Hydrographic observations in the rift valley of Southwest Indian Ridge from 63°E – 69°E

Abstract

The Southwest Indian Ridge (SWIR) is poorly understood in terms of local variability in hydrographical characteristics because of a relative lack of data. Furthermore, previous hydrographic studies in SWIR were restricted to the west of 60°E region. We present a new set of hydrographic data which were collected during a survey for the search of hydrothermal plume/activity in between Mt. Jourdanne and Rodrigues Triple Junction (RTJ) over SWIR. The primary goal of our study is to understand the segment-scale hydrography in and above the SWIR rift valley between 63°E to 69°E, with emphasis on water mass propagation and variability of their physical properties. CTD/Oxygen profiles were examined along a ~650 km distance of SWIR axial valley segments. The properties of Antarctic Bottom Water (AABW) were identified in the rift valley section which passes through deep sills from the Crozet basin. Along the ridge, the physical parameters especially at deep and bottom layer depths have observed gradients formed by the obstruction of flow at sills in the valley, along with a unidirectional density driven flow.