ORCID Profile
0000-0002-6662-6650
Current Organisation
Uppsala Universitet
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Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 07-2013
Publisher: Springer Science and Business Media LLC
Date: 15-10-2018
Publisher: Elsevier BV
Date: 12-2014
Publisher: Elsevier BV
Date: 04-2011
Publisher: Elsevier BV
Date: 06-2014
Publisher: Springer Science and Business Media LLC
Date: 07-03-2018
DOI: 10.1038/S41467-018-03329-2
Abstract: The International Commission on Stratigraphy (ICS) utilises benchmark chronostratigraphies to ide geologic time. The reliability of these records is fundamental to understand past global change. Here we use the most detailed luminescence dating age model yet published to show that the ICS chronology for the Quaternary terrestrial type section at Jingbian, desert marginal Chinese Loess Plateau, is inaccurate. There are large hiatuses and depositional changes expressed across a dynamic gully landform at the site, which demonstrates rapid environmental shifts at the East Asian desert margin. We propose a new independent age model and reconstruct monsoon climate and desert expansion/contraction for the last ~250 ka. Our record demonstrates the dominant influence of ice volume on desert expansion, dust dynamics and sediment preservation, and further shows that East Asian Summer Monsoon (EASM) variation closely matches that of ice volume, but lags insolation by ~5 ka. These observations show that the EASM at the monsoon margin does not respond directly to precessional forcing.
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-17138
Abstract: The west coast of Ireland is currently one of the wettest environments in Europe, with year-round precipitation, high humidity, and minimal thermal seasonality maintained by a strongly North Atlantic climate. While such conditions are not conducive to dust entrainment, transport, and deposition today, we report geologic evidence from the limestone Burren uplands for a period of sustained aeolian sedimentation during the last glacial termination. Contrasting with Ireland& #8217 s till- and glacial-outwash-dominated lowlands, the Burren& #8217 s extant sediment cover comprises a homogenous mineral silt preserved in lee-side zones and karst depressions, the outer reaches of caves, and amongst drumlins. Compositionally, our sedimentologic-geochemical data confirm the quartz minerology of these silts, which are consistent in composition and morphology to similar deposits reported from the England and France previously identified as loess. We used U-Pb age profiling of zircons to establish the primary source of the loess, providing a robust test of whether Irish deposits are locally sourced or instead derived from more distal regions (e.g., central Europe-Asia) both scenarios have ramifications for atmospheric circulation patterns during glacial-interglacial transitions and abrupt climate shifts. While OSL dating of the Burren silts is ongoing, the sedimentary stratigraphy is consistent with deposition during or immediately following ice sheet retreat, which our 10Be-dating of glacial surfaces places during early Heinrich Stadial 1 (HS1). In Ireland, HS1 was also characterised by winter sea ice, extreme thermal seasonality, and relatively low sea level. At multiple Burren sites, a bi-fold stratigraphy suggests the in situ (i.e., airfall) loess is overlain by a subsequently reworked unit of silt that was remobilised during the mid-Holocene, potentially reflecting a combination of climatic and anthropogenic drivers. Thus far, the Burren loess is providing a new aeolian vantage on Europe& #8217 s Atlantic margin during the close of the last ice age and has considerable potential for exploring environmental conditions during climatic transitions.
Publisher: Elsevier BV
Date: 05-2009
Publisher: Copernicus GmbH
Date: 11-06-2015
Abstract: Abstract. Mineral dust plays an important role in the climate system by interacting with radiation, clouds, and biogeochemical cycles. In addition, natural archives show that the dust cycle experienced variability in the past in response to global and local climate change. The compilation of the DIRTMAP (Dust Indicators and Records from Terrestrial and MArine Palaeoenvironments) paleodust data sets in the last 2 decades provided a benchmark for paleoclimate models that include the dust cycle, following a time slice approach. We propose an innovative framework to organize a paleodust data set that builds on the positive experience of DIRTMAP and takes into account new scientific challenges by providing a concise and accessible data set of temporally resolved records of dust mass accumulation rates and particle grain size distributions. We consider data from ice cores, marine sediments, loess–paleosol sequences, lake sediments, and peat bogs for this compilation, with a temporal focus on the Holocene period. This global compilation allows the investigation of the potential, uncertainties, and confidence level of dust mass accumulation rate reconstructions and highlights the importance of dust particle size information for accurate and quantitative reconstructions of the dust cycle. After applying criteria that help to establish that the data considered represent changes in dust deposition, 45 paleodust records have been identified, with the highest density of dust deposition data occurring in the North Atlantic region. Although the temporal evolution of dust in the North Atlantic appears consistent across several cores and suggests that minimum dust fluxes are likely observed during the early to mid-Holocene period (6000–8000 years ago), the magnitude of dust fluxes in these observations is not fully consistent, suggesting that more work needs to be done to synthesize data sets for the Holocene. Based on the data compilation, we used the Community Earth System Model to estimate the mass balance of and variability in the global dust cycle during the Holocene, with dust loads ranging from 17.2 to 20.8 Tg between 2000 and 10 000 years ago and with a minimum in the early to mid-Holocene (6000–8000 years ago).
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Thomas Stevens.