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A fault-controlled depositional model for the Aberystwyth Grits turbidite system

Published online by Cambridge University Press:  01 May 2009

D. Wilson ,
J. R. Davies ,
R. A. Waters  and
J. A. Zalasiewiczt
D. Wilson
Affiliation:
British Geological Survey, Bryn Eithyn Hall, Llanfarian, Aberystwyth, Dyfed SY23 4BY, U.K.
J. R. Davies
Affiliation:
British Geological Survey, Bryn Eithyn Hall, Llanfarian, Aberystwyth, Dyfed SY23 4BY, U.K.
R. A. Waters
Affiliation:
British Geological Survey, Bryn Eithyn Hall, Llanfarian, Aberystwyth, Dyfed SY23 4BY, U.K.
J. A. Zalasiewiczt
Affiliation:
British Geological Survey, Keyworth, Nottingham NG 12 5GG, U.K.
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Abstract

The Aberystwyth Grits Group was the first in a series of southerly-supplied sandstone-rich turbidite systems that invaded the Welsh Basin during the Telychian Stage (late Llandovery; Silurian). Structural and stratigraphical evidence indicates that deposition of the sand-dominated parts of the system was largely restricted to the east by a zone of syndepositional faulting, now marked by a major vergence divide. Downfaulting and reverse drag along the fault hangingwall created a bathymetric low, which focused deposition of high-density, sand-carrying turbidite flows and flow components, allowing substantial thicknesses of sediment to accumulate. In contrast, low-density, mud-rich turbidites were deposited over a wider area, enhancing the topographic relief generated by uplift above the fault footwall, to form a feature which restricted the spread of the coeval easterly-supplied turbidites of the Devil's Bridge Formation.

Type
Articles
Information
Geological Magazine , Volume 129 , Issue 5 , September 1992 , pp. 595 - 607
Copyright
Copyright © Cambridge University Press 1992

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