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Abstracts / Quaternary International 279-280 (2012) 346–461 403
THE LAACHER SEE-ERUPTION (C. 13KY BP) AND SOCIETAL CHANGEAMONGST PERIPHERAL LATE GLACIAL HUNTER-GATHERERS INSOUTHERN SCANDINAVIA
Felix Riede. Aarhus University, DenmarkE-mail address: [email protected]
This paper is concerned with the palaeolecological, societal and culture-historical impact of the catastrophic Laacher See volcanic eruption (c. 13kyBP), especially at a great distance from the eruptive center. It has beensuggested that various mechanistic links (e.g. increased dental abrasion,negative respiratory effects as well as F-poisoning) may have contributedto animals and humans deserting the areas affected by tephra fall-out fromthis eruption. Consequently, a case can be made that at least one particulararchaeological phenomenon of this period - the so-called Bromme cultureof southern Scandinavia - emerged as a result of the redistribution ofhuman populations following the eruption. The potential full extent of thesocietal impact of this eruption cannot, however, be understood withreference to direct negative impacts alone. Many of these would have beenof insufficient duration to cause a medium-to-long term fragmentation ofotherwise highly mobile hunter-gatherers. In considering aspects of theperception of this dramatic events, it is possible to suggest that a) mobilitywould have been the response of choice for these foragers in avoiding theimmediate effects of the eruption, and that b) other, less tangible factorsmay have played an important role in extending the temporality of thisextreme event beyond these immediate effects. A coupled consideration ofboth the ecological, demographic as well as the psychological and culturaleffects of this high magnitude/low frequency event throws new light onthe origin of the Bromme culture. Some 200-300 years after this event therapid cooling of GS-1 once again reshuffled populations on the NorthernEuropean Plain, leading to the disappearance or transformation of thisculture.
A LAACHER SEE-ERUPTION SUPPLEMENT TO TEPHRABASE. A REVISEDTEPHRA FALLOUT MAP AND NEW GEOCHEMICAL DATA
Felix Riede. Aarhus University, DenmarkE-mail address: [email protected]
Tephrabase (www.tephrabase.org) is an online data repository andresearch tool for tephrochronological investigations in northern Europe.Here we present an update to Tephrabase that contains geographic and, asfar as available, geochemical data on 444 data-points for the widespreadisochronous Laacher See tephra. This tephra is dated to c. 12,920 calendaryears BP and acts as an important chronostratigraphic marker for theLateglacial GI-1a/late Allerød chronozone in terrestrial and lacustrinepalaeoenvironmental archives as well as in archaeological stratigraphies.Based on these data, we present a revised map of the total tephra distri-bution, suggesting that it is even more widespread than previously statedand that the north-eastern fallout lobe might contain a secondary thick-ness maximum between 200-300 km distance from the eruptive centre. Inaddition, new geochemical data from a series of distal tephra depositsspanning most of the north-eastern fallout lobe are used to evaluateprevious suggestions regarding the distribution of fallout from distincteruption phases. The aim of our study is that future tephrochronologicalinvestigations can use this database and our revised distribution map foreffectively targeting sites for analysis.
CONSTRUCT THE MIDDLE PLEISTOCENE CLIMATE OF SOUTH EASTMEDITERRANEAN USING SPELEOTHEM ISOTOPIC AND ELEMENTALCOMPOSITIONS, EGYPT
Rifai Rifai. Environmental Studies & Research Institute, Minufi, EgyptE-mail address: [email protected]
The Wadi Sannur speleothems record climate changes spanning 188 and136 kyr before present. Petrographically, the studied speleothem laminaeare made up entirely of fibrous calcite except for one lamina that displaysmicrospar fabric. Time-series analysis of the data set reveals regularchanges in Sr/Ca and Mg/Ca at a scale that matches the thickness of the
different laminae. d18O values of the stalactite laminae range from -7.2 to-10.1 VPDB&. The lower d18Ocalcite values, which are correspond to thesecond oldest lamina (WSS5), indicate that the drip-waters were likelyaffected by evaporative fractionation and that the speleothem activity hasprobably stopped due to the very arid conditions that followed the pluvialperiod. The variations of the d13C values between -5.0 and -2.3& VPDBargue that the drip water composition is influenced by the interactionwiththe overlying grass-covered ecosystem and the degree of aridity ratherthan the bedrock (d13C -0.9&VBDP). 87Sr/86Sr ratios of the interglaciallamina are low (0.70781-0.70808), whereas the glacial lamina displayhigher ratios (0.70826- 0.70859) in comparison with the nummuliticlimestone bedrock (0.70823).Keywords: Egypt, Mediterranean, Wadi Sannur speleothems, fibroustextures, U-series dates, Middle Pleistocene, stalactite, pluvial period.
DEPOSITIONAL PALAEO-ENVIRONMENTS OF THE BOTETI DELTA,MAKGADIKGADI PANS (BOTSWANA KALAHARI)
Susan Ringrose. ORI-University of Botswana, BotswanaE-mail address: [email protected]
The Boteti delta (Delta 1) forms an important link between the Okavango-Boteti drainage system and the Makgadikgadi salt pans and comprises anextensive plain which is incised (3m) by the present Boteti river channel.This channel flows across the distal margin of Delta 1 before cuttingthrough a mainland peninsula (as the inter-delta channel) before dis-gorging into a second pan delta (Delta 2). The aims of this work are toascertain the relative ages of Delta 1 and Delta 2 and to determine thenature of deposition in Delta 1 and the inter-delta channel. Using heightdata from SRTM 2 imagery, we determined that Delta 1 increases in heightdistally throughout its downstream length (12 km) from 907 to 913 mabove sea level while elevations along the inter-delta channel are higher.Sediment analysis using SEM and XRD techniques showed that the inter-delta channel was underlain by 40 m of ‘silcrete’, comprising halite,amorphous silica and clay with upper diatomaceous units. Sediments fromDelta 1 comprised at least two metres of massive sediment made up offragmented calcite-rich plates (< 2 mm), silica (diatoms mainly withamorphous silica), halite and minor clay, being mostly smectite with illititeand halloysite. The sediments appear to represent a weathering suiteinterspersed with and surmounted by evaporates and diatoms indicativeof shallow, rapidly drying aquatic environments. The results shed light onthe anomaly of co-deposited calcium and silca rich sediments in salineenvironments and imply that the inter-delta channel and Delta 2 pre-datethe formation of Delta 1. Although radiocarbon dates are pending it isexpected that the results have wider applications for palaeo-climaticinterpretations in the southern African region.
400-YEAR MAY-AUGUST PRECIPITATION RECONSTRUCTION FORENGLAND USING STABLE OXYGEN ISOTOPE RATIOS (d 18O) OF TREERINGS
Katja Rinne. Paul Scherrer Institute, SwitzerlandE-mail address: [email protected]
We present annually resolved data of precipitation covering the mostrecent 400 years for England. The May-August precipitation series, whichwas formed by combining reconstructed values (1613-1893) and instru-mental data (1894-2003), indicates significant decadal and centennialprecipitation variability culminating in dry conditions in the early-middle17th century and the late 20th century. The period 1613-1893 is based ond18O in tree ring cellulose of pedunculate oak (Quercus robur). The analysisdemonstrated statistically robust May-August precipitation signal in thed18O values of Woburn oak cellulose back to 1697, the first year of theoldest instrumental precipitation series in England. Independent proxyNAO reconstructions have reported a prevailing low winter NAO indexprior to the end of the 17th century possibly induced by the decreased solarirradiance. The observed late spring-summer precipitation patternobserved in the present study may indicate the extension of these atmo-spheric conditions to summer months at this time. A potential problem inusing tree ring parameters for climate reconstruction is the effect of non-
