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Paleorecharge by the Niger River (Mali) Deduced from groundwater geochemistry
Author(s) -
Fontes JeanCharles,
Andrews John N.,
Edmunds W. Michael,
Guerre Alain,
Travi Yves
Publication year - 1991
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/90wr01703
Subject(s) - groundwater recharge , groundwater , geology , holocene , aquifer , hydrology (agriculture) , flood myth , ridge , environmental isotopes , geochemistry , oceanography , paleontology , geography , archaeology , geotechnical engineering
Stable isotopes, major elements, trace elements, and noble gases in groundwater from northern Mali permit a reconstruction of the paleohydrology of the Sahelian and sub‐Saharan regions of west Africa. Major floods of the Niger River during the more humid episodes of the Holocene, probably associated with northward migration of the interior river delta (flood zone), were responsible for groundwater recharge. A marine aerosol input, somewhat modified by rock‐water interaction, dominates the groundwater chemistry. Stable isotope compositions distinguish the Saharan zone groundwater from waters recharged in the Sahelian zone south of the Azaouad ridge. Carbon 14 dating shows that whereas the latter are modem, the Saharan zone was recharged in the Early to Middle Holocene. Noble gas contents suggest that recharge north of Azaouad occurred under cooler climatic conditions than presently prevail.