1887

Abstract

The Curlew Field is located on the western margin of the Central Graben and comprises a number of accumulations in a variety of Jurassic and Cretaceous reservoirs. The reservoir interval in the Curlew D Field is the Upper Jurassic Fulmar Formation, which is displayed here. Curlew is unusual in the Central Graben in that whilst regionally the upper Jurassic is largely represented by shoreface facies (Fulmar Formation sensu stricto) in this area the formation also comprises a succession of coastal plain and paralic facies informally assigned to the Curlew Member. Overall the upper Jurassic section seen in Curlew is a transgressive interval comprising coastal plain, tidal inlet, shoreface and shelfal facies. However, this succession is punctuated by a number of major flooding events, and candidate sequence boundaries can be identified also. Three discrete facies associations are displayed: The Lower Fulmar represents the lower part of the Curlew Member and is characterised by a heterogeneous assemblage of burrowed and stratified sandstones, siltstones, mudstones, coals and oyster beds. Towards the lower part of the succession rooted horizons and coals are more common. Overall this interval records variably brackish to fully marine, low energy conditions on a shallow, variably submerged fault terrace which ranged from salt marsh and tidal creek, to flood-tidal delta environments. The Middle Fulmar corresponds to the uppermost unit of the Curlew Member and comprises a series of stacked cross-stratified sandstone bodies interleaved with bioturbated intervals (mainly Ophiomorpha). Drifted woody material and carbonaceous drapes are present together with bivalve lags. Belemnite and ammonite fragments have been identified within the coarser grained lags. The base of this interval is a major erosional surface which may represent a sequence boundary. The fill comprises marine influenced channel-fills interpreted as tidal inlet deposits. The upper boundary of this unit is a regional transgressive surface. The Upper Fulmar, above the transgressive surface truncating the middle Fulmar tidal inlet facies, comprises intensely bioturbated, fine-grained lower shoreface facies arranged into a broadly transgressive succession which passes into offshore muds (Heather Formation).

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/content/papers/10.3997/2214-4609.201405143
2007-06-10
2020-04-07
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