A review of coastal dunefield evolution in Southeastern Queensland

The Southern Queensland subtropical coastline represents a major depositional system containing 3 of the largest sand islands in the world. The surface of these sand masses comprises foredune ridges and predominantly large transgressive dunefields, deposited episodically during the Quaternary. The chronological sequence of these dunefield phases, however, is still poorly understood. This paper summarizes the information available regarding dunefield transgression events on the southern coast of Queensland and indicates that both marine and climate effects are important controlling factors for dunefield evolution but that an understanding of the relative thresholds of each factor as the main trigger of dune emplacement phases remains a challenge

A chironomid based transfer function for reconstructing summer temperatures in south eastern Australia

We present a new chironomid based temperature transfer function which was developed from a training set of 33 natural and artificial lakes from southeast Australia from subtropical Queensland to cool temperate Tasmania. Multivariate statistical analyses (CCA, pCCA) were used to study the distribution of chironomids in relation to the environmental and climatic variables. Seven out of eighteen available variables were significantly (

El Nino Suppresses Aantarctic Warming

Here we present new isotope records derived from snow samples from the McMurdo Dry Valleys, Antarctica and re-analysis data of the European Centre for Medium-Range Weather Forecasts (ERA-40) to explain the connection between the warming of the Pacific sector of the Southern Ocean [Jacka and Budd, 1998; Jacobs et al., 2002] and the current cooling of the terrestrial Ross Sea region [Doran et al., 2002a]. Our analysis confirms previous findings that the warming is linked to the El Nino Southern Oscillation (ENSO) [Kwok and Comiso, 2002a, 2002b; Carleton, 2003; Ribera and Mann, 2003; Turner, 2004], and provides new evidence that the terrestrial cooling is caused by a simultaneous ENSO driven change in atmospheric circulation, sourced in the Amundsen Sea and West Antarctica

Archaeal lipid-inferred paleohydrology and paleotemperature of Lake Chenghai during the Pleistocene-Holocene transition

Over the past decades, paleoenvironmental studies in the Indian summer monsoon region have mainly focused on precipitation change, with few published terrestrial temperature records from the region. We analysed the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) in the sediments of Lake Chenghai in southwest China across the Pleistocene-Holocene transition, to extract both regional hydrological and temperature signals for this important transition period. The lake level was reconstructed from the relative abundance of crenarchaeol in isoGDGTs (%cren) and the crenarchaeol'/crenarchaeol ratio. The %cren-inferred lake level identified a single lowstand (15.4-14.4 ka cal BP), while the crenarchaeol'/crenarchaeol ratio suggests a relatively lower lake level between 15.4-14.4 and 12.5-11.7 ka cal BP, corresponding to periods of weakened ISM during the Heinrich 1 and Younger Dryas cold event. A filtered TetraEther indeX consisting of 86 carbon atoms (TEX86 index) revealed that lake surface temperature was similar to present-day values during the last deglacial period and suggests a substantial warming of similar to 4 degrees C from the early Holocene to the mid-Holocene. Our paleotemperature record is generally consistent with other records in southwest China, suggesting that the distribution of isoGDGTs in Lake Cheng-hai sediments has potential for quantitative paleotemperature reconstruction

Ice-contact proglacial lakes associated with the Last Glacial Maximum across the Southern Alps, New Zealand

Proglacial lakes can affect the stability of mountain glaciers and can partly disengage glacier behaviour from climatic perturbations. However, their role in controlling the onset and progression of deglaciation from the Last Glacial Maximum (LGM) remains poorly understood. This lack of understanding is partly because the evidence required to consistently and robustly identify the location and evolution of ice-contact lakes is not standardised. In this paper we therefore firstly present a new set of criteria for identifying the landform and sedimentary evidence that defines and characterises ice-marginal lakes. Secondly, we then apply these key criteria with the aid of high-resolution topographic mapping to produce the first holistic definition and assessment of major proglacial lake landforms and sediments pertaining to the end of the LGM across South Island, New Zealand. The major findings of this assessment can be grouped to include that: (i) The localised constraints to proglacial lake extent were topography, glacier size and meltwater/sediment fluxes, (ii) Lake damming was initiated by outwash fan-heads that interrupted water and sediment flows down-valley, and (iii) New Zealand LGM lakes were unequivocally in contact with a calving ice margin. These findings will be useful for reconstructing ice dynamics and landscape evolution in this region

A Holocene Pollen record from Lowland Tropical Australia

A pollen record from a dunefield lake on Groote Eylandt, Northern Australia is presented. This is the first substantially complete Holocene terrestrial record from the seasonally humid lowland tropics of Northern Australia. The lake originated as a seasonal swamp prior to 10 000 BP. A progressive rise in water tables occurred until a permanent lake was established at about 9000 BP. From 9000 to 7500 BP the lake shows evidence of disruption in the surrounding dunefield. Prior to 7500 BP an open grassland covered the dunefield. After 7500 BP the area was rapidly colonized by Eucalyptus open forest and acacias. These types remain dominant to the present. The data suggest that conditions continuously ameliorated from the base of the record to the mid-Holocene and there is evidence of an effective precipitation maximum at about 4000 BP. Effective precipitation declined after 3800 BP but a recovery took place about 1000 BP