Measuring plume-related exhumation of the British Isles in Early Cenozoic times

Cogné, N., Doepke, D., Chew, D., Stuart, F. M. and Mark, C. (2016) Measuring plume-related exhumation of the British Isles in Early Cenozoic times. Earth and Planetary Science Letters, 456, pp. 1-15. (doi:10.1016/j.epsl.2016.09.053)

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Abstract

Mantle plumes have been proposed to exert a first-order control on the morphology of Earth's surface. However, there is little consensus on the lifespan of the convectively supported topography. Here, we focus on the Cenozoic uplift and exhumation history of the British Isles. While uplift in the absence of major regional tectonic activity has long been documented, the causative mechanism is highly controversial, and direct exhumation estimates are hindered by the near-complete absence of onshore post-Cretaceous sediments (outside Northern Ireland) and the truncated stratigraphic record of many offshore basins. Two main hypotheses have been developed by previous studies: epeirogenic exhumation driven by the proto-Iceland plume, or multiple phases of Cenozoic compression driven by far-field stresses. Here, we present a new thermochronological dataset comprising 43 apatite fission track (AFT) and 102 (U–Th–Sm)/He (AHe) dates from the onshore British Isles. Inverse modelling of vertical sample profiles allows us to define well-constrained regional cooling histories. Crucially, during the Paleocene, the thermal history models show that a rapid exhumation pulse (1–2.5 km) occurred, focused on the Irish Sea. Exhumation is greatest in the north of the Irish Sea region, and decreases in intensity to the south and west. The spatial pattern of Paleocene exhumation is in agreement with the extent of magmatic underplating inferred from geophysical studies, and the timing of uplift and exhumation is synchronous with emplacement of the plume-related British and Irish Paleogene Igneous Province (BIPIP). Prior to the Paleocene exhumation pulse, the Mesozoic onshore exhumation pulse is mainly linked to the uplift and erosion of the hinterland during the complex and long-lived rifting history of the neighbouring offshore basins. The extent of Neogene exhumation is difficult to constrain due to the poor sensitivity of the AHe and AFT systems at low temperatures. We conclude that the Cenozoic topographic evolution of the British Isles is the result of plume-driven uplift and exhumation, with inversion under compressive stress playing a secondary role.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Stuart, Professor Finlay
Authors: Cogné, N., Doepke, D., Chew, D., Stuart, F. M., and Mark, C.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Earth and Planetary Science Letters
Publisher:Elsevier
ISSN:0012-821X
ISSN (Online):1385-013X
Published Online:17 October 2016
Copyright Holders:Copyright © 2016 Elsevier B.V.
First Published:First published in Earth and Planetary Science Letters 456:1-15
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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