Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia

Abstract

Rare earth elements (REEs) have been analysed from fossil vertebrate microremains (thelodont scales) from the Vesiku Bone Bed, Saaremaa, Estonia, using in situ microsampling by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Well-preserved scales of three species of the genus Thelodus (T. carinatus, T. laevis and Thelodus sp.) show very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with enrichment in middle REEs, depletion in heavy REEs and pronounced negative europium anomaly, but no cerium anomaly. The results of this study suggest a similar diagenetic history and possibly contemporaneous habitats for all three Thelodus species, as well as possible suboxic to anoxic conditions of the bottom and pore waters during the formation of the Vesiku Bone Bed.

Patterns of ecological diversification in thelodonts

“…; Fadel et al . ) and the sedimentology and taphonomy of several thelodont localities (Turner ; Märss et al . , ; Märss & Männik ) have also provided valuable information about the environments these fishes inhabited.…”

Preservation of successive diagenetic stages in Middle Triassic bonebeds: Evidence from in situ trace element and strontium isotope analysis of vertebrate fossils

“…At low temperatures under near surface conditions, the aqueous solution should be dominantly trivalent, except perhaps in alkaline, very strongly reducing pore waters of anoxic marine sediments (Sverjensky, 1984). Therefore, Eu anomalies in fossil biogenic apatite and phosphate concretions have often been associated with strongly reducing environments (e.g., Iliopoulos et al, 2010) regardless if the anomaly is positive (e.g., Kidder et al, 2003;Jiang et al, 2007;Khan et al, 2012;Garnit et al, 2012) or negative (e.g., Kowal-Linka et al, 2014;Fadel et al, 2015).…”

Rare earth elements (REEs) in vertebrate microremains from the upper Pridoli Ohesaare beds of Saaremaa Island, Estonia: geochemical clues to palaeoenvironment c

“…The obtained in situ REE compositions are explored below using basic geochemical calculations and quantifications in order to determine early burial palaeoenvironmental conditions. The analytical methods used in this study are similar to those used in Fadel et al (2015).…”

“…In our work, we use fossil bioapatite of dental tissues, such as enamel and enameloid, which is composed of compact and large crystallite (micrometre-sized) biomineral with as little as 1 wt% organic matter (Kohn et al 1999;Sire et al 2009;Enax et al 2012) and in contrast to long bones, demonstrated high potential to preserve an early REE signal (Trueman & Palmer 1997;Kohn et al 1999;Kemp & Trueman 2003;Trotter & Eggins 2006;Tütken et al 2008;Trueman et al 2011). Given the above, REE concentrations can serve as a record of depositional or early diagenetic conditions only as long as it is demonstrated that the later contribution of REEs such as from diagenetic pore fluids, is relatively minor (e.g., Reynard et al 1999;Trueman 1999;Patrick et al 2004) and the histology and crystallinity of fossil remains are taken into account (Žigaitė et al 2013;Fadel et al 2015).…”