Archeological deposits at Abric Romaní extend to 110 ka: U-series dating of a newly cored, 30 meter-thick section. (February 2016)

• Record Type: Journal Article
• Authors: Sharp, Warren D.; Mertz-Kraus, Regina; Vallverdu, Josep; Vaquero, Manuel; Burjachs, Fancesc; Carbonell, Eudald; Bischoff, James L.
• Is Part Of: Journal of archaeological science. Volume 5(2016)
• Page Start: 400
• Page End: 406
• Publication Date: 2016-02
• Subjects: Abric Romaní -- U-series dating -- Mousterian -- Rock shelter -- Middle Paleolithic; Archaeology -- Periodicals; Archaeology -- Research -- Periodicals; 930.1
• DOI: 10.1016/j.jasrep.2015.12.015
• Languages: English
• ISSNs: 2352-409X

Abstract

Abstract: Recent exploratory drilling at Abric Romaní reveals that carbonate tufas similar to the archeologically rich levels excavated to date extend at least 30 m beneath the current base of excavation. The present project focused on sampling and measuring a suite of new U-series dates on core samples to determine whether reliable dates could be obtained from the older tufas and, if so, their temporal extent. Using relatively small (~ 100 mg), carefully selected samples analyzed by inductively coupled plasma mass spectrometry, we obtained a total of 20 dates for 10 core samples and one sample near the base of the current excavation. Corrections for thorium from contaminating detritus were generally negligible, as indicated by a median 230 Th/ 232 Th activity ratio of 360. At selected levels in the sequence, two or three coeval samples were prepared and analyzed in order to determine the reproducibility of their dates. Reproducibility at most levels was similar to analytical errors, consistent with rapid carbonate deposition followed by evolution of closed U–Th systems. In contrast in the sample nearest the base of the core, scatter of dates beyond analytical errors was observed among sub-samples, probably indicating failure of the U–Th system to remain closed. The dates, which preserve stratigraphic order in all cases, range from ~ 55 ka for a sample from level N of the existing excavation to ~ 110 ka at the base of the core. The new dates show that tufas at Abric Romaní extend at least to early Marine Isotope Stage (MIS) 5. Mean accumulation rates in the core varied widely, from a minimum of 17 cm/ka during the later parts of MIS 5 to a maximum of 130 cm/ka during the Last Interglacial in early MIS 5, suggesting that a wetter hydroclimate prevailed in the region during periods of low global ice volume. The new dates show that burned travertine and sand intersected by the drill-core, which are likely indicators of human presence, are as old as ~ 100 ka. Thus, evidence for human presence at Abric Romaní now extends over ~ 60 thousand years. Highlights: Drilling below the current excavation level at Abric Romaní recovered > 30 m of core. Strata similar to known archeologically rich levels occur throughout the core. Twenty new U-series dates preserve stratigraphic order and range from 55 to ~ 110 ka. Burned materials in the core suggest human presence at the site by ~ 100 ka.