Formation of the Cameroon Volcanic Line by Lithospheric Basal Erosion: Insight from Mantle Seismic Anisotropy

Abstract

The formation mechanism of intraplate volcanism such as that along the Cameroon Volcanic Line (CVL) is one of the controversial problems in global tectonics. Models proposed by previous studies include re-activation of ancient suture zones, lithospheric thinning by mantle plumes, and edge-driven mantle convection. To provide additional constraints on the models for the formation of the CVL, we measured shear-wave splitting parameters at 36 stations in the vicinity of the CVL using a robust procedure involving automatic batch processing and manual screening to reliably assess and objectively rank shear-wave splitting parameters (fast polarization directions and splitting times). The resulting 432 pairs of splitting parameters show a systematic spatial variation. Most of the measurements with ray-piercing points (at 200. km depth) beneath the CVL show a fast direction that is parallel to the volcanic line, while the fast directions along the coastline are parallel to the continental margin. The observations can best be interpreted using a model that involves a channel flow at the bottom of the lithosphere originated from the NE-ward movement of the asthenosphere relative to the African plate. We hypothesize that progressive thinning of the lithosphere through basal erosion by the flow leads to decompression melting and is responsible for the formation of the CVL. The model is consistent with the lack of age progression of the volcanoes in the CVL, can explain the formation of both the continental and oceanic sections of the CVL, and is supported by previous geophysical observations and geodynamic modeling results.

Department(s)

Geosciences and Geological and Petroleum Engineering

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Continental Margin; Intraplate Process; Lithospheric Structure; Mantle Convection; Mantle Plume; S-Wave; Seismic Anisotropy; Spatial Variation; Suture Zone; Crustal Thinning; Formation Mechanism; Mantle Process; Volcanic Belt; Atlantic Ocean; Cameroon; Cameroon Volcanic Line; Gulf of Guinea

International Standard Serial Number (ISSN)

1464-343X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2014 Elsevier Ltd, All rights reserved.

Publication Date

01 Dec 2014

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