Optically stimulated luminescence (OSL) dating of sand-filled wedge structures and their alluvial host sediment from Jonzac, Southwest France
Guhl, A., Bertran, P., Zielhofer, C., Fitzsimmons, K.E. (in press) Optically stimulated luminescence (OSL) dating of sand-filled wedge structures and their alluvial host sediment from Jonzac, Southwest France. Boreas.
Two sand wedge structures and their host sediments, from Jonzac in Southwest France, were successfully dated using... more Two sand wedge structures and their host sediments, from Jonzac in Southwest France, were successfully dated using optically stimulated luminescence (OSL) measurements on both small aliquots and single grains of quartz from the 180-212 µm size fraction. One of both the sand wedges clearly contains primary infilling. However, grain-size analysis and field observations do not clearly indicate if the other feature represents a primary sand wedge or a composite sand wedge with primary and secondary infilling. OSL results and the geological setting justify using the Central Age Model (CAM) for the calculation of age estimates. Grain-size analysis and detailed investigations of OSL results revealed contamination of one sand wedge sample with host sediment. However, age calculation using the Finite Mixture Model (FMM) provided what is considered the most reliable age estimate for the contaminated sample. The age estimates for all samples correspond to Marine Isotope Stage (MIS) 3. While fine-grained sediments were deposited in the middle of MIS 3 (~43-55 ka), the sand wedges unexpectedly correspond to the end of this period (~33 ka) or the onset of MIS 2 (~27 ka). The sand wedges are most likely to have formed during a relatively short period of comparatively cold conditions, and may correlate to a Heinrich event. Resolution limits of OSL age estimates and differing statements regarding the ages of Heinrich events within this time period prevent an unequivocal correlation of the sand wedge ages to Heinrich events, but the most likely association is with events H2 and H3. The results help to assess the capability of luminescence dating on sand wedges and contribute to the debate on timing of cryogenic formation processes and the permafrost distribution in Southwest France.
Dealul Guran: evidence for Lower Paleolithic occupation of the Lower Danube loess steppe
Iovita, R.P., Fitzsimmons, K.E., Dobos, A., Hambach, U., Hilgers, A., Zander, A. (2012, in press) Dealul Guran: evidence for Lower Paleolithic occupation of the Lower Danube loess steppe. Antiquity.
We report here on the discovery, and subsequent excavation and dating, of the site of Dealul Guran (county Constanța,... more
We report here on the discovery, and subsequent excavation and dating, of the site of Dealul Guran (county Constanța, Romania, pronounced DAlu GuRAN). This site was discovered during a systematic survey project (Lower Danube Survey for Palaeolithic Sites (LoDanS), http://lodans.wordpress.com/), and is currently the oldest dated Palaeolithic site in Romania, and one of the most secure Lower Palaeolithic contexts in Eastern Europe.
Aridity in the monsoon zone as indicated by desert dune formation in the Gregory Lakes basin, northwestern Australia
Fitzsimmons, K.E., Miller, G.H., Spooner, N.A., Magee, J.W. (2012, in press) Aridity in the monsoon zone as indicated by desert dune formation in the Gregory Lakes basin, northwestern Australia. Australian Journal of Earth Sciences.
Desert dunes within the monsoon-fed Gregory Lakes basin form valuable archives for Quaternary paleoenvironments, in a... more Desert dunes within the monsoon-fed Gregory Lakes basin form valuable archives for Quaternary paleoenvironments, in a region where such records are scarce. Optically stimulated luminescence (OSL) chronologies from two dunes identify the timing of aeolian processes, interpreted as a complex response to aridification and increased sediment availability during lake transgressions and associated fluvial activity. The earliest aeolian deposition in our record occurred ca 91.5 ka, which postdates the last “mega-lake” phase but predates a smaller lake transgression during early MIS 3. Sand plain accretion took place around ca 47 ka during contemporaneous periodic high lake levels. This was followed by intermittent linear dune building, between ca 35 and 11.5 ka, which most likely took place during an interval of relative aridity. Close spacing of mid-Holocene ages within one dune indicates rapid sediment accumulation in a single arid event ca 5 ka. At no time in the last 50 ka have lake levels reached those of the last "mega-lake” phase prior to ca 91.5 ka, suggesting a substantially weakened present-day monsoon.
Download (.pdf) New U/Th ages for Pleistocene megafauna deposits of southeastern Queensland, Australia
Price, G.J., Zhao, J.-x., Feng, Y.-x., Hocknull, S.A., 2009. New U/Th ages for Pleistocene megafauna deposits of southeastern Queensland, Australia. Journal of Asian Earth Sciences 34, 190-197.
Arguments over the extinction of Pleistocene megafauna have become particularly polarised in recent years. Causes for... more
Arguments over the extinction of Pleistocene megafauna have become particularly polarised in recent years. Causes for the extinctions are widely debated with climate change, human hunting and/or habitat modification, or a combination of those factors, being the dominant hypotheses. However, a lack of a spatially constrained chronology for many megafauna renders most hypotheses difficult to test. Here, we present several new U/Th dates for a series of previously undated, megafauna-bearing localities from southeastern Queensland, Australia. The sites were previously used to argue for or against various megafauna extinction hypotheses, and are the type localities for two now-extinct Pleistocene marsupials (including the giant koala, Phascolarctos stirtoni). The new dating allows the deposits to be placed in a spatially-
and temporally constrained context relevant to the understanding of Australian megafaunal extinctions. The results indicate that The Joint (Texas Caves) megafaunal assemblage is middle Pleistocene or older (>292 ky); the Cement Mills (Gore) megafaunal assemblage is late Pleistocene or older (>53 ky); and the Russenden Cave Bone Chamber (Texas Caves) megafaunal assemblage is late Pleistocene (55 ky). Importantly, the new results broadly show that the sites date prior to the hypothesised megafaunal extinction ‘window’ (i.e., 30–50 ky), and therefore, cannot be used to argue exclusively for or against human/climate change extinction models, without first exploring their palaeoecological significance on wider temporal and spatial scales.
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Dating megafaunal extinction on the Pleistocene Darling Downs, eastern Australia: the promise and pitfalls of dating as a test of extinction hypotheses
Price, G.J., Webb, G.E., Zhao, J.-x., Feng, Y.-x., Murray, A.S., Cooke, B.N., Hocknull, S.A., Sobbe, I.H., 2011. Dating megafaunal extinction on the Pleistocene Darling Downs, eastern Australia: the promise and pitfalls of dating as a test of extinction hypotheses. Quaternary Science Reviews 30, 899-914.
A key to understanding Late Pleistocene megafaunal extinction dynamics is knowledge of megafaunal ecological... more A key to understanding Late Pleistocene megafaunal extinction dynamics is knowledge of megafaunal ecological response(s) to long-term environmental perturbations. Strategically, that requires targeting fossil deposits that accumulated during glacial and interglacial intervals both before and after human arrival, with subsequent palaeoecological models underpinned by robust and reliable chronologies. Late Pleistocene vertebrate fossil localities from the Darling Downs, eastern Australia, provide stratigraphically-intact, abundant megafaunal sequences, which allows for testing of anthropogenic versus climate change megafauna extinction hypotheses. Each stratigraphic unit at site QML796, Kings Creek Catchment, was previously shown to have had similar sampling potential, and the basal units contain both small-sized taxa (e.g., land snails, frogs, bandicoots, rodents) and megafauna. Importantly, sequential faunal horizons show stepwise decrease in taxonomic diversity with the loss of some, but not all, megafauna in the geographically-small palaeocatchment. The purpose of this paper is to present the results of our intensive, multidisciplinary dating study of the deposits (>40 dates). Dating by means of accelerator mass spectrometry (AMS) 14C (targeting bone, freshwater molluscs, and charcoal) and thermal ionisation mass spectrometry U/Th (targeting teeth and freshwater molluscs) do not agree with each other and, in the case of AMS 14C dating, lack internal consistency. Scanning electron microscopy and rare earth element analyses demonstrate that the dated molluscs are diagenetically altered and contain aragonite cements that incorporated secondary young C, suggesting that such dates should be regarded as minimum ages. AMS 14C dated charcoals provide ages that occur out of stratigraphic order, and cluster in the upper chronological limits of the technique (~40-48 ka). Again, we suggest that such results should be regarded as suspicious and only minimum ages. Subsequent OSL and U/Th (teeth) dating provide complimentary results and demonstrate that the faunal sequences actually span ~120-83 ka, thus occurring beyond the AMS 14C dating window. Importantly, the dates suggest that the local decline in biological diversity was initiated ~75,000 years before the colonisation of humans on the continent. Collectively, the data are most parsimoniously consistent with a pre-human climate change model for local habitat change and megafauna extinction, but not with a nearly simultaneous extinction of megafauna as required by the human-induced blitzkrieg extinction hypothesis. This study demonstrates the problems inherent in dating deposits that lie near the chronological limits of the radiocarbon dating technique, and highlights the need to cross-check previously-dated archaeological and megafauna deposits within the timeframe of earliest human colonisation and latest megafaunal survival.
Late Pleistocene aeolian reactivation downwind of the Naracoorte East range, South Australia
Fitzsimmons, K.E., Barrows, T.T. (2012) Late Pleistocene aeolian reactivation downwind of the Naracoorte East range, South Australia. Zeitschrift für Geomorphologie 56(2), 225-237.
Southeastern South Australia, straddling the coastal zone and semi-arid desert margins of the lower Murray-Darling... more 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.
Evaluating Controls on Ice Dynamics In the North-East Atlantic Using An Event Stratigraphy Approach
Quaternary International, 2003, v 99-100, 45-57.
An event stratigraphy approach is used to examine controls on late Devensian-age glacial events in Ireland. The event... more An event stratigraphy approach is used to examine controls on late Devensian-age glacial events in Ireland. The event stratigraphy, based on onshore geological evidence, is constructed from relative-age relationships of cross-cutting bedforms found behind ice margins, and radiometric dates from ice-marginal landforms. The event stratigraphy can be compared with the Greenland GRIP ice core δ18O proxy climate record and high-resolution marine records in the north-east Atlantic. These records reflect different aspects of the coupled ice–ocean–atmosphere system on different scales. Prior to Heinrich event 1 at not, vert, similar14.5 14C kyr BP (cal. not, vert, similar17 kyr BP) the glacial event stratigraphy in Ireland more closely matches events recorded in North Atlantic marine cores. After Heinrich event 1 the Ireland glacial event stratigraphy better fits with the Greenland δ18O record. This shift in phasing relations in the north-east Atlantic following Heinrich event 1 reflects a range of variables including onshore ice retreat, changes in sea-ice cover and strengthened thermohaline circulation. The GRIP event stratigraphy may therefore not always be the most appropriate ‘standard’ against which to compare all glacial/climate records in the north-east Atlantic region. Late Devensian glacial events in Ireland match better to shifts observed in the marine record, suggesting an ocean driver of glacial events in north-west Europe.
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Pleistocene Glaciations In Ireland
Knight, J., Coxon, P., McCabe, A.M. and McCarron, S.G. 2004. Pleistocene glaciations in Ireland. In: Ehlers, J. and Gibbard, P.L. (eds) Quaternary Glaciations - Extent and Chronology: Part 1: Europe. Elsevier, Amsterdam, 183-191
A literature survey and data from recent investigations are used to reconstruct ice limits in Ireland during the last... more
A literature survey and data from recent investigations are used to reconstruct ice limits in Ireland during the last (Midlandian) and penultimate (Munsterian) cold periods which are correlated with Marine Isotope Stages (MIS) 2–5d (Weichselian) and 6–8 (Saalian) respectively. Evidence for Munsterian ice limits and flow directions is equivocal and based mainly on erratic carriage and the presence of striae and subdued glacial landforms found outside well-marked Midlandian end moraines. Ice extent and flow direction is known only from the late Midlandian (MIS 2; 24-10 kyr BP) although ice may well have been present in the early Midlandian (MIS 3–5d; 24–117 kyr BP). Six late Midlandian glacial stages are identified on the basis of morphosedimentary and dating evidence, and patterns of subglacial bedforms including drumlins and Rogen moraines. Previous late Midlandian glacial models are well-established but are generally based on incomplete and/or erroneous datasets, are not age-constrained, and do not consider time-transgressive sedimentation and landform-shaping events.
Recent work shows that repeated ice advance-retreat cycles (oscillations) occurred during the late Midlandian. Oscillations resulted in stratigraphically superimposed, overprinted and cross-cut landform and sediment patterns that record ice activity throughout the glacial cycle. Additionally, subglacial bedforms previously unrecorded in the British Isles, such as flow-transverse ridges (Rogen moraines), are also present. Late Midlandian ice oscillations in Ireland occurred in tempo with millennial-scale changes in North Atlantic climate suggesting connection to hemispheric shifts of the ice-ocean-atmosphere system.
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Sier, Roebroeks, Bakels, Dekkers, Brühl, de Loecker, Gaudzinski-Windheuser, Hesse, Jagich, Kindler, Kuijper, Laurat, Mücher, Penkman, Richter, van Hinsbergen, 2011 - QR 75- Direct terrestrial-marine correlation demonstrates surprisingly late onset of the last interglacial in central Europe
by Lutz Kindler
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The Early Pleistocene Praetiglian and Ludhamian pollen stages in the North Sea Basin and their relationship to the marine isotope record
by Tom Meijer
Published in: Journal of Quaternary Science, 21: 307-310 (2006)
Co-authored with: Cleveringa, P., Munsterman, D.K. and Verreussel, R.M.C.H.
In this paper, the currently accepted correlation of the Early Pleistocene Ludhamian stage of England with the... more
In this paper, the currently accepted correlation of the Early Pleistocene Ludhamian stage of England with the Tiglian-A sub-stage of the Netherlands is challenged. Recent investigations of Early Pleistocene marine North Sea deposits from a borehole near Noordwijk (the Netherlands) yielded evidence from molluscs, dinoflagellate cysts and sporomorphs for an alternation of warm temperate and arctic intervals within the Praetiglian and Tiglian stages. Marine equivalents of the terrestrial-based pollen sub-stages Tiglian A and B have been recognised in the upper part of the sequence. A Praetiglian age can be assigned to the lower part of the sequence on the basis of mollusc analysis. Within the Praetiglian, an alternation of warm and cold phases has been recognised from both the dinoflagellate cyst and molluscan records. Three cold phases within the Praetiglian are tentatively correlated with marine isotope stages (MIS) 96-100. The molluscan assemblages provide evidence for climate forcing of the sea level: highest sea levels are reached in the warm-temperate intervals. Within the Praetiglian, an interval with an acme zone of the dinoflagellate cyst Impagidinium multiplexum, is correlated with the Ludhamian and tentatively linked to MIS 97 and/or MIS 96.
The cold molluscan assemblages from the Noordwijk borehole include an acme zone of Megayoldia thraciaeformis, the first and only occurrence of this North Pacific bivalve in the North Sea Basin.
Early and early Middle Pleistocene correlations in the southern North Sea Basin
by Tom Meijer
Published in: Quaternary Science Reviews, 10: 23-52 (1991)
Co-authored with: P.L. Gibbard, R.G. West, W.H. Zagwijn, P.S. Balson, A.W. Burger, B.M. Funnell, D.H. Jeffery, J. de Jong, T. van Kolfschoten, A.M. Lister, P.E.P. Norton, R.C. Preece, J. Rose, A.J. Stuart, C.A. Whiteman, J.A. Zalasiewicz
On April 8, 1988 a discussion meeting took place at Norwich with the aim of establishing correlations of the Early and... more
On April 8, 1988 a discussion meeting took place at Norwich with the aim of establishing correlations of the Early and Middle Pleistocene stages across the southern North Sea. On the basis of faunal, floral, and palaeoclimatic data the following correlations were considered highly probable. The Pastonian Stage of East Anglia is correlated with the Late Tiglian (TC5) Stage of the Netherlands, and the Bramertonian with the Middle Tiglian (TCI-4b). The possibility that the British Antian and Bramertonian Stages may represent parts of a single climatic event is mentioned. The Ludhamian is probably of Early Tiglian age and the Pre-Ludhamian may equate in part with the Praetiglian Stage. Possible correlation of the Wallonian with part of the Pliocene Reuverian Stage is also suggested.
In the later Middle Pleistocene, the Anglian Stage correlates with the continental Elsterian. The precise correlation of the British type Cromerian Stage with part of the 'Cromerian Complex' Stage in the Netherlands remains uncertain.
Aminostratigraphy of Middle and Late Pleistocene deposits in The Netherlands and the southern part of the North Sea Basin
by Tom Meijer
Published in: Global and Planetary Change, 68: 326-345 (2009)
Co-authored with: P. Cleveringa
A review of all available amino acid racemization D (alloisoleucine)/L (isoleucine) data from the whole shell of four... more A review of all available amino acid racemization D (alloisoleucine)/L (isoleucine) data from the whole shell of four molluscan species from Late and late Middle Pleistocene deposits of the Netherlands is presented. The data allow the distinction of 5 aminostratigraphical units, NAZ (Netherlands Amino Zone) A-E, each representing a temperate stage. The zones are correlated with marine isotope stages 1, 5e, 7, 9, and 11 respectively. Apart from NAZ-D (MIS 9), in all aminozones the marine transgression reached the present-day onshore area of the Netherlands. The transgression during NAZ-C (Oostermeer Interglacial: MIS 7) seems to be at least as widespread as its counterpart during NAZ-B (Eemian: MIS 5e) in the southern bight of the North Sea Basin. The stratigraphic position of the Oostermeer Interglacial is just below deposits of the Drente phase of the Saalian and because of this position the interglacial marine deposits have formerly erroneously considered to be of Holsteinian age. Neede, the ‘classic’ Dutch Holsteinian site, is dated in NAZ-E (MIS 11), like Noordbergum. Although the validity of these zones has been checked with independent data, some overlap between succeeding zones may occur. The relation between amino acid data from elsewhere in the North Sea Basin and the Netherlands amino zonation is discussed. The deposits at the Holsteinian stratotype Hummelsbüttel in North West Germany are dated in NAZ-D. This interglacial correlates with MIS 9. The Belvédère Interglacial, which is of importance for its archaeology, is in NAZ-D (MIS 9) and therefore of Holsteinian age as well. The lacustroglacial ‘pottery clays’ in the Noordbergum area are deposits from two glacial stages, which can be correlated with MIS 8 and 10 (the Elsterian). The pottery clay that is considered equivalent to the German ‘Lauenburger Ton’ correlates with MIS 10
Timing of Post-Glacial Reinhabitation and Ecological Development of Two New England, USA, Drainages Based on Trace Fossil Evidence
by Jacob Benner
http://dx.doi.org/10.1016/j.palaeo.2008.10.029
Trace fossils as paleoecological and paleobiogeographical tools in Pleistocene glaciolacustrine sediments have been... more Trace fossils as paleoecological and paleobiogeographical tools in Pleistocene glaciolacustrine sediments have been largely ignored. Combining high resolution varve stratigraphy with trace fossil data can lead to refined paleoenvironmental interpretations during times of rapid climate change. Based on trace fossils from glaciolacustrine varves in the Connecticut and Merrimack River valleys, a new timeline for the reinhabitation of New England by fish and associated invertebrates has been constructed. In addition, it appears that colonization of the recently deglaciated environments occurred in at least four successional stages. If these stages can be recognized elsewhere, it may be possible to accurately model other postglacial migrations using trace fossils and varve chronostratigraphy.
Holocene transgression of the Rhine river mouth area, The Netherlands/Southern North Sea: palaeogeography and sequence stratigraphy
by Kim Cohen
Hijma, M.P., Cohen, K.M. (2011) Holocene transgression of the Rhine river mouth area, The Netherlands/Southern North Sea: palaeogeography and sequence stratigraphy. Sedimentology, 58, p.1453-1485.
This study presents a detailed reconstruction of the palaeogeography of the Rhine valley (western Netherlands) during... more This study presents a detailed reconstruction of the palaeogeography of the Rhine valley (western Netherlands) during the Holocene transgression with systems tracts placed in a precise sea-level context. This approach permits comparison of actual versus conceptual boundaries of the lowstand, transgressive and highstand systems tracts. The inland position of the highstand Rhine river mouth on a wide, low-gradient continental shelf meant that base-level changes were the dominant control on sedimentation for a relatively short period of the last glacial cycle. Systems in such inland positions predominantly record changes in the balance between river discharge and sediment load, and preserve excellent records of climatic changes or other catchment-induced forcing. It is shown here that the transgressive systems tract-part of the coastal prism formed in three stages: (i) the millennium before 8·45 ka bp, when the area was dominated by fluvial environments with extensive wetlands; (ii) the millennium after 8·45 ka, characterized by strong erosion, increasing tidal amplitudes and bay-head delta development; and (iii) the period between 7·5 and 6·3 ka bp when the Rhine avulsed multiple times and the maximum flooding surface formed. The diachroneity of the transgressive surface is strongly suppressed because of a pulse of accelerated sea-level rise at 8·45 ka bp. That event not only had a strong effect on preservation, but has circum-oceanic stratigraphical relevance as it divides the early and middle Holocene parts of coastal successions worldwide. The palaeogeographical reconstruction offers a unique full spatial–temporal view on the coastal and fluvial dynamics of a major river mouth under brief rapid forced transgression. This reconstruction is of relevance for Holocene and ancient transgressive systems worldwide, and for next-century natural coasts that are predicted to experience a 1 m sea-level rise.
Out of tune: the dangers of aligning proxy archives
Quaternary Science Reviews
Tuning is a widespread technique to combine, date and interpret multiple fossil proxy archives through aligning... more Tuning is a widespread technique to combine, date and interpret multiple fossil proxy archives through aligning supposedly synchronous events between the archives. The approach will be reviewed by discussing a number of literature examples, ranging from peat and tephra layers to orbital tuning and δ18O series from marine and ice deposits. Potential problems will be highlighted such as the dangers of circular reasoning and unrecognised chronological uncertainties, and some solutions suggested. Fossil proxy research could become enhanced if tuning were approached in a more quantitative, reliable and objective way, and especially if individual proxy archives were non-tuned and kept on independent time-scales.
Can 234U–230Th dating be used to date large semi-arid tufas? Challenges from a study in the Naukluft Mountains, Namibia
by Abi Stone
Published in the Journal of Quaternary Science 25(8), 1360-1372.
My co-authors on this paper are Heather Viles, who supervised my DPhil and my collaborators at the Open Univeristy Uranium Series Facility - Peter van Calsteren and Louise Thomas.