Browsing by Author "May, JH"
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- ItemContinental aridification and the vanishing of Australia's megalakes(Geological Society of America, 2011-02) Cohen, TJ; Nanson, GC; Jansen, JD; Jones, BG; Jacobs, Z; Treble, PC; Price, DM; May, JH; Smith, AM; Ayliffe, LK; Hellstrom, JCThe nature of the Australian climate at about the time of rapid megafaunal extinctions and humans arriving in Australia is poorly understood and is an important element in the contentious debate as to whether humans or climate caused the extinctions. Here we present a new paleoshoreline chronology that extends over the past 100 k.y. for Lake Mega-Frome, the coalescence of Lakes Frome, Blanche, Callabonna and Gregory, in the southern latitudes of central Australia. We show that Lake Mega-Frome was connected for the last time to adjacent Lake Eyre at 50–47 ka, forming the largest remaining interconnected system of paleolakes on the Australian continent. The final disconnection and a progressive drop in the level of Lake Mega-Frome represents a major climate shift to aridification that coincided with the arrival of humans and the demise of the megafauna. The supply of moisture to the Australian continent at various times in the Quaternary has commonly been ascribed to an enhanced monsoon. This study, in combination with other paleoclimate data, provides reliable evidence for periods of enhanced tropical and enhanced Southern Ocean sources of water filling these lakes at different times during the last full glacial cycle. © 2011, Geological Society of America
- ItemDeciphering the role of terrigenous sediment supply for headwater channels in the Pilbara, WA(Australasian Quaternary Association Inc., 2022-12-06) Flatley, AJ; May, JH; Fujioka, T; Fink, DUsing a multi cosmogenic nuclide approach (10Be and 26Al) we investigate terrigenous sediment supply in catchments to provide much needed baseline denudation rates in the Pilbara region. Detailed analysis of catchment morphometric properties and lithology have been combined with cosmogenic nuclide measurements to improve our understanding of sediment pathways, residence times and storage in headwater catchments. Our results suggest that this region has some of the lowest erosion rates in the world, between 0.94-4.04 mMyr-1, a range similar to previously measured channel bedrock rates in the region, but somewhat higher than results from outcrops on mesa summits previously measured using 53Mn (0.8 ± 0.6 mMyr-1). This apparent offset in erosion rates between horizontal bedrock surfaces and basin wide averages infers that the vast areas of iron-rich rock surfaces within the region are unlikely a major contributor of sediment to the system. Instead, vertical faces in the catchments have a role as a dominant sediment source and there is a complex erosional history of in-channel sediments within the headwater streams. Our results show 26Al/10Be ratios lower than the nominal production ratio, suggesting that the channel sediments are provided from either (or combination of) long-term, shallow buried regolith, or non-horizontal surfaces in the landscape (e.g., gorges and exposed cliffs). Erosion at the margins of the river channels is hence a key source of sediment supply and broadly the hillslope-headwater channel sediment conveyer is a minor contributor. Base-level stability and highly resistant nature of the prevailing lithology in the region results in these extremely low erosion rates in a high slope environment. Within these headwater catchments, sediment contributions are compounded by topographic inversion, increased albeit episodic fluvial activity and highly erosion resistant Banded Iron Formation. The study demonstrates that a multi cosmogenic nuclide approach is useful, not only to evaluate denudation rates, but also to decipher the complex history of sediment production and transport.
- ItemDiscordant 26Al/10Be ratios as an indicator of bedrock plucking: case studies from northern Australia(Australian Nuclear Science and Technology Organisation, 2021-11-17) Fujioka, T; May, JH; Fink, D; Nanson, GCWith the number of multi cosmogenic nuclide data from detrital samples increased, it becomes apparent that discordant ²⁶ Al/¹⁰ Be ratios are not exception but common. Traditionally, depressed ²⁶ Al/¹⁰ Be ratios, below the nominal production ratio of 6.8, have been interpreted as prior burial. However, in northern Australia, such scenario is highly unlikely as the region is subject to intensive annual floods and therefore river channels normally lack long-term sediment storage. Another possible interpretation for lower ²⁶ Al/¹⁰ Be ratios is non-steady state erosion, such as stochastic bedrock plucking. Such interpretation has an important implication to the sediment source and production mechanism, and therefore to the basin-wide erosion rate approach that assumes a steady-state erosion at sediment source. In this study, we measured ¹⁰ Be and ²⁶ Al concentrations from three different waterfall sites in northern Australia with contrasting lithological and physical characteristics, in an attempt to capture depleted ²⁶ Al/¹⁰ Be ratios. Our results indicate that ²⁶ Al/¹⁰ Be ratios from two sandstone-dominated sites show consistently lower values (4.3-6.1), consistent with non-steady erosion interpretation, whereas data from a quartzite-dominated site (5.9-6.9) are indistinguishable from steady-state interpretation. Detrital samples collected downstream at each site indicate the similar trend as respective bedrock sites, implying that sediments are largely derived from the waterfall bedrock surfaces. In this paper, we discuss the results in the context of lithological difference and physical erosion mechanism between the sites. © The Authors
- ItemDust deposition tracks late-Holocene shifts in monsoon activity and the increasing role of human disturbance in the Puna-Altiplano, northwest Argentina(SAGE, 2020-04-01) Hooper, J; Marx, SK; May, JH; Lupo, LC; Kulemeyer, JJ; Pereira, EdlÁ; Seki, O; Heijnis, H; Child, DP; Gadd, PS; Zawadzki, AThe Puna-Altiplano plateau represents a regionally significant dust source, which is critically located at the nexus between the tropical and sub-polar synoptic systems that dominate the South American climate. Dust emissions in this region would therefore be expected to be sensitive to changes in these systems, in particular the strength and position of the South American Summer Monsoon (SASM). Here, we present a late-Holocene multi-proxy study where changes in dust flux, reconstructed from a high-altitude peat mire, are examined in light of climate variability and human impacts. Results show that for most the 4300 cal. yr BP record, dust flux sensitively tracked changes in SASM activity. Prior to 2600 cal. yr BP relatively high dust flux implies dry conditions prevailed across the Puna-Altiplao in association with reduced SASM activity. The chemistry of dust deposited at this time matched the large endorheic basins on the Puna, which host ephemeral lakes and terminal fans, indicating these were actively supplying dust to the airstream. After 2600 cal. yr BP, SASM activity increased while dust flux decreased and the dust chemistry changed, collectively implying the shutting down of the Puna-Altiplano as a significant dust source. Dust flux increased after 1000 cal. yr BP during the ‘Medieval Warm Period’, associated with a return to drier conditions and reactivation of dust sources across the endorheic basins of the Puna. Natural variability in dust flux was dwarfed, however, by the very significant increase in flux after 400 cal. yr BP following Spanish Colonisation and associated changing landuse practices. This finding attests to the globally significant role of humans on dust emissions. © 2020 by SAGE Publications
- ItemEcosystem and landscape change in the ‘Top End’ of Australia during the past 35 kyr(Elsevier, 2021-12-01) Samuel, KM; Reynolds, W; May, JH; Forbes, MS; Stromsoe, N; Fletcher, MS; Cohen, T; Moss, PT; Mazumder, D; Gadd, PSThe Indo-Australian Summer Monsoon (IASM) is the dominant climate feature of northern Australia, affecting rainfall/runoff patterns over a large portion of the continent and exerting a major control on the ecosystems of the Australia's Top End, including the viability of wetland ecosystems and the structure of the woody savanna, which characterises Northern Australia. We examined the behaviour the IASM from 35 ka using proxy data preserved in the sediments of Table Top Swamp, a small seasonal swamp in northern Australia. Elemental data, stable C and N isotopes, pollen and sedimentary data were combined to develop a picture of monsoon activity and ecosystem response. Results demonstrated that between 35 and 25 ka conditions were drier and more stable than present, with a more grass dominated savanna and limited wetland development, implying reduced IASM activity. After ~25 ka, there is evidence of increased moisture at the study site, but also increased IASM variability. However, despite evidence of at least periodic increases in moisture, including periods of wetland establishment, the IASM displayed a subdued response to peak precession insolation forcing by comparison to the other global monsoon systems. Instead, the greatest change occurred from ~10 ka when the continental shelf flooded, increasing moisture advection to the study site and resulting in establishment of a quasi-permeant wetland. Whereas the early Holocene was marked by both the onset of pollen preservation and a wetter vegetation mosaic, indicative of a consistently active IASM, the mid-late Holocene was marked by drier vegetation, increased fire, but also increased C3 vegetation and runoff, implying increased IASM variability. Holocene changes in ecosystem dynamics occur coincident with an expansion in human population, which likely also influenced vegetation and landscape response at the study site. © 2021 Elsevier B.V.
- ItemEvolution of sandstone peak-forest landscapes – insights from quantifying erosional processes with cosmogenic nuclides(Wiley, 2017-10-16) May, JH; Huang, HQ; Fujioka, T; Fink, D; Codilean, AT; Yu, GA; Ma, Y; Wulf, G; Gu, JThe sandstone peak-forest landscape in Zhangjiajie UNESCO Global Geopark of Hunan Province, China, is characterized by >3000 vertical pillars and peak walls of up to 350 m height, representing a spectacular example of sandstone landform variety. Few studies have addressed the mechanisms and timescales of the longer-term evolution of this landscape, and have focused on fluvial incision. We use in situ cosmogenic nuclides combined with GIS analysis to investigate the erosional processes contributing to the formation of pillars and peak-forests, and discuss their relative roles in the formation and decay of the landscape. Model maximum-limiting bedrock erosion rates are the highest along the narrow fluvial channels and valleys at the base of the sandstone pillars (~83–122 mm kyr−1), and lowest on the peak wall tops (~2.5 mm kyr−1). Erosion rates are highly variable and intermediate along vertical sandstone peak walls and pillars (~30 to 84 mm kyr−1). Catchment-wide denudation rates from river sediment vary between ~26 and 96 mm kyr−1 and are generally consistent with vertical wall retreat rates. This highlights the importance of wall retreat for overall erosion in the sandstone peak-forest. In combination with GIS-derived erosional volumes, our results suggest that the peak-forest formation in Zhangjiajie commenced in the Pliocene, and that the general evolution of the landscape followed our sequential refined model: (i) slow lowering rates following initial uplift; (ii) fast plateau dissection by headward knickpoint propagation along joints and faults followed by; (iii) increasing contribution of wall retreat in the well-developed pillars and peak-forests and a gradual decrease in overall denudation rates, leading to; (iv) the final consumption of pillars and peak-forests. Our study provides an approach for quantifying the complex interplay between multiple geomorphic processes as required to assess the evolutionary pathways of other sandstone peak-forest landscapes across the globe. Copyright © 2017 John Wiley & Sons, Ltd.
- ItemLake Quaternary mega-lakes fed by the northern and southern river systems of central Australia: varying moisture sources and increased continental aridity(Elsevier Science BV, 2012-10-15) Cohen, TJ; Nanson, GC; Jansen, JD; Jones, BG; Jacobs, Z; Larsen, JR; May, JH; Treble, PC; Price, DM; Smith, AMOptically stimulated and thermoluminescence ages from relict shorelines, along with accelerator mass spectrometer C-14 ages from freshwater molluscs reveal a record of variable moisture sources supplied by northern and southern river systems to Lake Mega-frome in southern central Australia during the late Quaternary. Additional lacustrine, palynological and terrestrial proxies are used to reconstruct a record that extends back to 105 ka, confirming that Lakes Mega-frome and Mega-Eyre were joined to create the largest system of palaeolakes on the Australian continent as recently as 50-47 ka. The palaeohydrological record indicates a progressive shift to more arid conditions, with marked drying after 45 ka. Subsequently, lake Mega-Frome has filled independently at 33-31 ka and at the termination of the Last Glacial Maximum to volumes some 40 times those of today. Further sequentially declining filling episodes (to volumes 25-10 those of today) occurred immediately prior to the Younger Dryas stadial, in the mid Holocene and during the medieval climatic anomaly. Southern hemisphere summer insolation maxima are a poor predictor of palaeolake-filling episodes. An examination of multiple active moisture sources suggests that palaeolake phases were driven independently of insolation and at times by some combination of enhanced Southern Ocean circulation and strengthened tropical moisture sources. © 2012, Elsevier Ltd.
- ItemLast Glacial pluvial periods evident in subaqueous speleothems from Australia’s southern arid-margin(Australasian Quaternary Association Inc., 2022-12-06) Gould-Whaley, C; Drysdale, RN; May, JH; Hellstrom, JC; Treble, PC; Grieg, A; Cheng, H; Buswell, CArchives from Kati Thanda (Lake Eyre) basin indicate at least three distinct periods of lake filling during the Last Glacial Period. The headwaters of the megalake lie as far north as -19 °, therefore filling events are indicative of increased intensity of the Indo-Australian Summer Monsoon (IASM). However, due to the nature of unconsolidated materials, these archives are limited in how precisely they can constrain the timing of Last Glacial pluvial periods, and they cannot capture millennial-scale climate variability. Speleothems from Mairs Cave (Flinders Ranges, South Australia), present an opportunity to address these issues. The cave lies on the boundary between the arid and semi-arid regions and currently receives rainfall from both the Southern Hemisphere Westerly Winds (SHWW) and the IASM. The cave contains pendulites: stalactites with an external overgrowth of subaqueously precipitated calcite. The stalactites were initially submerged ~ 89 ka by rising groundwaters, which flooded the cave. From that point forward, the pendulites grew subaqueously during periods of regional groundwater recharge. Preliminary findings suggest periods of subaqueous growth align with higher Southern Hemisphere summer insolation, suggesting the site received enhanced tropical rainfall due to moisture delivery from the IASM. Growth rate and magnesium concentrations both appear to be responsive to millennial-scale climate change, exhibiting increases during both Heinrich events and the cold limbs of Dansgaard-Oeschger events. This is consistent with increased delivery of tropical moisture due to southerly incursions of the IASM. The study site lies near the intersection of two ‘superhighways’ of early human expansion proposed by Crabtree et al. (2021). The cave is also 200 km directly south of the Warratyi shelter, one of the earliest sites of human occupation in southern-central Australia. Therefore, the palaeoclimate record to emerge from this research could potentially provide a more detailed climatic contextualisation for this period of human history.
- ItemLate quaternary fluvial incision and aggradation in the Lesser Himalaya, India(Elsevier, 2018-10-01) Dosseto, A; May, JH; Choi, JH; Swander, ZJ; Fink, D; Korup, O; Hesse, PP; Singh, T; Mifsud, C; Srivastava, PReconstructing how rivers respond to changes in runoff or sediment supply by incising or aggrading has been pivotal in gauging the role of the Indian Summer Monsoon (ISM) as a geomorphic driver in the Himalayas. Here we present new chronological data for fluvial aggradation and incision from the Donga alluvial fan and the upper Alaknanda River, as well as a compilation of previous work. In addition to conventional OSL-SAR (Single-Aliquot Regenerative-Dose) dating method, we have tested and applied pulsed OSL (POSL) dating for quartz samples that include K-rich feldspar inclusions, which is expected to improve the applicability and validity of OSL ages in the Lesser Himalaya. For previously dated deposits, our OSL ages are shown to be systematically older than previously reported ages. These results suggest periods of aggradation in the Alaknanda and Dehradun Valleys mainly between ∼25 and 35 ka. This most likely reflects decreased stream power during periods of weakened monsoon. In addition, in-situ cosmogenic beryllium-10 was used to infer bedrock surface exposure ages, which are interpreted as episodes of active fluvial erosion. Resulting exposure ages span from 3 to 6 ka, suggesting that strath terraces were exposed relatively recently, and incision was dominant through most of the Holocene. In combination, our results support precipitation-driven fluvial dynamics, which regulates the balance between stream power and sediment supply. On a larger spatial scale, however, fluvial dynamics are probably not spatially homogeneous as aggradation could have been taking place in adjacent catchments while incision dominated in the study area. © 2018 Elsevier Ltd.
- ItemLate quaternary palaeoenvironmental change in the Australian drylands(Elsevier, 2013-08-15) Fitzsimmons, KE; Cohen, TJ; Hesse, PP; Jansen, JD; Nanson, GC; May, JH; Barrows, TT; Haberlah, D; Hilgers, A; Kelly, T; Larsen, JR; Lomax, J; Treble, PCIn this paper we synthesise existing palaeoenvironmental data from the arid and semi-arid interior of the Australian continent for the period 40–0 ka. Moisture is the predominant variable controlling environmental change in the arid zone. Landscapes in this region respond more noticeably to changes in precipitation than to temperature. Depending on their location, arid zone records broadly respond to tropical monsoon-influenced climate regimes, the temperate latitude westerly systems, or a combination of both. The timing and extent of relatively arid and humid phases vary across the continent, in particular between the westerly wind-controlled temperate latitudes, and the interior and north which are influenced by tropically sourced precipitation. Relatively humid phases in the Murray-Darling Basin on the semi-arid margins, which were characterised by large rivers most likely fed by snow melt, prevailed from 40 ka to the Last Glacial Maximum (LGM), and from the deglacial to the mid Holocene. By contrast, the Lake Eyre basin in central Australia remained relatively dry throughout the last 40 ka, with lake high stands at Lake Frome around 35–30 ka, and parts of the deglacial period and the mid-Holocene. The LGM was characterised by widespread relative aridity and colder conditions, as evidenced by extensive desert dune activity and dust transport, lake level fall, and reduced but episodic fluvial activity. The climate of the deglacial period was spatially divergent. The southern part of the continent experienced a brief humid phase around ∼17–15 ka, followed by increased dune activity around ∼14–10 ka. This contrasts with the post-LGM persistence of arid conditions in the north, associated with a lapsed monsoon and reflected in lake level lows and reduced fluvial activity, followed by intensification of the monsoon and increasingly effective precipitation from ∼14 ka. Palaeoenvironmental change during the Holocene was also spatially variable. The early to mid-Holocene was, however, generally characterised by moderately humid conditions, demonstrated by lake level rise, source-bordering dune activity, and speleothem growth, persisting at different times across the continent. Increasingly arid conditions developed into the late Holocene, particularly in the central arid zone. © 2012 Elsevier Ltd.
- ItemLong-term waterfall dynamics in monsoonal Australia based on cosmogenic Be-10(AMS-13 The Thirteenth International Conference on Accelerator Mass Spectrometry, 2014-08-24) Fujioka, T; May, JH; Fink, D; Nanson, GC; Jansen, JD; Codilean, ATExtensive plateaus, arrays of escarpments and a variety of waterfalls are iconic to northern Australia. How old and stable are these features ? Tectonically, northern Australia has been quiescent during the Quaternary. Rainfall is highly seasonal and dominated by the summer monsoon. In this setting, regional landscape dynamics should be strongly afected by uctuations in monsoon and the associated uvial processes. Here, we examine timescales and processes of waterfall evolution in northern Australia. Situated in the Kimberley sandstone plateau, Durack Falls comprise a series of 1-3 m falls, while Bindoola Fall is a large 15 m fall. Surprise Creek, 100 km south of Darwin, has three 3-5 m waterfalls with deep plunge pools developed at the edge of a quartzite plateau. Over 30 samples were collected from bedrock straths up- and downstream of the waterfalls and on their headwall. Their 10Be exposure ages (assuming zero erosion) reveal contrasting results. While two waterfalls in the Kimberley show relatively young, variable ages (15-110 ka for Durack and 11-57 ka for Bindoola), Surprise Creek indicates old, but uniform ages (94-160 ka). Out-of-channel,undisturbed bedrock exhibits consistently high 10Be equivalent to steady-state erosion rates of 2-5 mm/ka, in agreement with typical bedrock erosion rates observed across Australia. Based on these data, we here present a model to evaluate process and rates of waterfalls formation, and discuss the controlling factors.
- ItemLowland river responses to intraplate tectonism and climate forcing quantified with luminescence and cosmogenic 10Be(Elesevier Science BV, 2013-03-15) Jansen, JD; Nanson, GC; Cohen, TJ; Fujioka, T; Fabel, D; Larsen, JR; Codilean, AT; Price, DM; Bowman, HH; May, JH; Gliganic, LAIntraplate tectonism has produced large-scale folding that steers regional drainage systems, such as the 1600 km-long Cooper Ck, en route to Australia's continental depocentre at Lake Eyre. We apply cosmogenic Be-10 exposure dating in bedrock, and luminescence dating in sediment, to quantify the erosional and depositional response of Cooper Ck where it incises the rising Innamincka Dome. The detachment of bedrock joint-blocks during extreme floods governs the minimum rate of incision (17.4 +/- 6.5 mm/ky) estimated using a numerical model of episodic erosion calibrated with our 10Be measurements. The last big-flood phase occurred no earlier than similar to 112-121 ka. Upstream of the Innamincka Dome long-term rates of alluvial deposition, partly reflecting synclinal-basin subsidence, are estimated from 47 luminescence dates in sediments accumulated since similar to 270 ka. Sequestration of sediment in subsiding basins such as these may account for the lack of Quaternary accumulation in Lake Eyre, and moreover suggests that notions of a single primary depocentre at base-level may poorly represent lowland, arid-zone rivers. Over the period similar to 75-55 ka Cooper Ck changed from a bedload-dominant, laterally-active meandering river to a muddy anabranching channel network up to 60 km wide. We propose that this shift in river pattern was a product of base-level rise linked with the slowly deforming syncline-anticline structure, coupled with a climate-forced reduction in discharge. The uniform valley slope along this subsiding alluvial and rising bedrock system represents an adjustment between the relative rates of deformation and the ability of greatly enhanced flows at times during the Quaternary to incise the rising anticline. Hence, tectonic and climate controls are balanced in the long term. © 2013, Elsevier Ltd.
- ItemA multi-cosmogenic nuclide approach to assess sediment provenance and long-term denudation in the ancient Pilbara region, Western Australia(Australian Nuclear Science and Technology Organisation, 2021-11-17) Flatley, AJ; May, JH; Fujioka, T; Fink, D; Wilcken, KM; Rutherfurd, IThe Pilbara region is characterized by extremely iron-rich Proterozoic bedrock geology which represents an enormous economic interest for Australia and the reason for extensive open-pit mining in the region. Investigating the role of terrigenous sediment supply is important to provide a baseline value of spatially averaged regional erosion rates across the landscape to help decipher in-channel responses of anthropogenically modified landscapes. In particular, quantifying long-term denudation rates within the region improves our understanding of sediment pathways, residence times and storage within the catchment setting. In this study, cosmogenic nuclides 26Al and 10Be from detrital samples are used to quantify basinwide erosion rates and sediment flux within the Upper Fortescue River and to understand sediment provenance and its transport process in the area where mining operations are active. Detailed analysis of catchment morphometric properties and lithology have been combined with multi cosmogenic nuclide (10Be and 26Al) measurements to provide much needed long-term denudation rates for the region, in addition to improving our understanding of first-order controls on catchment wide erosion. Our results indicate that erosion rates within the Upper Fortescue catchments are between 0.94-4.04 m/Ma. This value is similar to channel bedrock erosion rates (2.5 ± 0.8 m/Ma; n = 4), but somewhat higher than mesa summit or alluvial fan surfaces (0.8 ± 0.6 m/Ma; n = 13) in the Pilbara region, previously determined by cosmogenic 53Mn measurements (unpublished data). A two-isotope plot (10Be vs 26Al/10Be) shows that most of our sediment samples plot below the steady-state erosion-exposure island (26Al/10Be = 4.7 - 5.8), indicating a complex exposure history (or perhaps a reduced production rate) despite the shallow and transitory nature of Quaternary deposits in the generally bedrock-controlled landscape. The apparent offset between bedrock erosion rates (in-channel, mesa plateau) and basin-wide average denudation rates infers that vast areas of iron-rich outcropping rock surfaces in the region are not the major contributor of sediments to the system. We consider two scenarios - i) sediment samples, after an initial exposure on exposed parent rock, experienced episodes of deep burial for a minimum few hundred thousand years, and/or ii) sediments are derived from reworked river bank and floodplain deposits into the channel system following storage at shallow depth for a prolonged period of time. Most of our data can be explained by being sourced from the average depth of 0.5-2 m. Surprisingly, our cosmogenic nuclide derived erosion rates also show an apparent inverse relationship against average basin slopes. Hence, we explore various interpretations of our data in the context of specific morphometric, lithologic and environmental settings in the Pilbara region, and discuss the contribution of retreating vertical faces (e.g., gully, cliff) as a potential sediment source. Ultimately, this approach thereby contributes to the question whether foundational relationships between underlying morphometric conventions for catchment analyses are appropriate with these ancient, quiescent dryland landscapes. © The Authors
- ItemWhat happened at the end of the mid-Pleistocene transition in the Southern Hemisphere? Insights from western Tasmania, Australia(International Union for Quaternary Research (INQUA), 2019-07-30) Fletcher, MS; Lisé-Pronovost, A; Mallett, T; Mariani, M; Cooley, S; May, JH; Gadd, PS; Herries, A; Blaauw, M; Heijnis, H; Hodgson, DA; Pedro, JBThe current southward shift in the southern westerlies that is stripping southern Australia of rainfall is unprecedented over the past 12 kyrs years at least, and is due to the effects of both the anthropogenic hole in the ozone layer and greenhouse gas-driven global warming. Predictions of future climate suggest the Earth is moving in to a “super-interglacial” (peak warming) because of anthropogenic greenhouse gas release. “Super-interglacials”, which are warmer than today, are uncommon in the geological record. A recent increase in the frequency of these peak warming events since ca. 450 ka (the end of the mid-Pleistocene transition; MPT) is associated with a 7° latitude southward shift of the southern westerlies and an increase in atmospheric CO2 that warmed the atmosphere - a stark similarity to current trends. Here, we present multi-proxy analyses of two closely spaced (<50 km) sediment cores that comprise a complete sequence from the mid-Pleistocene to the present from western Tasmania, Australia - in the mid-latitudes of the Southern Hemisphere. Lake Selina is a modern-day lake with a continuous ca. 230 kyr sediment sequence, while Darwin Crater is a palaeo-lake within a meteorite impact crater that formed at ca. 816 ka and which completely in-filled during MIS5 (ca. 120 ka). We report on petrophysical whole core logging, lithological core description, spectrophotometry, grain size, natural gamma ray, paleo- and rock-magnetism, loss-on-ignition, pollen analyses and micro-XRF geochemisrty. The composite record is unique in the Australian sector of the Southern Hemisphere and we discuss the data in the context of the global and regional changes that occurred at the end of MPT, paying particular attention to impact of the shift toward warmer super-interglacials, the large-scale southward shift of the southern westerlies and higher atmospheric CO2 content that occurred at ca. 450 ka (MIS11 to present).