Magmato-tectonic mechanism of Southwest Indian Ridge (49°-50°E) inferred from quantitative morphotectonic analysis based on high-resolution multibeam bathymetry

• Published in: Marine geology 2021-04, Vol.434, p.106421, Article 106421
• Main Authors: Xu, Yaochen, Chen, Ninghua, Tao, Chunhui, Chen, Jianyu, Gao, Bowen
• Format: Article
• Language: English
• Subjects: Asymmetric spreading; Magmato-tectonic mechanism; Quantitative geomorphology; Southwest Indian Ridge; Ultra-slow spreading ridge
• ISSN: 0025-3227
• DOI: 10.1016/j.margeo.2021.106421

Southwest Indian Ridge (SWIR) is a typical ultra-slow spreading ridge which has been extensively studied based on geophysical survey, geochemical sampling and morphological feature extraction. In this paper, based on the high-resolution multibeam bathymetric data, we extract seven types of topography, including fault, axial rift, axial volcanic ridge (AVR), axial trough, AVR's remnant, volcanic cone and oceanic core complex (OCC). We perform quantitative morphotectonic statistic, verifying the relations between the topography and magmato-tectonic mechanism of SWIR 49–50°E. The analyzed results of flank topography show that the average seafloor depth of the southern flank is shallower than that of the northern flank. The Total Cumulative Length of the faults in the northern and southern flank is 624.6 km and 948.2 km. The number, Total density, Average Length and Maximum Length of the faults in the southern flank are higher than those in the northern flank. An OCC and detachment faults locate in the southern flank. The asymmetry in flank topography indicates the asymmetric spreading mode of the study area. The analyzed results of the axial topography show that AVRs and troughs develop in the rift. The rift is narrower and shallower in the AVR regions, and wider and deeper in the trough regions. These observations support the partition of magmatic and less-magmatic stretching in the study area, and indicate the relation between the variation of rift's depth-width and the magmato-tectonic accretion. •Topographic indices reveal the magmato-tectonic mechanism quantitatively.•Asymmetry of faults in two flanks indicates the asymmetric spreading of the region.•Depth, width and dip of axial rift are related with the magmato-tectonic accretion.