Sedimentary Dosimetry for the Saradj-Chuko Grotto: A Cave in a Lava Tube in the North-Central Caucasus, Russia.

Karst caves host most European Paleolithic sites. Near the Eurasian-Arabian Plate convergence in the Caucasus' Lower Chegem Formation, Saradj-Chuko Grotto (SCG), a lava tube, contains 16 geoarchaeologically distinct horizons yielding modern to laminar obsidian-rich Middle Paleolithic (MP) assemblages. Since electron spin resonance (ESR) can date MP teeth with 2-5% uncertainty, 40 sediment samples were analyzed by neutron activation analysis to measure volumetrically averaged sedimentary dose rates. SCG's rhyolitic ignimbrite walls produce very acidic clay-rich conglomeratic silts that retain 16-24 wt% water today. In Layers 6A-6B, the most prolific MP layers, strongly decalcified bones hinder species identification, but large ungulates inhabited deciduous interglacial forests. Unlike in karst caves, most SCG's layers had sedimentary U concentrations > 4 ppm and Th, > 12 ppm, but Layer 6B2 exceeded 20.8 ppm U, and Layer 7, > 5 ppm Th. Such high concentrations emit dose rates averaging ~ 1.9-3.7 mGy/y, but locally up to 4.1-5.0 mGy/y. Within Layer 6, dose rate variations reflect bone occurrence, necessitating that several samples must be geochemically analyzed around each tooth to ensure age accuracy. Coupled with dentinal dose rates up to 3.7-4.5 mGy/y, SCG's maximum datable ages likely averages ~ 500-800 ka.

SEDIMENTARY RADIOACTIVITY IN AN UPPER PALEOLITHIC-MIDDLE PALEOLITHIC (MP-UP) TRANSITION SITE: INCREASING ESR TOOTH DATING ACCURACY AT GOLEMA PEsT, NORTH MACEDONIA.

ESR (electron spin resonance) can date sites that span the whole Paleolithic, but requires accurate sedimentary dose rates, especially in caves where the internal and cosmic dose rates can approach 0 mGy/yr. This study examines the sedimentary radioactivity in the upper layers at Golema Pest, North Macedonia. Reaching > 5.5 m deep, > 21 flatly lying, silty-sandy matrix-supported gravel layers with éboulis clasts fill the cave. In Sondage 2, Layers 0-5 contained many hearths and yielded thousands of bones and teeth, many from ungulates. In Layers 2-5a sat thousands of lithics and small tools, many made on tiny quartz crystals. Layers 2c-6 have Mousterian assemblages with denticulates, notched tools, Levallois cores and flakes. To measure the volumetrically averaged sedimentary dose rates for ungulate teeth dated by ESR from Sondage 2, 66 sediment samples were analyzed by NAA. Adding éboulis, calcined bone, and charcoal associated with the hearths lowered the sedimentary dose rates or left them unchanged. In Layer 2 at 198 cm below the cave datum, the Campanian Ignimbrite (CI) cryptotephra occurred, where it caused abnormally high sedimentary U, Th, and K concentrations and dose rates. Since the CI tephra lay 28-30 cm above AT77, a tooth dated from Layer 3, using time- and volumetrically averaging increased AT77's sedimentary dose rate by 32%, and dropped its calculated age by 25%. Analyzing the sedimentary compositions at every 2 cm in Layers 0-2 yielded a highly detailed stratigraphy that reduced the uncertainty in the sedimentary dose rates and the ESR ages, but more detailed geochemical analyses must be completed within the lower layers in Sondage 2.

Shell We Date? ESR Dating Sangamon Interglacial Episode Deposits at Hopwood Farm, IL.

During the Sangamon Episode, North America occasionally experienced warm climates. At Hopwood Farm, IL, a small kettle lake filled with sediment after the Illinois Episode glaciers retreated from southern Illinois. To date those deposits, 14 mollusc samples newly collected with associated sediment from three depths at Hopwood Farm were dated by standard electron spin resonance (ESR) dating. ESR can date molluscs from ~0.5 ka to >2 Ma in age with 5-10% precision, by comparing the accumulated radiation dose with the total radiation dose rate from the mollusc and its environment. Because all molluscs contained ≤0.6 ppm U, their ages do not depend on the assumed U uptake model. Using five different species, ESR analyses for 14 mollusc subsamples from Hopwood Farm showed that Unit 3, a layer rich in lacustrine molluscs, dates at 102 ± 7 ka to 90 ± 6 ka, which correlates with Marine (Oxygen) Isotope Stage 5c-b. Thus, the period with the highest non-arboreal pollen at Hopwood also correlates with the European Brørup, Dansgaard-Oeschger Event DO 23, a time period when climates were cooling and drying somewhat over the same period.

Monitoring tectonic uplift and paleoenvironmental reconstruction for marine terraces near Maǧaracik and Samandaǧ, Hatay Province, Turkey.

Near Hatay, the Antakya-Samandag-Cyprus Fault (ASCF), East Anatolian and Dead Sea Fault Zones, the large faults that form the edges of the African, Anatolian, Cyprus and Arabian Plates, all produce large earthquakes, which have decimated Hatay repeatedly. Near Samandag, Hatay, differential vertical displacement on the ASCF has uplifted the southeastern side relative to northwestern side, producing large fault scarps that parallel the Asi (Orontes) River. Tectonic uplift coupled with Quaternary sealevel fluctuations has produced several stacked marine terraces stranded above current sealevel. This study dated 24 mollusc samples from 10 outcrops on six marine terraces near Samandag electron spin resonance (ESR). Ages were calculated using time-averaged and volumetrically averaged external dose rates, modelled by assuming typical water depths for the individual species and sediment thicknesses estimated from geological criteria. Uplift rates were then calculated for each fault block. At all the Magaracik terraces, the dates suggest that many shells were likely reworked. On the 30 m terrace at Magaracik IV (UTM 766588-3999880), Lithophagus burrows with in situ shells cross the unconformity. One such shell dated to 62 ± 6 ka, setting the minimum possible age for the terrace. For all the Magaracik terraces at ∼30 m above mean sealevel (amsl), the youngest ages for the reworked shells, which averaged 60 ± 3 ka for six separate analyses, sets the maximum possible age for this unit. Thus, the terrace must date to 60-62 ± 3 ka, at the MIS 3/4 boundary when temperatures and sealevels were fluctuating rapidly. Older units dating to MIS 7, 6, and 5 likely were being eroded to supply some fossils found in this terrace. At Magaracik Dump (UTM 765391-4001048), ∼103 m amsl, Ostrea and other shells were found cemented in growth position to the limestone boulders outcropping there <2.0 m above a wave-eroded notch. If the oysters grew at the same time as the wave-cut notch and the related terrace, the date, 91 ± 13 ka, for the oysters, this fault block has been uplifted at 1.19 ± 0.15 m ky(-1), since MIS 5c. At Samandag Kurt Stream at 38 m amsl, molluscs were deposited fine sandy gravel, which was likely formed in a large tidal channel. Four molluscs averaged 116 ± 5 ka. If these molluscs have not been reworked, this fault block has uplifted at 0.34 ± 0.05 m ky(-1) since the MIS 5d/5e boundary. The differences in these uplift rates suggests that at least one, and possibly two, hitherto undiscovered faults may separate the Magaracik Dump site from the other Magaracik sites and from the Samandag Kurt Stream site.

On the industrial attributions of the Aterian and Mousterian of the Maghreb.

North Africa is quickly emerging as one of the more important regions yielding information on the origins of modern Homo sapiens. Associated with significant fossil hominin remains are two stone tool industries, the Aterian and Mousterian, which have been differentiated, respectively, primarily on the basis of the presence and absence of tanged, or stemmed, stone tools. Largely because of historical reasons, these two industries have been attributed to the western Eurasian Middle Paleolithic rather than the African Middle Stone Age. In this paper, drawing on our recent excavation of Contrebandiers Cave and other published data, we show that, aside from the presence or absence of tanged pieces, there are no other distinctions between these two industries in terms of either lithic attributes or chronology. Together, these results demonstrate that these two 'industries' are instead variants of the same entity. Moreover, several additional characteristics of these assemblages, such as distinctive stone implements and the manufacture and use of bone tools and possible shell ornaments, suggest a closer affinity to other Late Pleistocene African Middle Stone Age industries rather than to the Middle Paleolithic of western Eurasia.

ESR dating pleistocene barnacles from BC and Maine: a new method for tracking sea level change.

Barnacles have never been successfully dated by electron spin resonance (ESR). Living mainly in the intertidal zone, barnacles die when sea level changes cause their permanent exposure. Thus, dating the barnacles dates past sea level changes. From this, we can measure apparent sea level changes that occur due to ocean volume changes, crustal isostasy, and tectonics. ESR can date aragonitic mollusc shells ranging in age from 5 ka to at least 500 ka. By modifying the standard ESR method for molluscs to chemically dissolve 20 microm from off the shells, six barnacle samples from Norridgewock, Maine, and Khyex River, British Columbia, were tested for suitability for ESR dating. Due to Mn2+ interference peaks, the four Maine barnacle samples were not datable by ESR. Two barnacles from BC, which lacked Mn2+ interference, yielded a mean ESR age of 15.1 +/- 1.0 ka. These ages agree well with 14C dates on the barnacles themselves and wood in the overlying glaciomarine sediment. Although stability tests to calculate the mean dating signal lifetime and more ESR calibration tests against other barnacles of known age are needed to ensure the method's accuracy, ESR can indeed date Balanus, and thus, sea level changes.

ESR at Treugol'naya Cave, Northern Caucasus Mt., Russia: dating Russia's oldest archaeological site and paleoclimatic change in Oxygen Isotope Stage 11.

At 1510 m asl, Treugol'naya Cave, Russia, is the highest cave showing evidence for human occupation in eastern Europe. Layers 4-7 in the 4.5-m-thick sequence yielded many artifacts representing Lower Paleolithic pebble and flake tool industries. Abundant faunal remains include extinct Middle Pleistocene species. Palynological, paleomagnetic, and microsedimentological analyses indicate that several climatic changes of different magnitudes occurred in the sequence. To determine absolute ages for Treugol'naya, 32 independent subsamples from nine ungulate teeth collected from the Lower Paleolithic layers were dated by standard and isochron electron spin resonance (ESR) analyses. Isochron analyses indicate that the teeth experienced no significant U leaching or secondary uptake, and that linear uptake (LU) provides accurate ages. Layers 4b through 5b dated to 365+/-12-406+/-15 ka. Therefore, hominids visited the site periodically throughout Oxygen Isotope Stage (OIS) 11, indicating that they utilized resources at elevations >1000 m at least seasonally by 400 ka. ESR, paleomagnetic, palynological and paleontological analyses all indicate that the Lower Paleolithic Layers 4-5 correlate with OIS 11. The thickness of Layers 4-5 (more than 1.5 m) makes this one of the thickest OIS 11 terrestrial deposits known.