Radiometric dating of Meipu hominin site in China by coupled ESR/U-series and cosmogenic 26Al/10Be burial dating methods

The Three Gorges and Western Hubei area in the geographic central part of China was a potential migration corridor for early hominin and mammals linking South and North China during the Pleistocene period. Some key early hominin sites are known in this region where limestone cave and fissure sites are numerous but difficult to date as beyond the dating range of OSL and mass spectrometry U-series method. Here, we report radiometric dating study for such a hominin site, Meipu (Hubei Province), by coupled ESR and U-series dating of nine fossil teeth and cosmogenic ²⁶Al/¹⁰Be burial dating of one quartz sediment. The burial age calculated by simple burial model (573 ± 266 ka) gives a minimum age constraint of the sediment. The fossil dating provided two main age groups at 541 ± 48 ka and 849 ± 39 ka, the older age group is in agreement with the U-series age (>630 ka) of the flowstone overlying the fossil layer and the paleomagnetic data which placed the Brunhes-Matuyama boundary in the fossil layer. The reason of this age difference is probably caused by the U-content discrepancy in the enamel of the dated fossil samples. This study exhibits the limitation of ESR/U-series fossil dating and the importance of using multiple dating approach when it is possible in order to identify the problematic ages.     

ESR/U-series dating of Eemian human occupations of Northern France

Palaeolithic sites associated with the Eemian Interglacial (MIS 5e) are very rare in NW Europe, and especially in Northern France, where their preservation is restricted to very specific geological contexts, in association with carbonated tufa (Caours) or peat deposits (Waziers). In order to check the reliability of ESR/U-series method to date teeth recovered from archaeological levels in such specific geological environments, teeth were sampled on these two Middle Palaeolithic sites and systematic in situ dosimetry was performed using portable gamma spectrometer. The ESR/U-series ages obtained on the Caours site are very homogeneous allowing the calculation of a mean age equal to 125 ± 11 ka, in agreement with the geological age, mammal's association and other available geochronological data (U-series on tufa carbonate, TL on burnt flints, OSL on sediments), despite a relatively heterogeneous dosimetric environment (gamma dose rate ranging between ca 200–450 μGy/a). At Waziers, reducing (water logging) environment linked to the peat leads to very specific U-series data of the analysed teeth (U content lower than 0.1 ppm in all the dental tissues, evidence of leaching in some tissues), but the mean ESR/U-series age, 129 ± 4 ka, is also in agreement with the available geological and palaeoenvironmental data indicating that the dated teeth were associated with Late Glacial deposits prior to the climatic interglacial optimum. These two case studies then confirm the reliability of ESR/U-series method to date with good reliability and accuracy the archaeological levels linked to such relatively short climatic events (ca 10 ka).     

Applying a Bayesian approach for refining the chronostratigraphy of the Yumidong site in the Three Gorges region,central China

Yumidong (Corn Cave) is a newly discovered Paleolithic site in the Three Gorges region of central China. Numerous Paleolithic artifacts have been excavated from the sedimentary deposits of the cave in association with faunal remains attributed to the Middle-Late Pleistocene Ailuropoda-Stegodon fauna of southern China. To establish the chronology of the sedimentary sequence (>5 m thick), ¹⁴C dating was applied to bone and charcoal samples (n = 6); the U-series method was used to date in situ precipitated speleothems (n = 12), transported speleothem samples (n = 6) and 18 subsamples of a fossil tooth; and the coupled ESR/U-series method was used to date fossil teeth (n = 6). The derived dates were combined using a hierarchical Bayesian approach to generate a unified chronostratigraphy for the Yumidong sequence. In our Bayesian analyses, the ¹⁴C and coupled ESR/U-series dates were considered to provide direct age estimates for the target layers, while the U-series dates of the in situ precipitated speleothems and fossil tooth were used as minimum age constraints and those of the transported speleothem fragments as maximum age constraints. The Bayesian analyses provided robust time intervals for the archeological layers: L2-Upper (14–23 ka), L2-Lower (27–63 ka), L3 (106–171 ka), L4 (140–192 ka), L10 (157–229 ka), L11 (181–256 ka), and L12 (214–274 ka) with a probability of 95%, allowing the establishment of a ∼300 ka long geological and archeological history for the Yumidong site and placing it as a reference site for Paleolithic cultural evolution in the Three Gorges region from the late Middle Pleistocene to Late Pleistocene.     

40Ar/39Ar temporal framework for the Alleret maar lacustrine sequence (French Massif-Central): Volcanological and paleoclimatic implications

The Alleret maar (Massif Central, France) is part of the few Western European early middle Pleistocene lacustrine sequences. In the AL3 core several new ash layers were recovered in the 10 first meters of the sedimentary filling. We obtained three ⁴⁰Ar/³⁹Ar ages, which range from 683 ± 5 ka (MSWD: 1.2, n = 17) to 722 ± 6 ka (MSWD: 3.2, n = 18). All the studied ash layers belong to the Super-Besse eruptive cycle of the Sancy volcano. Based on the chronostratigraphy that we have derived we estimate that the age of the main eruption could correspond to the Sancy volcano caldera formation at 725 ka close to the end of MIS 18 and that the Super-Besse explosive episode duration lasted only about 40 ka. The time framework we build evidences that the Alleret lacustrine sequence represents a time interval of probably 180 ka spanning from MIS 18 to MIS 14. This sequence offers the first well constrained comparison between terrestrial environmental history and that preserved in marine sediments during the Mid-Pleistocene Revolution.     

Dating results on sedimentary quartz,bones and teeth from the Middle Pleistocene archaeological site of Coudoulous I (Lot,SW France): A comparative study between TT-OSL and ESR/U-series methods

This study presents palaeodosimetric results from the Middle Pleistocene archaeological site of Coudoulous I (Lot, SW France). Nine sedimentary quartz samples (41–60 μm) have been analyzed using a multiple aliquot protocol based on the measurement of the TT-OSL signal. In addition, 7 teeth and 7 bones have been dated by combining the ESR method with U-series analyses. Both methods gave consistent age results allowing correlation of the Early Middle Paleolithic Human occupation of the site to MIS 6 and part of the Lower Paleolithic tools to MIS 7. Beyond the establishment of a radiometric chronology for the Coudoulous I sequence, this study focuses on the information extracted from the intercomparison of the methods. Our data suggest that 1) the TT-OSL signal is stable over at least the last 230 ka (considering the age range of the studied samples), 2) there are not significant problems of incomplete bleaching leading support to the applicability of the TT-OSL technique for sedimentary deposits associated with karstic contexts. This approach highlights the interest of combining luminescence and ESR/U-series methods to discuss the reliability of the dating results.     

High-precision 40Ar/39Ar dating of pleistocene tuffs and temporal anchoring of the Matuyama-Brunhes boundary

High-precision ⁴⁰Ar/³⁹Ar ages for a series of proximal tuffs from the Toba super-volcano in Indonesia, and the Bishop Tuff and Lava Creek Tuff B in North America have been obtained. Core from Ocean Drilling Project Site 758 in the eastern equatorial Indian Ocean contains discrete tephra layers that we have geochemically correlated to the Young Toba Tuff (73.7 ± 0.3 ka), Middle Toba Tuff (502 ± 0.7 ka) and two eruptions (OTTA and OTTB) related to the Old Toba Tuff (792.4 ± 0.5 and 785.6 ± 0.7 ka, respectively) (⁴⁰Ar/³⁹Ar data reported as full external precision, 1 sigma). Within ODP 758 Termination IX is coincident with OTTB and hence this age tightly constrains the transition from Marine Isotope Stage 19–20 for the Indian Ocean. The core also preserves the location of the Australasian tektites, and the Matuyama-Brunhes boundary with Bayesian age-depth models used to determine the ages of these events, c. 786 and c. 784 ka, respectively. In North America, the Bishop Tuff (766.6 ± 0.4 ka) and Lava Creek Tuff B (627.0 ± 1.5 ka) have quantifiable stratigraphic relationships to the Matuyama-Brunhes boundary. Linear age-depth extrapolation, allowing for uncertainties associated with potential hiatuses in five different terrestrial sections, defines a geomagnetic reversal age of 789 ± 6 ka. Considering our data with respect to the previously published age data for the Matuyama-Brunhes boundary of Sagnotti et al. (2014), we suggest at the level of temporal resolution currently attainable using radioisotopic dating the last reversal of Earths geomagnetic field was isochronous. An overall Matuyama-Brunhes reversal age of 783.4 ± 0.6 ka is calculated, which allowing for inherent uncertainties in the astronomical dating approach, is indistinguishable from the LR04 stack age (780 ± 5 ka) for the geomagnetic boundary. Our high-precision age is 10 ± 2 ka older than the Matuyama-Brunhes boundary age of 773 ± 1 ka, as reported previously by Channell et al. (2010) for Atlantic Ocean records. As ODP 758 features in the LR04 marine stack, the high-precision ⁴⁰Ar/³⁹Ar ages determined here, as well as the Matuyama-Brunhes boundary age, can be used as temporally accurate and precise anchors for the Pleistocene time scale.     

Late-stage volcano geomorphic evolution of the Pleistocene San Francisco Mountain, Arizona (USA), based on high-resolution DEM analysis and 40Ar/39Ar chronology

The cone-building volcanic activity and subsequent erosion of San Francisco Mountain, AZ, USA, were studied by using high-resolution digital elevation model (DEM) analysis and new ⁴⁰Ar/³⁹Ar dating. By defining remnants or planèzes of the volcano flanks in DEM-derived images, the original edifice can be reconstructed. We propose a two-cone model with adjacent summit vents which were active in different times. The reconstructed cones were 4,460 and 4,350 m high a.s.l., corresponding to ∼2,160 and 2,050 m relative height, respectively. New ⁴⁰Ar/³⁹Ar data allow us to decipher the chronological details of the cone-building activity. We dated the Older and Younger Andesites of the volcano that, according to previous mapping, built the stage 2 and stage 3 stratocones, respectively. The new ⁴⁰Ar/³⁹Ar plateau ages yielded 589–556 ka for the Older and 514–505 ka for the Younger Andesites, supporting their distinct nature with a possible dormant period between. The obtained ages imply an intense final (≤100 ka long) cone-building activity, terminating ∼100 ka earlier than indicated by previous K-Ar ages. Moreover, ⁴⁰Ar/³⁹Ar dating constrains the formation of the Inner Basin, an elliptical depression in the center of the volcano initially created by flank collapse. A 530 ka age (with a ±58.4 ka 2σ error) for a post-depression dacite suggests that the collapse event is geochronologically indistinguishable from the termination of the andesitic cone-building activity. According to our DEM analysis, the original cone of San Francisco Mountain had a volume of about 80 km³. Of this volume, ∼7.5 km³ was removed by the flank collapse and subsequent glacial erosion, creating the present-day enlarged Inner Basin, and ∼2 km³ was removed from the outer valleys by erosion. Based on volumetric analysis and previous and new radiometric ages, the average long-term eruption rate of San Francisco Mountain was ∼0.2 km³/ka, which is a medium rate for long-lived stratovolcanoes. However, according to the new ⁴⁰Ar/³⁹Ar dates for the last ≤100 ka period, the final stratovolcanic activity was characterized by a greater ∼0.3 km³/ka rate.     

40Ar/39Ar dating of the SP and Bar Ten lava flows AZ,USA: Laying the foundation for the SPICE cosmogenic nuclide production-rate calibration project

Precise ⁴⁰Ar/³⁹Ar age determinations made on basalt groundmass collected from the SP and upper and lower Bar Ten lava flows in the San Francisco and Uinkaret volcanic fields of Arizona, USA, yield ages of 72 ± 4, 97 ± 10, and 123 ± 12 ka (2σ; relative to Renne et al., 2010, 2011, full external precision), respectively. Previous ages of the SP lava flow include a K–Ar age of 70 ± 8 ka and OSL ages of 5.5–6 ka. ⁴⁰Ar/³⁹Ar age constraints, relative to the optimization model of Renne et al. (2010, 2011), of 81 ± 50 and 118 ± 64 ka (2σ; full external precision) were previously reported for the upper and lower Bar Ten lava flows, respectively. The new ⁴⁰Ar/³⁹Ar ages are within uncertainty of previous age constraints, and are more robust, accurate, and precise. Preliminary cosmogenic ³He and ²¹Ne production rates from the Bar Ten flows reported by Fenton et al. (2009) are updated here, to account for the improved quality of the ⁴⁰Ar/³⁹Ar data. The new ⁴⁰Ar/³⁹Ar age for the SP flow yields cosmogenic ³He and ²¹Ne production rates for pyroxene (119 ± 8 and 26.8 ± 1.9 at/g/yr; error-weighted mean, 2σ uncertainty; Dunai (2000) scaling method) that are consistent with production rate values reported throughout the literature. The ⁴⁰Ar/³⁹Ar and cosmogenic ³He and ²¹Ne data support field observations indicating the SP flow has undergone negligible erosion. The SP flow contains co-existing phenocrysts of olivine and pyroxene, as well as xenocrysts of quartz in a fine-grained groundmass facilitating cross-calibration of cosmogenic production rates and production-rate (³He, ¹⁰Be, ¹⁴C, ²¹Ne, ²⁶Al, and ³⁶Cl). Thus, we propose the SP flow is an excellent location for a cosmogenic nuclide production-rate calibration site (SPICE: the SP Flow Production-Rate Inter-Calibration Site for Cosmogenic-Nuclide Evaluations).     

Geomorphic response to late Quaternary tectonics in the axial portion of the Southern Apennines (Italy): A case study from the Calore River valley

The present study focuses on the morphotectonic evolution of the axial portion of the Southern Apennine chain between the lower Calore River valley and the northern Camposauro mountain front (Campania Region). A multidisciplinary approach was used, including geomorphological, field‐geology, stratigraphical, morphotectonic, structural, ⁴⁰Ar/³⁹Ar and tephrostratigraphical data. Results indicate that, from the Lower Pleistocene onwards, this sector of the chain was affected by extensional tectonics responsible for the onset of the sedimentation of Quaternary fluvial, alluvial fan and slope deposits. Fault systems are mainly composed of NW‐SE, NE–SW and W‐E trending strike‐slip and normal faults, associated to NW‐SE and NE–SW oriented extensions. Fault scarps, stratigraphical and structural data and morphotectonic indicators suggest that these faults affected the wide piedmont area of the northern Camposauro mountain front in the Lower Pleistocene–Upper Pleistocene time span. Faults affected both the oldest Quaternary slope deposits (Laiano Synthem, Lower Pleistocene) and the overlying alluvial fan system deposits constrained between the late Middle Pleistocene and the Holocene. The latter are geomorphologically and chrono‐stratigraphically grouped into four generations, I generation: late Middle Pleistocene–early Upper Pleistocene, with tephra layers ⁴⁰Ar/³⁹Ar dated to 158±6 and 113±7 ka; II generation: Upper Pleistocene, with tephra layers correlated with the Campanian Ignimbrite (39 ka) and with the slightly older Campi Flegrei activity (⁴⁰Ar/³⁹Ar age 48±7 ka); III generation: late Upper Pleistocene–Lower Holocene, with tephra layers correlated with the Neapolitan Yellow Tuff (~15 ka); IV generation: Holocene in age. The evolution of the first three generations was controlled by Middle Pleistocene extensional tectonics, while Holocene fans do not show evidence of tectonic activity. Nevertheless, considering the moderate to high magnitude historical seismicity of the study area, we cannot rule out that some of the recognized faults may still be active. Copyright © 2018 John Wiley & Sons, Ltd.     

Radiometric dates for the Middle Palaeolithic sequence of Payre (Ardèche, France)

The archaeological site of Payre (France) yielded Middle Palaeolithic layers with Neanderthal remains, which are partly bracketed by two stalagmitic flowstones. To obtain a precise chronological framework for the human occupation and the faunal remains of this site, several dating methods were used: uranium-series (U-series by alpha spectrometry and TIMS) and electron spin resonance (ESR) on stalagmitic flowstones, combined ESR/U-series on teeth and bones, and thermoluminescence (TL) on burnt flints. Most of the ages obtained for levels H to C range from 300 to 140 ka. The age-spread obtained for the anthropic (burnt flints) and faunal remains (bones and teeth) suggests that the dated levels represent several human occupation periods, near the transition from MIS8 to MIS7 (levels G–F) and from MIS6 to MIS5 (levels D–E).     

New 40Ar/39Ar ages for selected young (<1 Ma) basalt flows of the Newer Volcanic Province,southeastern Australia

The Pliocene-Holocene Newer Volcanic Province (NVP) of southeastern Australia is an extensive, relatively well-preserved, intra-plate basaltic lava field containing more than 400 eruptive centres. This study reports new, high-precision ⁴⁰Ar/³⁹Ar ages for six young (300–600 ka) basalt flows from the NVP and is part of a broader initiative to constrain the extent, duration, episodicity and causation of NVP volcanism. Six fresh, holocrystalline alkali basalt flows were selected from the Warrnambool-Port Fairy area in the Western Plains sub-province for ⁴⁰Ar/³⁹Ar dating. These flows were chosen on the basis of pre-existing K-Ar age constraints, which, although variable, indicated eruption during a period of apparent relative volcanic quiescence (0.8–0.06 Ma).⁴⁰Ar/³⁹Ar ages were measured on multiple aliquots of whole rock basalt samples. Three separate flows from the Mount Rouse volcanic field yielded concordant ⁴⁰Ar/³⁹Ar age results, with a mean eruption age of 303 ± 13 ka (95% CI). An older weighted mean age of 382 ± 24 ka (2σ) was obtained for one sample from the central Rouse-Port Fairy Flow, suggesting extraneous argon contamination. Two basalt flows from the Mount Warrnambool volcano also yielded analogous results, with an average ⁴⁰Ar/³⁹Ar age of 542 ± 17 ka (95% CI). The results confirm volcanic activity during the interval of relative quiescence. Most previous K-Ar ages for these flows are generally older than the weighted mean ⁴⁰Ar/³⁹Ar ages, suggesting the presence of extraneous ⁴⁰Ar. This study demonstrates the suitability of the ⁴⁰Ar/³⁹Ar incremental-heating method to obtain precise eruption ages for young, holocrystalline alkali basalt samples in the NVP.     

First Ar/Ar age of the Ceprano man (central Italy)

The Ceprano calvarium, found in 1994 in Italy and attributed to Homo cepranensis, is one of the most celebrated hominin remains of Europe. It was considered at least 700 ka-old until a recent investigation incorporating magnetostratigraphy and K-Ar ages from the literature assigned to the calvarium an age of ∼450 (+50, −100) ka. Here we pin down the age of the Ceprano calvarium to 353 ± 4 ka (±1σ external) by means of new ⁴⁰Ar/³⁹Ar dating on K-feldspars retrieved from the sediments that hosted the skull. In absence of evidence of reworking, this refined age sinks the conviction that H. cepranensis belonged to human evolution at the Brunhes–Matuyama boundary (c.a. 781 ka). Our refined age indicates that H. cepranensis lived in central Italy probably during the cold period of marine isotope stage (MIS) 10, and that despite his archaic morphology and lack of Neanderthal traits, he was contemporaneous with more advanced species such as H. heidelbergensis.     

Chronology of Upper Pleistocene sequences at Sidi Messaoud (wadi Noun, southwestern Morocco) based on C, optical and U-series dating

The Sidi Messaoud site provides a 40 m thick sedimentary infilling of great importance for the study of environmental changes and landscape evolution during the Upper Pleistocene in the Western Sahara. In this study, chronological results obtained by the ¹⁴C, U-series and optical dating techniques are compared. Each individual age, depositional environment and post-deposition history of the various samples are evaluated, in order to explain the methodological reasons for discordances and concordances. Stratigraphic and palaeoenvironmental implications for the last 120 ka history in southwestern Morocco are also inferred: the wadi Noun gorges had been incised before MIS 5, and later, during MIS 3, the valley has been filled in with a mean sedimentation rate of 1 m/ka.     

Coupled ESR and U-series dating of early Pleistocene Gigantopithecus faunas at Mohui and Sanhe Caves,Guangxi, southern China

Several caves of the Guangxi Zhuang Autonomous Region, southern China, have delivered Gigantopithecus blacki remains, an extinct Pleistocene giant ape, in association with abundant mammalian faunas. To determine their geological ages, fossil teeth from Mohui and Sanhe Caves were dated using the coupled ESR/U-series method. The teeth from Mohui Cave gave age estimates of 1.69 ± 0.22 Ma and 1.29 ± 0.11 Ma. The Sanhe Cave samples had age estimates ranging from 910 ± 200 ka to 600 ± 150 ka with error weighted mean ages of 890 ± 130 ka and 720 ± 90 ka for the layers 5 and 4, respectively. Our results and previous paleomagnestism data place the Gigantopithecus fauna at Mohui Cave between Olduvai and Jaramillo subchrons and suggest that it was coeval with Chuifeng, Longgupo and Liucheng assemblages. The Sanhe fauna is younger, of late early Pleistocene age, and can be dated to the period between Jaramillo subchron and B/M boundary.     

Fuerteventura – Assessment of a calibration site for cosmogenic 3He exposure dating with the 40Ar/39Ar incremental heating method

In situ Terrestrial Cosmogenic Nuclides (hereafter TCNs) are increasingly important for absolutely dating terrestrial events and processes. This study aimed at improving our knowledge of the production rate of Terrestrial Cosmogenic ³He formed in situ in rock surfaces at low latitude and sea level as well as re-evaluation of the Canary Islands as a calibration site for TCNs. For this purpose, we sampled basaltic lava flows from some of the youngest and yet undated volcanic sites and used the ⁴⁰Ar/³⁹Ar incremental heating method on groundmass samples and in situ cosmogenic ³He on olivine and clinopyroxene phenocrysts. ⁴⁰Ar/³⁹Ar analysis was done on a Hiden HAL Series 1000 triple filter quadrupole mass spectrometer with extraction furnace. Incremental heating data shows ages in the Late Pleistocene from 52.7 ± 21.6 ka to 398.6 ± 27.6 ka.We measured cosmogenic ³He concentrations in olivine and clinopyroxene phenocrysts from flow top samples on a MAP 215-50 sector mass spectrometer with a crushing device and a diode laser extraction system. Exposure age calculations yielded ages in the range 38.9 ± 4.0 ka to 62.3 ± 6.7 ka for the youngest lava flow and the data series is in broad agreement with the argon data up to 250 ka and reveals a more continuous time line of volcanism during the late Pleistocene on the island. However, the dataset was not sufficient for calculation of production rates for in situ Terrestrial Cosmogenic ³He as many samples showed signs of erosion. Calculated erosion rates range from none to as high as 7.3 mm/kyr assuming a rock density of 2.9 g/cm². This finding puts a constraint on the use of Fuerteventura as a calibration site for exposure histories older than 50–100 ka. A comparison with cosmogenic ³⁶Cl data supports these findings and indicates substantial weathering.     

40Ar/39Ar constraints on some French landmark Late Pliocene to Early Pleistocene large mammalian paleofaunas: Paleoenvironmental and paleoecological implications

To improve the French Plio-Pleistocene biostratigraphy scheme based on mammal biozone boundaries or “Mammal Neogene/Quaternary Zones” (MNQ) we collected volcanic material that could be dated using the ⁴⁰Ar/³⁹Ar method in five exceptional mammalian paleofauna sites located in the Massif Central (France). We present ⁴⁰Ar/³⁹Ar ages that we obtained for Perrier-Les Etouaires, Roca-Neyra, Chilhac, Senèze and le Creux de Peyrolles. We show that the overall stratigraphic position of these sites based on faunal assemblages is valid from the relative point of view. However, we greatly improve both the accuracy and precision of the age of these mammalian paleofaunas. We obtained ⁴⁰Ar/³⁹Ar ages varying between 2.78 ± 0.01 Ma (1σ external) for Les Etouaires (Lower MNQ 16b) and 1.47 ± 0.01 Ma for the Creux de Peyrolles site (MNQ 19). Based on these new dates we estimate the duration of several biozones including MNQ 16b, 17a and 17b. We suggest that the first Late Villafranchian biozone (MNQ 18) starts as early as the Reunion subchron or just after. The first occurrence of Equus stenonis in Roca-Neyra (i.e. 2.60 ± 0.02 Ma) is close to or synchronous with the Gauss–Matuyama transition (i.e. 2.59 Ma) and the Pliocene/Pleistocene boundary. The chronological framework we build shows the very rapid increase of the large grazers community in French faunal assemblages at the beginning of MNQ 17 (i.e. 2.6 to 2.4 Ma). This rapid faunal turnover is probably associated with a general decrease of woodland habitat in the Massif Central contemporaneous with the onset of the Northern Hemisphere glaciations. The faunal assemblages in France, Spain, and Italy covering the period between 2.1 and 2.0 Ma suggest that favorable conditions for early hominin settlement (mainly savannah prairies, grassland with open forest patches) existed in southwestern Europe at least 200 ka before the first traces of Homo in Eurasia. This period also shows the arrival of taxa originating in Asia and Africa, suggesting dispersal events within southwestern Europe well before the Olduvai subchron and with no indication (as yet) of Homo as a “fellow traveler”.     

Surface exposure dating of young basalts (1–200 ka) in the San Francisco volcanic field (Arizona,USA) using cosmogenic 3He and 21Ne

K–Ar ages of young basalts (<500 ka) are often higher than the actual eruption age, due to low potassium contents and the frequent presence of excess Ar in olivine and pyroxene phenocrysts. Geological studies in the San Francisco and Uinkaret volcanic fields in Arizona have documented the presence of excess ⁴⁰Ar and have concluded that K–Ar ages of young basalts in these fields tend to be inaccurate. This new study in the San Francisco volcanic field presents ³He_c and ²¹Ne_c ages yielded by olivine and pyroxene collected from three Pleistocene basalt flows – the South Sheba (∼190 ka), SP (∼70 ka), and Doney Mountain (∼67 ka) lava flows, – and from one Holocene basalt, the Bonito Lava Flow (∼1.4 ka) at Sunset Crater. These data indicate that, in two of three cases, ⁴⁰Ar/³⁹Ar and K–Ar ages of the young basalts agree well with cosmic-ray surface exposure ages of the same lava flow, thus suggesting that excess ⁴⁰Ar is not always a problem in young basalt flows in the San Francisco volcanic field. The exposure age of the Bonito lava flow agrees within uncertainty with dendrochronological and archeological age determinations. K–Ar and cosmogenic ³He and ²¹Ne ages from the SP flow are in agreement and much older than the OSL age (5.5–6 ka) reported for this lava flow. Furthermore, if the non-cosmogenic ages are assumed to be accurate, the subsequent calculated production rates at South Sheba and SP flow sample sites agree well with values in the literature.     

New ESR/U-series dates of the lowest Acheuleo-Yabrudian levels of Qesem cave

Qesem cave is a Middle Pleistocene site located close to Tel Aviv, Israel, assigned to the Acheuleo-Yabrudian Cultural Complex (AYCC) of the Lower Palaeolithic. The site provides rich assemblages of knapped flint, animal remains and some human teeth making it of particular interest. Its location in the Levantine corridor confers a major interest to the understanding of human dynamics during the Middle Pleistocene.A series of 6 herbivorous teeth from the base of the 11 m archaeological sequence of AYCC Qesem Cave was analysed by combined ESR/U-series method; this complements previous dating series carried out on teeth and on heated flints on higher parts of the sequence (Mercier et al., 2013; Falguères et al., 2016) The teeth were measured according a regular protocol for which each tissue was analysed by inductively coupled plasma-quadrupole mass spectrometry (ICP-Q-MS) for U-series using a combination of a Thermo iCAP-RQ mass spectrometer coupled to a Cetac Aridus III desolvator system, and ESR analyses were implemented on enamel tissue. All these data were combined in order to yield modelled ages.The goal was to find out whether there was a time gap between the carbonates layers dated to 420 ka (Gopher et al., 2010) and archaeological layers of the AYCC found throughout the cave's sequence. The new results yield ages ranging between 220 and 430 ka confirming a great antiquity and a long duration of AYCC in the Levant.     

Age comparison by luminescence using quartz and feldspar on core HPQK01 from the Pearl River delta in China

Reliable chronology is critical for reconstructing estuarine delta process. In this study, detailed chronological framework has been performed on a core HPQK01 (52 m in depth) from the central Pearl River delta (PRD) of China. Both quartz OSL and feldspar post-IR IRSL (pIRIR) methods for late Pleistocene sediments, as well as radiocarbon dating for Holocene sediments, were applied to date the core. Results show that quartz OSL ages range from 125 ± 18 ka to 58 ± 6 ka, and that all of them were minimum ages due to the OSL signal saturation. Feldspar pIR₂₀₀IR₂₉₀ protocol shows some overestimation in dose recovery test, with the recovered to the given ratio of 1.2, while a ratio of around 1 was obtained for feldspar pIR₅₀IR₂₅₀ signals. Robust ages have been obtained from feldspar fading corrected pIR₅₀IR₂₅₀ dating with ages ranging from 150 ± 17 ka to 98 ± 12 ka. AMS ¹⁴C results suggest that subtidal-intertidal zone was deposited during the middle Holocene from 8.21 ± 0.19 cal ka BP to 4.99 ± 0.25 cal ka BP. The sedimentology of core HPQK01 record two marine transgressive-regressive cycles. Based on the dating results, the lower fluvial sediment unit (T2) could be correlated to marine isotope stage (MIS) 6, and the lower marine unit (M2) was deposited during MIS 5. A sedimentary hiatus occurred with age range of from MIS 4 to MIS 2. Since middle Holocene, another marine stratum (M1) has been accumulated. Overall, our findings suggest that feldspar pIRIR dating method has the potential to establish the Quaternary chronostratigraphic framework of the PRD for samples with ages within 150 ka.     

Contribution of ESR/U-series dating to the chronology of late Middle Palaeolithic sites in the middle Rhône valley,southeastern France

The establishment of a chronology for late Middle Palaeolithic sites on the right bank of the Rhône valley in southeastern France is important for the knowledge of Neandertal dynamics and their demise in this area. The suite of dating methods that are directly applicable to fossils is limited for this period, especially around 50 ka where radiocarbon dating is beyond its technical limits. Currently applied to Middle and Lower Pleistocene periods, the use of combined ESR/U-series dating on Upper Pleistocene samples led to new issues, such as the acquisition of an age for samples yielding low equivalent doses and low uranium content in dental tissues. The gamma dose rate measurement thus plays a key role in age calculation. Beyond the discussion on methodological issues, the present study contributes to the establishment of a chronological framework that covers the Neandertal occupations between MIS 5 and MIS 3 for this area.