An aminostratigraphy for the British Quaternary based on Bithynia opercula

Abstract

Aminostratigraphies of Quaternary non-marine deposits in Europe have been previously based on the racemization of a single amino acid in aragonitic shells from land and freshwater molluscs. The value of analysing multiple amino acids from the opercula of the freshwater gastropod Bithynia, which are composed of calcite, has been demonstrated. The protocol used for the isolation of intra-crystalline proteins from shells has been applied to these calcitic opercula, which have been shown to more closely approximate a closed system for indigenous protein residues. Original amino acids are even preserved in bithyniid opercula from the Eocene, showing persistence of indigenous organics for over 30 million years. Geochronological data from opercula are superior to those from shells in two respects: first, in showing less natural variability, and second, in the far better preservation of the intra-crystalline proteins, possibly resulting from the greater stability of calcite. These features allow greater temporal resolution and an extension of the dating range beyond the early Middle Pleistocene. Here we provide full details of the analyses for 480 samples from 100 horizons (75 sites), ranging from Late Pliocene to modern. These show that the dating technique is applicable to the entire Quaternary. Data are provided from all the stratotypes from British stages to have yielded opercula, which are shown to be clearly separable using this revised method. Further checks on the data are provided by reference to other type-sites for different stages (including some not formally defined). Additional tests are provided by sites with independent geochronology, or which can be associated with a terrace stratigraphy or biostratigraphy. This new aminostratigraphy for the non-marine Quaternary deposits of southern Britain provides a framework for understanding the regional geological and archaeological record. Comparison with reference to sites yielding independent geochronology, in combination with other lines of evidence, allows tentative correlation with the marine oxygen isotope record.

On the origins ofCyprideis torosa(Jones, 1850) and a short biography of Professor T. R. Jones

“…From a stratigraphical viewpoint, the deposits at Grays were originally regarded as being of Ipswichian/last interglacial age (Hinton & Kennard 1900), broadly equivalent with MIS 5e, but they are now ascribed a MIS 9 age on the basis of terrace stratigraphy (Bridgland 1994), mammalian biostratigraphy (Schreve 2001;Schreve et al 2002) and aminostratigraphy (Penkman et al 2011(Penkman et al , 2013. Grays is (Woodward, 1912).…”

Quaternary fluvial archives and landscape evolution: a global synthesis

“…Dating of speleothems can be relevant to the interpretation of fluvial sequences, because the chronology of the former can reflect the history of adjacent valley entrenchment (e.g., Westaway, 2009aWestaway, , 2010Bridgland et al, 2014a). Where molluscan fossils are preserved their biostratigraphical value as age indicators can be reinforced by amino-acid dating, which is a measure of protein degradation since death (Bowen et al, 1989;Penkman et al, 2011Penkman et al, , 2013.…”

Fluvial archives as a framework for the Lower and Middle Palaeolithic: patterns of British artefact distribution and potential chronological implications

“…This new paradigm was used recently as a template for a sophisticated dating scheme based on amino acid diagenesis (racemisation) in the opercula of gastropods of the genus Bithynia, a scheme that was also applied to the British Palaeolithic record (Penkman et al 2011(Penkman et al , 2013. Armed with this new extended chronology, the archaeological record from fluvial sequences has proved useful for the provision of chronological pinning points for the uplift modelling of terrace sequences, with the aim of achieving a pattern of dating, especially in sequences where other means of age determination are scarce or absent.…”