| 1. |
|
|
| 2. |
|
|
| 3. |
- Gribenski, Natacha, et al.
(author)
-
Re-evaluation of MIS 3 glaciation using cosmogenic radionuclide and single grain luminescence ages, Kanas Valley, Chinese Altai
- 2018
-
In: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 33:1, s. 55-67
-
Journal article (peer-reviewed)abstract
- Previous investigations observed a period of major glacial advances in Central Asia during marine oxygen isotope stage (MIS) 3 (57–29 ka), out of phase with global ice volume records. We have re-examined the Kanas moraine complex in the Altai Mountains of Central Asia, where an MIS 3 glaciation had been previously inferred. New and consistent cosmogenic exposure and single-grain luminescence ages indicate that the Kanas complex was formed during MIS 2 (29–12 ka), which brings its timing in line with the global ice volume record. We also identified a lateral moraine from a more extensive ice extent that dates to late MIS 5/MIS 4. To place our results in a wider contextual framework, we review the chronologies of another 26 proposed major MIS 3 glacial advances in Central Asia. For most of these sites, we find that the chronological data do not provide an unequivocal case for MIS 3 glaciation. Copyright © 2017 John Wiley & Sons, Ltd.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Stokes, Chris R., et al.
(author)
-
On the reconstruction of palaeo-ice sheets : Recent advances and future challenges
- 2015
-
In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 125, s. 15-49
-
Research review (peer-reviewed)abstract
- Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding mechanisms of global climate change and associated sea-level fluctuations in the past, present and future. The significance of palaeo-ice sheets is further underlined by the broad range of disciplines concerned with reconstructing their behaviour, many of which have undergone a rapid expansion since the 1980s. In particular, there has been a major increase in the size and qualitative diversity of empirical data used to reconstruct and date ice sheets, and major improvements in our ability to simulate their dynamics in numerical ice sheet models. These developments have made it increasingly necessary to forge interdisciplinary links between sub-disciplines and to link numerical modelling with observations and dating of proxy records. The aim of this paper is to evaluate recent developments in the methods used to reconstruct ice sheets and outline some key challenges that remain, with an emphasis on how future work might integrate terrestrial and marine evidence together with numerical modelling. Our focus is on pan-ice sheet reconstructions of the last deglaciation, but regional case studies are used to illustrate methodological achievements, challenges and opportunities. Whilst various disciplines have made important progress in our understanding of ice-sheet dynamics, it is clear that data-model integration remains under-used, and that uncertainties remain poorly quantified in both empirically-based and numerical ice-Sheet reconstructions. The representation of past climate will continue to be the largest source of uncertainty for numerical modelling. As such, palaeo-observations are critical to constrain and validate modelling. State-of-the-art numerical models will continue to improve both in model resolution and in the breadth of inclusion of relevant processes, thereby enabling more accurate and more direct comparison with the increasing range of palaeo-observations. Thus, the capability is developing to use all relevant palaeo-records to more strongly constrain deglacial (and to a lesser extent pre-LGM) ice sheet evolution. In working towards that goal, the accurate representation of uncertainties is required for both constraint data and model outputs. Close cooperation between modelling and data-gathering communities is essential to ensure this capability is realised and continues to progress.
|
|
| 8. |
- Tobias, J., et al.
(author)
-
A New Strategy Toward B Cell-Based Cancer Vaccines by Active Immunization With Mimotopes of Immune Checkpoint Inhibitors
- 2020
-
In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 11
-
Journal article (peer-reviewed)abstract
- Therapeutic monoclonal antibodies (mAbs), targeting tumor antigens, or immune checkpoints, have demonstrated a remarkable anti-tumor effect against various malignancies. However, high costs for mono- or combination therapies, associated with adverse effects or possible development of resistance in some patients, warrant further development and modification to gain more flexibility for this immunotherapy approach. An attractive alternative to passive immunization with therapeutic antibodies might be active immunization with mimotopes (B-cell peptides) representing the mAbs' binding epitopes, to activate the patient's own anti-tumor immune response following immunization. Here, we identified and examined the feasibility of inducing anti-tumor effectsin vivofollowing active immunization with a mimotope of the immune checkpoint programmed cell death 1 (PD1), alone or in combination with a Her-2/neu B-cell peptide vaccine. Overlapping peptides spanning the extracellular domains of human PD1 (hPD1) were used to identify hPD1-derived mimotopes, using the therapeutic mAb Nivolumab as a proof of concept. Additionally, forin vivoevaluation in a tumor mouse model, a mouse PD1 (mPD1)-derived mimotope was identified using an anti-mPD1 mAb with mPD1/mPDL-1 blocking capacity. The identified mimotopes were characterized byin vitroassays, including a reporter cell-based assay, and their anti-tumor effects were evaluated in a syngeneic tumor mouse model stably expressing human Her-2/neu. The identified PD1-derived mimotopes were shown to significantly block the mAbs' capacity in inhibiting the respective PD1/PD-L1 interactions. A significant reduction in tumor growthin vivowas observed following active immunization with the mPD1-derived mimotope, associated with a significant reduction in proliferation and increased apoptotic rates in the tumors. Particularly, combined vaccination with the mPD1-derived mimotope and a multiple B-cell epitope Her-2/neu vaccine potentiated the vaccine's anti-tumor effect. Our results suggest active immunization with mimotopes of immune checkpoint inhibitors either as monotherapy or as combination therapy with tumor-specific vaccines, as a new strategy for cancer treatment.
|
|
| 9. |
|
|
| 10. |
- Guralnik, B., et al.
(author)
-
OSL-thermochronometry using bedrock quartz : A note of caution
- 2015
-
In: Quaternary Geochronology. - : Elsevier BV. - 1871-1014 .- 1878-0350. ; 25, s. 37-48
-
Journal article (peer-reviewed)abstract
- Optically stimulated luminescence (OSL) thermochronometry is an emerging application, whose capability to record sub-Million-year thermal histories is of increasing interest to a growing number of subdisciplines of Quaternary research. However, several recent studies have encountered difficulties both in extraction of OSL signals from bedrock quartz, and in their thermochronometric interpretation, thus highlighting the need for a methodological benchmark. Here, we investigate the characteristic OSL signals from quartz samples across all major types of bedrock and covering a wide range of chemical purities. High ratios of infrared to blue stimulated luminescence (IRSL/BLSL), an insensitive 'fast' OSL component, and anomalously short recombination lifetimes seen in time-resolved luminescence (TROSL), are often encountered in quartz from crystalline (magmatic and metamorphic) bedrock, and may hamper successful OSL dating. Furthermore, even when the desirable signal is present, its concentration might be indistinguishable from its environmental steady-state prediction, thus preventing its conversion to a cooling or heating history. We explore the saturation properties and the thermal activation parameters of various OSL signals in quartz to outline the capabilities and limitations for their use in low-temperature thermochronometry.
|
|
| 11. |
- Hoang-Xuan, Khe, et al.
(author)
-
Diagnosis and treatment of primary CNS lymphoma in immunocompetent patients : guidelines from the European Association for Neuro-Oncology
- 2015
-
In: The Lancet Oncology. - 1470-2045 .- 1474-5488. ; 16:7, s. E322-E332
-
Research review (peer-reviewed)abstract
- The management of primary CNS lymphoma is one of the most controversial topics in neuro-oncology because of the complexity of the disease and the very few controlled studies available. In 2013, the European Association of Neuro-Oncology created a multidisciplinary task force to establish evidence-based guidelines for immunocompetent adults with primary CNS lymphoma. In this Review, we present these guidelines, which provide consensus considerations and recommendations for diagnosis, assessment, staging, and treatment of primary CNS lymphoma. Specifically, we address aspects of care related to surgery, systemic and intrathecal chemotherapy, intensive chemotherapy with autologous stem-cell transplantation, radiotherapy, intraocular manifestations, and management of elderly patients. The guidelines should aid clinicians in their daily practice and decision making, and serve as a basis for future investigations in neuro-oncology.
|
|
| 12. |
- Rosenberg, T. M., et al.
(author)
-
Humid periods in southern Arabia : Windows of opportunity for modern human dispersal
- 2011
-
In: Geology. - 0091-7613 .- 1943-2682. ; 39:12, s. 1115-1118
-
Journal article (peer-reviewed)abstract
- Arabia is a key area for the dispersal of anatomically modern humans (AMH, Homo sapiens) out of Africa. Given its modern hostile environment, the question of the timing of dispersal is also a question of climatic conditions. Fresh water and food were crucial factors facilitating AMH expansions into Arabia. By dating relict lake deposits, four periods of lake formation were identified: one during the early Holocene and three during the late Pleistocene centered ca. 80, ca. 100, and ca. 125 ka. Favorable environmental conditions during these periods allowed AMH to migrate across southern Arabia. Between ca. 75 and 10.5 ka, arid conditions prevailed and turned southern Arabia into a natural barrier for human dispersal. Thus, expansion of AMH through the southern corridor into Asia must have taken place before 75 ka, possibly in multiple dispersals.
|
|
| 13. |
- Blaauw, M., et al.
(author)
-
Bayesian testing for synchrony of events in glacial proxy archives
- 2007
-
In: European Geosciences Union, 2007. ; , s. 00301-
-
Conference paper (other academic/artistic)abstract
- Often chronological uncertainties are ignored in multi-site comparisons, resulting inpotentially wrong assumptions concerning (a)synchrony of events between archives.We explore this problem in a Bayesian framework, constructing millions of plausiblewiggle-match age-models in order to quantify the chronological uncertainties withinand between proxy archives. Using these data we can now calculate the statisticalprobability that events indeed coincided. The method is applied to a high-resolution14C and OSL dated lake core from south-eastern France which largely predates theIntCal04 14C calibration curve. Depending on the applied comparison curve, eventsin this core appear synchronous or asynchronous with events in the NGRIP ice core.
|
|
| 14. |
- Blaauw, M., et al.
(author)
-
Were last glacial climate events simultaneous between Greenland and France?
- 2010
-
In: Journal of Quaternary Science. - : Wiley. - 0267-8179 .- 1099-1417. ; 25:3, s. 387-394
-
Journal article (peer-reviewed)abstract
- Several large abrupt climate fluctuations during the last glacial have been recorded in Greenland ice cores and archives from other regions. Often these Dansgaard–Oeschger events are assumed to have been synchronous over wide areas, and then used as tie-points to link chronologies between the proxy archives. However, it has not yet been tested independently whether or not these events were indeed synchronous over large areas. Here, we compare Dansgaard–Oeschger-type events in a well-dated record from southeastern France with those in Greenland ice cores. Instead of assuming simultaneous climate events between both archives, we keep their age models independent. Even these well-dated archives possess large chronological uncertainties that prevent us from inferring synchronous climate events at decadal to multi-centennial time scales. If possible, comparisons between proxy archives should be based on independent, non-tuned time-scales.
|
|
| 15. |
- Gribenski, Natacha, 1986-
(author)
-
Comparison of dating methods for paleoglacial reconstruction in Central Asia
- 2016
-
Doctoral thesis (other academic/artistic)abstract
- Reconstruction of former Central Asian glaciers extents can provide valuable information about past atmospheric circulation variations. These extents, often marked by terminal moraines, need to be chronologically constrained. Cosmogenic nuclide exposure (CNE) dating is widely used to directly date moraines. In addition, there is increasing interest on using optically stimulated luminescence (OSL) techniques for dating glacial landforms. This thesis focuses on the methodological aspects of directly dating glacial landforms to perform paleoglacial reconstructions in Central Asia, with an emphasis on OSL dating.For OSL dating of sediments from glacial settings, it is important to measure the luminescence signal at the single grain scale, because the sediments are likely affected by partial bleaching due to short light exposure during glacial or glaciofluvial transport. The use of an Electron Multiplying Charges Coupled Device (EMCCD)-based imaging system for single grain OSL measurements would offer larger flexibility in light stimulation and sediment type, compared to the current Single Grain Risø reader. An automated image processing procedure has been developed to compensate for sample carrier displacement over repeated measurements and for attributing pixels to each grain for signal integration when using this imaging system. However, significant cross talk contamination, demonstrated by laboratory and simulation experiments, prohibits accurate single grain luminescence measurements. Preliminary experiments using a basic image processing algorithm show good potential for software correction solutions.Paleoglacial reconstructions conducted in the Altai Mountains, Central Asia, using both CNE and OSL dating demonstrate that luminescence measurements of glaciofluvial sediments performed at the multi-grain scale result in large age overestimates, and that single grain measurements allow for more accurate dating of glacial landforms. However, uncertainties remain that are related to the model used for extracting equivalent doses for well-bleached grains and to fading corrections when using feldspar minerals. The timing of glaciation can be inferred from scattered CNE moraine boulder ages if most of the ages are concentrated within a few thousand years, with only few ages clearly older or younger. Overall, combining CNE and OSL techniques for dating a glacial landform is a powerful approach for producing robust glacial chronologies, despite uncertainties inherent to each technique.Paleoglacial reconstructions from the Altai Mountains indicate Marine Isotope Stage (MIS) 2 and MIS 4/late MIS 5 local Last Glacial Maximums. In Central Asia, in addition to a regional MIS 2 glaciation, previous studies indicate a period of major glacial advances during MIS 3 that is out of phase with global ice volume records. However, most MIS 3 glacial chronologies from Central Asia are based on too few or too heavily scattered CNE data sets, or on OSL or Electron Spin Resonance (ESR) ages for which partial bleaching has not been properly investigated. Hence, at this stage, chronological evidence is insufficient to demonstrate a regional MIS 3 glaciation in Central Asia.Surge-related glacial features identified in the Russian Altai also highlight the importance of conducting detailed geomorphology and sedimentology studies to understand former ice dynamics, which is essential for inferring appropriate paleoclimate information from paleoglacial reconstructions.
|
|
| 16. |
- Gribenski, Natacha, 1986-, et al.
(author)
-
Major glaciation in Central Asia during MIS 3: reality or dating artefact?
-
Other publication (other academic/artistic)abstract
- Previous investigations have concluded that a period of major glacial advances occurred during Marine Isotope Stage (MIS) 3 (57-29 ka) in Central Asia, out of phase with global ice volume records. We have re-examined the Kanas moraine complex in the Altai Mountains, where an MIS 3 glaciation has been previously inferred. New cosmogenic exposure and single grain luminescence ages indicate that the Kanas complex was formed during MIS 2 (29-12 ka); we regard the initial MIS 3 interpretation as a result of dating artefacts. Building on this example, we reanalyze chronological data associated with proposed major MIS 3 glacial advances in Central Asia (24 sites). We find that chronological data do not allow glaciation timing inferences for most of the sites, and that chronological evidence for major MIS 3 glacial advance only exists at one site.
|
|
| 17. |
- Hoang-Xuan, Khê, et al.
(author)
-
European Association of Neuro-Oncology (EANO) guidelines for treatment of primary central nervous system lymphoma (PCNSL)
- 2023
-
In: Neuro-Oncology. - : Oxford University Press. - 1522-8517 .- 1523-5866. ; 25:1, s. 37-53
-
Journal article (peer-reviewed)abstract
- The management of primary central nervous system (PCNSL) is one of the most controversial topics in neuro-oncology because of the complexity of the disease and the limited number of controlled studies available. In 2021, given recent advances and the publication of practice-changing randomized trials, the European Association of Neuro-Oncology (EANO) created a multidisciplinary task force to update the previously published evidence-based guidelines for immunocompetent adult patients with PCNSL and added a section on immunosuppressed patients. The guideline provides consensus considerations and recommendations for the treatment of PCNSL, including intraocular manifestations and specific management of the elderly. The main changes from the previous guideline include strengthened evidence for the consolidation with ASCT in first-line treatment, prospectively assessed chemotherapy combinations for both young and elderly patients, clarification of the role of rituximab even though the data remain inconclusive, of the role of new agents, and the incorporation of immunosuppressed patients and primary ocular lymphoma. The guideline should aid the clinicians in everyday practice and decision making and serve as a basis for future research in the field.
|
|
| 18. |
- Kiesel, Barbara, et al.
(author)
-
PERIOPERATIVE IMAGING OF BRAIN METASTASES : A EUROPEAN ASSOCIATION OF NEURO-ONCOLOGY (EANO) YOUNGSTERS SURVEY
- 2018
-
In: Neuro-Oncology. - : OXFORD UNIV PRESS INC. - 1522-8517 .- 1523-5866. ; 20, s. 59-59
-
Journal article (other academic/artistic)abstract
- BACKGROUNDNeurosurgical resection is an important treatment option in the multimodal therapy of brain metastases (BM). Perioperative imaging is established in primary brain tumors to assess the extent of resection. However, structured guidelines on the use of perioperative imaging for BM patients are so far missing.METHODSThe European Association of Neuro-Oncology (EANO) Youngsters committee designed a comprehensive questionnaire on the use of perioperative imaging. The survey was distributed to physicians with neuro-oncologic focus via the EANO and the European Association of Neurosurgical Societies (EANS) network.RESULTS120 physicians from non-European countries and European countries responded to the survey. 76/120 neurosurgeons, 18/120 radiation oncologists and 17/120 neurologists participated. 89/120 participants worked at academic hospitals and 39/40 participants worked in high patient volume centers as defined by >50 BM cases per year. Local standard operating procedures for perioperative imaging were applied by 94/120 physicians. The preferred preoperative imaging method represented MRI for 112/120 (93.3%) participants. Postsurgical imaging was routinely performed by 106/120 physicians. 77/120 participants indicated MRI as the preferred postoperative imaging method, however, only 71/120 performed postoperative MRI imaging within 72 hours after resection. No correlation of postsurgical MRI and localization at an academic hospital (58/79 [73.4%] vs. 19/27 [70.4%], p>0.05) or patient volume (49/71 [69%] vs 25/40 [62.5%], p>0.05) was evident. The most frequently indicated reason for postsurgical imaging was the assessment of extent of resection as participants indicated to adjust the radiotherapy plan or even considered re-surgery to achieve complete resection. CONCLUSIONS: This EANO survey indicates that preoperative MRI is the preferred imaging technique for the majority of physicians, whereas a high variability of postoperative neuroimaging routines including CT and MRI was observed. International guidelines for perioperative imaging with special focus on postoperative MRI are warranted in order to optimize perioperative treatment modalities for BM patients.
|
|
| 19. |
|
|
| 20. |
- Rosenberg, Thomas M., et al.
(author)
-
A comparison of single and multiple aliquot TT-OSL data sets for sand-sized quartzfrom the Arabian Peninsula
- 2011
-
In: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 46:6-7, s. 573-579
-
Journal article (peer-reviewed)abstract
- The quartz OSL signal from dune sands from Saudi Arabia and Oman start to saturate at doses of about100 Gy. In order to try to date dune sands with greater expected doses, a previously published,single-aliquot, regenerative-dose protocol (SAR) for thermally-transferred optically stimulatedluminescence (TT-OSL) was tested. Dose recovery tests, recycling and recuperation ratios showed robustfunctioning and dose response curves demonstrated the potential to extend the dose range to beyond600 Gy. Multiple aliquot additive dose (MAAD) TT-OSL protocols were used to test for sensitivity changesin the SAR TT-OSL protocol up to doses of 1200 Gy. A strong dose dependent deviation of the SAR TT-OSLrelative to the MAAD TT-OSL dose response is observed. Comparison of the TT-OSL and OSL sensitivitydata obtained from the MAAD and SAR data sets shows a lack of proportionality between TT-OSL and OSLfor the SAR data which will result in a problem when SAR dose response curves are constructed usingmany regeneration points with doses above 300 Gy.
|
|
| 21. |
- Rosenberg, Thomas M., et al.
(author)
-
Middle and Late Pleistocene humid periods recorded in palaeolake deposits of the Nafud desert, Saudi Arabia
- 2013
-
In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 70, s. 109-123
-
Journal article (peer-reviewed)abstract
- Present climate in the Nafud desert of northern Saudi Arabia is hyper-arid and moisture brought by north-westerly winds scarcely reaches the region. The existence of abundant palaeolake sediments provides evidence for a considerably wetter climate in the past. However, the existing chronological framework of these deposits is solely based on radiocarbon dating of questionable reliability, due to potential post-depositional contamination with younger C-14. By using luminescence dating, we show that the lake deposits were not formed between 40 and 20 ka as suggested previously, but approximately ca 410 ka, 320 ka, 200 ka, 125 ka, and 100 ka ago. All of these humid phases are in good agreement with those recorded in lake sediments and speleothems from southern Arabia. Surprisingly, no Holocene lake deposits were identified. Geological characteristics of the deposits and diatom analysis suggest that a single, perennial lake covered the entire south-western Nafud ca 320 ka ago. In contrast, lakes of the 200 ka, 125 ka, and 100 ka humid intervals were smaller and restricted to interdune depressions of a preexisting dune relief. The concurrent occurrence of humid phases in the Nafud, southern Arabia and the eastern Mediterranean suggests that moisture in northern Arabia originated either from the Mediterranean due to more frequent frontal depression systems or from stronger Indian monsoon circulation, respectively. However, based on previously published climate model simulations and palaecolimate evidence from central Arabia and the Negev desert, we argue that humid climate conditions in the Nafud were probably caused by a stronger African monsoon and a distinct change in zonal atmospheric circulation.
|
|
| 22. |
- Rudà, Roberta, et al.
(author)
-
Eano-Euracan-Sno Guidelines on Circumscribed Astrocytic GLIOMAS, Glioneuronal and Neuronaltumors.
- 2022
-
In: Neuro-oncology. - : Oxford University Press (OUP). - 1523-5866 .- 1522-8517. ; 24:12, s. 2015-2034
-
Research review (peer-reviewed)abstract
- In the new WHO 2021 Classification of CNS Tumors the chapter "Circumscribed astrocytic gliomas, glioneuronal and neuronal tumors" encompasses several different rare tumor entities, which occur more frequently in children, adolescents and young adults. The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is low particularly for adult patients, and draw recommendations accordingly. Tumor diagnosis, based on WHO 2021, is primarily performed using conventional histological techniques; however, molecular workup is important for differential diagnosis, in particular DNA methylation profiling for the definitive classification of histologically unresolved cases. Molecular factors are increasingly of prognostic and predictive importance. MRI finding are non specific, but for some tumors are characteristic and suggestive. Gross total resection, when feasible, is the most important treatment in terms of prolonging survival and achieving long-term seizure control. Conformal radiotherapy should be considered in grade 3 and incompletely resected grade 2 tumors. In recurrent tumors reoperation and radiotherapy, including stereotactic radiotherapy, can be useful. Targeted therapies may be used in selected patients: BRAF and MEK inhibitors in pilocytic astrocytomas, pleomorphic xanthoastrocytomas, and gangliogliomas when BRAF altered, and mTOR inhibitor everolimus in subependymal giant cells astrocytomas .Sequencing to identify molecular targets is advocated for diagnostic clarification and to direct potential targeted therapies.
|
|
| 23. |
- Schmidt, C., et al.
(author)
-
THE ASSESSMENT OF RADIONUCLIDE DISTRIBUTION IN SILEX BY AUTORADIOGRAPHY IN THE CONTEXT OF DOSE RATE DETERMINATION FOR THERMOLUMINESCENCE DATING
- 2013
-
In: Archaeometry. - : Wiley. - 0003-813X .- 1475-4754. ; 55, s. 407-422
-
Journal article (peer-reviewed)abstract
- A combination of two autoradiography methods was applied to investigate the radionuclide distribution patterns in a range of different silices. We obtained greyscale images (-radiation) and -track patterns for qualitative assessment, and used a statistical approach to quantify the degree of uniformity of the radiation fields. It was found that almost all samples are poor in potassium, thorium and uranium, and that locally high concentrations are present only in dark-coloured veins and inclusions. Statistical analyses reveal evidence of radionuclide clustering in more than half of the 21 specimens. Concerning thermoluminescence dating of burnt lithics, such gradients should be taken into account to improve precision and accuracy in cases where the external radiation is not strongly dominating for the sample under consideration.
|
|
| 24. |
- Veres, Daniel, et al.
(author)
-
Age, origin and significance of a new middle MIS 3 tephra horizon identified within a long-core sequence from Les Echets, France
- 2008
-
In: Boreas. - : Wiley. - 0300-9483 .- 1502-3885. ; 37:3, s. 434-443
-
Journal article (peer-reviewed)abstract
- A new tephra has been identified within a long core (EC 3) sequence recovered from Les Echets, near Lyon, France. This visible tephra was discovered as part of a high resolution multiproxy re-investigation of the Les Echets sequence. Independent chronological information suggests that the tephra is c. 2 000-45 000 years old, and geochemical analysis indicates that it is of basanitic composition. The latter suggests a possible origin in the Eifel, however, as yet, no other volcanic events or deposits can be correlated to the Les Echets tephra. New sedimentological and chronological data are presented indicating that the tephra falls within an interval that most likely correlates with Dansgaard-Oeschger events 12-9. Thus, this tephra could potentially be an important middle MIS 3 marker horizon in central Europe if it can be traced in other palaeorecords.
|
|
| 25. |
- Wohlfarth, Barbara, et al.
(author)
-
Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40-16 ka
- 2008
-
In: Geology. - 0091-7613 .- 1943-2682. ; 36:5, s. 407-410
-
Journal article (peer-reviewed)abstract
- We present a high-resolution and independently dated multiproxy lake sediment record from the paleolake at Les Echets in southeastern France that displays synchronous changes in independent limnic and terrestrial ecosystem proxies, in concert with millennial-scale climate oscillations during the last glacial period. Distinct lake-level fluctuations, low lake organic productivity, and open, treeless vegetation indicate cold and dry conditions in response to Heinrich events. Alternating phases of higher and low lake organic productivity, stratified surface waters and long-lasting lake ice cover, decreased or increased catchment erosion, and tree-dominated or herb-dominated vegetation resemble Dansgaard-Oeschger interstadial-stadial variability. Transitions between different ecological states occurred in as little as 40-230 yr and seem to have been controlled by the position of the Polar Front. Ecosystem response after 30 ka suggests that local climate conditions became more important. Our results demonstrate that all parts of the terrestrial system responded to the abrupt and dramatic climatic changes associated with Dansgaard-Oeschger and Heinrich events, and that regional factors modulated ecosystem response.
|
|
