Ore-controlling Structural Characteristics of the Bankangmu Copper-Gold Deposit in Laos:Magmatic Core Complex Uplift-Detachment Zone
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 mag-matism.Despite the significant resource potential of this area,some key geological questions remain unre-solved,such as those related to ore-forming models and evolutionary processes.This paper investigates the dis-tributions 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 hydrother-mal copper-gold deposit formed in this magmatic core complex uplift-detachment zone.The magmatic core com-plex 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 grano-diorite.At the contact zone between the granodiorite-andesite and limestone in the footwall,a gneiss-like tex-ture 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 in-duced polarization measurements reveal the relationship between the mineralized zone and the magmatic core com-plex in the Bangkangmu deposit.Combined with geological survey data on the distribution of intrusions,we sug-gest 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 detach-ment 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 pa-per 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.
Bankangmu copper-gold depositmagmatic core complex upliftdetachment zone structureore-forming characteristics
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