Abstract:

The Jinchuan giant Cu-Ni sulfide deposit in Gansu formed during the Neoproterozoic.From the initial emplacement of its parent magma to subsequent tectonic superposition, this deposit has undergone a complex geological evolution.Despite the fact that many previous studies have been conducted, significant controversy regarding the tectonics of the deposits still remains.Furthermore, it is of great significance to clarify the rock- and ore-controlling structures for magma intrusion and its emplacement processes, as well as to prospect for ore deposits at depths.In this study, we analyzed the stress field based on the classification, correlation, cross-cutting relationships, and chronological sequence of structures in the deposit area, using nodal production statistics.In the end, we determined three primary compressive stress directions: N-S, NE-SW, and NNE-SSW.Finally, by integrating regional and mining tectonics, we concluded that there are six stages of tectonic evolution in the Longshoushan area: Lüliang, Jinning, Caledonian, Hercynian, Yanshan, and Himalayan.We also established a model of tectonic evolution for the Jinchuan Cu-Ni sulfide deposit, including the pre-, syn-, and post-mineralization stages.The model for the tectonic evolution of the Jinchuan Cu-Ni sulfide deposit illustrates the emplacement of parental magma to form the deposit, providing new insights into mineral prospecting in both within the deposit and in its periphery.

Key words: Jinchuan, Gansu, Cu-Ni sulfide deposit, tectonic resolution, tectonic evolution