The influence of sediment blanketing on subduction-zone seismicity

McKenzie, Dan and Jackson, James (2020) The influence of sediment blanketing on subduction-zone seismicity. Earth and Planetary Science Letters, 552. p. 116612. ISSN 0012 821X DOI https://doi.org/10.1016/j.epsl.2020.116612

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Abstract

Subduction of oceanic lithosphere is now occurring beneath the Aegean and central Caspian Seas, and beneath the Indo-Burman Ranges in NE India, generating zones of earthquakes that reach depths of more than 150 km. Their existence is surprising. In general, where the temperature of the mantle part of the oceanic lithosphere can be estimated, earthquakes are confined to material whose temperature is below . In these three regions the oceanic lithosphere is overlain by sediments with low thermal conductivity whose thickness is probably 10–25 km. The temperature of the oceanic crust and upper half of the lithosphere should be considerably increased by such a thick sedimentary cover, yet there is no obvious difference between these subduction zones and those where there is little sediment on the subducting plate. Detailed thermal modelling of the temperature shows that, for the first 40 Ma, the deposition of even a thick sedimentary layer has little effect on the thickness of the region of lithosphere whose temperature is below , principally because little heat is conducted across the Moho. The modest effect of sediment blanketing over a period as long as 40 Ma was quite unexpected. Over the next 200 Ma the lithospheric temperature increases, until the Moho temperature reaches . This behaviour has important implications for oil and gas generation in the sediments, and for the existence of large earthquakes at depths of 150 km or more beneath the Hindu Kush, Pamirs and Romania.

Item Type:	Article
Uncontrolled Keywords:	2020AREP; IA76
Subjects:	02 - Geodynamics, Geophysics and Tectonics
Divisions:	02 - Geodynamics, Geophysics and Tectonics 08 - Green Open Access
Journal or Publication Title:	Earth and Planetary Science Letters
Volume:	552
Page Range:	p. 116612
Identification Number:	https://doi.org/10.1016/j.epsl.2020.116612
Depositing User:	Sarah Humbert
Date Deposited:	09 Oct 2020 17:07
Last Modified:	09 Oct 2020 17:07
URI:	http://eprints.esc.cam.ac.uk/id/eprint/4891

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