Scale and Structure of Time-Averaging (Age Mixing) in Terrestrial Gastropod Assemblages from Quaternary Eolian Deposits of the E
Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 283–299 www.elsevier.com/locate/palaeo Scale and structure of time-averaging (age mixing) in terrestrial gastropod assemblages from Quaternary eolian deposits of the eastern Canary Islands ⁎ Yurena Yanes a, , Michał Kowalewski a, José Eugenio Ortiz b, Carolina Castillo c, Trinidad de Torres b, Julio de la Nuez d a Department of Geosciences, Virginia Polytechnic Institute and State University, 4044 Derring Hall, Blacksburg, VA, 24061, US b Biomolecular Stratigraphy Laboratory, Escuela Técnica Superior de Ingenieros de Minas de Madrid, C/ Ríos Rosas 21, 28003, Madrid, Spain c Departamento de Biología Animal, Facultad de Biología, Universidad de La Laguna, Avda. Astrofísico Fco. Sánchez, s/n. 38206, La Laguna, Tenerife, Canary Islands, Spain d Departamento de Edafología y Geología, Facultad de Biología, Universidad de La Laguna, Avda. Astrofísico Fco. Sánchez, s/n. 38206, La Laguna, Tenerife, Canary Islands, Spain Received 13 November 2006; received in revised form 10 March 2007; accepted 9 April 2007 Abstract Quantitative estimates of time-averaging (age mixing) in gastropod shell accumulations from Quaternary (the late Pleistocene and Holocene) eolian deposits of Canary Islands were obtained by direct dating of individual gastropods obtained from exceptionally well-preserved dune and paleosol shell assemblages. A total of 203 shells of the gastropods Theba geminata and T. arinagae, representing 44 samples (=stratigraphic horizons) from 14 sections, were dated using amino acid (isoleucine) epimerization ratios calibrated with 12 radiocarbon dates. Most samples reveal a substantial variation in shell age that exceeds the error that could be generated by dating imprecision, with the mean within-sample shell age range of 6670 years and the mean standard deviation of 2920 years.
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