The impact of syn-rift halokinesis to sediment deposition and distribution : a case study in the Central North Sea Basin, UK

This study looks at the effect of rifting and halokinesis to sediment distribution in the Central Graben, which is one of a few basins that have been subjected to both rifting and halokinesis at the same time. The main aim of this study is to integrate the plethora of well and 3D seismic data in the...

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Bibliographic Details
Main Author: Abu Bakar, Azli
Other Authors: Johnson, Howard ; Jackson, Christopher
Published: Imperial College London 2016
Subjects:
Online Access:https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.718426
Description
Summary:This study looks at the effect of rifting and halokinesis to sediment distribution in the Central Graben, which is one of a few basins that have been subjected to both rifting and halokinesis at the same time. The main aim of this study is to integrate the plethora of well and 3D seismic data in the Central Graben in order to re-evaluate the tectono-stratigraphic evolution of the rifting- and halokinesis-influenced Upper Jurassic rocks in the basin. In general, the basin was controlled by three major structural trends: (1) NW- and NE-striking Caledonian structures; (2) E-striking Variscan structures; and (3) NNW- to NW-striking Permo-Triassic structure. The initial opening of the basin during the Late Jurassic period rejuvenated and exploited the NW-striking Permo-Triassic structures before being taken over by a NNW-striking fault pattern. The complex fault pattern resulted in the CG being subdivided into several structural domains, which define areas of different salt wall patterns and distribution of the major Jurassic depocentres. The Upper Jurassic stratigraphy was divided into six major sequences bounded by major flooding surfaces. Nine sedimentary facies were also identified, associated with non-marine to deepwater depositional environments. Non-marine facies associations are found at the edge of the basin whereas shallow marine facies association could be found throughout the basin. Deep marine facies association, mainly made of low density turbidites, is rare but might be found in the axial part of each structural domains. No major submarine fan was identified, perhaps due to the lack of incised valley network that typically feed large fan system. In general, Oxfordian sequences were more influenced by halokinesis, indicated by thickening of sediments towards salt-withdrawal mini-basins and sporadic distribution of turbidites related to over-steepened Triassic’s mini-basin flanks, than the younger Kimmeridgian to Tithonian sequences. However, the younger sediments on the flanks were also affected by salt diapirs resulting in a compartmentalized architecture.