Spatial coupling relationship between faults and gold deposits in the Jiaodong ore concentration area and the effect of thermal doming-extension on mineralisation

Abstract

As the third largest gold ore-forming province in the world, the deep metallogenic potential of and exploration strategies for Jiaodong gold deposits have attracted substantial attention. By applying three-dimensional (3D) geological modelling to these super-giant and giant gold deposits, this study reveals the 3D morphological characteristics of the ore-bearing faults and the ore-related granites, analyses the relationships between ore body locations and slope dip angle changes in the faults, and discusses the coupling relationships among gold mineralisation, ore-controlling faults, and magmatic activities. In the 3D model, the dip angles of ore-controlling faults gradually decrease downwards and alternate between steep and gentle along the fault dip direction. The ore bodies mainly occur in areas with relatively high fault-dip-angle change rates. Hence, positions with fault dip angles of 20°–50° and change rates of ≥0.91 should be considered as target areas for prospecting deep gold ore bodies. In-depth analysis suggests that the ore-hosting faults, granites, and gold mineralisation resulted from regional thermal doming and extensional movements. Gold ore bodies in the Jiaodong Peninsula occur inside or on the periphery of Mesozoic granite. Strong magmatic activities during the transition from enriched to depleted mantle provided the necessary metallogenic and thermal dynamic environment for gold mineralisation. In particular, the magmatic evolution provided abundant ore-forming materials. The detachment faults with varied dip angles provided favourable space for gold mineralisation, as the fluctuations of ore-forming fluid pressure caused by sudden changes in these dip angles served as the primary mechanism underlying the step-like gold mineralisation pattern.