Geological and geochronological reconstruction of the Cagayan valley (Luzon island, Philippines) : Recent advances in human first arrival date in the archipelago
Résumé
The Paleolithic site of Kalinga, in the Cagayan River basin in the Philippines, is associated with the oldest known human occupation traces of the archipelago and dated to 709 ± 68 ka by our research group. This work presents the geomorphological and geochronological study carried out in the region of the site. After the discovery of several surfaces paleontological remains and lithic productions, the region was the subject of numerous excavations from the 1970s, but the chronological framework remained to be specified. In the 2010s, on the Kalinga site, lithic tools and a rhinoceros carcass showing butchery traces were discovered undisturbed in the sedimentary levels, dated afterwards by our team in 2019. Despite these dates, the geomorphology and geochronology of the area are still little known. This work aims to clarify them through the use of ESR dating methods on quartz and 40Ar/39Ar on plagioclase. The sedimentary deposits of the Cagayan Basin are mainly composed of fluvial sands partly formed from minerals of volcanic origin. This composition allows the application of these two absolute dating methods. Our results reveal a human occupation before 900 and after 400 ka.