AMS-14C Chronology of a Lacustrine Sequence from Lake Langano (Main Ethiopian Rift): Correction and Validation Steps in Relation with Volcanism, Lake Water and Carbon Balances
Issue Date
2002-01-01Keywords
paleohydrologyEthiopian Rift
Lake Langano
paleolimnology
Ziway Shala Basin
lake sediments
East Africa
lacustrine environment
residence time
accelerator mass spectra
reconstruction
mass spectra
spectra
Africa
isotope ratios
Holocene
correlation
volcanism
chronology
Pleistocene
upper Pleistocene
sediments
Cenozoic
Quaternary
C 14
carbon
dates
isotopes
radioactive isotopes
C 13 C 12
stable isotopes
absolute age
geochemistry
Metadata
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Gibert, E., Travi, Y., Massault, M., Tiercelin, J.-J., & Chernet, T. (2002). AMS-14C Chronology of a lacustrine sequence from Lake Langano (Main Ethiopian Rift): Correction and validation steps in relation with volcanism, lake water and carbon balances. Radiocarbon, 44(1), 75-92.Journal
RadiocarbonAdditional Links
http://radiocarbon.webhost.uits.arizona.edu/Abstract
Located in the Ziway-Shala Basin of the Main Ethiopian Rift, Lake Langano is part of an asymmetric half-graben, defined by a series of north-northeast-trending faults in the tectonically active zone of the rift. A 15-m deep succession of organic homogeneous muds, silts, bioclastic sands, and pyroclastic layers was cored in 1994. The definition of a certified radiocarbon chronology on these deposits required the indispensable establishment of modern hydrological and geochemical balances. The isotopic contents of the total dissolved inorganic carbon (TDIC) of surface water clearly show the influence of a deep CO2 rising along the main fault crossing the lake basin. The 5.8 pMC disequilibrium existing in 1994 with the atmosphere likely produces the aging of authigenic materials developing at the lake surface. However, with a mean residence time of approximately 15 years, this apparent 14C aging of Lake Langano water still integrates the 14C produced by the nuclear tests in the 1960s. Reconstructing the natural 14C activity of the lake TDIC allows for the quantification of the deep CO2 influence, and for the correction of AMS-14C datings performed along the core. The correction of the AMS14C chronology defined on Lake Langano allows for a better understanding of paleohydrological changes at a regional scale for at least the last 12,700 cal BP.Type
Articletext
Language
enISSN
0033-8222ae974a485f413a2113503eed53cd6c53
10.1017/S0033822200064699