Abstract Dissolution of secondary clay minerals during continental weathering (hereafter clay dissolution) has been proposed as a mechanism to explain some of the low seawater lithium isotopic ratios (δ7Li) observed in the geologic past. However, direct evidence for clay dissolution on Earth surface remains limited, and the controlling factors are poorly understood. Here, we suggest that δ7Li of fine sediments can serve as a proxy for clay dissolution. We analyzed δ7Li of the sediments from the Ocean Drilling Program site 1148, and developed a stoichiometric model to disentangle the respective contributions of source rock fragments and marine authigenic aluminosilicate clays to the sediment Li budget. Our results reveal low δ7Li in continentally formed clays during the warm interval of 23–15 Ma, followed by a progressive increase during 15–5 Ma, coinciding with global cooling. We suggest that warm and tectonically stable conditions might have promoted clay dissolution on continents.
Observations from the Little Bunker
Last updated: November 30, 2025 04:25 AM
Atmospheric CO₂
426.8 ppm
+18.1
ppm/year
Atmospheric CH₄
1927.61 ppb
+2.73
ppb/year
Global Temperature
+1.48 °C
Peak: +1.73°C
World Population
8.1 billion
+67
million/year