Palaeoenvironmental and stratigraphic reconstruction of the Lower-Middle Eocene Foraminiferal Limestone of Pag Island (Croatia) - Raw Data

This dataset contains the raw data resulting from the quantitative analysis of the benthic foraminifera association and the skeletal assemblage within the lower to middle Eocene carbonate succession exposed at the Island of Pag (Croatia). The aim of this work is to provide the palaeoenvironmental, palaeobathymetric, and stratigraphic reconstructions and clarify the dynamics of the carbonate factories in the Dinaric Foreland Basin. More than 100 samples have been collected within the Foraminiferal Limestone and the overlying Transitional beds units. Quantitative analysis takes into account both large benthic (LBF) and small benthic (SBF) foraminifera. Based on the analysed LBF and nannofossil associations, the Foraminiferal Limestone has been dated to the early Eocene (Ypresian) and the Middle Eocene (late Lutetian/early Bartonian). Thanks to the analysis of the skeletal assemblage and the foraminiferal assemblage, and multivariate statistics, it was possible to identify seven main biofacies within the Foraminiferal Limestone and one biofacies within the Transitional Beds. The porcelaneous and agglutinated benthic foraminifera biofacies (BF1) indicates a well-illuminated, oligotrophic to mesotrophic, shallow-water, lagoonal environment. The hyaline SBF and encrusting benthic foraminifera biofacies (BF2) developed in a shallow water, inner-ramp environment, and is related to a vegetated seafloor. The nummulitid biofacies (BF3) indicates a moderately high energy, shallow water environment, whereas the comminuted bioclasts and nummulitid biofacies (BF4) indicates a low-energy, shallow water environment, both deposited in inner-to-middle ramp settings. The nummulitid and orthophragminid biofacies (BF5) indicates a moderate energy environment, deposited in middle ramp settings. The nummulitid and serpulid biofacies (BF6) consists of transported material from the inner ramp deposited in middle ramps settings. The orthophragminid and nummulitid biofacies (BF7) indicates a below-wave base, outer shelf setting and the planktic foraminifera biofacies (BF8), which is recorded in the Transitional Beds, deposited in hemipelagic environment, indicating the final drowning of the carbonate ramp. Based on the foraminiferal counting, quantitative parameters such as the orthophragminids/nummulitids ratio (O/N), the planktic/benthic foraminifera ratio (P/B), and the hyaline/porcelaneous foraminifera ratio (H/P) were calculated, indicating that the succession formed along a distally steepened ramp profile, with a progressively deepening of the depositional environment. Quantification serves as a crucial instrument for precise and reliable palaeoenvironmental reconstruction, playing a pivotal role in comparing diverse successions.

本数据集包含克罗地亚帕格岛出露的始新世中下部碳酸盐岩序列内底栖有孔虫组合与骨骼组合定量分析所得的原始数据。本研究旨在开展古环境、古水深及地层重建，并阐明迪纳里克前陆盆地内碳酸盐工厂的演化动态。研究团队在有孔虫灰岩及其上覆过渡层单元中采集了百余件样品。定量分析涵盖大型底栖有孔虫（large benthic foraminifera, LBF）与小型底栖有孔虫（small benthic foraminifera, SBF）两类。基于对大型底栖有孔虫及超微化石（nannofossil）组合的分析，有孔虫灰岩的形成时代被厘定为始新世早期（伊普雷斯期，Ypresian）与始新世中期（吕特期末/巴顿期初，Lutetian/Bartonian）。通过对骨骼组合与有孔虫组合的分析，并结合多元统计（multivariate statistics）方法，研究人员在有孔虫灰岩中识别出7种主要生物相（biofacies），在过渡层中识别出1种生物相。瓷质壳与胶结壳底栖有孔虫生物相（BF1）指示光照充足、贫营养（oligotrophic）至中营养（mesotrophic）的浅水泻湖环境。透明质壳小型底栖有孔虫与附生底栖有孔虫生物相（BF2）形成于浅水内缓坡（inner-ramp）环境，与植被覆盖的海底（vegetated seafloor）相关。货币虫（nummulitid）生物相（BF3）指示中等高能的浅水环境；而破碎生物碎屑（comminuted bioclasts）与货币虫生物相（BF4）则指示低能浅水环境，二者均沉积于内缓坡至中缓坡环境。货币虫与直室有孔虫（orthophragminid）生物相（BF5）指示中等能量环境，沉积于中缓坡环境。货币虫与龙介虫（serpulid）生物相（BF6）由来自内缓坡的搬运物质组成，沉积于中缓坡环境。直室有孔虫与货币虫生物相（BF7）指示浪基面（wave base）以下的外陆棚（outer shelf）环境；而记录于过渡层中的浮游有孔虫（planktic foraminifera）生物相（BF8）则沉积于半远洋环境（hemipelagic environment），指示碳酸盐缓坡最终被淹没。基于有孔虫计数结果，研究人员计算得到直室有孔虫/货币虫比值（O/N）、浮游/底栖有孔虫比值（P/B）以及透明质壳/瓷质壳有孔虫比值（H/P）等定量参数，结果表明该序列形成于远端变陡缓坡剖面，沉积环境持续加深。定量分析是实现精准可靠古环境重建的关键手段，在对比不同碳酸盐岩序列的研究中发挥着核心作用。