Mid Pleistocene arid shift in southern Australia, dated by magnetostratigraphy

Soil Research ◽  
2001 ◽  
Vol 39 (1) ◽  
pp. 89 ◽  
Author(s):  
Brad Pillans ◽  
Robert Bourman
Keyword(s):  
Marked Change ◽  
Source Area ◽  
Pronounced Change ◽  
Sea Levels ◽  
Leeuwin Current ◽  
Polarity Transition ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Regional Climates ◽  
Regional Rainfall

In coastal sections at Hallett Cove and Sellicks Beach, south of Adelaide, and at Redbanks section on Kangaroo Island, the Brunhes/Matuyama polarity transition (780 ka) is identified in the strongly oxide-mottled Ochre Cove Formation. At all 3 sections, the Ochre Cove Formation is overlain by a calcareous grey-green aeolian clay, called Ngaltinga Clay, which in turn is overlain by calcareous sediments of the Taringa and Christies Beach Formations. The marked change from an oxide-dominated weathering regime to a carbonate-dominated weathering regime, estimated to have occurred at about 500–600 ka, is interpreted as a major arid shift in regional climates. Similar arid shifts are known from Lake Bungunnia in the Murray Basin and Lake Lefroy in southern Western Australia, where changes from lacustrine clays to evaporites and dune sediments are estimated to have occurred between 400 and 700 ka, and about 500 ka, respectively. An increase in aeolian dust accession in south-eastern Australia, consistent with increased aridity in the interior source area, occurred after 780 ka, and was probably coeval with increased dust input to Tasman Sea sediments since 350 ka. Between 600 and 900 ka, oxygen isotope fluctuations in deep-sea cores showed a pronounced change in frequency, from a 40 ka (obliquity dominated) to a 100 ka (eccentricity dominated) pattern. At the same time, glacial-interglacial amplitudes increased, with a marked enrichment of glacial d18O values consistent with larger continental based ice-sheets. Colder global temperatures, and lower sea levels during glacials, may have played a part in the mid Pleistocene arid shift recorded in southern Australia. Associated variations in the strength of the warm Leeuwin Current may also have affected regional rainfall patterns in southern Australia.

scholarly journals Response of the Snowy River Estuary to two environmental flows

2015 ◽  
Vol 127 (2) ◽  
pp. 28
Author(s):  
Errol J. McLean ◽  
Jon B. Hinwood
Keyword(s):  
Fresh Water ◽  
Peak Flow ◽  
Environmental Flows ◽  
River Estuary ◽  
Environmental Flow ◽  
River Channel ◽  
Salinity Gradients ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Major River

The Snowy River is a major river in south-eastern Australia, discharging to the Tasman Sea via a barrier estuary, with its entrance constricted by marine sands. Since the construction of the Snowy Mountains Scheme, river flows have not been sufficient to maintain the river channel. A program of environmental flow releases (EFR) is returning water to the river to restore the fluvial reaches and is now trialling flow regimes that may also benefit the estuarine reaches. This paper documents the response of the estuarine segments of the Snowy River to two EFRs; the release in 2010 was designed to scour the upper reaches of the Snowy River while the larger 2011 release was intended to extend the scouring downstream. For each release, the effects on the entrance morphology, tides and salinity through the flow peak and recovery are described. Each EFR caused minor increases in depth and very minor longshore movement of the entrance channel, although each EFR had been preceded by a larger fresh flow that would have scoured the channels. The small increase in fresh water inflow in the 2010 EFR pushed salinity contours seawards and steepened vertical salinity gradients. The larger inflow in the 2011 EFR purged the upper estuary of saltwater. After the peak flow, salinity recovery was rapid in the principal estuarine channels but took weeks where poorly connected wetlands could store fresh flood waters. Critical flows for scouring the entrance and purging salinity are estimated.

FISSION TRACK THERMOCHRONOLOGY: APPLICATION TO CONTINENTAL RIFTING OF SOUTH-EASTERN AUSTRALIA

1991 ◽  
Vol 31 (1) ◽  
pp. 131 ◽  
Author(s):  
T. A. Dumitru ◽  
K. C. Hill ◽  
D. A. Coyle ◽  
I. R. Duddy ◽  
D. A. Foster ◽  
...  
Keyword(s):  
Thermal History ◽  
Fission Track ◽  
Apatite Fission Track ◽  
South Eastern ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Uplift And Erosion ◽  
Track Analysis ◽  
Plate Type ◽  
South Eastern Australia

Over the last five to ten years, apatite fission track analysis has developed into a sophisticated technique for studying the low-temperature thermal history of rocks. It has particular utility in oil exploration because its temperature range of sensitivity, about 20° to 125°C, overlaps the oil generation window. Whereas older fission track thermal history approaches relied solely on the sample fission track age, the new interpretive approaches use sample age, single grain age and track length data. They also emphasise the analysis of systematic variations in data patterns in sequences of samples, such as samples from various depths in a well. Laboratory study of the thermal annealing of fission tracks and compilation of fission track data from geological case studies has greatly improved our understanding of apatite fission track systematics, allowing considerably more detailed interpretations of thermal histories.Application of apatite fission track analysis to the rifted continental margins of south-eastern Australia shows that rifting and separation of Australia from Antarctica and the Lord Howe Rise were accompanied by at least 1.5-3 km of uplift and erosion along the Tasman Sea and Bass Strait coasts. Uplift and erosion were much less 100 km or so inland. This shows that the uplift of the south-eastern Australian margins was caused by the continental rifting process, the same process that initiated major subsidence in the sedimentary basins in Bass Strait. The consistent fission track data patterns around south-eastern Australia suggest a generally similar tectonic setting for the Tasman Sea and Bass Strait parts of the margin. Lister et al. (in press) propose that the Tasman part of the margin is an upper plate type of margin that formed above a west-dipping detachment zone. The fission track data suggest that the Bass Strait part of the margin may also be of upper plate type.

Indurated sand horizon influences present day coastal geomorphology of nearshore Northern Moreton Bay, South-East Queensland, Australia

2020 ◽  
Author(s):  
Craig Heatherington ◽  
Simon Albert ◽  
Remo Cossu ◽  
Justine Kemp ◽  
Alistair Grinham
Keyword(s):  
Sea Level ◽  
Sand Dunes ◽  
Historical Context ◽  
Soil Formation ◽  
Coastal Geomorphology ◽  
Sea Levels ◽  
Moreton Bay ◽  
Core Samples ◽  
Marine Sand ◽  
Eastern Australia

<p>Sea-level rise will lead to substantial changes to coastal geomorphology over the coming century and it is imperative to understand the implications. This includes the underlying stratigraphic influences on seabed morphology and the historical context with which they have formed. On the densely populated coastline of Eastern Australia, coastal erosion is a significant concern for residents and stakeholders. In South East Queensland, and particularly the coastal zone surrounding Bribie Island spit in Northern Moreton Bay, the accelerated erosion of the spit and discovery of indurated sand horizons in nearshore regions both above and below the seabed create a convergence of the past influencing the present.</p><p>Indurated sand horizons are predominantly considered to be the relict B horizon of the pedogenic processes that formed a podosol soil profile. Whilst not ubiquitous under present sea level, their presence presents a unique opportunity to study an accessible palaeosol unaltered by further pedogenesis and carbon input (as opposed to terrestrial indurated sand formations). This allows for an analysis of a time in Northern Moreton Bay during lower sea levels and how these horizons affect present day morphology. Data acquisition consisted of high and low frequency acoustics, coupled with core samples for geological analysis.</p><p>Our results show the indurated sands buried under 1-2 m of marine sands sloping downwards to the east. This suggests the present-day seabed follows the contours of the sub-surface indurated sand. High-resolution bathymetry of exposed indurated sand outcrops near Bribie Island spit indicate a dune-like shape suggesting a formation from coastal sand dunes into active terrestrial soil during lower sea levels. The dune troughs having accumulated greater mineral and organic material than the peaks, which can be attributed to the former surviving inundation from rising sea levels and the latter having undergone a weaker pedogenesis and subsequently erosion. Exposed indurated sand outcrops with a vertical face or ‘scour step’ are elevated to the surrounding marine sand seabed. Similar elevated structures were found to be a barrier to onshore sediment transport from offshore deposits and limiting beach replenishment whilst also offering protection from dampening long period waves and large storm swells. Core samples taken through the indurated layer from behind the spit to the shipping channel offshore showed elevated levels of aluminium and iron compared to surrounding marine sands, and consistent with podosol soil formation.</p><p>The techniques used here suggest that historical terrestrial geomorphology has determined the shape, mineralogy and strength of indurated sand layers. As these indurated sand layers were submerged and further modified by present day sea level, they may play an important role in coastal geomorphology and protection as sea levels rise further in the coming century.</p>

Putting the ‘Indo’ back into the Indo-Pacific: resolving marine phylogeographic gaps

2016 ◽  
Vol 30 (1) ◽  
pp. 86 ◽  
Author(s):  
N. G. Wilson ◽  
L. A. Kirkendale
Keyword(s):  
Indian Ocean ◽  
Large Body ◽  
Western Indian Ocean ◽  
Marine Biodiversity ◽  
Coral Triangle ◽  
West Pacific ◽  
Sea Levels ◽  
Leeuwin Current ◽  
Marine Realm ◽  
The Indian Ocean

The Indo-Pacific is an extremely large marine realm that unites two oceans via a restricted Coral Triangle corridor, which was historically subjected to lowered sea levels during global glaciation. Although a strong phylogeographic focus on the Central and West Pacific has produced a large body of research, the Indian Ocean has been largely neglected. This may have serious consequences, because the Indian Ocean hosts a large number of marine centres of endemism, yet a large number of nations rely on its marine resources. We examine reasons for this neglect and review what is known about this region and its connectivity to the Indo-West Pacific. We draw attention to the ‘Leeuwin Effect’, a phenomenon where the southward flow of the Leeuwin Current is responsible for transporting larval propagules from the Coral Triangle region down the coast of Western Australia, resulting in broader Indo-West Pacific rather than Indian Ocean affinities. Given challenges in accessing infrastructure and samples, collaboration will inevitably be key to resolving data gaps. We challenge the assumption that the peak of shallow-water marine biodiversity is solely centred in the Coral Triangle, and raise awareness of a seemingly forgotten hypothesis promoting a secondary peak of biodiversity in the western Indian Ocean.

Radiocarbon evidence against higher Postglacial sea levels in eastern Australia

1969 ◽  
Vol 7 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Bruce G. Thom ◽  
John R. Hails ◽  
A.R.H. Martin
Keyword(s):  
Sea Levels ◽  
Eastern Australia

CONTINENTAL DRIFT AND BASIN DEVELOPMENT IN SOUTH EASTERN AUSTRALIA

1972 ◽  
Vol 12 (2) ◽  
pp. 46
Author(s):  
John L. Elliott
Keyword(s):  
Continental Drift ◽  
Fluvial Sediments ◽  
Block Rotation ◽  
Southeastern Australia ◽  
Early Tertiary ◽  
The Pacific ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Pacific Margin ◽  
Gippsland Basin

The Gippsland, Bass and Otway Basins in southeastern Australia are filled with sediments ranging in age from earliest Cretaceous to Recent. These basins were formed from the processes and forces which fragmented the Pacific margin of Gondwanaland. Their sedimentary histories and tectonic styles locate and date the movement of those continental masses now detached.An Early Cretaceous rift valley extended from the Otway Basin through the Gippsland Basin and on to Lord Howe Rise, (a part of eastern Australia at that time). A transform fault separated Tasmania and Antarctica resulting in the continuing detachment of Antarctica.During the Late Cretaceous, Australia drifted from Antarctica sufficiently to allow the Southern Indian Ocean to invade the Otway Basin and the build-out of river deltas. The Otway continental crust was further stretched, resulting in normal faulting and block rotation. Crustal tension continued in the Gippsland Basin and opened the Bass Basin. Fluvial sediments were deposited in both basins. The Tasman Basin was opened.During the Early Tertiary, crustal tension continued to shape the Bass and Gippsland Basins, where thick, fluvial sediments were deposited. The first marine indicators in Gippsland are Paleocene in age and, during the Eocene, two large submarine valleys were cut and filled and a regional unconformity was developed. Early Tertiary marine elastics prograded into the Southern Indian Ocean.Mid-Tertiary marine shales, marls and limestones formed the continental margin of the Otway Basin and gently filled the Bass Basin. In the Gippsland Basin the same -aged sediments unconformably truncated and sealed Early Tertiary sandstones and contructed the continental slope into the Tasman Sea, while a right lateral shear formed the producing structures.

scholarly journals Beyond Capricornia: Tropical Sea Slugs (Gastropoda, Heterobranchia) Extend Their Distributions into the Tasman Sea

Diversity ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 99 ◽  
Author(s):  
Matt Nimbs ◽  
Stephen Smith
Keyword(s):  
Research Effort ◽  
Tropical Species ◽  
Sea Slug ◽  
Sea Slugs ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Taxonomic Uncertainty ◽  
Tropical Sea ◽  
First Time ◽  
Unambiguous Interpretation

There is increasing evidence of poleward migration of a broad range of taxa under the influence of a warming ocean. However, patchy research effort, the lack of pre-existing baseline data, and taxonomic uncertainty for some taxa means that unambiguous interpretation of observations is often difficult. Here, we propose that heterobranch sea slugs provide a useful target group for monitoring shifts in distribution. As many sea slugs are highly colourful, popular with underwater photographers and rock-pool ramblers, and found in accessible habitats, they provide an ideal target for citizen scientist programs, such as the Sea Slug Census. This maximises our ability to rapidly gain usable diversity and distributional data. Here, we review records of recent range extensions by tropical species into the subtropical and temperate waters of eastern Australia and document, for the first time in Australian waters, observations of three tropical species of sea slug as well as range extensions for a further six to various locations in the Tasman Sea.

Microgeographic, Genetic and Morphological-Differentiation of Fresh-Water Snails - the Hydrobiidae of Wilson Promontory, Victoria, South-Eastern Australia

1994 ◽  
Vol 42 (5) ◽  
pp. 557 ◽  
Author(s):  
WF Ponder ◽  
DJ Colgan ◽  
GA Clark ◽  
AC Miller ◽  
T Terzis
Keyword(s):  
Morphological Differentiation ◽  
Geographic Area ◽  
Low Flow ◽  
Secondary Contact ◽  
Shell Shape ◽  
Population Subdivision ◽  
Additional Species ◽  
Sea Levels ◽  
Eastern Australia ◽  
Genetic Patterns

Population differentiation and speciation in freshwater snails in a small geographic area were investigated in a study of the morphology and genetics of 75 populations of hydrobiid snails from streams on Wilsons Promontory, Victoria, Australia. At least four genetically definable species occur in sympatry. One (Fluvidona recta sp. nov.) is genetically isolated from the others and the other three (of which only F: turbata sp. nov. is named) appear to be closely related and distinguished by a nearly fixed allozyme (MPI) difference. Heterozygote frequencies for the diagnostic Mpi locus fall well below Hardy-Weinberg expectations in zones of sympatry. There is significant population subdivision within at least two of the genetic species, but as the partitions are allopatric they are not categorised taxonomically. The situation may be explained by the divergence of upland and lowland populations when sea levels fell during the Pleistocene with subsequent secondary contact and low levels of hybridisation in the contact zones. Generally, there is very low gene flow between even closely adjacent populations and extremely low flow between different catchments, F-ST between populations within the same tributary ranging from 0.02 to 0.14 and within adjacent tributaries of the same catchment ranging from 0.03 to 0.59. Some correlations between allozyme data and measured environmental variables were observed but none of these were consistent over all taxa. Size (shell length) appears to be influenced by environment, but shell shape and the length of the opercular smear are more correlated with genetic patterns. A notable lack of correlation between anatomy and genetic groupings was found, although there was some with shell and opercular morphology. Two additional species (F: gippslandica, sp. nov. and F: foris, sp. nov.) from areas adjacent to the Promontory are used as outgroups.

Sign in / Sign up

Export Citation Format

Share Document