- Email: [email protected]
Establishing a geochronology of Middle and Late Pleistocene glaciations in northern Switzerland using luminescence dating
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Abstracts / Quaternary International 279-280 (2012) 121–232
damaged freshwater diatoms and foram linings occur. Dinocysts and non-pollen palynomorphs evidence diverse environmentally incompatible floras with temperate, boreal, and Arctic glaciomarine taxa. This contrasts with proven glaciomarine sequences south of the CDB showing well developed foraminiferal communities and in situ boreal and Arctic molluscs. CDB material is more in keeping with a retreating ice margin reworking marine sediments into a lacustrine basin. However, similar conditions may also be found within a semi-enclosed marine embayment. Nonetheless, compared to similar glaciolacustrine records from the Isle of Man, the CDB laminated muds are particularly sparse. CDB sediments are thus tentatively interpreted as glaciolacustrine, truncated by a Late Devensian/Midlandian to Holocene marine incursion, fining upwards into modern marine. Despite 67 molluscan 14C dates the chronology remains problematic, lacking dateable basal material. Fauna from overlying facies have been subject to intense reworking, condensation, and mixing. Rare intertidal species (e.g. Hydrobia ulvae, Tornus subcarinatus) dating to w13.9 cal ka BP providing a minimum age on deglaciation and subsequent marine ingression into the CDB. However, given their bathymetric and taphonomic context, they are not considered in situ. Despite this negative evidence, the exact timing and nature of CDB deglaciation remains equivocal. PLEISTOCENE HORSE REMAINS FROM NW BANKS ISLAND, CANADIAN ARCTIC ARCHIPELAGO: IMPLICATIONS FOR LONG-TERM LANDSCAPE EVOLUTION Mark F.A. Furze. MacEwan University, Canada E-mail address: [email protected]
Recent work on NW Banks Island in the western Canadian Arctic Archipelago (CAA) has overturned the long-held paradigm that the area was never glaciated. However, occurrence of rare remains of mammoth from Banks and Melville islands (25.9-24.6 cal ka BP) suggests herb-rich tundra persisted for much of the Wisconsinan, and constrains the timing of glaciation. The 2010 discovery, from the Ballast Brook area of NW Banks Island, of a metacarpal and other fragments of a horse, tentatively identified as Equus lambei, further elucidates the regional palaeogeography and timing of glaciation. Fossils were collected from a gravel unit previously assigned to the Late Pliocene Beaufort Formation. The site lies within the zone occupied by Late Wisconsinan M'Clure Strait ice that became confluent with cold-based ice from the interior to the south; a cryoturbated till capping the gravel unit. The fossils occur stratigraphically above the majority of pre-glacial fluvial incision into the surrounding landscape. The occurrence of putative Mid to Late Pleistocene horse remains requires reassessment of the upper Beaufort Formation as being Late Pliocene and may imply more extensive Quaternary fluvial deposition across this sector of the CAA than previously recognized. In particular, their position in high elevation water-lain gravels above significant N and NW modern and Late Wisconsinan drainages has major implications for the timing of (glaciofluvial?) valley incision. Their position and altitude are hard to reconcile with modern northerly drainage into M'Clure Strait and imply a significant tectonic component to landscape evolution with either recent major uplift along the north coast of Banks Island, or a pre-rifting westward drainage to the Beaufort Sea with subsequent post-rift northward -flowing stream capture. More Pleistocene vertebrate remains may occur in a similar stratigraphic context throughout this area. HOW ‘CLOSE’ CAN WE PUSH DATA? THE CHALLENGES AND POTENTIAL OF FOSSIL POLLEN DATA FOR LOCAL-SCALE RECONSTRUCTION OF VEGETATION CHANGE Ralph Fyfe. University of Plymouth, United Kingdom E-mail address: [email protected]
The reconstruction of local-scale vegetation change, and vegetation patterning, from fossil pollen data has long been the goal of the environmental archaeologist. It is argued that traditional interpretations of vegetation change from pollen data are essentially aspatial, and deal mainly with temporal change (Fyfe et al., 2010). This is a consequence of
several factors, including the reliance on single sequences to derive palaeoenvironmental histories, the uncertainties of correlation between different sequences, comparison of records from sites with different taphonomic processes, and the difficulties of disentangling regional signals from local signals in the pollen record. This paper will discuss methodological advances that have begun to allow for true spatial quantification of vegetation cover, and the possible implications for using pollen analysis to reconstruct local vegetation change, using data from the UK (Sugita, 2007). It will consider the extent to which existing fossil pollen data can be used to determine landscape changes at a spatial scale relevant to the archaeological community. ESTABLISHING A GEOCHRONOLOGY OF MIDDLE AND LATE PLEISTOCENE GLACIATIONS IN NORTHERN SWITZERLAND USING LUMINESCENCE DATING Dorian Gaar. Institute of Geological Sciences, University of Be, Switzerland E-mail address: [email protected]
Recent research in the alpine foreland of northern Switzerland reveals a detailed multiphase history of foreland glaciations during Middle and Late Pleistocene. Four to five glacial periods each comprising several glacial advances are distinguished by means of sedimentology and lithostratigraphy (Graf, 2009). Nevertheless, very little is known about the exact timing of these paleoglacial events. An independent chronological framework is crucial for comparing the regional environmental changes to the general trends of global climate as they are inferred from ice cores and deep sea sediments. In this project, glaciofluvial sediments related to different glacial advances during Middle and Late Pleistocene are dated using different luminescence approaches (cf. Preusser et al., 2008). Due to the proximity of the sampled sites to the former ice margin, signal resetting in the grains is likely to be differential and single-grain techniques on both quartz and feldspar separates are used to detect and overcome this problem. THE HEIDELBERG BASIN – AN UNIQUE ARCHIVE OF QUATERNARY SEDIMENTS PROVIDES NEW INSIGHTS INTO THE QUATERNARY ON MULTIPLE SCALES Gerald Gabriel. Leibniz Institute for Applied Geophysics, Germany E-mail address: [email protected]
The Heidelberg Basin, northern part of the Upper Rhine Graben (URG, Germany), hosts one of the thickest and most complete successions of Plio-/Pleistocene sediments in Central Europe, as revealed by new cored boreholes at three different locations. These boreholes expose different types of the basin facies: (a) three 300 m deep boreholes in Ludwigshafen represent the western margin of the basin; (b) a 350 m deep borehole close to Viernheim reveals information about the central basin facies, and (c) the 500 m deep borehole Heidelberg UniNord is located above the depocentre. One of our goals of this drilling project is to establish a reference profile for Quaternary stratigraphy for the region north of the Alps. As suggested by the first pollen data, the succession is complete in the sense of climate stratigraphy, a unique situation in Western Europe. In this context special emphasize is on the characterization of the Quaternary as revealed by different data sets. During the last decades a petrographical marker has been used to identify “Base Quaternary” in the URG, i.e. the first deposition of sediments of alpine origin imaged by a significant change in the heavy mineral spectrum. First data from the new boreholes suggests that this definition must be re-evaluated. For the Ludwigshafen borehole correlation between the heavy mineral data indicating the transition between sediments of alpine and local origin, the biostratigraphic boundary between Plio-/Pleistocene, and a significant change in magnetomineralogy that is interpreted to have been caused by environmental change, is observed at 177 m depth. In contrast, the palynological data from the location Heidelberg UniNord suggest that this borehole did not even reach Base Quaternary, whereas the base of the sediments of alpine character is found at 300 m depth. In addition the new data provide also insight on smaller scales, e.g. climate variations at the beginning and the end of the Tiglian.
Abstracts / Quaternary International 279-280 (2012) 121–232
damaged freshwater diatoms and foram linings occur. Dinocysts and non-pollen palynomorphs evidence diverse environmentally incompatible floras with temperate, boreal, and Arctic glaciomarine taxa. This contrasts with proven glaciomarine sequences south of the CDB showing well developed foraminiferal communities and in situ boreal and Arctic molluscs. CDB material is more in keeping with a retreating ice margin reworking marine sediments into a lacustrine basin. However, similar conditions may also be found within a semi-enclosed marine embayment. Nonetheless, compared to similar glaciolacustrine records from the Isle of Man, the CDB laminated muds are particularly sparse. CDB sediments are thus tentatively interpreted as glaciolacustrine, truncated by a Late Devensian/Midlandian to Holocene marine incursion, fining upwards into modern marine. Despite 67 molluscan 14C dates the chronology remains problematic, lacking dateable basal material. Fauna from overlying facies have been subject to intense reworking, condensation, and mixing. Rare intertidal species (e.g. Hydrobia ulvae, Tornus subcarinatus) dating to w13.9 cal ka BP providing a minimum age on deglaciation and subsequent marine ingression into the CDB. However, given their bathymetric and taphonomic context, they are not considered in situ. Despite this negative evidence, the exact timing and nature of CDB deglaciation remains equivocal. PLEISTOCENE HORSE REMAINS FROM NW BANKS ISLAND, CANADIAN ARCTIC ARCHIPELAGO: IMPLICATIONS FOR LONG-TERM LANDSCAPE EVOLUTION Mark F.A. Furze. MacEwan University, Canada E-mail address: [email protected]
Recent work on NW Banks Island in the western Canadian Arctic Archipelago (CAA) has overturned the long-held paradigm that the area was never glaciated. However, occurrence of rare remains of mammoth from Banks and Melville islands (25.9-24.6 cal ka BP) suggests herb-rich tundra persisted for much of the Wisconsinan, and constrains the timing of glaciation. The 2010 discovery, from the Ballast Brook area of NW Banks Island, of a metacarpal and other fragments of a horse, tentatively identified as Equus lambei, further elucidates the regional palaeogeography and timing of glaciation. Fossils were collected from a gravel unit previously assigned to the Late Pliocene Beaufort Formation. The site lies within the zone occupied by Late Wisconsinan M'Clure Strait ice that became confluent with cold-based ice from the interior to the south; a cryoturbated till capping the gravel unit. The fossils occur stratigraphically above the majority of pre-glacial fluvial incision into the surrounding landscape. The occurrence of putative Mid to Late Pleistocene horse remains requires reassessment of the upper Beaufort Formation as being Late Pliocene and may imply more extensive Quaternary fluvial deposition across this sector of the CAA than previously recognized. In particular, their position in high elevation water-lain gravels above significant N and NW modern and Late Wisconsinan drainages has major implications for the timing of (glaciofluvial?) valley incision. Their position and altitude are hard to reconcile with modern northerly drainage into M'Clure Strait and imply a significant tectonic component to landscape evolution with either recent major uplift along the north coast of Banks Island, or a pre-rifting westward drainage to the Beaufort Sea with subsequent post-rift northward -flowing stream capture. More Pleistocene vertebrate remains may occur in a similar stratigraphic context throughout this area. HOW ‘CLOSE’ CAN WE PUSH DATA? THE CHALLENGES AND POTENTIAL OF FOSSIL POLLEN DATA FOR LOCAL-SCALE RECONSTRUCTION OF VEGETATION CHANGE Ralph Fyfe. University of Plymouth, United Kingdom E-mail address: [email protected]
The reconstruction of local-scale vegetation change, and vegetation patterning, from fossil pollen data has long been the goal of the environmental archaeologist. It is argued that traditional interpretations of vegetation change from pollen data are essentially aspatial, and deal mainly with temporal change (Fyfe et al., 2010). This is a consequence of
several factors, including the reliance on single sequences to derive palaeoenvironmental histories, the uncertainties of correlation between different sequences, comparison of records from sites with different taphonomic processes, and the difficulties of disentangling regional signals from local signals in the pollen record. This paper will discuss methodological advances that have begun to allow for true spatial quantification of vegetation cover, and the possible implications for using pollen analysis to reconstruct local vegetation change, using data from the UK (Sugita, 2007). It will consider the extent to which existing fossil pollen data can be used to determine landscape changes at a spatial scale relevant to the archaeological community. ESTABLISHING A GEOCHRONOLOGY OF MIDDLE AND LATE PLEISTOCENE GLACIATIONS IN NORTHERN SWITZERLAND USING LUMINESCENCE DATING Dorian Gaar. Institute of Geological Sciences, University of Be, Switzerland E-mail address: [email protected]
Recent research in the alpine foreland of northern Switzerland reveals a detailed multiphase history of foreland glaciations during Middle and Late Pleistocene. Four to five glacial periods each comprising several glacial advances are distinguished by means of sedimentology and lithostratigraphy (Graf, 2009). Nevertheless, very little is known about the exact timing of these paleoglacial events. An independent chronological framework is crucial for comparing the regional environmental changes to the general trends of global climate as they are inferred from ice cores and deep sea sediments. In this project, glaciofluvial sediments related to different glacial advances during Middle and Late Pleistocene are dated using different luminescence approaches (cf. Preusser et al., 2008). Due to the proximity of the sampled sites to the former ice margin, signal resetting in the grains is likely to be differential and single-grain techniques on both quartz and feldspar separates are used to detect and overcome this problem. THE HEIDELBERG BASIN – AN UNIQUE ARCHIVE OF QUATERNARY SEDIMENTS PROVIDES NEW INSIGHTS INTO THE QUATERNARY ON MULTIPLE SCALES Gerald Gabriel. Leibniz Institute for Applied Geophysics, Germany E-mail address: [email protected]
The Heidelberg Basin, northern part of the Upper Rhine Graben (URG, Germany), hosts one of the thickest and most complete successions of Plio-/Pleistocene sediments in Central Europe, as revealed by new cored boreholes at three different locations. These boreholes expose different types of the basin facies: (a) three 300 m deep boreholes in Ludwigshafen represent the western margin of the basin; (b) a 350 m deep borehole close to Viernheim reveals information about the central basin facies, and (c) the 500 m deep borehole Heidelberg UniNord is located above the depocentre. One of our goals of this drilling project is to establish a reference profile for Quaternary stratigraphy for the region north of the Alps. As suggested by the first pollen data, the succession is complete in the sense of climate stratigraphy, a unique situation in Western Europe. In this context special emphasize is on the characterization of the Quaternary as revealed by different data sets. During the last decades a petrographical marker has been used to identify “Base Quaternary” in the URG, i.e. the first deposition of sediments of alpine origin imaged by a significant change in the heavy mineral spectrum. First data from the new boreholes suggests that this definition must be re-evaluated. For the Ludwigshafen borehole correlation between the heavy mineral data indicating the transition between sediments of alpine and local origin, the biostratigraphic boundary between Plio-/Pleistocene, and a significant change in magnetomineralogy that is interpreted to have been caused by environmental change, is observed at 177 m depth. In contrast, the palynological data from the location Heidelberg UniNord suggest that this borehole did not even reach Base Quaternary, whereas the base of the sediments of alpine character is found at 300 m depth. In addition the new data provide also insight on smaller scales, e.g. climate variations at the beginning and the end of the Tiglian.