Eugenia Mintz

Radiocarbon Concentrations of Wood Ash Calcite: Potential for Dating

Ash is formed when plant calcium oxalate crystals (CaC2O4) decompose to form calcite (CaCO3). We found that ash does retain the original calcium oxalate radiocarbon concentration, but in addition, there is another minor 14C source. This is shown by the presence of a consistent small shift in the pMC and δ13C levels when comparing cellulose and ash from modern and archaeological woods. Possible mechanisms for 14C exchange during combustion or due to diagenesis are considered in order to define parameters for identifying better-preserved wood ash samples.

An attempt at absolute 14C dating

The accepted state-of-the-art (super 14) C dating method relies on calibration curves to determine initial (super 14) C levels in a sample. The paper reconsiders the basis of (super 14) C dating and offers a possible alternative that eliminates the need to employ calibration curves. The idea is to measure the level of radiogenic nitrogen atoms retained in the sample molecules after (super 14) C beta -decay. The practicality of this alternative method still has to be proven.

D-REAMS: A New Compact AMS System for Radiocarbon Measurements at the Weizmann Institute of Science, Rehovot, Israel

The Dangoor REsearch Accelerator Mass Spectrometer (D-REAMS) is a dedicated carbon-only AMS system, built by National Electrostatics Corporation (NEC). It is based on the 1.5SDH Pelletron, operating at 460 keV. The machine was installed at the Weizmann Institute of Science, Rehovot, Israel, in January–February 2013, and passed the acceptance test on March 2013. Since then, over 4500 samples have been successfully measured. Here, we present the results of an intercomparison experiment, done in collaboration with the Vienna Environmental Research Accelerator (VERA), and some typical operation parameters and measurement values of the new AMS system.

Radiocarbon chronology of Manot Cave, Israel and Upper Paleolithic dispersals

Manot Cave radiocarbon dates establish Levantine chronology, which is critical for understanding Upper Paleolithic dispersals. The timing of archeological industries in the Levant is central for understanding the spread of modern humans with Upper Paleolithic traditions. We report a high-resolution radiocarbon chronology for Early Upper Paleolithic industries (Early Ahmarian and Levantine Aurignacian) from the newly excavated site of Manot Cave, Israel. The dates confirm that the Early Ahmarian industry was present by 46,000 calibrated years before the present (cal BP), and the Levantine Aurignacian occurred at least between 38,000 and 34,000 cal BP. This timing is consistent with proposed migrations or technological diffusions between the Near East and Europe. Specifically, the Ahmarian could have led to the development of the Protoaurignacian in Europe, and the Aurignacian in Europe could have spread back to the Near East as the Levantine Aurignacian.

Accurate Radiocarbon Dating of Archaeological Ash Using Pyrogenic Aragonite

Obtaining accurate age determinations from minerals in archaeological ash is a major unsolved issue in radiocarbon (14C) dating. This is because the original 14C content of calcite, the main component of ash, is altered by isotopic exchange. Pyrogenic aragonite, another mineral phase recently discovered in ash, might preserve its 14C signature through time. Using a new method based on density separation and step combustion, we were able to isolate and date aragonitic ash from an archaeological destruction horizon of known age. Here we show that the 14C age of aragonite matches the age of the destruction horizon. Our results demonstrate that pyrogenic aragonite is a short-lived material suitable for 14C dating and directly related to human activities involving the use of fire, thus bearing major implications for the establishment of absolute chronologies for the past 50,000 yr.

Radiocarbon Assessment of Early Bronze Arad: The 20 Year Lifespan of Stratum II

The rich remains from the Early Bronze II at Tel Arad have been interpreted as representing several centuries of activity. According to conventional wisdom, after the destruction of Stratum III by fire, Stratum II endured for about 150 years. However, high precision dates obtained for Stratum II as well as a subsequent destruction event suggest that rapid reconstruction took place in the span of one or two decades. The results point to a short duration of the EB II occupation in Arad and these are in agreement with the south Levantine radiocarbon chronology for the Early Bronze Age. They suggest that the end of the EB II occupation was synchronous with the 1st Egyptian Dynasty ruler Qaʿa.

DNA analysis of a 30,000-year-old Urocitellus glacialis from northeastern Siberia reveals phylogenetic relationships between ancient and present-day arctic ground squirrels

In contrast to the abundant fossil record of arctic ground squirrels, Urocitellus parryii, from eastern Beringia, only a limited number of fossils is known from its western part. In 1946, unnamed GULAG prisoners discovered a nest with three mummified carcasses of arctic ground squirrels in the permafrost sediments of the El’ga river, Yakutia, Russia, that were later attributed to a new species, Citellus (Urocitellus) glacialis Vinogr. To verify this assignment and to explore phylogenetic relationships between ancient and present-day arctic ground squirrels, we performed 14C dating and ancient DNA analyses of one of the El’ga mummies and four contemporaneous fossils from Duvanny Yar, northeastern Yakutia. Phylogenetic reconstructions, based on complete cytochrome b gene sequences of five Late Pleistocene arctic ground squirrels and those of modern U. parryii from 21 locations across western Beringia, provided no support for earlier proposals that ancient arctic ground squirrels from Siberia constitute a distinct species. In fact, we observed genetic continuity of the glacialis mitochondrial DNA lineage in modern U. parryii of the Kamchatka peninsula. When viewed in a broader geographic perspective, our findings provide new insights into the genetic history of U. parryii in Late Pleistocene Beringia.