A Late Cretaceous Aborted Spreading Center in the Northern Arabian Sea Recorded by the Laxmi Basin

Abstract

The Laxmi Basin (LB), a marginal depression, is a prominent geomorphic feature in the northern Arabian Sea. Understanding how the basin formed has important implications for the India–Seychelles breakup and the evolution of the western Indian Ocean. Despite its geodynamic significance, the nature of the basin and its crust remain uncertain, with differing views on its origin ranging from a stretched continental crust to pre‐Paleogene oceanic crust. In this study, we reexamine existing geodynamic models using new geochemical and Sr–Nd–Pb isotopic data obtained from the igneous basement recovered during the International Ocean Discovery Program Expedition 355. The new data from the basaltic crust show that it formed from mid‐oceanic ridge basalt‐like magmas derived primarily from the depleted asthenospheric mantle, with a minor contribution from the subcontinental lithospheric mantle (<25%). Isotopic and thermodynamic modeling indicates melting during the earliest stages of oceanic spreading. These observations exclude continental‐rift and subduction‐related models and instead indicate that the LB records a short‐lived Late Cretaceous spreading episode. We interpret the basin as a preserved, aborted rift‐to‐ridge transition system that briefly accommodated extension during India–Seychelles separation before spreading migrated westward to the Arabian Basin–Carlsberg Ridge system.