Quantifying the influence of magmatism and tectonism on ultraslow-spreading-ridge hydrothermal activity:Evidence from the Southwest Indian Ridge  

作　　者：Xing Xu Shili Liao Chunhui Tao Lushi Liu 

机构地区：[1]School of Oceanography,Shanghai Jiaotong University,Shanghai 200030,China [2]Key Laboratory of Submarine Geosciences,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China [3]Northeast Institute of Geography and Agroecology,CAS,Changchun 130102,China

出　　处：《Geoscience Frontiers》2023年第5期39-54,共16页地学前缘（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.42127807);Key Research and Development Program of Zhejiang Province(Grant No.2021C03016);Scientific Research Fund of the Second Institute of Oceanography,MNR(Grant No.SZ2201);China Ocean Mineral Resources R&D Association Project(Grant No.DY135-S1-1-01).

摘　　要：Hydrothermal activity in mid-ocean ridges(MORs)is an important intermediary for the mass and heat exchange between the ocean and lithosphere.The development of hydrothermal activity on MORs is primarily controlled by coupled magmatic and tectonic activities.In ultraslow-spreading ridges,deepdipping low-angle normal faults with large offsets,typically detachment faults in the inside corners of ridge offsets,favor the formation of tectonic-related hydrothermal activities,whereas volcanic-related hydrothermal fields are typically developed in neovolcanic zones in this category of the ridge system.However,whether tectonic or magmatic activity is dominant and to what extent they control the formation of hydrothermal activities on ultraslow-spreading ridges remain unclear.Segments in the west and east of the Gallieni transform fault(TF)located in the ultraslow-spreading Southwest Indian Ridge(SWIR),namely,western area(WA)and eastern area(EA),exhibit distinct magma-supply conditions that provide favorable conditions for examining the influence of magmatic and tectonic activities.We generated prediction models for these areas using the spatial analysis of the water depth,minor faults,large faults,ridge axis,nontransform discontinuity(NTD)inside corners,TF inside corners,Bouguer gravity anomaly,magnetic anomalies,and seismic activities.By employing the weights of evidence method,we reported that the formation of seafloor hydrothermal systems in SWIR was primarily correlated to the NTD inside corner,ridge axis,and minor fault(i.e.,contrast values(C)of 4.186,3.727,and 3.482 in WA and 4.278,3.769,and 3.135 in EA).Furthermore,EA was significantly affected by the TF inside corner(C=3.501),whereas WA was influenced by large faults(C=4.062).Our results demonstrated that tectonism was the primary controlling factor in the development of hydrothermal activities in the study area,and the contribution of magmatism was secondary,even in WA,which has a relatively robust magma supply.We delimited prominent prospecting areas at each sid

关 键 词：Southwest Indian Ridge Hydrothermal activity Weights of evidence Spatial analysis Magmatism and tectonism 

分 类 号：P736.4[天文地球—海洋地质]