Eucla Basin Research Articles

Cenozoic biogenic mounds and buried Miocene(?) barrier reef on a predominantly cool-water carbonate continental margin—Eucla basin, western Great Australian Bight

Research Article| May 01, 1995 Cenozoic biogenic mounds and buried Miocene(?) barrier reef on a predominantly cool-water carbonate continental margin—Eucla basin, western Great Australian Bight David A. Feary; David A. Feary 1Australian Geological Survey Organisation, Department of Geology and Geophysics, University of Sydney, New South Wales 2006, Australia Search for other works by this author on: GSW Google Scholar Noel P. James Noel P. James 2Department of Geological Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada Search for other works by this author on: GSW Google Scholar Geology (1995) 23 (5): 427–430. https://doi.org/10.1130/0091-7613(1995)023<0427:CBMABM>2.3.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation David A. Feary, Noel P. James; Cenozoic biogenic mounds and buried Miocene(?) barrier reef on a predominantly cool-water carbonate continental margin—Eucla basin, western Great Australian Bight. Geology 1995;; 23 (5): 427–430. doi: https://doi.org/10.1130/0091-7613(1995)023<0427:CBMABM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The southern continental margin of Australia is the largest area of cool-water carbonate shelf deposition on the globe. Interpretation of 5495 km of airgun seismic-reflection data in the western part of the Great Australian Bight indicates that the 700-m-thick Cenozoic section of the offshore Eucla basin was deposited largely as a prograding cool-water, middle- to high-latitude carbonate ramp, characterized by widespread development of broad, low-relief, biogenic (bryozoan[?]-sponge), shelf and upper-slope mounds. The succession also contains a spectacular and extensive (>475 km long) buried middle Miocene barrier reef (the Miocene Little Barrier Reef) parallel to the modern shelf edge. This rimmed carbonate platform margin represents an episode of warm-water sedimentation during a global climatic optimum, probably coupled with strong eastward flow of a proto-Leeuwin Current. The late Miocene eustatic sea-level fall produced an areally restricted debris-apron sequence at the foot of the reef escarpment. The carbonate platform is capped by a Neogene cool-water carbonate ramp succession typified by aggradational to sigmoidal sequences, punctuated by periods of cold(?)-water, sea-floor erosion. Interpretation of this succession in the light of global and local tectonic and oceanographic events illustrates the dominant influence of water temperature on carbonate platform and reef growth throughout the Cenozoic. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Evolution of the Lefroy and Cowan palaeodrainage channels, Western Australia

A dendritic system of palaeodrainage channels is a prominent feature of the Yilgarn Craton of Western Australia. The history of the Cowan and Lefroy palaeodrainage channels described herein is typical of the mid‐lower reaches of these features. Incision of the palaeodrainage system occurred during Jurassic times. Reversal of the Cowan palaeodrainage channel occurred prior to Jurassic deposition in the Bremer Basin, resulting in the Cowan palaeodrainage channel flowing south to the Bremer Basin and the Lefroy palaeodrainage channel flowing east to the Eucla Basin. Earliest preserved strata consist of the Early to Middle Eocene non‐marine Hampton Sandstone and Pidinga Formation in the Lefroy palaeodrainage channel, and the Werillup Formation in the Cowan palaeodrainage channel. Subsequently, two transgressive sequences (Tortachilla and Aldinga transgressions) were deposited. During the Tortachilla transgression, estuarine‐deltaic facies of the Pidinga Formation and Hampton Sandstone were deposited in the Le...

Cretaceous and Tertiary sedimentation on the western margin of the Eucla Basin

Sedimentation on the northwestern margin of the Eucla Basin has been defined by drilling and palaeontological data to include Early Cretaceous to Miocene sequences. Channel, floodplain and lacustrine deposits of the Loongana Sandstone and Madura Formation indicate that the Early Cretaceous sea did not reach the Kitchener area. Middle to Late Eocene deposits unconformably overlie the Cretaceous sequence and extend up the Lefroy Palaeoriver towards Norseman where they merge with the Bremer Basin sediments. The Hampton Sandstone extends up the Lefroy Palaeoriver and was deposited under shallow high energy marine conditions probably in a well‐flushed large estuary. An erosional break at the top of the Hampton Sandstone and a wedge of fluvial sand in the Chifley palaeochannel provide evidence for a regression. The succeeding Late Eocene transgression covered wide areas around the Lefroy Palaeoriver and led to deposition of the Princess Royal Spongolite. Low oxygen levels and abundant silica, possibly derived from volcanic ash, allowed sponges to thrive in areas with restricted circulation on the basin margin while limestone accumulated in the sediment starved centre of the basin. The break between the Hampton Sandstone and Princess Royal Spongolite in the Harris Lake area is probably equivalent to the major sea level lowstand at 39.5 Ma.

Tertiary coastal dunes of the Eucla Basin, Australia

On the northeast margin of the Nullarbor Plain in western South Australia, there is preserved an assemblage of coastal aeolian landforms that includes coastal dune, dune ridge and possible beach ridge. One of these landforms is the Ooldea Range, a 650 km long coastal dune that lies 25–300 km from the present coast. These landforms are believed to have formed at the end of the Eocene, after maximum marine transgression in the Eucla Basin. The Ooldea, Barton and Paling ranges formed in a tectonically stable region of topographically subdued terrain. Their orientation and position may be related in part to crustal fractures that were active during initial break-up of Australia and Antarctica. The large quantities of sand required for their construction were supplied to the coast by rivers which drained a hinterland of various suitable source rocks. Growth may have begun as chains of barrier islands, which amalgamated to form large coast-parallel dunes during progradation. These coastal dunes provide evidence about climate at and after the time of their formation. Their formation indicates an atmospheric circulation of at least moderate intensity and prevailing winds with a major westerly component. This occurred at a time when the climate is likely to have been temperate. If the interpretation of the dunes age is correct, they may be viewed as landforms bearing testimony to the global change in climate which occurred at the end of the Eocene. Their excellent preservation in the landscape today, some 34–37 million years after formation, is remarkable. Implied, is a degree of aridity for much of the remainder of the Cainozoic. This appears to have been more significant in the Nullarbor Plain region than in the southeastern part of Australia. Other factors responsible for their preservation are likely to include vegetation cover, the permeability of their quartz sands, subsequent history of sea level and hydrodynamics of the basin.

Oil and Gas Developments in Australia in 1989

Offshore discoveries at the beginning and end of 1989 brightened an otherwise uneventful year. Wanaea 1, spudded in 1988 in the Dampier subbasin, flowed oil in February. Cowle 1, in the offshore Carnarvon basin, was testing at year end. Talbot 1 became the only discovery in the Vulcan basin (at the opposite end of Australia's vast North West Shelf) in the closing days of 1989. It was a year of reduced onshore exploration activity (the lowest since 1980), but there was more offshore activity than since 1984 in the Gippsland, Carnarvon, and Bonaparte basins, and the Vulcan subbasin. At year end, 5 offshore wildcats and 1 development well were in progress: 3 in the Carnarvon basin, 2 in the Vulcan subbasin, and 1 in the Otway basin. Onshore, no finds of significance were recorded in 1989. Although appraisal drilling at Katnook in the Otway basin was successful and 1 wildcat was completed as a gas well, 2 neighboring prospects were found wanting. In the Cooper-Eromanga region, the 15 discoveries were small, and no discoveries were made in the Surat basin, Denison trough, Pedirka basin, or onshore Canning and Carnarvon basins. Geophysical activity was the lowest onshore since 1978, but offshore activity was the highest for the decade. Average daily production of 472,000 bbl (compared with 519,000 bbl in 1988) of crude oil and condensate amounted to about 80% of Australian refinery capacity. Sixty-six percent of the production came from Gippsland basin fields and 15% from Carnarvon basin, where new fields came on-stream. LNG from the North West Shelf was brought on-stream for the first time. While the number of exploration permits in force throughout the nation did not change significantly, large tracts were relinquished in the Canning basin in Western Australia and over portions of the southern Eromanga, Arrowie, Eucla, Murray, Pedirka, and Pirie-Torrens basins in South Australia. Agreement during 1989 between Australia and Indonesia about sharing of potential production in the eastern Timor Sea off Austral a's North West Shelf is expected to open this area to exploration in the near future.

The regional geology and gross structure of the Cundeelee area, Western Australia

A large, remote area on the eastern margin of the Archaean Yilgarn Block was studied by interpreting aeromagnetic, radiometric and gravity data. This tract was previously part of a magnetic-trend study over a much larger area in which a distinct change in magnetic character was observed between Archaean and Proterozoic terrain. Four major provinces were delineated: a western Archaean Yilgarn province, dominantly granite/gneiss; a gneissic/migmatitic transition province; a Proterozoic granulitic province; and an eastern plutonic complex underneath a veneer of Eucla Basin Tertiary sediments. A basic dyke sub-province containing remanently magnetized bodies transects the Yilgarn Province. To account for the interpreted features: an intercontinental collision, an intracratonic fault trough, and an upfaulted crustal block are considered as tectonic processes. However, at the present low level of geological knowledge it is difficult to propound a definitive tectonic model.

Tertiary stratigraphy of Western Australia

Abstract This paper is a summary of the present knowledge of the Tertiary stratigraphy of Western Australia. Also included is new information on the Cainozoic of the Carnarvon Basin, a result of petroleum exploration in the area. Tertiary rocks formed during more than one cycle of deposition in three basins (Eucla, Perth, and Carnarvon), and also as thin units deposited in a single transgression along the south coast. The Tertiary stratigraphy of the Bonaparte Gulf Basin is not well known. Drilling in the Eucla Basin has encountered up to 400 m of Tertiary in the south central part, with uniform thinning towards the margins. The section begins with a middle‐upper Eocene carbonate unit which represents the dominant event in the Tertiary sedimentation in this basin. More carbonates were deposited in the late Oligocene‐early Miocene and middle Miocene. Along the south coast, the so‐called Bremer Basin, the Plantagenet Group (up to 100 m) of siltstone, sandstone, spongolite, and minor limestone, was deposited...

Phanerozoic history of Western Australia related to continental drift

Abstract From north to south, the sedimentary basins of Western Australia change from broad platforms of wholly marine strata that span the entire Phanerozoic (Bonaparte Gulf and Canning Basins) through the intermediate Carnarvon Basin to rifts of nonmarine Permian and Mesozoic strata (Perth Basin). These contrasts in age, facies, and structure reflect different positions of the basins in Gondwanaland: the Bonaparte Gulf and Canning Basins have lain at the continental margin facing an open ocean during the entire Phanerozoic, whereas the Perth Basin lay in the interior of Gondwanaland until India and Australia moved apart in the Cretaceous. The Eucla Basin came about by events connected with the dispersal of Antarctica and Australia in the Eocene. The northwest part of the Australian Block (Timor and the Timor Sea) was deformed in the Miocene when Australia collided with southeast Asia.

GEOLOGICAL FRAMEWORK OF THE GREAT AUSTRALIAN BIGHT

Geophysical exploration carried out in the Great Australian Bight since 1966, combined with geological fieldwork in the adjacent land areas, has made it possible to outline the broad geological framework of the area.The "basement" consists of two major units, an offshore extension of the locally metamorphic Cambrian Kanmantoo Group in the south-east and the extension of the West Australian Archaean shield in the north-west. The boundary is thought to follow a trend extending westerly from the Cygnet-Snelling fault zone on Kangaroo Island.In two areas the basement has been downfaulted, thus creating depositional areas for thick sequences of sediments, namely the Elliston trough to the west of Eyre Peninsula and the Duntroon basin, south of Eyre Peninsula and west of Kangaroo Island.The geological setting of the Duntroon basin appears to be comparable with the Otway basin and a Jurassic- Cretaceous age is assumed for the folded sequence of sediments overlying the basement and underlying the Tertiary with angular unconformity. The basin was possibly partially and temporarily closed to the south and open to marine influences from the west.In the Elliston trough the lower part of the section which has low to medium velocity seismic character, is probably Mesozoic, as is evidenced by the Upper Jurassic encountered in its onshore extension. Proterozoic-Cambrian sediments may overlie the basement in the eastern part of the trough. Deformation of the Mesozoic is limited to the mouth of the trough where there is indication of a base- Tertiary unconformity. This trough was probably also open to marine influences to the west.Along the continental margin between the basins and also south of the Eucla basin a thin Mesozoic section, conformably underlying the Tertiary, is probably present, gradually thickening towards the continental slope.In the onshore area Tertiary sedimentation started with local deposition of clastics during the Middle Eocene, which also may have been the case off the Eucla basin, in the Elliston trough and in the Duntroon basin. Carbonate sedimentation took place from the Middle-Upper Eocene onwards, to reach its widest areal extent during the Lower Miocene. A hiatus during the Oligocene may have occurred in the western part of the Bight as is the case in the Eucla basin.Only weak deformation of the Tertiary in the offshore area has been observed. This generally occurs over Mesozoic structures in the Duntroon basin and as draping over topographic basement highs at the mouth of the Elliston trough.No significant hydrocarbon indications are known from the surrounding land areas, but the well-documented bitumen strandings along the coast point to offshore seepages indicating generation of hydrocarbons in the general area.At this stage prospects must be regarded as speculative.although a folded probable Mesozoic sequence forms an objective in the Duntroon basin while prospective Mesozoic-Tertiary section appears to be present in the Elliston trough, where structural evaluation is still at a relatively early stage.

Sedimentation and physiography of the sea floor south of Australia

Carbonate sedimentation has characterized the sea floor off the mainly arid and low-lying southern Australian continent during the Tertiary and Quaternary. The 30–100 mile wide and 600 mile long shelf of the Great Australian Bight lies seaward of the Tertirary Eucla Basin and is covered by coarse calcareous and mainly relic Pleistocene sands that are constantly shifted and rippled by bottom currents. Bryozoans, molluscs, sponges and other calcareous species live on the shelf and also comprise the bulk of the relic sands. Vittaticellid bryozoans, foraminifera and sponge spicules are abundant near the shelf and upper parts of the continental slope, while foraminiferal and coccolith oozes characterize the slope sediments. The shelf to the east and west of the Great Australian Bight is generally more narrow and flanked by steep continental slopes incised by the Albany Canyons lying seaward of the crystalline shield in the west, and the Murray Canyons lying seaward of the folded Adelaide geosyncline rocks to the east. The 350 mile-long Ceduna Plateau bounded by the 500–1,000 fathom isobaths flanks the eastern part of the Great Australian Bight and probably represents a downwarped extension of the Eucla Basin. The continental slope merges into a wide continental rise which extends the complete length of the continental margin and merges seawards around depths of 2,900 fathoms into the Great Australian Bight Abyssal Plain which has maximum depths around 3,100 fathoms. Eight piston cores from the rise and plain consist of greater than 90% light-coloured calcareous graded beds of clay, silt and sand interbedded with dark-coloured, burrow-mottled, calcareous-poor, pelagic or hemipelagic silts and clays. The calcareous sands consist of bryozoans, molluscs, foraminifera, algae, sponge spicules, beachrock, reworked Pleistocene to Tertiary organisms and a variety of other organisms derived from the continental shelf and slope and transported up to 700 miles across the sea floor by turbidity currents. The 1–2 km of poorly consolidated sediments that comprise the continental rise and abyssal plain may have been mainly deposited during the Quaternary.

The Mundrabilla Meteorite : a New Discovery in Western Australia

IN March 1966, while engaged on a geological survey of a portion of the Eucla Basin in Western Australia, we discovered two large iron meteorites. The two principal masses, lying some 600 ft. apart, are located on the Nullarbor Plain, to the north of the Transcontinental Railway (latitude 30° 47′ S., longitude 127° 33′ E.). Earlier reports of the sighting of a meteorite by a rabbit-trapper, now deceased, have led to several expeditions which failed, however, to discover these masses.

X. The Eucla Basin in South Australia

X. The Eucla Basin in South Australia