Late Pleistocene-Holocene Paleosecular Variation Dating of Cave Sediments: Insights From Grotta Romanelli (Apulia, Italy)

Grotta Romanelli, located in southern Italy, is a natural coastal cave renowned for its exceptional stratigraphical record and its critical role in understanding the Middle Pleistocene-Holocene geomorphological and paleoenvironmental evolution of the Mediterranean region. Its importance has long been recognized with numerous studies focusing on dating its deposits using radiocarbon analyses and biological proxies. In this study, we introduce the use of the Paleosecular Variation (PSV) of the geomagnetic field to compute a depth-age model for the uppermost stratigraphic unit of Grotta Romanelli (Unit IUS5), traditionally referred to as “Terre Brune.” This Unit, previously associated with the Late Pleistocene-Holocene transition, lacked a precise chronological framework. Using stepwise alternating field demagnetization, we obtained well-defined paleomagnetic directions which were compared with the reference geomagnetic field curves calculated from the SHA.DIF.14k global geomagnetic field model. By incorporating the available radiocarbon dates, and considering the principle of stratigraphic superposition, we established a continuous age model, spanning the 14,000 to 8,000 years BP period. This model sheds light on the most recent phases of sedimentation and human activity in the cave before its complete infilling. The results demonstrate the high potential of PSV dating in providing absolute ages for fine-grained cave deposits. Furthermore, the new age-model offers a coherent timeline for the Final Epigravettian archeological and faunal records of Grotta Romanelli, revealing their connection with the climate changes at the Late Pleistocene-Holocene boundary.