Palaeoclimate signals as inferred from stable-isotope composition of ground ice in the Verkhoyansk Foreland, Central Yakutia
Asian part of Russia ; C 14 dating ; Deuterium ; Ice wedge ; Isotopeanalysis ; Oxygen 18 ; Palaeoclimate ; Periglacial features ; Permafrost ; Quaternary ; Sakha ; Siberia
In this study, the AA. present stable-isotope data from ice-wedges of Weichselian and Holocene ages from the foreland of the Verkhoyansk Mountains, as well as from Central Yakutia, and discuss their palaeoclimatic implications.
In this study, the carbon and oxygen isotopic ratios of structural carbonate in fossil tooth enamel from a diverse group of herbivores from Zhoukoudian are analyzed. The objective is to determine the ratio of C3 to C4 plants in the diet
Pollen analysis of sediment deposited during stage 7b indicates climate at the time was up to 3oC cooler than present. The climate and sea-level evidence from Landguard Bluff are consistent with oxygen isotopic evidence from deep-sea cores
Stable carbon isotope record of Holocene environmental change in the central Great Plains
C 14 dating ; Climatic variation ; Drought ; Holocene ; Isotopeanalysis ; Loess ; Nebraska ; Organic materials ; Palaeo-environment ; United States of America
First the AA. review the background and methodology behind the use of stable isotopes of carbon in paleoenvironmental research; then, they consult the literature to describe their knowledge of ecosystem and climate change, including recurring
A detailed 31,000-year record of climate and vegetation change, from the isotope geochemistry of two New Zealand speleothems
Carbon ; Cave ; Glaciation ; Isotopeanalysis ; New Zealand ; Oxygen 18 ; Palaeo-environment ; Palaeobotany ; Palaeoclimate ; Pleistocene ; Quaternary ; South Island
This paper presents continuous high-resolution stable isotope records of environmental change in New Zealand from speleothems that grew over the last 31,000 yr. Oxygen isotope variation in these speleothems primarily represents changes
in the meteoric waters falling above the caves, possibly responding to latitudinal changes in the position of the Subtropical Front in the Tasman sea. Carbone isotope variations in the speleothems record changes in forest productivity, closely matching existing
Late Quaternary climate and hydrology of tropical South America inferred from an isotopic and chemical model of Lake Titicaca, Bolivia and Peru
Bolivia ; Climatic variation ; Geochemistry ; Isotopeanalysis ; Lake ; Lake level ; Model ; Oxygen 18 ; Palaeoclimate ; Palaeohydrology ; Peru ; Quaternary ; Salinity ; South America ; Tropical zone
A simple mass balance model provides insight into the hydrologic, isotopic, and chemical responses of Lake Titicaca to past climatic changes. Latest Pleistocene climate of the Altiplano is assumed to have been 20% wetter and 5°C colder than today
, based on previous modelling. The simulation of lacustrine change since 15,000 cal yr B.P. is forced by these modeled climate changes. Here the AA. employ an isotopic and chemical model in order to assess the magnitude of hydrologic changes required
to produce the observed lake-level changes and to investigate the expected isotopic and chemical response of the lake to water balance changes.
Climatic variation ; Global change ; Isotopeanalysis ; Marine quaternary ; Mollusca ; South Africa ; Temperature
The Holocene history of the southern Banguela upwelling regime has been constructed from the oxygen isotope and mineral analysis of midden shells. The timing and duration of significant changes in shell mineralogy approximated those in the isotope
Late Quaternary paleoclimate in the eastern Mediterranean Region from stable isotopeanalysis of speleothems at Soreq Cave, Israel
Carbon ; Cave ; Climatic variation ; Global change ; Holocene ; Isotopeanalysis ; Israel ; Oxygen 18 ; Palaeoclimate ; Palaeogeography ; Petrography ; Precipitation ; Quaternary ; Temperature
The eastern Mediterranean continental paleoclimate during the past 25,000 years was determined by a high-resolution petrographic, stable isotopic, and age study of speleothems from Soreq Cave, Israel. This study demonstrates that global events which
Holocene landscape history and palaeohydrology evidenced by stable carbon isotope (δ C 13)analysis of alluvial sediments in the Mbari valley (5°N/23°E), Central African Republic
an important role on the runoff processes and on the discharge of the draining river systems. Therefore, this study focuses on the examination of alluvial soils and the determination of stable carbon isotopes of organic sediments on the Mbomou plateau
Climatic records from annual layers and stable isotopes of a stalagmite in Beijing over the last 2300 years
Beijing ; C 14 dating ; China ; Climatic variation ; Geochemistry ; Holocene ; Human impact ; Isotopeanalysis ; Monsoon ; Oxygen 18 ; Palaeoclimatology
with the thickness of annual layers the AA. reconstruct the climatic variation history of the last 2300 years in Beijing area. The oxygen isotopic composition preserves monsoon variations, which is matched in interpretation of the change in layer thickness. Carbon
isotopic composition reflects the changes in vegetation activity likewise the anthropogenic activity.
Hainan soils contain a mixture of material derived from in situ weathering of parent material plus atmospheric inputs dominated by continental dust. The AA. use Nd isotope geochemistry to evaluate the impact of continental dust on a chronosequence
-averaged dust deposition rates in the old sites. They calculate long term dust accretion rates to quantify the deposition. The results also underscore the potential for neodymium isotopes to constrain the origin of soils and paleosols.
Changes in solar constant over an 11 yr cycle suggest a certain, but limited, degree of solar forcing of climate. The high-resolution climate (oxygen isotope) record of the Greenland GISP2 (Greenland Ice Sheet Project 2) ice core has been analyzed
for solar (and volcanic) influences. The atmospheric C 14 record is used as a proxy of solar change and compared to the oxygen isotope profile in the GISP2 ice core. Solar forcing during the surprisingly strong 1470 yr climate cycle of the 11,000-75,000 yr
Questions have been raised as to whether the isotopic composition of meteoric water can be used to reconstruct paleomonsoon intensity. Tree rings of two modern spruce trees were analyzed for hydrogen isotopic composition. On average, the older tree
is depleted in deuterium compared to the modern trees. The AA. attribute this isotopic depletion to the strength of summer monsoons, which were more intense in the early Holocene than at present. Although this study is not definitive, it suggests
that paleomonsoon intensity canbe reconstructed by direct or proxy methods that yield the oxygen or hydrogen isotopic composition of meteoric water.
In this paper, the AA. attempt to construct a detailed terrestrial late Pleistocene climatic record in India by studying oxygen and carbon stable isotopes in pedogenic calcrete from the Thar Desert. The nearly continuous calcrete record in eolian
intervals and the chronology from thermoluminescence, infrared- and green-light-stimulated luminescence dates give a good opportunity to examine the isotopic data for paleoclimatic variability and relate this to other marine and terrestrial records.
Based on the data of δO 18 in surface snow, snow pits, meltwater and the glacier-fed river water at Baishui Glacier No.1, Mt Yulong, the isotopic fractionation behaviors in the typical monsoonal temperate glacier system in winter and summer were
compared. The results indicate that the isotopic fractionation degree in summer is greater than that in winter, suggesting that the snow/ice melting is more intense in summer.
Palaeoclimate reconstruction on Big Lyakhovsky Island, North Siberia - hydrogen and oxygen isotopes in ice wedges
Asian part of Russia ; Deuterium ; Holocene ; Ice wedge ; Isotopeanalysis ; Oxygen 18 ; Palaeo-environment ; Palaeoclimate ; Periglacial features ; Pleistocene ; Quaternary ; Siberia
isotope analyses are presented for 6 different generations of ice wedges as well as for recent ice wedges and precipitation. An age of about 200 ka BP was determined for an autochtonous peat layer in ice-rich deposits by U/Th method, containing the oldest
ice wedges ever analysed for hydrogen and oxygen isotopes.
Isotopic evidence for glacial meltwater recharge to the Cambrian-Ordovician aquifer, north-central United States
The chemistry of water in the Cambrian-Ordovician aquifer in six midwestern states has been studied as part of the Northern Midwest Regional Aquifer-System Analysis of the US Geological Survey. The differences in isotopic ratios between groundwater
and modern recharge water reflect meteoric signatures of water during past recharge events rather than geochemical processes such as isotopic exchange with aquifer materials. The pronounced parallelism between the distribution of isotopes and dissolved solids
Altitude ; China ; Firn ; Fluvial water ; Hydrology ; Isotopeanalysis ; Meltwater ; Oxygen 18 ; Precipitation ; Sampling ; Temperature ; Water cycle ; Watershed ; Xinjiang
The variations of the stable oxygen isotope in different water mediums in Urumqi River Basin are analysed to provide the basic isotope data for the application of environmental isotopes in hydrological investigations and assess the impact
of different factors on water cycle. The stable oxygen isotope in precipitation has marked temperature effect either under synoptic or seasonal scale at the head of Urumqi River. Presentation and discussion of the results of delta O 18 in precipitation
Regional atmospheric circulation change in the North Pacific during the Holocene inferred from lacustrine carbonate oxygen isotopes, Yukon Territory, Canada
The AA. analyzed oxygen isotopes in sediment cores from Jellybean Lake, located in the southern Yukon interior, to improve the detail and resolution of the regional climatic history and investigate mechanisms for Holocene climatic change. Holocene
changes in North Pacific atmospheric circulation inferred from Jellybean Lake oxygen isotopes correspond with late Holocene glacial advances in the St. Elias Mountains, changes in North Pacific salmon abundance, and shifts in atmospheric circulation over