DEPOSITIONAL SYSTEMS AND SEQUENCE STRATIGRAPHY OF THE CRETACEOUS WARNBRO GROUP, VLAMING SUB-BASIN, WESTERN AUSTRALIA

1993 ◽  
Vol 33 (1) ◽  
pp. 190 ◽  
Author(s):  
D.E. Spring ◽  
N.A. Newell

Petroleum exploration of the Vlaming Sub-basin (offshore Perth Basin) has to date primarily focussed on targets sealed by the shale facies of the Early Cretaceous Warnbro Group, a predominantly marine succession. The Warnbro Group is formally sub-divided into the Gage Sandstone Member (base), South Perth Shale and Leederville Formation (top). However, owing to diachroneity between lithofacies, adherence to the formal nomenclature has rendered the prediction of shale facies at specific locations unreliable, resulting in a number of invalid exploration tests.To resolve this problem, sequence and seismic stratigraphic concepts have been used within exploration permit WA-221-P to provide a framework for a new stratigraphic model for the Warnbro Group. Seven depositional sequences have been identified.The model recognises that palaeogeography during Warnbro Group deposition was largely governed by tectonism associated with the Neocomian break-up event which produced a complex assemblage of fluvio-deltaic, shelfal and submarine fan systems. Sequence boundary development can be related to phases of tectonism following the Neocomian break-up as well as to eustatic fluctuations, while variations in base-level, subsidence rate, sediment supply, basin physiography and a basinwide marine transgression primarily control the environments of deposition and their spatial distribution.The model has enabled the lithofacies of the Warnbro Group to be assigned to a predictable succession of associated systems tracts, providing a practical approach to understanding the distribution and geometries of Warnbro Group reservoir and seal facies within the Vlaming Sub-basin.

2001 ◽  
Vol 41 (1) ◽  
pp. 463 ◽  
Author(s):  
K. Liu ◽  
C.M. Griffiths ◽  
C.P. Dyt

A 3D depositional modelling program, SEDSIM, was used to model the various depositional systems operating in the Kendrew Trough, Dampier Sub-basin during a two million year period of the Oxfordian. The simulation covers an area of 40 km by 100 km, from the Goodwyn Field in the southwest to the Lambert Field in the northeast, covering the Rankin Trend, Kendrew Trough, Madeleine Trend and part of the Lewis Trough. The simulation started from the Jurassic main unconformity (156.7 Ma) forward to 154.7 Ma using a spatial resolution of 1 km and a time step of 5 ka.The 3D model from the simulation quantitatively mimics the interaction of the palaeogeographic setting, sediment supply, sea level fluctuations, tectonic movement and palaeo-oceanographic setting in three dimensions, to simulate the spatial and temporal distribution of sedimentary facies. The model identified five Oxfordian leads within the Kendrew Trough, including two major slope and basin-floor fan systems, a shelfal-shoreface system, a deltaic system, and a submarine channel system.The study has shown that 3D depositional models produced by SEDSIM are not only able to depict the spatial and temporal distribution of depositional systems on a basin scale, but are also capable of making useful contributions to the understanding of play fairway and lead development.


2020 ◽  
Author(s):  
Johan M. Bonow ◽  
Peter Japsen ◽  
Paul F. Green ◽  
James A. Chalmers

<p>Many passive continental margins around the world are characterised by elevated plateaus at 1 to 2 km or more above sea level cut by deeply incised valleys and commonly separated from an adjacent coastal plain by one or more escarpments. Mesozoic–Cenozoic rift systems parallel to the coast are commonly present offshore with a transition from continental to oceanic crust further offshore. These landscapes occur in arctic, temperate and tropical climate and in different geological settings independent of the time span since break-up (e.g. along the Atlantic from south to north).</p><p>The plateaux are typically more than 100 km wide, much larger in some cases, and extend hundreds of kilometres along the margin, cutting across bedrock of different ages and resistances. The key to understanding the formation of regional, low-relief erosion surfaces is the base-level, as this is the level to which fluvial systems grade the landscape. The most likely base level is sea level, particularly for locations along continental margins during the post-rift development of passive margins.</p><p>It is commonly assumed that the characteristic, large-scale morphology of elevated, passive continental margins with  high-level plateaux and deeply incised valleys persisted since rifting and crustal separation Further, it is assumed that the absence of post-rift sediments is evidence of non-deposition, despite continental-stretching theory predicting deposition of a thick post-rift sequence overlying both the rift and its margins.</p><p>However, our studies of the passive continental margins of West and East Greenland, Norway, NE Brazil and southern Africa provide evidence of km-scale, post-rift subsidence and that the plateau surfaces were graded to sea level long after break-up and subsequently lifted to their present elevations. In some of these cases, the presence of post-rift marine sediments at high elevation provide direct proof of this interpretation. Since elevated plateaux cut by deeply incised valleys are a characteristic feature of these and other margins, this similarity suggests that such topography elsewhere in the world may also be unrelated to the processes of rifting and continental separation. We present a wide range of evidence from passive margins around the world in support of this hypothesis,</p><p> </p><p>Bonow et al. 2014: High-level landscapes along the margin of East Greenland – a record of tectonic uplift and incision after breakup in the NE Atlantic. Global and Planetary Change.</p><p>Green et al. 2018: Post-breakup burial and exhumation of passive continental margins: Seven propositions to inform geodynamic models. Gondwana Research.</p><p>Japsen et al. 2019: Elevated passive continental margins: Numerical modeling vs observations. A comment on Braun (2018). Gondwana Research.</p>


2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Mohamed O. Abouelresh

The high frequency and diversity of erosion surfaces throughout the Barnett Shale give a unique view into the short-duration stratigraphic intervals that were previously much more difficult to detect in such fine-grained rocks. The erosion surfaces in Barnett Shale exhibit variable relief (5.08–61 mm) which commonly consists of shelly laminae, shale rip-up clasts, reworked mud intraclasts, phosphatic pellets, and/or diagenetic minerals (dolomite and pyrite) mostly with clay-rich mudstone groundmass. Several factors control this lithological variation, including the energy conditions, rate of relative sea-level fluctuation, rate of sedimentation, sediment influx, and the lithofacies type of the underlying as well as the overlying beds. The erosional features and their associated surfaces make them serve at least in part as boundaries between different genetic types of deposits but with different scales according to their dependence on base level and/or sediment supply. Accordingly, the studied erosion surfaces of the Barnett Shale can be grouped into three different scales of sequence stratigraphic surfaces: sequence-scale surfaces, parasequence-scale surfaces, and within trend-scale surfaces.


2020 ◽  
Author(s):  
Jingzhe Li ◽  
Piyang Liu ◽  
Shuyu Sun ◽  
Zhifeng Sun ◽  
Yongzhang Zhou ◽  
...  

Abstract. The formation of stratigraphy in shallow marine environments has long been an important topic within the geologic community. Although many advances have been made in the field of forward stratigraphic modelling (FSM), there are still some shortcomings to the existing models. In this work, the authors present our recent development and application of Sedapp: a new non-linear open-source R code for FSM. This code uses an integrated depth-distance related function as the expression of the transport coefficient to underpin the FSM with more along-shore details. In addition to conventional parameters, a negative-feedback sediment supply rate and a differentiated deposition-erosion ratio were also introduced. All parameters were implemented in a non-linear manner. Sedapp is a 3D (2DH) tool while also capable of 2D (1DH) scenarios. Two simplified case studies were conducted. The results show that Sedapp can not only assist in geologic interpretation, but is also an efficient tool for internal architecture predictions.


2021 ◽  
Author(s):  
Euan Soutter ◽  
Ian Kane ◽  
Ander Martínez-Doñate ◽  
Adrian Boyce ◽  
Jack Stacey ◽  
...  

The Eocene-Oligocene transition (EOT) was a period of considerable environmental change, signifying the transition from Paleocene greenhouse to Oligocene icehouse conditions. Preservation of the sedimentary signal of such an environmental change is most likely in net-depositional environments, such as submarine fans, which are the terminal parts of sedimentary systems. Here, using sedimentological and stable isotope data from the Alpine foreland basin, we assess whether this major climatic transition influenced the stratigraphic evolution of submarine fans. Results indicate that submarine fan retreat in the Alpine foreland basin corresponds with positive δ13C excursions related to major global perturbations of the carbon cycle and cooling in the earliest Oligocene. Submarine fan retreat is suggested to be influenced by this cooling through enhanced aridity and reduced subaerial runoff from the Corsica-Sardinia hinterland. The influence of aridity was periodically overwhelmed by local environmental factors, such as hinterland uplift, which increased sediment supply to deep-water during arid periods. These results highlight that: 1) hinterland climate may play a greater role than sea-level in dictating sediment supply to deep-water and, 2) submarine fan evolution occurs through a complex interplay between climate, eustasy and tectonics, which makes robust interpretations of paleoenvironmental change from their stratigraphic record, without multi-proxy records, difficult.


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