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Evidence for unusually thin oceanic crust and strong mantle beneath the Amazon fan

Rodger, M.; Watts, A.B.; Greenroyd, C.; Peirce, C.; Hobbs, R.W.

Authors

M. Rodger

A.B. Watts

C. Greenroyd

R.W. Hobbs



Abstract

We used seismic and gravity data to determine the structure of the crust and mantle beneath the Amazon Fan. Seismic data suggest that the crust is of oceanic-type and is unusually thin (<4 km) compared to elsewhere in the Atlantic. We attribute the thin crust to ultraslow seafloor spreading following the breakup of South America and Africa during the Early Cretaceous. Gravity data suggest that the fan was emplaced on lithosphere that increased its elastic thickness, Te, and hence strength, following rifting. The increase, from 10 km to 40 km, is greater, however, than would be expected if Te were determined by a single controlling isotherm, based on a cooling plate model. Hence, we conclude that the Amazon Fan has been emplaced on, and is supported by, unusually thin oceanic crust and strong mantle.

Citation

Rodger, M., Watts, A., Greenroyd, C., Peirce, C., & Hobbs, R. (2006). Evidence for unusually thin oceanic crust and strong mantle beneath the Amazon fan. Geology, 34(12), 1081-1084. https://doi.org/10.1130/g22966a.1

Journal Article Type Article
Publication Date 2006-12
Deposit Date Mar 13, 2007
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 34
Issue 12
Pages 1081-1084
DOI https://doi.org/10.1130/g22966a.1
Keywords Amazon Fan, Crustal structure, Mantle, Gravity anomalies, Isostasy.

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