TY  - GEN
N2  - The aim of this multi-tracer study is the investigation of palaeoclimate changes in South Asia over the last 50,000 years based on data from a groundwater aquifer in North-West India. 14C, 3H, He isotopes, 222Rn and SF6 were used for dating, while stable water isotopes and excess air allow the reconstruction of palaeohumidity. Temperature records are derived by noble gas thermometry. A mass spectrometer setup was optimised, now allowing to quantify absolute noble gas amounts. Successful cryogenic separation of Ar from Kr reduced the o ffset of air equilibrated water standards (He, Ne, Ar, Kr and Xe) to 2.6, 0.5, 0.6, -0.2 and 0.4 % with a reproducibility of 0.2, 0.6, 0.3, 0.7 and 1.2 %, respectively. 14C dating agreed with a previous study and is confirmed by He-Rn ages. In deep wells of the sedimentary basin and near fault zones, mantle He was determined to contribute up to 10% of the total terrigenic He. In the crystalline aquifer, high concentrations of Rn (4 Bq/cm3) and radiogenic 4He (3x 10^-4 cm3STP/g) were found, and SF6 concentrations showed amounts several orders of magnitude above modern atmospheric equilibrium. Palaeohumidity is consistently reconstructed by excess air and stable water isotope data. Both signals reveal a dry glacial period followed by a humid Holocene, which is interrupted by a dry late Holocene. Monsoonal strength obtained from excess air supports older palaeoclimate studies of the region. Noble gas temperatures show a cold last glacial period compared to a warm Holocene, presuming a warming of (3.5 +- 0.5)°C. This record provides the  first quantitative information on palaeotemperature in South Asia.
TI  - Imprints of climatic and environmental change in a regional aquifer system in an arid part of India using noble gases and other environmental tracers
A1  - Wieser, Martin
AV  - public
KW  - palaeoclimate 
KW  -  hydrology 
KW  -  noble gases 
KW  -  mass spectrometry 
KW  -  groundwater
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/11615/
Y1  - 2010///
ID  - heidok11615
ER  -