Timothy T. Barrows

Airborne radio-echo sounding (RES) surveys are widely used to measure ice-sheet bed topography. Measuring bed topography as accurately and widely as possible is of critical importance to modelling ice dynamics and hence to constraining better future ice response to climate change. Measurement accuracy of RES surveys is influenced both by the geometry of bed topography and the survey design. Here we develop a novel approach for simulating RES surveys over glaciated terrain, to quantify the sensitivity of derived bed elevation to topographic geometry. Furthermore, we investigate how measurement errors influence the quantification of glacial valley geometry. We find a negative bias across RES measurements, where off-nadir return measurement error is typically −1.8 ± 11.6 m. Topographic highlands are under-measured an order of magnitude more than lowlands. Consequently, valley depth and cross-sectional area are largely under-estimated. While overall estimates of ice thickness are likely...

ABSTRACT Tectonically active mountain ranges are expected to respond rapidly to changes in base level. Sediment derived from such areas are expected to be rapidly delivered to sedimentary basins. A comprehensive terrestrial cosmogenic nuclide-based study aims to test these assumptions in an actively uplifting mountain block and to investigate particle transport paths prior to final deposition. The Sierra Nevada of western Spain is a tectonically active mountain range on the southern margin of the Eurasian plate. Thermochronological data indicate that the present day topography (maximum elevation 3480m) has developed within the past 10 Ma Our study focuses on the Rio Torrente catchment, a small (9km × 3km) east-west trending, 2000m relief catchment in the western Sierra Nevada. The Torrente has a denudationally stable headwater region of thick regolith cover and low slope angles, which passes abruptly downstream across a major knickpoint into the very steep topography of a drainage net that is currently experiencing a rejuvenation event. Frequent shallow bedrock landslides, promoted by a strong northward dipping bedrock schistosity, dominate rejuvenated areas. The distribution of Be-10 concentrations in sediment and bedrock corresponds very well with observed geomorphic processes within the Rio Torrente Catchment. Be-10 concentrations as low as 10 000 atoms/gram in bedrock and sediment, corresponding to apparent erosion rates in excess of 2mm per annum, characterise the steep landslide-dominated lower catchment. Areas of the catchment as yet unaffected by rejuvenation are readily identifiable through their relatively high Be-10 contents. GIS based data analysis, involving a simple tracking of particles across the landscape to estimate elevation histories during particle exhumation and transport, enables identification of the pattern of nuclide acquisition as sediment is generated and transported through the Rio Torrente Catchment.

Australia was glaciated several times during the Pleistocene and possibly during the Pliocene. On the Australian mainland, glaciers were restricted to only the highest elevations of the Kosciuszko massif. However, in Tasmania, a succession of glacial systems are recorded. The Early Pleistocene ice extent is the greatest with about 7000km2 of ice as a series of ice caps and valley

Uplift and denudation of the westernmost part of the Sierra Nevada, southern Spain has been assessed using a combination of optically stimulated luminescence (OSL) dating and 10Be and 26Al terrestrial cosmogenic nuclide (TCN) determinations, on both in-situ bedrock and detrital quartz from recent sediments, together with apatite fission track (AFT) ages from the metamorphic core. The Tertiary record of unroofing

The cosmogenic isotope concentrations (CICs) of detrital materials are used to estimate catchment erosion rates but have the potential to offer considerably more. This is because the detrital CIC of a grain leaving an erosional terrain reflects its particular history of erosion, transport and storage, meaning in effect that the CICs of a large number of grains provide an integrated signature of a catchment's history. This can readily be demonstrated in ideal cases, relying particularly on the co-variance of key variables (isotope production rate and perhaps erosion rate and storage time) with altitude. However, individual grains have a near-infinite range of possible histories so requiring (as yet) unfeasibly large numbers of samples. Thus, CICs cannot be used to decipher detailed catchment histories, but the approach may be used to differentiate competing hypotheses for the evolution of particular catchments. To assess the potential of this method we constructed a 1-Dimensiona...

ABSTRACT This special issue, produced by the members of the Australasian INTegration of Ice core, MArine and TErrestrial records (AUS-INTI-MATE) group, represents the culmination of a project spanning just on ten years. INTIMATE was first established as a core pro-gramme of the INQUA Palaeoclimate Commission in 1995 at the XIVth INQUA Congress in Berlin and aimed to establish a more detailed knowledge of the nature, timing and regional-to-global extent of climatic and environmental changes associated with Termination I (the end of the last glaciation). Facilitated through a series of international workshops, the project aimed to improve precision in correlating climatic events and associated ages for Termination I (e.g. Bjorck et al., 1998; Lowe and Hoek, 2001). INTI-MATE then gradually expanded its focus from the North Atlantic to other regions. 2. Australasian-INTIMATE Over the years, there have been several attempts to bring together the multiple lines of evidence to synthesise the history of climate change in the Australasian region over the last 30,000 yr. After the success of CLIMAP (CLIMAP Project Members, 1981), the CLIMANZ (CLImate Mapping of Australia and New Zealand project) meeting was held in 1981, with the aim of mapping quantitative estimates of climate change (temper-ature and precipitation) at key sites during important time slices (32 AE 5, 25–20, 18 AE 2, 15–10 and 7 AE 2 ka) across Australia, New Zealand and Papua New Guinea. The volume produced sum-marised the current state-of the art of climate change at this time (Chappell and Grindrod, 1983). The success was capitalised upon through a series of subsequent meetings. CLIMANZ II extended the focus back to 150 ka (Pillans, 1985) and there was a push to-wards more quantitative reconstructions and the inclusion of climate modelling for CLIMANZ III (Donnelly et al., 1989). A growing realisation of the valuable data being generated by the community for the interpretation of contemporary global warm-ing led to the funding by the Australian Greenhouse Office to establish the Australian Quaternary Database at the Australian Geological Survey Organisation (Hunt et al., 1996). The culmina-tion of this project was to provide CLIMANZ IV in 1996 with a greatly expanded data set for past climate mapping and compar-ison with climate models. As a result of this meeting, palaeocli-mate maps for a series of time slices (MIS 7, 6, 5a–e, 4, 3, 35– 30 ka, 25–15 ka, 15–10 ka, 6 ka) were developed focussing on tem-perature and hydrologic balance (Hunt and Barrows, 1999). How-ever, the CLIMANZ IV volume remained unpublished (Chappell and Hunt, 1996). Despite other excellent reviews of Australasian climate, it was recognised that only a group effort could tackle the problem of un-derstanding climate change over such a large region. The Austral-asian-INTIMATE group was established in 2003 at the XVIth INQUA Congress in Reno. The Australasian-INTIMATE approach was to form two subgroups for the New Zealand region (NZ-INTI-MATE) and the Australian region (OZ-INTIMATE) to collate detailed climate evidence and explore the possibility of an Australasian climate event stratigraphy (CES) for the interval from 30,000 to 8000 yr BP. AUS-INTIMATE was supported in two iterations by INQUA's Palaeoclimate Commission (PALCOMM). 3. NZ-INTIMATE Initial activities of the NZ-INTIMATE group were directed to-wards (1) to identifying key New Zealand onshore and offshore climate records for the last 30,000 years, and (2) to improve proce-dures for correlating the records and for dating them more pre-cisely. Two national workshops were subsequently convened, and were attended by over 50 NZ researchers from every institution in NZ engaged in Quaternary research (Alloway, 2004; Alloway and Shulmeister, 2005). As an output of the 2005 workshop, the NZ-INTIMATE group compiled well-dated onshore and offshore proxy records from a variety of latitudes and elevations in New Zea-land on a common calendar timescale (Barrell et al., 2005). This paved the way for two key NZ-INTIMATE publications. The first be-ing Alloway et al. (2007) who, based on the high resolution and fragmentary records, facilitated the construction of a provisional CES for the New Zealand region and Lowe et al. (2008) who out-lined the pivotal role of tephra beds in linking and dating these very records from which the CES was derived. In 2006, a NZ-INTIMATE meeting was convened at Kaikoura, the basis of the amended NZ-CES (as developed by Barrell et al., 2013) was derived and heralded the beginning of a second phase of NZ-INTIMATE led by Peter Almond, Marcus Vandergoes and Drew Lor-rey. An important and recurring theme of the subsequent meetings in 2009 and 2010 was the recognition that better data-model inter-comparisons were needed. This ultimately led to two papers being contributed to the 2012 North Atlantic INTIMATE group Special issue of QSR (Lorrey et al., 2012; Newnham et al., 2012). In addition, three other…

Snow-line elevations of former glaciers around the tropical Pacific Ocean during the Last Glacial Maximum (LGM) provide critical constraints on the state of the lower tropical troposphere. We present new moraine chronological information that pins down LGM snow-line elevations adjacent to the western Pacific warm-pool. We mapped several major sequences of glacier moraines on Mt. Giluwe, an extinct massive stratovolcano

... Liam J. Reinhardt,1* TB Hoey,2 TT Barrows,3 TJ Dempster,2 P. Bishop2 and LK Fifield3 1 Center for Earthquake ... 10Be concentrations measured in sediment samples from the high-relief Torrente catchment, southern Spain, allows us to investigate the sam-pling requirements ...

ABSTRACT Deep-sea core Fr10/95-GC17, collected offshore North West Cape at the western tip of Western Australia, is located beneath the path of the Leeuwin Current. This shallow, warm and low salinity current is an offshoot of the Indonesian Throughflow that transfers water and heat from the West Pacific Ocean into the Indian Ocean. The location is at the edge of the Indo Pacific Warm Pool, the source of large-scale transfer of moisture and heat from the ocean to the atmosphere. For this core, we combine previously published data with new research and use a revised chronology to re-examine the timing of climate change during the last 34,000 years in the tropics of northern Australia. The age model for the core is based on 15 radiocarbon dates complemented by luminescence ages and an oxygen isotope record. This study draws on an extensive range of analyses that have been performed on the core, including micropalaeontology of planktic and benthic foraminifera and coccoliths, stable isotopes analysis of foraminifera and their faunal composition, clay content, sediment composition and pollen analyses. Sea-surface and land temperatures are estimated from the foraminifer faunal analyses and from pollen spectra, respectively. The clay fraction and sediment composition and radiogenic isotopes of that fraction helped identify changes both on land and at sea: changes such as rainfall as shown by river discharge, and oceanic current tracing by neodymium, strontium and lead isotopes obtained from sediments.

... E-mail: keith. ... 1). These comprised four large, deep-seated landslides featuring well-preserved scarps, mainly in rock, and associated debris lobes (Sham Wat Debris Lobe, Sunset Peak West, Tsing Yi, and Ap Lei Chau); two sites of rock and boulder fall (Lion Rock and Fei Ngo ...

ABSTRACT Forested bouldery dolerite slope deposits of the Nicholas Range of northeast Tasmania are typical of those that have accumulated around moderate-altitude Tasmanian dolerite peaks. Many of these deposits, frequently referred to as having a periglacial origin, show evidence of mass movement, However, dating the deposits, elucidating their mode of formation and estimating risks of further movement has been difficult. An area around South Sister peak at the east end of the Nicholas Range was studied to address these issues. We conclude that here the aprons of colluvial boulders accumulated as slow moving debris flows rather than deep-seated bedrock slides. Three exposure ages in the range 80-90 ka, obtained from large dolerite boulders, indicate landslide movement during the last interglacial period; as the deposits show no evidence of movement since first accumulating the deposits must have formed under conditions different from those presently prevailing. We suggest that water-saturation at the contact of the dolerite slope deposits and the sedimentary rocks below, following seasonal snow melt in a period colder than at present, may have initiated instability. The risks associated with land use such as forest harvest on these and similar deposits elsewhere are considered to be low.

ABSTRACT Southeastern South Australia, straddling the coastal zone and semi-arid desert margins of the lower Murray-Darling Basin, provides an important record of landscape response to past environmental change during the Pleistocene. Previous research in the region has focussed either on the coastal barrier systems, which formed during interglacial periods, or the sub-parabolic and linear dune systems downwind, which generally formed under arid conditions out of phase with the strandlines. However, the geomorphologic and chronological relationship between these two systems is poorly understood. This study provides the first constraints on the initation of dune development downwind of the Naracoorte East strandline. In this preliminary study we show that aeolian deposition at Naracoorte was constrained by sediment supply from the strandline upwind, and was most likely gradual, more or less continuous, and took place under relatively arid climatic regimes. We demonstrate a genetic link between strandlines and the dune fields in the region.

ABSTRACT Several proxies have been developed to reconstruct past sea surface temperature (SST), but different proxies may reflect temperatures of different seasons and each proxy is characterized by certain uncertainties. Therefore, a multiproxy approach is preferred to precisely reconstruct SST. Here, we reconstruct SST of the ocean offshore southeastern Australia (Murray Canyons area) for the last ~135 ka using three independent organic proxies (TEXH86 based on glycerol dialkyl glycerol tetraethers (GDGTs), UK’37 based on alkenones, and LDI based on long-chain diols) in addition to foraminiferal faunal assemblages. The organic proxy records show similar trends, with the highest temperature (21°C for UK’37 and TEXH86, and 25°C for LDI) during the last interglacial and lowest temperature (8°C for TEXH86, 10°C for UK’37, and 12°C for LDI) during the Last Glacial Maximum. However, the differences in absolute SST estimates obtained by the organic proxies varied over time with differences of up to 9°C between LDI and TEXH86. The seasonal SST reconstructions based on the modern analogue of foraminiferal assemblages also show similar trends as the organic proxies with highest temperatures during the last interglacial (23°C for the warmest month SST, 20°C for mean annual, and 18°C for the coolest month) and lowest temperature during the Last Glacial Maximum (14°C for the warmest month, 11°C for mean annual, and 9°C for the coolest month). Down core comparison between the reconstructed SSTs of the organic and inorganic proxies shows that LDI-inferred temperatures compare well with the temperature of the warmest month, TEXH86 with the temperature of the coolest month, and UK’37 with mean annual temperature. An increase in TEXH86 SST estimates relative to those of other proxies during deglaciations and interglacials suggests that either winter temperatures rapidly warmed, possibly due to an invigoration of the Leeuwin Current over the core site, or there was a change in the growth season of the Thaumarchaeota, the source organism of GDGTs. Our study shows the benefits of a multiproxy approach in the interpretation of SST proxies, leading to a more robust knowledge of past ocean temperature changes.

Palaeoceanographic conditions in the eastern Indian Ocean for the last ∼30 kyr are documented by means of planktonic foraminiferal analyses of 10 gravity cores. Quantitative foraminiferal analysis (%), Q-mode factor analysis, the modern analog technique (MAT) and oxygen-isotope analyses are used. A conspicuous increase during the last glacial maximum (LGM) of foraminiferal fragmentation resulting from a more productive Java upwelling system and/or a more corrosive Antarctic Intermediate Water (AAIW) was found at intermediate water depths (∼1000 m). Contrasting Q-mode factors based on foraminifera between today and the LGM suggest changes in the thermocline depth, sea-surface temperature (SST), upwelling, and the strength of both the Australasian Mediterranean Water (AAMW) and the Indian Central Water (ICW). The decrease in the percentage abundance of shallow-dwelling and symbiont-bearing planktonic foraminifera, the increase in percentage of the upwelling-related species Globorotalia cultrata and Neogloboquadrina dutertrei, and factor 3 (dominated by Globorotalia tumida and Globigerinella siphonifera) suggest a stronger Java upwelling system during the LGM. A steeper, steric latitudinal gradient (in the presence of a weak Leeuwin Current), and a geostrophic flow similar to today's is postulated for the LGM, and this must have prevented upwelling offshore Western Australia. Today's AAMW–ICW sharp front was weaker during the LGM when the AAMW was saltier, cooler, and nutrient richer and more similar to the ICW. During the LGM, a more gentle SST latitudinal gradient over the ∼16 to ∼23°S region contrasts with today's steeper conditions at the AAMW–ICW Front. Also, for the LGM, a nutrient-rich ICW may explain previously documented increases in mass accumulation rates of CaCO3, organic carbon and benthonic foraminifera in a region where the nutricline was deep and within the lower euphotic zone.

... The EUC transports up to 35–40 Sv and is stronger during January–June and weaker during July–December (eg Tomczak and Godfrey, 1994). ... 75 to 200 m depths, thus resulting in chlorophyll values in excess of 2 mg m − 3 (eg [Wyrkti, 1964] , [Fiedler, 2002] and [McClain et al ...

Tasmania is important for understanding Quaternary climatic change because it is one of only three areas that experienced extensive mid-latitude Southern Hemisphere glaciation and it lies in a dominantly oceanic environment at a great distance from Northern Hemisphere ice sheet feedbacks. We applied exposure dating using 36Cl to an extensive sequence of moraines from the last glacial at Mt. Field,

ABSTRACT The last 35 years have seen rapid advances in our knowledge of climate change during the Quaternary Period in Tasmania. Extensive mapping and new dating studies, particularly since the advent of exposure dating, have revealed that maximum ice advance occurred 1 Ma ago and later advances were less extensive. Ice advances occurred several times during the last 100 ka, not only during the Last Glacial Maximum. Deglaciation was rapid after 18 ka and complete by 14 ka. Ice strongly affected limestone and produced extensive glaciokarst with deranged surface drainage. Glacial sediment plugged conduits to underground passages partially filled with glaciofluvial gravels. Periglacial erosion, and human impact since late oxygen isotope stage (OIS) 3, enhanced sediment influxes. New pollen records, particularly from Lake Selina, provide a 125 ka vegetation and climate record representative of the Southern Hemisphere. Finally, stable isotope studies of speleothem growth have revealed wide swings in climate. The climate was warm and moist during OIS 5e and early in OIS 1. Climate was cold and dry during OIS 5d and 4, and prevented speleothem growth during OIS 3 and OIS 2.

ABSTRACT The OZPACS project is a working group which aims to improve understanding of human impact on Australian ecosystems over the last 500 years. One of its major outcomes is the creation of a database of existing research relevant to the period of interest, which can be applied to assess baseline environmental conditions and identify drivers of environmental change. This work is intended to assist and improve communication between researchers and natural resource managers. We report on the results of the OZPACS database, which comprises metadata relating to various analytical methods, site locations presented in GIS format, a searchable reference list and raw data from published studies. This work highlights the spatial and temporal bias of existing studies, and can therefore also be used to assist in plans for future research.