Landscape evolution and chronostratigraphic correlations of the cave entrance depositional environments and palaeosols of the Gran Dolina unit TD10 (Sierra de Atapuerca, Spain)

Abstract

Gran Dolina Unit TD10 is a sedimentary succession located at the cave entrance depositional environment of the Sierra de Atapuerca multilevel cave complex (Burgos, Spain). Its lithostratigraphic units include four archaeostratigraphic subunits (TD10.1, TD10.2, TD10.3, TD10.4) dating to the Middle Pleistocene, which have been the focus of numerous multidisciplinary studies. This research is based on the examination of large-format thin sections (14 x 6 cm) cut from monolith samples of undisturbed sediments, combined with field descriptions of TD10. We divide unit TD10 in three lithostratigraphic units: TD10a, TD10b and TD10c. Our detailed description and interpretation of the TD10 microfacies classification is guided by facies models and sedimentary process of slope deposits. The primary findings support the identification of distinct sedimentary processes, illustrating the evolution of cave entrance talus scree deposits into stratified slope deposits. Field and microscopic observations of cave entrance deposits are closely integrated with palaeoecological reconstructions, particularly concerning the vanished middle Pleistocene soils of the slopes of Gran Dolina prehistoric site. Additionally, analogies with other archaeological sites and soil formation processes provide insights into palaeosol profiles and the formation processes of the archaeological record. Finally, we discuss and formalize depositional and palaeoenvironmental units, correlating them with marine isotopic stages and substages using Bayesian chronostratigraphic modelling and TD10 palaeosols. Chronological uncertainties arise in TD10b between Bayesian dates and permafrost and (paleo-argillic) brown earths buried horizons, which are correlated with MIS 12 and MIS 11 in north-western Europe. TD10a Bayesian chronology aligns with MIS 9 in agreement with a interglacial palaeosol record. This research emphasizes the complexity of cave entrance stratigraphy and its pivotal role in reconstructing past environments.