A Metallogenic Model of Gold Deposits of the Jiaodong Granite‐Greenstone Belt

Abstract

An analysis of trace elements and isotopic geochemistry suggest that the ore‐forming materials of gold deposits in the Jiaodong granite‐greenstone belt have multiple sources, especially the mantle source. Seismic wave, magnetic and gravity fields show that the crust‐mantle structure and its coupling mechanism are the fundamental dynamic causes for the exchange and accumulation of materials and energy in the metallogenic system. Considering the evolution history of the structural setting, the tectono‐metallogenic dynamics model of the area can be summarized as follows: (1) occurrence of the greenstone belt during the Archean‐Proterozoic—the embryonic form of Au‐source system; (2) stable tectonic setting in the Paleozoic—an intermittence in gold mineralization; (3) intensive activation and reformation of the greenstone belt in the Mesozoic—tectono‐mineralization and tectono‐diagensis; (4) posthumous structural activity in the Cenozoic—destruction of orebodies in the later stage. In the middle and late Indosinian, the Tancheng‐Lujiang fault zone cut deeply into the upper mantle so that the ore‐bearing fluids migrated to higher layers through the crust‐mantle interaction, resulting in alteration and mineralization.

Quantifying Fractal Dynamics of Metallogenic Systems with Detrended Fluctuation Analysis

“…Based on the grades, taking cut-off grade as 2 g/t, block cut-off as 2.8 g/t and minimum true thickness as 1.2m, the geometry of orebodies is defined. The drifts can be categorized into various mineralization ranks according to development of the orebodies as follows: non-mineralized areas(NM), where the grades are less than the cutoff grade 2 g/t; weakly mineralized areas(WM), where the grades are rarely greater than 2 g/t, the orebodies are barely developed; and intensely mineralized areas (IM), where the grades are greater than the cut-off and the orebodies are huge or continuous in the sample range [11][12][13].…”