Preliminarily report on rare earth element taphonomy of a Miocene mixed age fossil vertebrate assemblage (Pécs-Danitzpuszta, Mecsek Mts., Hungary): uptake mechanism and possible separation of palaeocommunities

The sand pit of Pécs-Danitzpuszta is one of the most important mixed Neogene vertebrate localities in Hungary, with older Miocene (Langhian – Serravallian) terrestrial and marine animal remains re-deposited into the upper Miocene (Tortonian) Lake Pannon sediments. Due to the mixed status of the Pécs-Danitzpuszta vertebrate assemblages, limited information is available about the former depositional environment and age of these fossils. However, the rare earth element (REE) composition of the fossil apatite can help to determine the stratigraphic origin and the early depositional environments of unprovenanced vertebrate remains. In this study, the REE composition of more than 60 vertebrate fossils, among them reworked and <i>in situ</i> remains from the Mecsek Mountain, were analysed. The results allowed separation between the Badenian, Sarmatian, and Pannonian aged fossils. The REE content and their distribution also helped us characterise the ancient depositional conditions of the investigated reworked fossils. Furthermore, several different types of vertebrate fossils were analysed, resulting in a large database that helped clarify the likely timings and mechanisms of REE uptake at this locality. Apparent variation in REE chemistry within bones (cortical vs cancellous) and teeth (enamel vs dentine) are best linked to fractionation along the REE series during their incorporation.

佩奇-达尼茨普什塔砂坑是匈牙利最重要的新近纪混合脊椎动物化石点之一，早中新世（朗热阶-塞拉瓦尔阶）的陆生与海生动物化石被再沉积于晚中新世（托尔托纳阶）的潘农湖沉积物中。由于佩奇-达尼茨普什塔的脊椎动物组合群具有混合特征，目前关于这批化石的原始沉积环境与形成时代的相关信息较为有限。不过，化石磷灰石的稀土元素（rare earth element, REE）组成可用于判定无确切产地的脊椎动物化石的地层成因与早期沉积环境。本研究对60余件脊椎动物化石的稀土元素组成开展了分析，其中涵盖梅切克山地区的再沉积化石与原位化石。分析结果可有效区分巴登阶、萨尔马特阶与潘农阶的化石。稀土元素的含量及其分布特征还有助于阐明本次研究涉及的再沉积化石的古沉积环境特征。此外，本研究还分析了多种不同类型的脊椎动物化石，构建了大型数据库，用于阐明该区域化石中稀土元素吸收的可能时间与机制。骨骼（皮质骨与松质骨）和牙齿（釉质与牙本质）内稀土元素化学特征的显著差异，最可能与稀土元素系列在掺入过程中发生的分馏作用相关。