Structural controls on the magma emplacement and distribution of sulfide orebodies in the Kalatongke Cu-Ni sulfide district, NW China

Abstract

Recent advances have significantly enhanced our understanding of the magma source, magma evolution, and sulfur saturation mechanisms of the Kalatongke Cu-Ni sulfide deposit in the Central Asian Orogenic Belt. However, limited systematic research has explored the structures that are critical to magma emplacement and sulfide accumulation. In this study, we perform a systematic multiscale analysis of the lithofacies distribution, morphology, and structural relationships between the northern and southern belts of the Kalatongke deposit. We propose that the emplacement and distribution of mafic intrusions and associated sulfide orebodies were controlled by fractures through syn-dextral shear deformation. The geometry of the Y1 and western Y2 intrusions and their mineralization were predominantly controlled by extensional T-fractures resulting from syn-shear deformation, whereas the eastern Y2 and Y3 intrusions were primarily governed by horizontal compressive-slip C-fractures, along with Riedel R and R’ fractures. In the northern belt, the Y7 intrusion and its mineralization were influenced by shear between two sets of horizontal fractures trending northeast, which are nearly perpendicular to the main fault orientation of the southern and northern belts. Based on the characteristics of the fractures and the distribution of orebodies across the northern and southern belts, we propose that the Kalatongke deposit was controlled by a negative flower structure, suggesting the presence of deep structural connectivity between the northern and southern belts. Moreover, the distribution pattern of the sulfide orebodies in the Kalatongke deposit was governed primarily by the structures and their associated stress regimes.