Journal article

Stalagmite carbon isotopes and dead carbon proportion (DCP) in a near-closed-system situation: An interplay between sulphuric and carbonic acid dissolution

Petra Bajo, Andrea Borsato, Russell Drysdale, Quan Hua, Silvia Frisia, Giovanni Zanchetta, John Hellstrom, Jon Woodhead

Geochimica et Cosmochimica Acta | Elsevier | Published : 2017

Abstract

In this study, the ‘dead carbon proportion’ (DCP) calculated from combined U-Th and radiocarbon analyses was used to explore the carbon isotope systematics in Corchia Cave (Italy) speleothems, using the example of stalagmite CC26 which grew during the last ∼12 ka. The DCP values in CC26 are among the highest ever recorded in a stalagmite, spanning the range 44.8–68.8%. A combination of almost closed-system conditions and sulphuric acid dissolution (SAD) are proposed as major drivers in producing such a high DCP with minor contribution from old organic matter from the deep vadose zone. The long-term decrease in both DCP and δ13C most likely reflects post-glacial soil recovery above the cave, ..

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Grants

Awarded by Australian Research Council


Awarded by Australian Institute of Nuclear Science and Engineering (AINSE Ltd)


Awarded by Australian Research Council Future Fellowship


Funding Acknowledgements

This study was funded by the Australian Research Council Discovery Projects scheme (DP110102185) awarded to RD, SF, JH, JW and GZ. The authors would also like to thank Australian Institute of Nuclear Science and Engineering (AINSE Ltd) for providing financial assistance (PGRA Award to PB (ALNSTU10104)) to enable radiocarbon analyses. We acknowledge the financial support from the Australian Government for the Centre for Accelerator Science at ANSTO through the National Collaborative Research Infrastructure Strategy (NCRIS). PB was the recipient of a University of Melbourne International Postgraduate Research Scholarship and Postgraduate Writing-Up Award supported by Albert Shimmins Fund and JH of an Australian Research Council Future Fellowship (FT130100801). AB is the recipient of a University of Newcastle Research Scholarship funded by the Australian Research Council Discovery Projects scheme (DP160101058) awarded to SF and JH. Finally, we thank Chris Hendy for his insightful comments, to Hagit Affek, Dan Breecker and two anonymous reviewers for comments which significantly improved the earlier version of the manuscript. Special thanks to Ilaria Isola for drawing the geological map in Fig. 1A, and the Federazione Speleologica Toscana for generous research support.