摘要
Polymetallic sulfides present in mid-ocean ridges(MORs)have become important strategic resources for humans,and a scientific metallogenic model is necessary for the investigation and exploration of these resources.Compared to fast-and slow-spreading MORs,ultraslow-spreading MORs show substantial differences in magma supply,tectonic activity,and oceanic crust structures.However,information on hydrothermal circulation and a metallogenic model related to sulfides along the ultraslow-spreading ridges is still limited,which hinders further exploration of these resources.In this study,the distribution of hydrothermal activities,as well as the characteristics of the structures,heat sources,fluid pathways,host rock types,fluid properties,and sulfide assemblages in typical hydrothermal fields along the ultraslow-spreading Southwest Indian Ridge(SWIR),have been studied.It is concluded that the hydrothermal systems along the SWIR can be categorized into three types,including local enhanced magma-controlled,one-way detachment/high-angle large-offset fault-controlled,and flip-flop detachment-controlled types,which are further categorized into five subtypes based on their distinct geological backgrounds.Herein,we present a sulfide metallogenic model called Local Enhanced Heat Supply-Deep Faults(eHeat-dFault)for the SWIR.The overall spreading rate remains almost constant(14-18 mm/year),while the magma supply is heterogeneous in the segment scale along the SWIR.Over the past two decades,various hydrothermal systems and sulfide deposits have been identified along the SWIR.A deep magma chamber(4-9 km)is developed in the ridge segment with sufficient magma supply owing to the local enhanced magma supply,while long-lived active deep detachment faults(up to 13 km)with associated metallogenic belts are developed in ridge segments with poor magma supply.Hence,the ultraslow-spreading MORs fulfill the necessary conditions of a sustained heat source and stable hydrothermal pathway for the formation of large-scale polymetallic sulfide depo
基金
supported by the National Key Research and Development Program(Grant No.2022YFE0140200)
the National Major Research Instrument Development Project of the National Natural Science Foundation of China(Grant No.42127807)
the Key Research and Development Program of Zhejiang Province(Grant No.2021C03016)
the China Ocean Mineral Resources R&D Association(COMRA)“the 13th Five-year”Project(Grant No.DY135-S1-1).
