Plume–MOR decoupling and the timing of India–Eurasia collision

Abstract

The debatable timing of India–Eurasia collision is based on geologic, stratigraphic, kinematic, and tectonic evidence. However, the collision event disturbed persistent processes, and the timing of disturbance in such processes could determine the onset of India–Eurasia collision precisely. We use the longevity of Southeast Indian Ridge (SEIR)—Kerguelen mantle plume (KMP) interaction cycles along the Ninetyeast ridge (NER) as a proxy to determine the commencement of India–Eurasia collision. The geochemical signature of the KMP tail along the NER is predominantly that of long-term coupling cycles, that was perturbed once by a short-term decoupling cycle. The long-term coupling cycles are mainly of enriched mid-ocean ridge basalts (E-MORBs). The short-term decoupling cycle is mostly derived from two distinct sources, MOR and plume separately, whereas the KMP is still being on-axis. The onset of India–Eurasia collision led to continental materials recycling into the mantle; hence the abrupt enrichment in incompatible elements at ca. 55 Ma, the MOR–plume on-axis decoupling, and the abrupt slowdown in the northward drift of the Indian plate was induced by the onset of India–Eurasia collision, thereafter MOR–plume recoupled.

Evolutionary response of cold‐adapted chasmophytic plants to Quaternary climatic oscillations in the Mountains of Central Asia (a world hotspot of biodiversity)

“…The India‐Eurasia collision taking place between ~55–52 Mya (initial contact) and ~34–20 Mya (final collision) led to the uplift of Central and South Asian mountain massifs, which later experienced further geo‐climatic changes favouring unusual radiation of plants (Aitchison et al, 2007; Luo & Li, 2022; Sehsah et al, 2022; Van Hinsbergen et al, 2012). The beginning of this collision can probably be estimated as the starting point of the evolution of Asian Campanula s.l., estimated at ~57 Mya, and coinciding with the onset of global climatic transitions when temperature fluctuations and mean temperatures decreased until the late Oligocene (Jones et al, 2017; Zachos et al, 2008).…”