Rare earth elements and yttrium in a stalagmite from Central China and potential paleoclimatic implications

• Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
• Main Authors: Zhou, Z. H., Wang, Q., Zhao, J. X., Zheng, L. N., Guan, H. Z., Feng, Y. X., Greig, A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science Bv 2008
• Subjects: Geography; Physical; Geosciences; Multidisciplinary; Paleontology; Physical Geography; Geology; C1; 960304 Climate Variability (excl. Social Impacts); 040303 Geochronology; North Atlantic
• Online Access: https://espace.library.uq.edu.au/view/UQ:167111

In a pilot study, the rare earth elements and yttrium (REE when discussed without Y or REY with Y) were measured by inductively-coupled plasma mass spectrometry (ICP-MS) on a stalagmite (SJ3) from northeast Sichuan, Central China. This stalagmite was dated by the thermal ionization mass spectrometry (TIMS) Th-230 method to between 38 and 10 thousand years before present (ka BP). The REY geochemical indices, including the concentrations, Lanthanum, Cerium and Yttrium anomalies and the fractionation between light and heavy REE (LREE and HREE), display significant stadial-interstadial changes corresponding to variations in past climates and environments. The North American Shale Composite (NASC)-normalized REY patterns for sub-samples of SJ3 display obvious negative Ce anomalies and positive Y anomalies. For most sub-samples, the LREE are relatively depleted relative to the HREE. La anomalies during relatively cold and dry climatic phases (including the last glacial maximum (LGM) and the period synchronous with Heinrich event one identified in the North Atlantic region) are usually positive, while the Ce and Yanomalies and the LREE-HREE fractionation are more pronounced. During relatively warm and humid phases the REY pattern displays an opposite signature. The REY sources for SJ3 include the overlying soil layer, which consists mainly of aeolian sediments. and the host rock of the Late Permian limestone. Source change may be the primary mechanism controlling the variations of the REY pattern for SJ3. The REY pattern for the youngest sub-sample from the top dirty section of SJ3, which is porous and rich in detrital materials, seems to be dominated by the overlying soil layer. The REY in sub-samples deposited during relatively cold and dry phases may come mainly from the host limestone and thus show patterns more similar to a marine signal. For the rest of the sub-samples, REY from both sources may be present. In addition to the sources, the REY pattern for SJ3 may also be influenced by REY mobilization from sources and transportation in groundwater. and prior carbonate deposition, all of which should be closely related with changes in climate and environment. Thus the REY pattern for speleothems might be a potential proxy for past climate and environment. (C) 2008 Elsevier B.V. All rights reserved.