Geochemical constraints on Lake Mega-Chad discharge to the Atlantic Ocean during the Holocene
Abstract
The Chad Basin in north Central Africa is one of the largest source of mineral aerosols on Earth. During the African Humid Period, much of this area was covered by a giant freshwater body – Lake Mega-Chad, which played an important role in controlling regional climate and Saharan dust emission. Geomorphic evidence and dating of ancient shoreline deposits indicate that Lake Mega-Chad overflowed into the Niger River catchment during the early to mid-Holocene, ultimately draining into the Atlantic Ocean. To date, however, the detailed hydrological evolution of the Chad Basin during the Holocene and the magnitude of inferred Lake Mega-Chad overflow events remain poorly constrained. In this study, we present a 30,000-year high-resolution record of sediment provenance, fluvial discharge and marine productivity from the Niger deep-sea fan. Using radiogenic neodymium isotopes and lipid biomarkers, we show that massive freshwater release from Lake Mega-Chad occurred between 11,000 and 4,500 years ago, episodically accounting for ~80% of the total detrital sediment deposited at the Niger deep-sea fan at that time. Additionally, our results indicate that the African Humid Period was punctuated with abrupt short-lived arid intervals linked to lake-level drops in the Chad Basin, and associated with enhanced dust-driven marine productivity. Finally, we argue that the extension of freshwater plumes in the Gulf of Guinea following Lake Mega-Chad overflow may have amplified regional ocean-atmosphere feedbacks.
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BibTeX
@article{bayon2026geochemical,
title = {{Geochemical constraints on Lake Mega-Chad discharge to the Atlantic Ocean during the Holocene}},
author = {Germain Bayon and Jung-Hyun Kim and Charlotte Skonieczny and Guillaume Soulet and Sujin Kang and Mathilde Levacher and Barnabé Djatibeye and Jean-François Ghienne and Bernard Dennielou and Eduardo Garzanti},
journal = {Earth and Planetary Science Letters},
year = {2026},
month = may,
doi = {10.1016/j.epsl.2026.120120},
url = {https://hal.science/hal-05828922v1},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - JOUR
TI - Geochemical constraints on Lake Mega-Chad discharge to the Atlantic Ocean during the Holocene
AU - Germain Bayon
AU - Jung-Hyun Kim
AU - Charlotte Skonieczny
AU - Guillaume Soulet
AU - Sujin Kang
AU - Mathilde Levacher
AU - Barnabé Djatibeye
AU - Jean-François Ghienne
AU - Bernard Dennielou
AU - Eduardo Garzanti
PY - 2026
DA - 2026/05/22
JO - Earth and Planetary Science Letters
DO - 10.1016/j.epsl.2026.120120
UR - https://hal.science/hal-05828922v1
AB - The Chad Basin in north Central Africa is one of the largest source of mineral aerosols on Earth. During the African Humid Period, much of this area was covered by a giant freshwater body – Lake Mega-Chad, which played an important role in controlling regional climate and Saharan dust emission. Geomorphic evidence and dating of ancient shoreline deposits indicate that Lake Mega-Chad overflowed into the Niger River catchment during the early to mid-Holocene, ultimately draining into the Atlantic Ocean. To date, however, the detailed hydrological evolution of the Chad Basin during the Holocene and the magnitude of inferred Lake Mega-Chad overflow events remain poorly constrained. In this study, we present a 30,000-year high-resolution record of sediment provenance, fluvial discharge and marine productivity from the Niger deep-sea fan. Using radiogenic neodymium isotopes and lipid biomarkers, we show that massive freshwater release from Lake Mega-Chad occurred between 11,000 and 4,500 years ago, episodically accounting for ~80% of the total detrital sediment deposited at the Niger deep-sea fan at that time. Additionally, our results indicate that the African Humid Period was punctuated with abrupt short-lived arid intervals linked to lake-level drops in the Chad Basin, and associated with enhanced dust-driven marine productivity. Finally, we argue that the extension of freshwater plumes in the Gulf of Guinea following Lake Mega-Chad overflow may have amplified regional ocean-atmosphere feedbacks.
SN - 0012-821X
ER -