| Session Details | |
| Section | SE - Solid Earth Sciences |
| Session Title | Post-Collision Magmatism: Plumes Versus ‘Top-Down’ Plate Tectonics? |
| Main Convener | Prof. Martin Flower (University of Illinois at Chicago, United States) |
| Co-convener(s) | Dr. Nguyen Hoang (Geological Survey of Japan, AIST, Japan) Prof. Jinfu Deng (China University of Geosciences, China) Prof. Xuanxue Mo (China University of Geosciences, Beijing, China) |
| Session Description | As subduction gives way to plate collision, magmatic activity tends to progress from HFSE-depleted calcalkaline to potassic and ultrapotassic types. These are succeeded by voluminous OIB-like basalts, marking post-collision transtensional ‘nodes’ and possibly reflecting perturbations of ductile sublithospheric mantle. These late-stage magmas are mostly non-potassic and rich in HFSE and include both tholeiites and variably SiO2-undersaturated types. Examples – linked in space and time to recent and ongoing Tethyan collisions – include those in western and eastern Europe, eastern and southeastern Asia, and the Levant and northern Africa. Rarely, strongly potassic types HFSE-rich basalts appear, distinct from the shoshonites and lamproites commonly associated with collisions, examples appearing in NE China, Central Spain, and the western Germany. Geochemical and geophysical studies have led to robust debates, for example, as to whether the basalts reflect deep-sourced plumes or the effects of plate-induced upper mantle displacement. This session will be an opportunity to discuss current models pertaining to subcontinental mantle flow fields in relation to intraplate basalt genesis. |