Tectonic-Mineralization Evolution Model of the Xiazhuang Uranium Ore Field, Northern Guangdong, showing the evolution of fault structures controlled the occurrence of different ore-body types in the deposit. The regional was under approximate NS stress, deep Indosinian magma emplaced during 230 210 Ma (Stage I). It changed to approximate EW stress during 210-170Ma, with early regional uplift and erosion, and the emplacement of Yanshanian magmatic (Stage II). During 170–140 Ma, the regional stress direction changed to NW-SE, with the intrusion of NWW-trending diabase dikes, and it changed to regional extensional deformation during 140-115Ma, combining with the formation of Cretaceous red bed basins (Stage III). First stage uranium orebodies formed within the NWW fault zone (Stage IV). The later stage (105Ma to 65 Ma) of large-scale uranium ore bodies within both the NNE and NEE direction fault zones, and the also formation of intersection-type orebodies, under a regional extensional tectonic background again (Stage V). Form 65 Ma to present time, it was probably approximate NS compression, causing regional uplift and erosion, and outcrop of ore-bodies (Stage VI). In this figure:1-main NNE-trending faults; 2-main NEE-trending faults; 3-main NWW trending faults. • The major faults in three different directions have undergone multi-phase tectonic evolution. • The Xiazhuang ore field experienced three periods and eight episodes of tectonic evolution during the Meso-Cenozoic eras. • The evolution of fault structures controlled the occurrence of different ore-body types in the deposit. The Xiazhuang uranium ore field in South China is a large-scale granite-type uranium ore field, yet the role of fault structures in controlling uranium mineralization remains controversial. Based on detailed field observations of fault striations (n > 250) and conjugate joints (n = 6), this study analyzes the multi-stage evolution of three fault sets (NWW, NNE, NEE) and inverts the Meso-Cenozoic tectonic stress field using Wulff net projection, to discuss how changes in mechanical properties control mineralization. It is inferred that the NWW-trending faults formed earliest and experienced multiple mechanical transitions. The NNE-trending faults controlled hydrothermal activity, evolving from compression to extension (during mineralization) to transtensional strike-slip. The NEE-trending faults controlled magmatic emplacement and post-mineralization uplift. The tectonic stress field evolution is divided into three periods and eight episodes: two pre-mineralization, four syn -mineralization, and two post-mineralization stages. The NWW-trending structural zone controlled early-stage mineralization, whereas the NNE- and NEE-trending fault zones controlled late-stage mineralization. Local superposition of these episodes forms rich orebodies. A tectonic stress field-mineralization model is constructed to guide regional exploration.
CHEN et al. (Fri,) studied this question.