The Uppermost Devonian And Lowermost Carboniferous Sediments Of The Canning Basin Kimberley District

Author : Zahra Seyedmehdi
Publisher :
ISBN 13 :
Total Pages : 227 pages
Book Rating : 4.:/5 (93 download)

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Download or read book Depositional History and Reservoir Characterisation of the Latest Devonian-Early Carboniferous Fairfield Group, Northwestern Lennard Shelf, Canning Basin, Western Australia written by Zahra Seyedmehdi and published by . This book was released on 2011 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] Detailed sedimentological analysis of core from 40 wells on the northwestern Lennard Shelf, northern Canning Basin, was undertaken to interpret the depositional history of the latest Devonian Early Carboniferous carbonate-siliciclastic Fairfi eld Group within a sequence stratigraphic framework. Integration of sedimentological and petrophysical interpretations with existing biostratigraphic data and new seismic interpretation was used to establish a geological model in which to examine the roles of depositional facies and diagenetic modifi cation on reservoir quality. The Fairfi eld Group is composed of fourteen facies associations (FA1- FA14) identifi ed from detailed sedimentological study of core. The majority of associations (FA1-FA9) were deposited on a broad inner ramp with open marine to restricted shallow subtidal intertidal supratidal conditions. FA1 represents a restricted supratidal area. Shallow subtidal intertidal fenestral microbial mats and bioclastic facies (FA2) were widely developed on the platform and are typically dolomitised. Sandstones and siltstones represent deposition on tidal fl ats and in open marine areas (FA3 and FA4). Protected and restricted shallow subtidal areas on the platform are typically fi ne carbonate facies (FA5 and FA6). Bioclastic sediments were deposited in high energy zones as shoals (FA8 and FA9) and FA7 represents deposition intermediate to shoals and the protected lagoon. Two facies associations represent the middle to outer ramp. They are characterized by carbonate mudstone deposited on the distal mid ramp (FA10) and bioclastic sandstones on the proximal mid ramp (FA11). Three outer ramp to slope facies associations (FA12-FA14) are composed of turbiditic sandstones and limestones. A distally steepened ramp morphology for the Fairfi eld Group, identifi ed from seismic data, is supported by a broad peritidal platform facies and turbiditic facies of the outer ramp. The Fairfi eld Group ramp evolved from the underlying Famennian platforms as a result of the global loss of reef-builders during extinction events in the Late Devonian, ongoing tectonic activity associated with the Fitzroy Trough, relative sea-level changes and antecedent topography. The base of the Fairfi eld Group is represented by a fl ooding surface in the majority of studied wells, and the upper contact is conformable in the northwestern part of the study area where it is overlain by the Early Carboniferous Anderson Formation. The Fairfi eld Group is subdivided into fi ve regional stratal packages (P1-P5) and two local packages (L1 and L2) that represent four third-order sequences (S1-S4). The sequences are bounded by fl ooding surfaces (FS) and include transgressive system tracts (TST) composed of mid to outer ramp facies associations and capping highstand system tracts (HST) composed of inner ramp facies associations. Lowstand system tracts (LST), identifi ed in S2 and S3, and are characterised by siliciclastic wedges deposited on the outer ramp. Overall, the Fairfi eld Group was largely deposited during sea-level highstands (HST) characterized by progradational trends and dominant shallow subtidal inner ramp facies associations...