The role of salt diapirism in controlling the sedimentology  and distribution of deep-water deposits, Pierce Field, East  Central Graben, North Sea

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Authors

Clara Abu , Christopher Aiden-Lee Jackson 

Abstract

Passively rising diapirs control flank deformation (i.e., within 1 km of the salt-sediment interface) and resultant stratigraphic architecture of syn-kinematic units. Growth strata associated with deformation at the flanks of passive diapirs are known as halokinetic sequences. Very few studies have conducted an integrated analysis of composite halokinetic sequences, CHS (stacked halokinetic sequences), and the damage occurring in host rocks during salt diapirism using seismic, petrophysical well data and core information.

This study integrates a 3D seismic reflection survey, core, and petrophysical data from the Pierce Field, northern North Sea, offshore UK to examine CHS in near-diapir strata and associated deformation. We recognize three tapered CHS in Units 6, 5, and 2. Two tabular CHS are recognized in Units 3 and 4, comprising the Miocene and Oligocene-aged sediments. The tapered CHS represents a rapid sediment-accumulation rate relative to the diapir-rise rate. The tabular CHS represents slow sediment accumulation rates relative to the diapir-rise rate.

Regarding near-diapir deformation, we observe large-scale fracturing associated with drape folding in the Ekofisk Formation resulting from the North and South Pierce salt movement. In the clastic successions, bedding parallel slip zones and slump folds dominate the Forties Sandstone Member and signify a destabilizing and rotational relationship of the Forties sandstone with the growing salt diapirs. Hybrid and remobilized flows interpreted from core data and lateral thickness changes support our interpretation of diapiric salt adjustment of deep-water deposition. Our study demonstrates the value of using an integrated dataset: 3D seismic reflection data and core to characterize the dynamic interaction between sediment gravity-flows and diapiric salt with North
and South Pierce diapirs controlling thickness and facies distributions in the North Sea Central Graben.

DOI

https://doi.org/10.31223/X5ZD6H

Subjects

Earth Sciences, Geology, Other Earth Sciences, Sedimentology, Tectonics and Structure

Keywords

salt tectonics, deep-water sedimentology, paleocene, North Sea, Central Graben

Dates

Published: 2024-03-04 17:48

Last Updated: 2024-03-05 00:48

License

CC BY Attribution 4.0 International