The Open UniversitySkip to content
 

Dead carbon in stalagmites: Carbonate bedrock paleodissolution vs. ageing of soil organic matter. Implications for C-13 variations in speleotherms

Genty, Dominique; Baker, Andy; Massault, Marc; Proctor, Chris; Gilmour, Mabs; Pons-Branchu, Edwige and Hamelin, Bruno (2001). Dead carbon in stalagmites: Carbonate bedrock paleodissolution vs. ageing of soil organic matter. Implications for C-13 variations in speleotherms. Geochimica Et Cosmochimica Acta, 65(20) pp. 3443–3457.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/S0016-7037(01)00697-4
Google Scholar: Look up in Google Scholar

Abstract

Twenty-one C-14 accelerator mass spectrometric analyses were obtained for three Holocene stalagmites from the Uamh-an-Tartair cave (Sutherland, Scotland) in order to estimate the past dead carbon proportion (dcp). Results show that the dcp increases from 22 to 38% from 3780 years ago to the present. Because delta C-13 variation is small within each sample, it is concluded that this dcp increase is the product of the ageing of soil organic matter related to peat bog development above the cave that produced older soil CO2 and not from a more intense dissolution of the surrounding carbonates, which would have led to a delta C-13 increase.
Comparison with samples from other sites in Europe shows no intersite correlation between dcp and delta C-13, but a relatively good intersite correlation is observed between dcp and average site temperature. Thus, temperature may be a major factor controlling the production of old soil organic matter CO2 and, therefore, the dead carbon content of seepage water, In contrast to the Scotland stalagmites, two other Holocene samples from sites in southern France and Belgium exhibit a good correlation between delta C-13 and dcp, which can be explained in terms of variations in the intensity of limestone dissolution. Consequently, delta C-13 variations observed in stalagmites are not always due to changes in the vegetation type (C3/C4) as has been commonly assumed; C-13/C-12 variations in speleothem calcite may also be controlled by the soil organic matter age and, in some cases, by the intensity of the limestone dissolution. Conversely, a largely constant speleothem delta C-13 signal, as observed for the Scotland stalagmites, does not necessarily imply that surface climate and vegetation conditions were stable since the dcp variations. in this case, are clearly related to the peat bog development during stalagmite growth.

Item Type: Journal Article
ISSN: 0016-7037
Keywords: Isotopic Composition; Cave; Fractionation; Geochemistry; Dynamics; Records; Climate; Precipitation; Evolution; Chemistry
Academic Unit/Department: Science > Physical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 8206
Depositing User: Astrid Peterkin
Date Deposited: 06 Jul 2007
Last Modified: 02 Dec 2010 20:00
URI: http://oro.open.ac.uk/id/eprint/8206
Share this page:

Actions (login may be required)

View Item
Report issue / request change

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340   general-enquiries@open.ac.uk