It is postulated the rate of the terrestrial organic carbon (OC) retention
around the moving ocean/continent interface is strongly affected by the
sea-level

Boski, T.

Correia, Victor

Fletcher, William

Moura, Delminda

Veiga-Pires, C.

Sapientia

40 Abstracts / Quaternary International 167–168 (2007) 3–486ina thickness and stable isotope variability reflecting a change in the hydrology. The Early Holocene was characterized by higher rainfall and higher inter-annual variability, and complete flooding of the cave probably occurred several times during the year, thus promoting cal-careous tufa deposition. In the Mid Holocene, both rainfall and inter-annual variability diminished. From ca. 4,900 cal yrs BP onwards a decrease in growth rate coincided with an increase in the degree of covariance between 13C and 18O and suggests a progressive lower-ing of the groundwater table, followed by the near-starvation of the flowstone that occurred soon after 4,500 cal yrs BP. In conclusion, the thickness of calcareous tufa annual laminae coupled with stable iso-tope analyses can be used as palaeo-hydrological indicators for region-al scale aquifers.0761Abrupt climatic events during OIS-3 recorded in terrestrial sediments in NW Europe: a multi-proxy approachJohanna AA Bos1, Sjoerd JP Bohncke1, Stefan Engels1, Karin F  Helmens2, Russell R Coope31Department of Paleoclimatology and Geomorphology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, The Netherlands2Department of Physical Geography and Quaternary Geology, Stockholm University, Sweden3Centre for Quaternary Research, Department of Geography, Royal Holloway, University of London, United KingdomAbrupt climatic changes during Oxygen Isotope Stage 3 (OIS-3 or Weich-selian Middle Pleniglacial) are revealed in the oxygen-isotope records of the Greenland ice-cores and in the North Atlantic marine-cores. In the Greenland ice-cores, these so-called D/O cycles start with a rapid warm-ing of 5-10 degrees Celsius within a few decades, followed by a phase of gradual cooling over several hundred to more than a thousand years and often end with a final reduction in temperature back to cold, stadial condi-tions. On the adjacent European continent, however, climatic variability during this time interval is poorly known. High-resolution terrestrial re-cords are scarce and the discontinuous nature of sedimentation and re-peated erosion on the continent combined with poor dating control often hampers a detailed study of the vegetation and climate. In this contribu-tion, shallow lacustrine sequences, intercalated with fluvial sediments or tills and dated to OIS-3, are presented from three different locations in NW Europe: 1. the opencast lignite mines Reichwalde and Nochten in eastern Germany, 2. Sourlie in Scotland, U.K., and 3. Sokli in Finland. Within these Middle Weichselian sequences, rapid warming events are assumed to have given rise to thaw-lake formation and deposition of or-ganic-rich lacustrine sediments, while the extreme cooling events of the D/O cycles are probably represented in the sequences by clastic intervals during which frost fissures and frost wedges developed or even till was deposited. A high-resolution multi-proxy study of these sequences includ-ing botanical analyses (pollen and macrofossils, e.g. seeds/fruits, mosses etc.), zoological analyses (e.g. Coleoptera, Chironomidae, Cladocera, Bryozoa) and 14C and OSL dating allowed a detailed environmental re-construction and quantification of the associated climate warming. Differ-ent approaches were applied and compared, i.e. the “climate indicator species method” was used for the botanical data, while the “transfer func-tion approach” was applied on the zoological data. In all studied sequenc-es, the botanical and zoological data give a similar temperature signal, i.e. showing relatively high mean July temperatures during the initial period of deposition, followed by a cooling of ca. 2-4 degrees Celsius and culmi-nating in a return of permafrost conditions in the upper part of the se-quences (i.e. eastern Germany) or overriding of the continental ice-sheet and final deposition of basal till (i.e. Sokli and Sourlie). The combined evidence suggests that the increased warming in response to a D/O event was a forcing factor for the formation of the lacustrine deposits.0279Does the glacial/interglacial sea-level changes modulate the atmospheric CO2 variations?Tomasz Boski1, Delminda M Moura1, Cristina Veiga-Pires1, William Fletcher2, Victor Correia11CIMA-FCMA, Universidade do Algarve, Portugal2Université de Bordeaux, FranceIt is postulated the rate of the terrestrial organic carbon (OC) retention around the moving ocean/continent interface is strongly affected by the sea-level. Therefore it must be to large extent controlled by sea level changes resulting from the glacial-interglacial cyclicity. In order to as-sess the changes in the rate of OC immobilization in the coastal areas, the OC content must be integrated with sediment accumulation rates on shelves, in lagoons and estuaries. For this purpose we determined or-ganic carbon content in several hundreds of samples taken from cored boreholes, which crossed the entire infill sequences of S. Iberian estuar-ies and represent the time span from ca 13000 yr calBP to present. These data were subsequently integrated into the sea-level/sediment accumula-tion curve during the postglacial times. The obtained figures indicate that until ca 7000 yr calBP, i.e. during the period of fast sea level rise, the organic carbon exported from the continent, accumulated at an average rate of 280 g/m2/yr. In the Middle and Upper Holocene, when the rate of the sea level rise was not exceeding 25 cm/century the organic carbon accumulation rate dropped to an average value of 80 g/m2/yr. From the other hand, the existing data on gas bubble composition in the Antarctic ice cores have shown that the atmospheric CO2 concentration evolved during the last glacial/interglacial transition, from 180 ppmv minimum during the LGM to the 270 ppmv pre-industrial level. Considering that the terrestrial particulate organic matter is an essential fertilizer of the ocean, we postulate that enhanced burial of the particulate organic mat-ter (POM) in the coastal areas during the period of fast postglacial sea level rise is responsible for decrease of primary productivity in the open ocean and may be in part at least responsible for the consequent transfer of 200 Gt of C in form of CO2, to the atmosphere.In order to prove the robustness of the above postulate it is neces-sary to accommodate in the appropriate (GCM+carbon?) models: (i) the data on the increased organic carbon burial in shelf/coastal sedi-ments observed during the deglaciation (ii) the withdrawal of the trapped carbon from global biogeochemical cycling and its impact on biological productivity of the shelf and open ocean.1292Geohazard mapping on the continental margins of Italy: the MaGIC ProjectAlessandro Bosman1, Francesco L Chiocci2, Domenico  Ridente31Università di Roma “La Sapienza”, Italy2Università di Roma “La Sapienza”; IGAG-CNR, Sede di Roma, Italy3ISMAR-CNR, Sede di Bologna, Italy2007 is the first of the five-year Project MaGIC (Marine Geohazard along the Italian Coasts), funded by the Italian Civil Protection Depart-ment, aimed at extensive mapping and monitoring by means of multi-beam bathymetry of most of the Italian continental margins. The main objective of the project is to produce a very large bathymetric database as well as a large number of 1:50000 maps of the geohazards present 

Does the glacial/interglacial sea-level changes modulate the atmospheric CO2 variations?

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