Palaeoenvironments revealed from rare earth element systematics in vertebrate bioapatite from the Lower Devonian of Svalbard

In-situ rare earth element compositions have been measured in early vertebrate microremains from the Lower Devonian basin of AndrĂŠe Land (Svalbard), aiming to obtain information about their early depositional environment and potential reworking. Vertebrate microremains with different histology were used for analyses, coming from two different localities of marginal marine to freshwater sediments from geographically distant parts of the Grey HĹ k Formation (Skamdalen and Tavlefjellet members). We selected thelodont and undescribed ?chondrichthyan scales, which allowed us to define potential taxonomic, histological, and taphonomic variables of the REE uptake. Results showed REE concentrations to be relatively uniform within the scales of each taxon, but apparent discrepancies were visible between the studied localities and separate taxa. The compilation of REE abundance patterns as well as REE ratios have revealed that thelodont and ?chondrichthyan originating from the same locality, must have had different burial and early diagenetic histories. The shapes of the REE profiles, together with the presence and absence of the Eu and Ce anomalies, equally suggested different depositional and diagenetic environments for these two sympatric taxa resulting from either stratigraphical or long-distance reworking. The REE concentrations appear to have visible differences between separate dental tissues, particularly between enameloid and dentine of thelodonts, emphasising the importance of in-situ measurements in microfossil biomineral geochemistry.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author