Birth of a Neotethyan intra-oceanic arc

How, when and why intra-oceanic island arcs are initiated is a topic of long-standing debate. On-land geological evidence along the Yarlung Tsangpo/Indus suture zone provides strong evidence for the former existence of at least one such arc within Neotethys. This is increasingly accepted and numerous recent diagrammatic reconstructions of Neotethys now depict such an arc. Notably, the arc portrayed in these cartoons is typically shown to be located close to, and orientated parallel with, the assumed location of the southern margin of Eurasia. Nevertheless, how this arc was initiated and why it formed where it is shown are not particularly well constrained by any published geological evidence. In examining existing geodynamic models and from our own University of Sydney paleogeographic reconstruction work using GPlates we have noticed the presence of a major ocean-crossing feature, possibly a fracture zone, that trends approximately North-South from the western margin of India to the Eurasian margin. We will present a new model that directly relates mid-Cretaceous Neotethyan ophiolite genesis to this structure. This interpretation accords with the most recent concepts developed to explain the inception of intra-oceanic island arcs and ophiolite generation. Moreover, it is consistent with the development of metamorphic soles as well as ophiolite emplacement onto passive continental margins