Deep-seated structure and metallogenic dynamics of the Ailaoshan polymetallic mineralization concentration area, Yunnan Province, China

摘要

The Ailaoshan poly-metallic mineralization concentrated area (MCA) consists of the well known Ailaoshan metallogenic belt and adjacent mineral districts and/or deposits. Located in an area of several complex and intersecting tectonic units, the Ailaoshan poly-metallic MCA is controlled by deep crustal and mantle tectonism. Through interpretation of remote sensing images, we identified a large ring structure system that surrounds the MCA. This ring structure encloses regional deep-crustal faults, ductile shear zones, geothermal anomalies, magmatic rocks, and the major mineral deposits, all of which are the reflections of deep tectonic geodynamics that have been long active in this area. Geophysical data indicate that the crust is comprised of relatively stable two or three layers, with some irregular lower-velocity belts. The Moho in the ring sutures occurs as an area of local uplift. There exists an obvious transitional zone between the crust and mantle boundaries. Asthenopheric mantle shows multi-layer upwelling, which indicates multiple events during different geological epochs. It is believed that these mantle events or pulses were responsible for the formation of the regional shear zones, magmatic rocks, and polymetallic orebodies. Furthermore, an integrated metallogenic dynamics model related to the asthenopheric upwelling pulses in the MCA is established, defining events as old as Late Paleozoic.