Andres , M., J. A. McKenzie and S. M.
Bernasconi (ETHZ (CH)). Paleoceanographic Controls on Carbonate Platform
Development: Part II Cool-water Carbonates, 14C in climate research.
The aim of this project was to define paleoceanographic and paleoclimatic
changes spanning the last glacial-interglacial cycle in the cool-water carbonate
depositional realm of the Great Australian Bight. Chemical, physical and
biological signatures of paleo-change were used in order to assess nature,
amplitude, timing and significance of recorded events on a regional and global
scale. AMS radiocarbon dated horizons formed the basis of the age model. The
dated cold reversals, which are interpreted from the oxygen isotope record, fall
within the Younger Dryas Chronozone, a cold reversal mostly documented in the
Northern Hemisphere, and thus contribute to the discussion on interhemispheric
climate linkage.
Ariztegui, D. (University of Geneva, (CH)). Little ice Age and varves
formation in Proglacial Lago Frias, Patagonia. (1)University of Neuchâtel,
Switzerland
(2)Universidad del Comahue, Argentina. P. Steinmann and G. Villarosa, 14C in
climate research.
Lago Frias is a proglacial lake located in Northern Patagonia. Previous
dendrochronological and moraine studies in the same area have shown a clear
signal attributed to prevailing cold conditions during the Little Ice Age. This
project aims to obtain a detailed record of this interval using laminated
sediments (varves). AMS dating of the sediments is critical to validate their
annual character.
Ariztegui, D. (University of Geneva, (CH)). The Lake Divangui (Gabon) record
of Holocene climate variations in Equatorial Africa. (1)CEREGE, France
(2)University of Neuchâtel, Switzerland
(3)ETH-Zürich. F. Gasse, P. Steinmann and F. Anselmetti, 14C in climate
research.
Lac Divangui is located in Equatorial Africa providing an unusual site to study
recent climate variations and their impact on human migration patterns. This
extremely organic-rich sediments have been previously studied in the framework
of a geophysical ETH-funded project. A series of short-cores covering the last
4000 years are under studied using a variety of proxy. A good chronology is
necessary to reconstruct the recent history of human interaction with the
environment.
Arnold (1), B. and N. Thew (2) ((1)Musée cantonal d'archéologie, Neuchâtel,
CH
(2) Archaeological Service for the Canton of Neuchâtel, CH). Reconstruction
of human settelments in the region of Lake Neuchâtel: the past 14,000 years,
C14 in archaeology.
In the latter part of the 20th century, when it was decided to build the A5
motorway along the littoral zone of the north-eastern part of the lake, it
became necessary to organise rescue excavations. Since the 1970's, the
Archaeological Service for the canton of Neuchâtel has undertaken large-scale
excavations at various sites in the Bay of Auvernier (1972-75), at Cortillod-Est
(1981-84), at Hauterive-Champréveyres (1983-86), and at Saint-Blaise/Bains des
Dames (1986-88), as well as a number of smaller interventions. Radiocarbon
dating of material (mostly charcoal) recovered during the 1990s (more than 800
samples) documents constant presence of human settelments in this region for the
past 14,000 years.
Bond, G. and W. S. Broecker (LDEO,
Columbia University, NY, USA). Ice Rafted Debries in the North Atlantic,
C14 in climate research.
The dominant modes of abrupt climate change in the North Atlantic are Dansgaard/Oeschger
(D/O) cycles and Heinrich events. AMS radiocarbon chronologies of studied
sediment cores from the North Atlantic provided radiocarbon ages of Heinrich
events (H1-H4) as well as time scales of those records (0-40kyr).
Broecker, W. S., S. Hemming, J. Lynch-Stieglitz and T. M. Marchito (LDEO,
Columbia University, NY, USA). Reconstruction of the end member contribution
and the ventilation rate of glacial-age lower Atlantic deep water, C14 in
climate research.
Reorganization of large scale ocean circulation very likely triggered the large
and abrupt climate change which punctuated the glacial world. Stable isotopes
measurements and radiocarbon ages of planktonic and benthic foraminifera of 21
sediment cores from Mid Atlantic Ridge are planned. Research objectives are: (1)
better constrain of the proportions of northern and southern component waters in
the Atlantic's late glacial age lower deep water mass (2) estimation of
ventilation rate by measuring the difference in C14/C12 in coexisting benthic
and planktonic foraminifera in the late glacial sediments (21kyr to 15 kyr BP).
Hadorn , P. and N. Thew (Archaeological Service for the Canton of Neuchâtel, CH). Hauterive/Rouges-Terres (Lake Neuchâtel): Reconstruction of Upper Palaeolithic and Early Mesolithic natural environments.
R. Coope (1), G. Lemdhal (2) and M. Magny(3)
(1) University of London, UK
(2) Vaxjo University, Sweden
(3) Laboratoire de Chrono-Ecologie, Besançon, France. C14 in climate
research.
At the site of Hauterive/Rouges-Terres 14 columns covering 120 m of horizontal
stratigraphy have been documented and sampled for sediment, pollen, plant
macrofossil, insect and mollusc analyses. Careful cleaning of the whole section
allowed layers to be followed and correlated between the columns, permitting
lithostratigraphic units to be established. The deposits formed in an embayment
at the margin of Lake Neuchâtel, with lake sediments predominating towards the
deeper part of the depression, passing laterally into lake margin and
supra-littoral marsh and colluvial deposits.
Pollen analysis on four of the columns has shown that these deposits represent a
complex sequence of Late-Glacial to middle Holocene sediments. An absolute
chronology has also been established based on 87 AMS dates (on Salix and Betula
twigs) ranging from 14,250 to 8,150 14C BP.
Hajdas (1), I. and G. Bonani (2) ((1)
PSI
(2) ETH). Ocean Records of Past Climate-radiocarbon based correlation. (1)
LDEO , Columbia University, NY, USA
(2) WHOI, Woods Hole, USA
(3) ETHZ. W. Broecker (1), G. Bond (1), S. Hemming (1), J. McManus (2) and
S. Bernasconi (3), 14C in climate research.
Hajdas (1), I. and G. Bonani (2) ((1) PSI
(2) ETH). High resolution radiocarbon chronologies of the Late Glacial
records--Global YD? (1) LDEO , Columbia University, NY, USA
(2) University of Geneva, (CH)
(3) ETHZ
(4) University of Santiago de Chile, Chile
(5) University of Bremen, Deutschland. D. Peteet (1), D. Ariztegui (2), P.
Moreno (3), P. Hadorn (4) and B. Zolitschka (5), 14C in climate research.
Hajdas (1), I. and G. Bonani (2) ((1) PSI
(2) ETH). Calibration problems beyond the tree ring curve--dramatic changes
in the atmospheric C14 content. (1) LDEO, Columbia University, NY, USA
(2) EAWAG, CH
(3) WHOI, Woods Hole, USA
(4) Jerusalem University (Israel). S. Hemming (1), J. Beer (2), J. McManus
(3) and M. Stein (4), 14C in climate research.
Hajdas, I. (PSI). Dating the late Glacial-Holocene Transition in Southern
South America. (1) University of Geneva, (CH)
(2) University of Santiago de Chile, Chile. D. Ariztegui and P. Moreno, 14C
in climate research.
Accurate dating of selected records of the late Glacial-Holocene transition in
South America. Well-studied multiproxy records of climate change were sampled in
high resolution in order to address key issues dealing with the timing, phase
and magnitude of major global climatic events.
Hajdas, I. (PSI). Age of Heinrich Event 4 in the North Atlantic ODP site 984.
WHOI, Woods Hole, USA. J. McManus, 14C in climate research.
Foraminifera shells were picked from sediments corresponding to the Heinrich
Event 4. This high resolution sampling allowed to pin point changes in C14
content and /or reservoir effect.
Hajdas, I. (PSI). Radiocarbon chronology of Wilson Creek (CA) formation.
Implications for chronology of Mono Lake and Laschamp paleomagnetic excursions.
LDEO, Columbia University, NY, USA. S. Hemming and M. Mendelson, 14C in
climate research.
Ostracodes shells were cleaned and leached to remove possible contaminantion.
This study focuses on chronology of the site where Mono Lake paleomagnetic
excursion was found and changes in atmospheric C14 content between 20 and 40 kyr
Hajdas, I. (PSI). Radiocarbon based chronology of climatic record from
Meditteranean deep-sea core. (1) ETHZ
(2) Universita' di Torino, Italy
(3) EAWAG, CH. S. Bernasconi(1), G. Castagnoli Cini (2), C. Taricco (2) and
J. Beer (3), 14C in climate research.
Climate change in the Mediterranean core CT85/5 was reconstructed using stable
isotopes (delta O18&deltaC13). Radiocarbon ages of planktonic foraminifera
construct chronology of the past 40,000 years which was used for correlation
with other Mediterranean cores.
Hajdas, I. (PSI). Lake Lisan: changes in the atmospheric C14 content between
20, 000 to 40, 000 BP. Jerusalem University (Israel). M. Stein, 14C
in climate research.
Aragonite layers were sampled from sediments of Lisan formation (Dead Sea) and
dated using AMS C14 dating method. Calendar ages were obtained using U/Th dating
method. We attempt to reconstruct changes in the atmospheric C14 content.
Hemming, S. and W. S. Broecker (LDEO, Columbia University, NY, USA). Age and
Isotope characterization of Ice-Rafted Sand Grains in the North Atlantic. University
of California, Santa Cruz, USA. R. Gwiazda, C14 in climate research.
The provenances of ice-rafted grains in the North Atlantic were investigated.
Application of new tracers such Pb isotope ratio of Ar/Ar dated feldspars was
developed. Radiocarbon dating was applied to build chronology of investigated
records.
Henderiks, J. and H. Thierstein (ETHZ (CH)). Coccolith studies in the Canary
Basin : glacial-interglacial paleoceanography of the Eastern Boundary Current
system, 14C in climate research.
Hormes, A., C. Schluechter and T. Stocker (University of Bern, CH). The 14C
perspective of glacier recessions in the Swiss Alps and New Zealand. University
of Koeln. F. Preusser, 14C in climate research.
Radiocarbon chronologies of glacier activity in the Swiss ALps and New Zealand
and comparison with other dating techniques
Langdon (1), C. and W. S. Broecker (2) ((1) Biosphere 2 Center of Columbia
University, (AZ, USA)
(2) LDEO of Columbia University NY USA). Effect of elevated CO2 on the
community metabolism of an experimental coral reef. (1) University of
Arizona (USA)
(2) NOAA-AOML Florida (USA). D. E. Hammond (1) , E. Glenn (1), S. G.
Nelson(1) and T.-H. Peng (2), C14 in environment.
A model marine ecosystem was subjected to a normal and an elevated CO2 level for
1-2 months and then the effects on various biological processes were observed.
Using a new radiocarbon isotope dilution method it was possible to observe that
the rate of respiration in the light was two to four times the rate in the dark
and that light respiration increased with increasing CO2 indicating that the
photorespiratory pathway can not account for the increased respiration in the
light.
Moreno, P. (University of Santiago de
Chile, Chile). Vegetation and climate near Lago Llanquihue in the Chilean
Lake District between 20200 and 9500 C-14 yr BP. U. of Main, USA. G.
Jacobson and G. Denton, C14 in climate research.
The pollen records of various sites from the Chilean Lake district have been
studied. Pattern of vegetation change at the end of the Last Glacial has been
established. Radiocarbon ages if macrofosssils and bulk sediment were used to
eastablish time scale of those changes. Samples from Huelmo site were dated to
be between 9,800 to 14,500 14C years old.
Peteet, D. (NASA/GISS and LDEO of Columbia Univ, NY USA). Paleovegetational
change in the Bering Glacier region, Alaska. (1) Oneonta Collage, SUNY,
NY, USA
(2) Syracuse University, USA. J. Fleisher (1) and E. Mueller (2), 14C in
climate research.
A series of sediment cores were taken from both sides of the remote Bering
Glacier, southeastern coastal Alaska. Basal dates were obtained on macrofossils
from these cores to first establish timing of deglaciation. Pollen and
macrofossil research is in progress on the cores to establish vegetational and
climate change.
Peteet, D. (NASA/GISS and LDEO of Columbia Univ, NY USA). Wetland Carbon
Storage in Black Rock Forest, New York. (1) NYU, NY, USA
(2) LLNL, Livermore, USA. T. Maenza-Gmelch (1), D. Kurdyla (2) and T.
Guildarson (2), 14C in climate research.
Wetlands were cored in Black Rock Forest, NY to link Carbon (C) sequestration in
the wetlands to paleovegetational change. The oldest core from Sutherland Fen
spans 12,500 years, and pollen and macrofossil stratigraphy is almost completed.
Late-glacial C sequestration is maximal at this site.
Piovano (1), E. and D. Ariztegui (2) (University of Cordoba, Argentina and ETH-Zürich
of GeCBva, (CH)). Holocene changes in the hydrological cycle during the
Holocene in subtropical South America: Laguna Mar Chiquita, Argentina. (1)
ETH-Zürich
(2) U. d'Angers, France. J. A. McKenzie (1), S. Bernasconi(1) and F.
Sylvestre(2), 14C in climate research.
Hypersaline Laguna Mar Chiquita is a very sensitive system to changes in the
hydrological cycle. The most recent sediments have been dated using Pb210 and
the sedimentary and geochemical imprint in the sediments have been calibrated
using documentary and instrumental data. New long cores have been retrieved
covering a longer time interval. The previously calibrated sedimentological and
geochemical models will now be applied to the rest of the sequence. An accurate
chronological model is necessary in order to built a robust time framework for
those changes.
Ryan, B., C. Major, et al. (LDEO, Columbia University). Study of the history
of basin connections along the Mediterranean-Marmara-Black Sea corridor in the
late Quaternary, 14C in climate research.
Connections between the Mediterranean, Marmara, and Black seas are a function of
eustatic sea-level change plus the regional hydrology. This study investigates
the relationship between base level and geochemical changes in the Black Sea
basin in order to determine when the Black Sea drainage basin was a net exporter
of fresh water to the basins downstream.
Schlüchter (1), C. and G. Denton (2) ((1) University of Berne (CH)
(2) University of Main (USA)). Interhemispheric correlations during the last
glacial cycle, 14C in climate research.
dating key sites
Schlüchter, C. (University of Berne (CH)). Holocene glacier variability.
(1) LDEO, Columbia University, NY, USA
(2) University of Berne (CH). W. S. Broecker (1), G. Bond (1) and T. Stocker
(2), 14C in climate research.
dating key glaciers
Shen, C. (Inst Geochemistry, Guangzhou , China). Climate Events on decadal
and centenary time scales in the monsoon region. EAWAG. J. Beer, 14C
in climate research.
The target of this project is to establish paleao-environmental change time
series since 2000 year BP or/and the Holocene, and obtain amplitude and phase of
climate events for monsoon and non-monsoon region. The material studied contain
Stalagmite, coral, lake sediments and tree rings
Shen, C. (Inst Geochemistry, Guangzhou , China). Investigation on Carbon
Cycle and Estimation of carbon sink of Soils in the Forest Ecosystem using
Isotopic Tracing, 14C in climate research.
This project will focus on the study of the typical forest soils in China.
Through measurements of 14C, 13C, etc. total carbon variation law and CO2
emission flux in the soil surface will be determined. The main factors
controlling CO2 emission in the forest soils will be revealed.