Magmatic and tectonic crustal accretion at the Southwest Indian Ridge between 49°E and 52°E
At slow-ultraslow spreading mid-ocean ridges,crustal accretion style can vary significantly along and across ridge segments.In magma-poor regions or periods,seafloor spreading can be accommodated largely by tectonic processes.However,the tectonic and magmatic characteristics and formation mechanism of such highly tectonized crust are not fully understood.In this study,we utilized the high-resolution shipboard multibeam bathymetry and gravity data to investigate the tectonic and magmatic crustal accretion of the Southwest Indian Ridge(SWIR)between 49°E and 52°E.The results show that the processes of crustal accretion and magma activity in the study area have undergone significant spatial and temporal changes.Based on the terrain slope,curvature,and roughness characteristics of the study area,three main geomorphic patterns were identified:volcanic,fault,and sedimentary geomorphology,along with three fault types:C-type,E-type,and detachment faults.The proportion of tectonic extension in the entire spreading process,referred to as the strain ratio(T-value),was calculated along the profile perpendicular to the ridge axis,which indirectly provided the value of magma accretion rate(M-value)as(1-T).Asymmetric crustal accretion regions exhibit significant differences in terms of water depth,T-value,and geomorphic features on both sides.Furthermore,there is a good correlation between T-value,geomorphic features,and particularly fault types,and the variations in magma supply reflected by the residual mantle Bouguer gravity anomaly(RMBA)in the along-axis direction.In regions with insufficient magma supply,thinner oceanic crust is typically produced,with a larger T-value and detachment faults and E-type faults with large horizontal fault heaves are mostly developed;In regions with sufficient magma supply,thicker oceanic crust is usually produced,with a small T-value and C-type faults with small horizontal fault offsets are mostly developed.
Southwest Indian RidgeMultibeam bathymetryTectonismMagmatism
万方数据
维普
