North-African paleodrainage discharges to the central Mediterranean during the last 18,000 years: A multiproxy characterization
Wu, J.; Liu, Z.; Stuut, J-B W.; Zhao, Y.; Schirone, A.; de Lange, G.J. (2017). North-African paleodrainage discharges to the central Mediterranean during the last 18,000 years: A multiproxy characterization. Quat. Sci. Rev. 163: 95-113. dx.doi.org/10.1016/j.quascirev.2017.03.015
In: Quaternary Science Reviews. Pergamon Press: Oxford; New York. ISSN 0277-3791; e-ISSN 1873-457X, meer
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| Author keywords |
Quaternary; Paleoclimatology; North Africa; Inorganic geochemistry; Clay minerals; Grain size end-member modeling; African humid period; Sapropel S1; Provenance; Paleodrainage systems |
| Auteurs | | Top |
- Wu, J.
- Liu, Z.
- Stuut, J-B W., meer
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- Zhao, Y.
- Schirone, A.
- de Lange, G.J.
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| Abstract |
Using elemental geochemistry, clay mineralogy, grain size end-member modeling, and planktonic foraminiferal δ18O, we characterize the provenance of central-Mediterranean sediments over the past 18 ka. The provenance is dust-dominated before and after the African Humid Period (AHP). By contrast, during the AHP (∼11–5 ka), largely concurrent with organic-rich sapropel S1 formation, it is predominantly riverine from North-African sources. Such fluvial supply is suggested to come from paleodrainage networks that were reactivated by intensified monsoon precipitation during the AHP. The supply is characterized by high Mg/Al and smectite contents, and has been accompanied by considerable freshwater influx, as indicated by the enhanced grain size and lighter foraminiferal δ18O. The clay-mineral assemblages in our core and in nearby cores correspond with a provenance from the Libyan-Tunisian margin, mainly via the paleo-river Irharhar. The inferred fluvial discharge is strongest during the late-AHP (∼8–5.5 ka), coinciding with reported enhanced fluvial dynamics and wettest conditions over western Libya and Tunisia/Algeria. This period is not only synchronous with the largest extension of open-water bodies in North Africa and lowest Saharan dust inputs, but also consistent with precipitation records of the West-African monsoon. Moreover, our records show a remarkable correspondence with that of a paleodrainage system towards the Atlantic West-African margin, inferring a common headwater region in the central Saharan mountains, and a similar climate mechanism. Taken together, we suggest a dominant control of North-African humid surfaces on the paleodrainage delivery, modulated by groundwater level, in response to the insolation-driven West-African monsoon precipitation. |
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