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  • 1
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    Magnesium in subaqueous speleothems as a potential palaeotemperature proxy (2021)
    Nature P.G.
    Details
    Publication Date: 2021-01-05
    Description: Few palaeoclimate archives beyond the polar regions preserve continuous and datable palaeotemperature proxy time series over multiple glacial-interglacial cycles. This hampers efforts to develop a more coherent picture of global patterns of past temperatures. Here we show that Mg concentrations in a subaqueous speleothem from an Italian cave track regional sea-surface temperatures over the last 350,000 years. The Mg shows higher values during warm climate intervals and converse patterns during cold climate stages. In contrast to previous studies, this implicates temperature, not rainfall, as the principal driver of Mg variability. The depositional setting of the speleothem gives rise to Mg partition coefficients that are more temperature dependent than other calcites, enabling the effect of temperature change on Mg partitioning to greatly exceed the effects of changes in source-water Mg/Ca. Subaqueous speleothems from similar deep-cave environments should be capable of providing palaeotemperature information over multiple glacial-interglacial cycles.
    Description: Published
    Description: 5027
    Description: 5A. Ricerche polari e paleoclima
    Description: JCR Journal
    Keywords: speleothem ; palaeotemperature ; magnesium ; Magnesium in subaqueous speleothems as a potential palaeotemperature proxy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Insolation and glacial–interglacial control on southwestern African hydroclimate over the past 140000 years (2014)
    Elsevier
    In:  EPIC3Earth and Planetary Science Letters, Elsevier, 398, pp. 1-10, ISSN: 0012-821X
    Details
    Publication Date: 2014-06-27
    Description: The past climate evolution of southwestern Africa is poorly understood and interpretations of past hydrological changes are sometimes The past climate evolution of southwestern Africa is poorly understood and interpretations of past hydrological changes are sometimes contradictory. Here we present a record of leaf-wax δD and δ13C taken from a marine sediment core at 23°S off the coast of Namibia to reconstruct the hydrology and C3 versus C4 vegetation of southwestern Africa over the last 140 000 years (140 ka). We find lower leaf-wax δD and higher δ13C (more C4 grasses), which we interpret to indicate wetter Southern Hemisphere (SH) summer conditions and increased seasonality, during SH insolation maxima relative to minima and during the last glacial period relative to the Holocene and the last interglacial period. Nonetheless, the dominance of C4 grasses throughout the record indicates that the wet season remained brief and that this region has remained semi-arid. Our data suggest that past precipitation increases were derived from the tropics rather than from the winter westerlies. Comparison with a record from the Congo Basin indicates that hydroclimate in southwestern Africa has evolved in antiphase with that of central Africa over the last 140 ka.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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