229-20 Lithospheric Structure Beneath the Cameroon Volcanic Line: Implications for the Melt Source

Session: Crustal Petrology (Posters)

Presenting Author:

Authors:

Abstract:

To understand the melt source of hotlines with asynchronous volcanoes, we investigate the lithospheric structure of the Cameroon Volcanic Line (CVL), a chain of volcanoes without age progression stretching from the Gulf of Guinea into Central Africa. We analyze Bouguer gravity anomalies from the World Gravity Model 2012 using 2‐D power spectrum techniques and 2-D forward modeling to estimate crustal and lithospheric thickness. We find: (1) thin crust (20–30 km) beneath the oceanic CVL; (2) thick crust (30–43 km) beneath the continental CVL and Oubanguides Belt, and thicker crust (43–50 km) beneath the Congo Craton; (3) thin lithosphere (90–120 km) beneath the oceanic CVL and thinner lithosphere (75–90 km) beneath the continental CVL; and (4) thicker lithosphere (150–234 km) beneath the Congo Craton. Our seismic-constrained forward models reveal a delaminated body beneath the continental CVL and a sharp transition from thick lithosphere beneath the Congo Craton to thin lithosphere beneath the Oubanguides Belt. We interpret lithospheric delamination as the cause of the thin lithosphere beneath the continental CVL. The delaminated body deflects rising mantle plume materials preferentially southward, producing the Y-shape distribution of continental volcanoes. The lithospheric architecture, through Edge-Driven Convection (EDC), modulates the interaction of rising plume materials, focusing them beneath the thin lithosphere at the Congo Craton's edges to produce the oceanic and southern continental CVL. We conclude that the lack of age progression along the CVL results from the complex trajectory of the rising plume, further deflected by a delaminated body and modulated by the lithospheric architecture.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-5754

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