Geochemical and sedimentary constraints on the formation of theVenta Micena early Pleistocene site (Guadix‑Baza Basin, Spain)

We acknowledge Víctor Fondevilla, who cooperated with sedimentology and was co-advisor for the master’s thesis of A.G. The funding of this research, together with the associated permission to conduct the field study, was provided by the ‘General Research Project of the Junta de Andalucía, First human occupations and paleoecological context from the Plio-Pleistocene deposits of the Guadix-Baza basin, Archaeological zone of the Orce basin (Granada, Spain)’. Servicio General de Análisis de Isótopos Estables (Nucleus, Salamanca University) is acknowledged for the quick delivery of isotopic data. Soledad Alvarez, from the XRD Service at GEO3BCN-CSIC, is acknowledged for technical support with the XRD measurements. O.O. is a member of the 2017SGR-1666 research group. A.K. was funded by the Academy of Finland. We are very grateful to L. Melim and an anonymous reviewer for their constructive and detailed review of this manuscript. Roy Siddall (Univ. Helsinki Language Centre) did an excellent revision of English language.Despite the paleontological relevance of the terrestrial Early Pleistocene Venta Micena bonebed (Baza Basin, Spain), it lacks a comprehensive geochemical/sedimentological study. Here, we demonstrate that the 1.5-m-thick Venta Micena limestone formed in a relatively small freshwater wetland/pond located at the periphery of the large saline Baza paleolake. Two microfacies are observed, with high and low contents of invertebrate fossils, and which originated in the centre and margin of the wetland, respectively. X-ray diffraction (XRD) mineralogy and paleohydrological characterization based on ostracod and bulk-rock geochemistry (δ13C and δ18O) indicate that the limestone reflects a general lowstand of the Baza lake, permitting the differentiation of freshwater wetlands that were fed by adjacent sources. Conversely, during highstands, the Baza lake flooded the Venta Micena area and the freshwater fauna was replaced by a saline one. Bulk-rock isotopic data indicate that the lower interval C1 of the limestone (bone-rich in marginal settings) displays general negative values, while the upper interval C2 (bone free) displays less negative values. The bones of predated mammals accumulated in the marginal areas, which were flooded and buried by recurring water-table fluctuations. Lake dynamics played a critical role in bone accumulation, which was previously considered as representing a hyena den.Academy of FinlandJunta de Andalucí