Ore-controlling structure and its control over gold mineralization in the Baolun gold deposit, Hainan

Abstract：The Baolun gold deposit, as one of the large gold deposits found in Hainan Province recently, is a structurally controlled, magmatic-hydrothermal gold deposit formed in the Indosinian. In the gold district there outcrop the Lower Silurian Tuolie Formation low-grade metamorphic series and Indosinian red clastic rocks, and in addition Indosinian granite is distributed on its northwest side. The NNE-trending Haogangling fault and the NNW-trending fracture zone in the hanging wall of the fault form the basic structural framework of the ore district. Magnetic fabric analysis indicates that： flattening deformation predominates in phyllite of the district； the principal compressive stress is oriented in a nearly E-W direction； the structural deformation was stronger before the mineralization thermal event and weaker after mineralization. The structural stress field in the mineralization stage is featured by E-W extension (the principal compressive stress was oriented in a N-S direction). The NNW-trending fracture zone is the main ore-hosting (ore-bearing) structure, which exerts an important controlling effect on the shape, attitude, scale and special distribution of the gold orebodies.