proterozoic Suberathem in northern Guangxi is characterized by primordial enrichment of As and Sb, significant depletion in Sr and Hg, bimodal or polymodal distribution of Au and other ore-forming elements, and high variation coefficients and strong mobilities of Sn, Cu, Ni, Au, Ag, As and Sb. The trace element association is characterized by the predominance of siderophile and chalcophile elements occurring in the Middle Proterozoic and that of lithophile elements occurring in the Upper Proterozoic. It is suggested that in northern Guangxi is developed a series of ore-bearing formations with the Sibao Group as the protogenous basement and the Danzhou Group and Lower Sinian series as the derivative cap strata.