Geology and Exploration of Three Greater Bass Strait Basins, Australia: ABSTRACT (original) (raw)
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2017
The aim of this study was to construct a new stratigraphic framework for the Victorian section of the onshore Otway Basin, while answering unresolved questions about the basin's early rift history. These include the order in which individual depocentres were formed, the timing of deposition of laterally varying stratigraphic packages, which units were confined to individual rift depocentres and how the transition between depositional environments was controlled by rift related tectonism. The approach first involved the integration of stratigraphic correlations, petrophysical interpretation, drill-core descriptions and biostratigraphy with seismic facies analysis. This resulted in the identification of at least two new lithostratigraphic members and the construction of a new stratigraphic framework for the sediments. Structural analysis was then undertaken by building a 3D structural model which was used to calculate cumulative displacement rate across depocentre bounding faults ...
Tectonophysics, 2003
The Melbourne Zone comprises Early Ordovician to Early Devonian marine turbidites, which pass conformably upward into a mid-Devonian fluviatile succession. There are four pulses of Silurian to mid-Devonian deep-marine sandstone-dominated sedimentation: Early Silurian (late Llandovery), Late Silurian (Ludlow), earliest Devonian (Lochkovian) and late Early Devonian (Emsian). Two dispersal patterns have been defined using more than 1100 palaeocurrent measurements, mainly from sole marks and cross-laminations in graded beds, together with sandstone compositions. The older pattern, of Silurian to earliest Devonian age, contains the lowest three sandstone pulses. Palaeocurrents and provenance define a wedge of southwesterly derived sediment, of largely cratonic provenance, thinning eastward. This older dispersal pattern is part of an Early Ordovician to earliest Devonian east-facing passive continental margin succession. Palaeocurrents and provenance in the Emsian sandstone pulse comprise three patterns: (1) west-to southwesterly directed palaeocurrents associated with fine-to coarse-grained, locally conglomeratic, lithic sandstones containing a high proportion of volcanic detritus; (2) east-to northeasterly directed palaeocurrents associated with fine-to medium-grained quartz-lithic sandstones; (3) north-to northwesterly and south-to southeasterly directed palaeocurrents associated with fine-to medium-grained sandstones of variable lithic composition. The palaeocurrent and provenance pattern defines a NNW-elongate basin with a tectonically active eastern margin, and is similar to the coeval Mathinna basin of northeastern Tasmania. Both basins are part of the same system of wrench basins, which developed along the western side of the Wagga -Omeo Metamorphic Belt during the earliest Devonian to Middle Devonian. The change in tectonic setting in the earliest Devonian appears to have occurred during an interval of significant dextral translation of the eastern Lachlan Fold Belt towards the SSE along the Governor and associated fault zones. D
Marine and Petroleum Geology, 2015
Assessment and successful exploration for, and exploitation of, aquifers in the Perth Basin require knowledge of their petrophysical and sedimentological characteristics and geometries. This study provides a sedimentological and lithofacies analysis of core from the Mesozoic Yarragadee Formation, Cadda Formation, Cattamarra Coal Measures, Eneabba Formation and Lesueur Sandstone of Western Australia recovered from Pinjarra-1, Cockburn-1, Gingin-1 and Gingin-2 wells provide insights into changes in depositional environment over time and space in the central Perth Basin. In studied sections, nine different fluvial-dominated lithofacies have been identified in the Yarragadee Formation, Cadda Formation and Cattamarra Coal Measures that occur in similar proportions, whereas the Lesueur Sandstone is dominated by coarse-grained deposits of high energy fluvial systems. Vertical variation in lithofacies on the order of 10 cm to approximately 2 m vertical scale is observed in all formations and wells. Changes in the lithofacies, linked to local depositional environments, are probably associated with fluvial-alluvial to fluvio-deltaic systems that have complex 3D architecture, including braided and to probably meandering systems, and are affected by channel avulsion. Point counting and automated mineral analysis of thin sections of core showed detrital mineralogy dominated by monocrystalline quartz, with rare polycrystalline quartz, a moderate amount of alkali feldspar and very minor amounts of garnet, organic fragments, muscovite and biotite. These data show a lithofacies-dependence of the proportion of minerals, with little variation between equivalent lithofacies from different depths, formations or wells. Grain size and sorting, that have a first order control on porosity, are strongly lithofacies dependent. Individual lithofacies types show a trend of decreasing porosity with depth due to the increasing effects of compaction, quartz overgrowth cementation and authigenic clay mineral development. Lithofacies and depth are the main controls on permeability, and so lithofacies distribution exerts a key control on hydraulic behaviour. Crown
1977
Upper Ordovician through Lower Devonian formations in the southwestern Great Basin include the Ely Springs Dolomite, Hidden Valley Dolomite, Roberts Mountains Formation, Vaughn Gulch Limestone, and Sunday Canyon Formation. Evidence from'conodont studies has allowe d for refined correlations of these formations and for recognition of time lines extending through different facies. These facies are interpreted as having formed in shallow shelf and transition to deeper shelf or possibly slope environments existing in the Cordilleran geocline. The most distinctive lithologic features of the rocks are the completely dolomitized sequences towards the southeast and central parts of the region and the limestone sequences in the northwestern part of the region. Major depositional regimes recognized within these sequences include intertidal/supratidal, subtidal shelf, and deeper water shelf or slope.
Gondwana Research
Sedimentary rocks along the southern margin of Australia host an important record of the 18 break-up history of east Gondwana, as well as fragments of a deeper geological history, which collectively help inform the geological evolution of a vast and largely underexplored 20 region. New drilling through Cenozoic cover has allowed examination of the Cretaceous riftrelated Madura Shelf sequence (Bight Basin), and identification of two new stratigraphic units beneath the shelf; the possibly Proterozoic Shanes Dam Conglomerate and the 1 interpreted Palaeozoic southern Officer Basin unit, the Decoration Sandstone. Recognition of these new units indicates an earlier basinal history than previously known. Lithostratigraphy of the new drillcore has been integrated with that published from onshore and offshore cores to present isopach maps of sedimentary cover on the Madura Shelf. New palynological data demonstrate progression from more localized freshwater-brackish fluviolacustrine clastics in the early Cretaceous (Foraminisporis wonthaggiensis-Valanginian to Barremian) to widespread topography-blanketing, fully marine, glauconitic mudrocks in the mid Cretaceous (Endoceratium ludbrookiae-Albian). Geochronology and Hf-isotope geochemistry show detrital zircon populations from the Madura Shelf are comparable to those from the southern Officer Basin, as well as Cenozoic shoreline and palaeovalley sediments in the region. The detrital zircon population from the Shanes Dam Conglomerate is defined by a unimodal ~1400 Ma peak, which correlates with directly underlying crystalline basement of the Madura Province. Peak ages of ~1150 Ma and ~1650 Ma dominate the age spectra of all other samples, indicating a stable sediment reservoir through much of the Phanerozoic, with sediments largely sourced from the Albany-Fraser and Musgrave Orogens (directly and via multiple recycling events). The Madura Shelf data differ from published data for the Upper Cretaceous Ceduna Delta to the east, indicating significant differences in sediment provenance and routing between the Ceduna Sub-basin and central Bight Basin.
Lower Carboniferous strata are preserved only north of 24°S, but during the Middle Carboniferous to Permian the northern Perth and Southern Carnarvon Basins formed a single intracratonic depositional realm from 32°S to 23°S within the East Gondwana interior rift system. This succession is dominantly of shallow marine to fluvial origin, and is relatively undeformed (outcrop dips rarely exceed 15°) and has not been deeply buried due to a general lack of sedimentation on the eastern margin of the Perth Basin and across the Southern Carnarvon Basin throughout the Triassic–Jurassic and Cenozoic. This guide describes the most informative Carboniferous–Permian outcrops in the basins in terms of stratigraphy, sedimentology and paleontology, but also includes Pleistocene–Holocene localities that have been used as models for carbonate deposition, of which the carbonate banks and stromatolites at Shark Bay are the most renowned. Early Carboniferous deposition in a broad interior sag basin produced two major carbonate–sandstone sequences: the Tournaisian Moogooree Limestone to Williambury Sandstone cycle; and the possible Visean Yindagindy Formation to Harris Sandstone cycle. Carbonates in the basal formations of each cycle, although poorly dated, include microbialites, ooid–peloidal and skeletal grainstones–packstones, indicating warm and occasionally hypersaline conditions. Mid-Carboniferous–Permian deposition in a narrow interior rift, over 1000 km long, was dominated by alternating marine and terrestrial facies with marine conditions increasing to the north. A 5-km thick shallow-marine succession formed in the Merlinleigh Sub-basin in the north, and a somewhat thinner succession, including coal measures, accumulated to the south in the Perth Basin. Carboniferous to early Sakmarian glacially-influenced sediment rapidly infilled the initial basin that had an irregular topography (probably shaped by thick continental ice sheets, and affected by a later phase of the Alice Springs Orogeny). By the mid-Sakmarian, a shallow sea floor with a very low gradient developed throughout the region: water depths probably did not exceed 50 m during the Early–Middle Permian. Subsidence apparently just exceeded sediment influx, and variations in these parameters resulted in distinct depositional cyclicity of several orders. In the post-glacial successions, two major depositional cycles of late Sakmarian to mid-Artinskian and late Artinskian to at least Roadian indicate warming sea conditions during the Sakmarian, with a minor cooling phase during the middle or late Artinskian.