Abstract:

The Bankangmu copper-gold deposit, located in the tectonically active zone at the southern margin of the Simao-Phetchabun block in Southeast Asia, is a large copper-gold deposit associated with Mesozoic magmatism.Despite the significant resource potential of this area, some key geological questions remain unresolved, such as those related to ore-forming models and evolutionary processes.This paper investigates the distributions of ore-forming intrusions, fault structure deformation features, and ore-forming characteristics within the detachment zone to reveal the uplift features of the magmatic core complex and the structural characteristics of the deposit in this zone.This study posits that the Bankangmu deposit is controlled by the structure of the “magmatic core complex” and its boundaries within the uplift-detachment zone, categorizing it as a hydrothermal copper-gold deposit formed in this magmatic core complex uplift-detachment zone.The magmatic core complex structure of the Bankangmu deposit consists of three parts: the magmatic complex core, the detachment zone structure, and the volcanic-sedimentary rocks.The magmatic complex core is mainly composed of granodiorite.At the contact zone between the granodiorite-andesite and limestone in the footwall, a gneiss-like texture has developed.The foliation, centered on the core granodiorite, exhibits an outward dip and is inferred to have formed under regional compressive shear stress during the magmatic intrusion processes.Magnetic and induced polarization measurements reveal the relationship between the mineralized zone and the magmatic core complex in the Bangkangmu deposit.Combined with geological survey data on the distribution of intrusions, we suggest that there is a concealed intrusion deeper whithin the structure.The detachment zone structure, developed between the footwall granodiorite and the hanging wall volcanic-sedimentary rocks, is the focal area for copper-gold mineralization.The formation age of the mineralized alteration rocks in the detachment zone (244-251 Ma) is younger than the emplacement age of the complex (264±10 Ma).Observations and analyses of the detachment zone structure and small-scale structures on both sides indicate that the detachment zone exhibits a shovel-shaped morphology in cross-section.It is characterized by distinct early ductile deformation followed by later brittle deformation, with the main movement direction of the hanging wall being NWW.Consequently, this paper suggests that the southeastern part of the Bankangmu copper-gold deposit also exhibits characteristics of the magmatic core complex uplift-detachment zone ore-forming pattern, making it a potential target for exploration.

Key words: Bankangmu copper-gold deposit, magmatic core complex uplift, detachment zone structure, ore-forming characteristics