U-series Dates Research Articles

Thermoluminescence dating of gypsum in loess deposits

Gypsum deposits within loess deposits are an important indicator of weathering processes and climate change. We conducted a thermoluminescence (TL) dating study of the gypsum from loess deposits of the Jiuzhoutai section in the western Chinese Loess Plateau. Determination of the equivalent doses (De) of gypsum samples was conducted using several protocols, including single-aliquot regenerative-dose (SAR-TL), multiple-aliquot additive dose (MAAD-TL), and Isothermal TL of SAR (SAR-ITL). The TL glow peak at 280 °C was targeted because of its reported stable signals. The test dose check, estimation of sensitivity changes, and the dose recovery test were applied to assess the applicability of the different protocols, and the characteristics of the thermoluminescence signals for gypsum were evaluated. The De results for the SAR-TL, MAAD-TL, and SAR-ITL protocols were within the error ranges. Among the three protocols, SAR-ITL did not involve high-temperature heating and it provided a more accurate De value, and thus it was used for De determinations for gypsum dating. With a dose rate of 1.74 ± 0.07 Gy/ka, the minimum TL age of the gypsum veins was ∼182 ± 7 ka. U-series dating was also applied to the same samples for comparison. However, the extremely low ratio of 230Th/232Th (≤4 × 10−6) of the gypsum veins deposited within the loess resulted in a large error of the U-series dates. We conclude that TL dating is more appropriate for the dating of gypsum in loess deposits.

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), 14 C 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 14 C 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.

Natural Trap Cave tephra correlation to Yellowstone using U-series (230Th/238U) dates and oxygen isotopes of zircon and chemical composition of adherent glass

Zircon crystals from ash layers intercalated with fossil-rich sediment from Natural Trap Cave (NTC) in Wyoming (USA) were investigated to refine the chronostratigraphy of this unique late-Quaternary megafaunal assemblage. Glass compositions of individual glass spicules and glass adherent to zircon along with a characteristic low-δ18O signature of zircon (on average + 2.4‰ relative to Vienna standard mean ocean water) indicate tephra provenance from post-Lava Creek Tuff activity of Yellowstone. Yellowstone glass composition was hence used to anchor the 230Th/238U zircon isochron and to compute model crystallization ages, which translate into maximum depositional ages. For the lowermost visible tephra layer in new excavations in NTC strata, an upper age limit of 138 ± 9 ka (1σ age uncertainty) was thus obtained. A younger tephra with a230Th/238U zircon date of 111 ± 8 ka is tentatively correlated with Tuff of Cold Mountain Creek from the Central Plateau Member of Yellowstone, suggesting a minor lag time between zircon crystallization and eruption. The NTC tephra record thus has high potential for refining the explosive volcanic history and tephra distribution patterns of Yellowstone during the late Pleistocene.

A revised, Last Interglacial chronology for the Middle Palaeolithic sequence of Gruta da Oliveira (Almonda karst system, Torres Novas, Portugal)

Based on previous radiocarbon and U-series (Diffusion/Adsorption) dating of bone samples, the Middle Palaeolithic has been thought to persist at Gruta da Oliveira until ∼37 thousand years (ka) ago. New U-series ages for stratigraphically constraining speleothems, coupled with new luminescence ages for sediment infill, show that the site’s ∼6 m-thick archaeological stratigraphy dates entirely within a <30 ka interval spanning substages 5a-5b of Marine Isotope Stage (MIS) 5. Significant technological change is observed across the sequence, akin to that seen in the Upper Palaeolithic over similar timescales. Flake-cleavers and bifaces, normatively definitional of the Vasconian facies, are restricted to a short interval correlated with Greenland Stadial (GS) 22, 85.1–87.6 ka ago. In cave and rock-shelter sites of southern and western Iberia, intact archaeological deposits securely dated to the ∼37–42 ka interval remain elusive. Geological dynamics (e.g., erosion, sedimentation hiatuses, palimpsest formation) and human adaptive responses to climate-driven environmental change (e.g., abandonment of now forest-covered low- and mid-altitude karst areas, concentration of settlement in alluvial plains and coastal settings) are possible explanations for this pattern.

New U-series dates from Stump Cross Caverns, Yorkshire, UK, and constraints on the age of the Banwell Bone Cave Mammal Assemblage Zone

Stump Cross Caverns house one of the important Pleistocene fossil bone beds of the UK. Yet, the dates of the Banwell Bone Cave Mammal Assemblage Zone (MAZ), to which these belong, have not yet been well constrained. Here we present new U-Th dates showing that Late-MIS 5 bison-reindeer-wolverine fauna was present in northern England at least as early as 91.9 ± 0.5 ka (the oldest date yet published); and that the Banwell Bone Cave fauna probably occupied the Yorkshire Dales from soon after ∼100 ka to 80 ka (late MIS 5c-early MIS 5a). This adds to the very small number of dates for this fauna, is somewhat older than the timing proposed in the literature, and suggests that the fauna arrived in NW Britain more than 5 kyr in advance of SW Britain. We also found an older bone bed dating from 175 to 172 ka, MIS 6d. This is only the second reported occurrence in the Yorkshire Dales of a fauna that pre-dates the Last Interglacial. Our results confirm that calcite deposition in this cave is precluded during interglacial peaks by local flooding, but at other times is similar to other caves of NW Europe. The oldest dates, on calcites from the uppermost levels, show dewatering by at least ∼430 ka (early MIS 11), adding to our understanding of the antiquity of the caves and the geomorphology of the region.

U-series dating of carbonate accretions reveals late Neolithic age for the rock paintings in Cangyuan, southwestern China

Abstract The ancient rock paintings drawn with ochre on the limestone cliffs at 15 sites in Cangyuan County, in southwestern China, contain more than 1200 identifiable figures. The paintings portray scenes of daily life in a remote mountainous area. The inhabitants probably led a sedentary life of animal herding and cultivation and in the scenes they are engaged in activities such as dancing, hunting and fighting. These rock paintings have been known more than 50 years, and have been registered by the State Council of China as major cultural relics under national protection since 2001, but their ages have remained uncertain. In this study, we carried out MC-ICPMS U-series (n = 57) and AMS 14C (n = 4) dating of the carbonate accretions associated with the rock paintings at eight sites. Among them, 25 samples overlying pigment and 14 samples underlying pigment with insignificant initial 230Th contamination yielded highly precise U-series ages. The samples overlying pigment provided reliable minimum ages of 3760, 2920, 2680 and 1110 yr BP for the dated motifs at Sites 2, 7, 14, and 11, respectively. The age ranges for the underlying carbonate accretions overlap those of the overlying ones, from ~3800 to ~3200 yr BP at Site 2 and from ~3000 to ~2700 yr BP at Site 7, suggesting that rock painting was a long-lasting tradition in this region. The combination of all of the reliable U-series dates enables us to constrain the time interval of the main rock painting phase to ~3800–2700 yr BP, which is coeval with the regional late Neolithic culture.

Late Cenozoic uplift history of the Peak District, central England, inferred from dated cave deposits and integrated with regional drainage development: A review and synthesis

The White Peak upland in the Peak District region of central England extends over an area of >100 km2, locally exceeding 400 m above sea-level, formed in extensively karstified limestone of Early Carboniferous age. Historically regarded as palaeo-karst, following the availability of U-series dates since the 1980s, it has become apparent that the superimposed cave levels in this region formed during the succession of Pleistocene interglacials, their differences in height reflecting downcutting by the River Derwent and its tributaries, in response to regional uplift. However, quantitative interpretation is complicated because of effects of glaciation, most importantly glacial diversion of rivers in adjoining lowland regions, making the determination of uplift from fluvial incision particularly difficult. The Derwent terrace dataset is also complicated by lithologically-controlled knickpoints, which can remain localized or propagate upstream depending on individual details. Cave, fluvial, and glacial datasets for this region are integrated to quantify the uplift history, establishing the Quaternary uplift history of a wide region of Britain. Uplift of >100 m since the Mid-Pleistocene Revolution, and by ~300–400 m since the Miocene, is thus inferred. These amounts exceed the uplift deduced over corresponding timescales in surrounding regions, indicating that the Quaternary uplift has slightly accentuated the overall domal form of this Carboniferous limestone inlier. The analysis supports the previous assignment of the Wragby Glaciation in the surrounding lowland regions to MIS 8 and constrains the most recent glaciation within the Peak District, represented by the Bakewell Till, also to MIS 8. Overall, this work provides an important case study demonstrating integrated use of multi-disciplinary datasets to quantify Late Cenozoic landscape development.

U-Th dated speleothem recorded geomagnetic excursions in the Lower Brunhes

The study of geomagnetic excursions is key for understanding the behavior of the magnetic field of the Earth. In this paper, we present the geomagnetic record in a 2.29-m-long continuous core sampled in a flowstone in Liguria (Italy) and dated to the Lower Brunhes. The cored flowstone developed from Marine Isotopic Stage (MIS) 13 to MIS 7, according to 21 U-series dates. The mean growth rate is closely related to glacial and interglacial isotopic stages. Magnetic remanence was measured using u-channel and deconvolved. Four geomagnetic excursions were recorded at the same location, in a single flowstone, during interglacial MIS 11 and 13; Basura 1, 2, 3 and 4, at depths of 213 cm, 181, 160 and 92 cm, respectively. Due to the uncertainties of U-Th dating, the timing of the three events, namely Basura 1, 2 and 3 overlaps. The Basura 4 is well-dated to 417 + −7/8 ka and is clearly distinguishable from the others. It should therefore be considered as a possible excursion.

Stable isotope ratios and speleothem chronology from a high-elevation alpine cave, southern San Juan Mountains, Colorado (USA): Evidence for substantial deglaciation as early as 13.5 ka

Deglaciation ages for valley glaciers from the last glacial maximum are difficult to obtain with precision. The unequal or non-uniform loss of glacial ice cover (spatial heterogeneity) during glacial retreat results in exposure of considerable land surface area prior to complete deglaciation. New U-series dates from an 11cm long stalagmite in a shallow, high elevation (3242 m) cave in the southern San Juan Mountains of southwestern Colorado (USA), indicate that substantial, high-elevation glacial ice ablation occurred prior to 13.5 ka. The stalagmite dates compare well with other deglaciation studies in central and southern Colorado that show deglaciation occurred between ca. 13 ka to 15 ka. Low δ¹³C values from 13.5 ka speleothem growth bands, relative to the δ¹³C value of the host carbonate, suggest that alpine plant and soil cover was established at this location, aspect, and elevation prior to 13.5 ka. Calcite luminescence in the 13.5 ka growth bands indicates the presence of humic and fulvic acids released by the roots of living plants and decomposition of vegetative matter. The carbon isotope ratios, calcite luminescence, and U-series dates suggest that the southern San Juan Mountains, at this high elevation site and southern aspect were substantially ice-free prior to 13.5 ka.

Middle Paleolithic variability in Central Asia: Lithic assemblage of Sel’Ungur cave

Since the beginning of 21st century, a new stage began in investigations of the Central Asian Palaeolithic. The main concern is to re-study the key regional sites, applying modern excavation techniques and up-to-date laboratory methods (including chronometric dating) in order to clarify the rationale and chronology of the local cultural sequences. This research allowed some crucial corrections about the chronological and cultural interpretations of the lithic industries in western Central Asia. This paper presents the first results obtained during our reexcavation of Sel’Ungur cave – usually assumed to be one of the earliest Paleolithic sites in Central Asia, described in the late 1980s as belonging to the early Acheulian technocomplex. Sel’Ungur cave is among the most important pre-Upper Palaeolithic site for our understanding of the Pleistocene inhabitants of Central Asia, as did not only yield rich lithic collections found stratified context but also numerous fossil faunal and even some hominin remains. Re-started at 2014, the new excavations at the site have provided enough evidence to refuse an Acheulian interpretation of site's assemblages. Based on detailed technological and typological analyses of the new lithic collection we argue that Sel’Ungurian complex fits better into the early stage of the regional Middle Paleolithic cultural variability. The previously available U-series date of around 126 ka (albeit without a reliable stratigraphic and spatial context), the new TL date 112 ± 19 ka establishing the lower limit, paleontological analyses of newly obtained material as well as the re-examination of the available information on macro- and microfaunal remains excavated in the earlier excavations, as well as the re-study of the anthropological finds support this assessment.

Speleothem evidence for the greening of the Sahara and its implications for the early human dispersal out of sub-Saharan Africa

Although there is a consensus that there were wet periods (greening events) in the Sahara in the past, the spatial extent and the timing of these greening events are still in dispute, yet critical to our understanding of the early human dispersal out of Africa. Our U-series dates of speleothems from the Northeastern Sahara (Wadi Sannur cave, Egypt) reveal that the periods of speleothem growth were brief and restricted to the interglacial Marine Isotope Stages MIS 5.5, MIS 7.3, and the early MIS 9 with a remarkable absence of the Holocene deposition of speleothems. These growth periods of Wadi Sannur cave speleothems correspond to periods of high rainfall and spread of vegetation (green Sahara). Distinct low δ18O values of speleothems indicate a distal moisture source that we interpret to be the Atlantic Ocean. These two lines of evidence from the Wadi Sannur speleothems thus suggest that maximal northward shifts in the West African monsoon system occurred during the growth periods of the speleothems, leading to greening of the Sahara, facilitating human migration into Eurasia. The periods of speleothem growth at Wadi Sannur cave are contemporaneous with important archeological events: (1) the earliest occurrence of the Middle Stone Age assemblages and Homo sapiens in North Africa (Jebel Irhoud), suggesting wide spread of greening conditions over the East–West transect of the Sahara, (2) the sharp technological break between the Acheulo-Yabrudian and the Mousterian industries, and (3) the arrival of Homo sapiens in Levant, indicating a key role of the Sahara route in early human dispersal out of Africa.

Post-IR IRSL290 dating of K-rich feldspar sand grains in a wind-dominated system on Sardinia

The reliability of a post-IR elevated temperature IRSL (290 °C; pIRIR290) is tested on wind-blown, sand-sized (180–250 μm) K-rich feldspar grains. The pIRIR290 ages were compared with quartz SAR-OSL data, other independent age controls and historical information. Three study areas along the coast of Sardinia (Italy) were selected: the south Alghero coast, the Bue Marino cave (E Sardinia) and the Alghero bay (NW Sardinia). Along the south Alghero coastline a thick dunefield system is widely recognised in the literature to represent the beginning of the last glacial phase (post 80 ka). From a single block sand-sized grains for quartz SAR-OSL and K-feldspar pIRIR dating were collected. The natural quartz SAR-OSL sample lies below the saturation limit of the dose response curve (De < 2xD0) giving a reliable age of 76 ± 6 ka. The fading-uncorrected pIRIR290 age of 73 ± 5 ka is in good agreement with the quartz result. A further test on older samples was carried out on the sedimentary succession at Bue Marino cave, which includes a sandy wind-blown unit, enclosed between two calcareous crusts. U-series dates of crusts constrain the aeolianite formation between ∼130 and ∼86 ka. The quartz SAR-OSL signals for aeolianite samples lies close to saturation and the resulting ages underestimate the independent age control. Instead, uncorrected pIRIR290 ages on K-feldspar extracts point to a formation of the wind-blown unit between ∼100 and ∼80 ka, in good agreement with the U-series data. The bleachability of the pIRIR290 signal was further investigated using samples from a modern coastal barrier system backing the Alghero bay. The dunefield was stabilized by plantation during the 1950s. The quartz SAR-OSL ages span from 2450 ± 170 years to 60 ± 13 years ago, consistent with the known coastal barrier stabilization. The pIRIR290 ages indicate an offset up to ∼1000 years. We can conclude that the pIRIR290 method on sand-sized K-feldspar grains shows great promise for samples at or beyond the quartz OSL age limit but should not be applied to Late Holocene or modern deposits.

CO2 outburst events in relation to seismicity: Constraints from microscale geochronology, geochemistry of late Quaternary vein carbonates, SW Turkey

Vein and breccia carbonates precipitated in a highly fractured/faulted carbonate bedrock in SW Turkey were investigated through high-resolution U-series geochronology, microstructural and geochemical studies including C–O–Sr isotope and rare-earth element and yttrium (REY) analyses. Petrographical observations and geochronological data are interpreted as evidence that the calcite veins formed through a crack-seal mechanism, mostly accompanied/initiated by intensive hydraulic fracturing of the host limestone in response to high-pressure fluids, which is manifested by multi-stage breccia deposits. Microscale U-series dates (272.6–20.5kyr) and geochemical compositions of the vein/breccia samples provide information on the timing and mechanism of the vein formation and identify the source of CO2-bearing fluids responsible for the carbonate precipitation. δ18OVPDB and δ13CVPDB values of the calcite veins range between −5.9 and −1.7‰, and −10.6 and −4.6‰, respectively. The isotopic compositions of the veins show highly fluctuating values as calcite grew successively perpendicular to vein walls, which, in combination with microstructural and geochronological constraints, are interpreted to reflect episodic CO2 degassing events associated with seismic and aseismic deformation. Oxygen and Sr isotope compositions (δ18OVPDB: −5.9 to −1.7‰; 87Sr/86Sr: 0.7082 to 0.7085) together with REY concentrations indicate deep infiltration of meteoric waters with various degrees of interactions mostly with the host limestone and siliciclastic parts of the basement rocks. Oxygen and carbon isotope compositions suggest CO2 degassing through intensive limestone dissolution. While majority of the veins display similar Post-Archaean Australian Shale (PAAS)-normalised REY variations, some of the veins show positive EuPAAS anomalies, which could be indicative of contributions from a deeply derived, heated, and reduced fluid component, giving rise to multiple fluid sources for the calcite veins. Vein calcite formed in fault-induced fractures offers insights into structural features, genetic characterisation of the parental fluids, and late Quaternary degassing of subsurface CO2 accumulations.

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

Recent exploratory drilling at Abric Romaní reveals that carbonate tufas similar to the archeologically rich levels excavated to date extend at least 30m 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 (~100mg), 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 230Th/232Th 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 ~55ka for a sample from level N of the existing excavation to ~110ka 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 17cm/ka during the later parts of MIS 5 to a maximum of 130cm/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 ~100ka. Thus, evidence for human presence at Abric Romaní now extends over ~60thousandyears.

LA-ICP-MS-derived U-concentrations and microstructural domains within biogenic aragonite of Arctica islandica shell.

Understanding of the uranium uptake processes (both in vivo and post-mortem) into the skeletal structures of marine calcifiers is a subject of multi-disciplinary interest. U-concentration changes within the molluscan shell may serve as a paleoceanographic proxy of the pH history. A proxy of this type is needed to track the effects of fossil fuel emissions to ocean acidification. Moreover, attaining reliable U-series dates using shell materials would be a geochronological breakthrough. Picturing the high-resolution changes of U-concentrations in shell profiles is now possible by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Here, we analyzed in situ U-concentration variations in sub-fossilized shells of ocean quahog (Arctica islandica), a commonly studied bivalve species in Quaternary geoscience, using LA-ICP-MS. Microstructural details of the shell profiles were achieved by the scanning electron microscopy (SEM). Comparison of the shell aragonite microstructure with the changes in U-concentration revealed that uranium of possibly secondary origin is concentrated into the porous granular layers of the shell. Our results reinforce the hypothesis that U-concentration variations can be linked with microstructural differences within the shell. A combination of LA-ICP-MS and SEM analyses is recommended as an interesting approach for understanding the U-concentration variations in similar materials.

New ESR and U-series dating at Caune de l'Arago, France: A key-site for European Middle Pleistocene

The Caune de l'Arago, located at Tautavel in the southern part of France, is one of the best documented Middle Pleistocene sites allowing a good understanding of human evolution in Europe. Since its discovery in 1829, the cave yielded more than 140 human remains associated with abundant lithic industries and thousands of faunal remains in a 10 m thick stratigraphical sequence divided in three complexes (Lumley et al., 2014). The Lower stratigraphic complex is only known from cores while the Middle and Upper ones can be divided into about 17 main archaeological levels indexed from the bottom to the top: from level Q to level A. Since 1981, a number of dates were done using practically all the methods available for dating Quaternary period up to 700 ka. U-series dates performed on the upper stalagmitic floor yielded a minimum age of 400 ka for human remains found in the underneath level G (Falguères et al., 2004). This age range confirmed the direct non-destructive gamma-ray age published more than 30 years before (Yokoyama and Nguyen, 1981). Recently, a methodological work was published on herbivorous teeth coming from different parts of the G level highlighting the difficulties to get reliable radiometric dates on a level so rich in bones and partly weathered by guano deposits or issues associated with carbonate accumulation (Han et al., 2010).This study presents new ESR/U-Series dates obtained on herbivorous teeth coming from the lowest excavated layers (Q–P levels) which yield an age range for the entire thick archaeological infilling. The new results suggest that the sedimentological levels containing lithic and faunal artefacts began to be deposited at 550 ka in the P–Q levels and a younger age of 350–400 ka for the F level. The P–Q levels which have yielded bifaces are one of the oldest evidence of the Acheulian culture in the southern part of Western Europe while the dates obtained on G level suggest a contemporaneity with la Sima de los Huesos and TD10 Dolina level at Atapuerca.

Combined uranium series and 10Be cosmogenic exposure dating of surface abandonment: A case study from the Ölgiy strike-slip fault in western Mongolia

Time-averaged fault slip-rates can be established by reliably dating the abandonment of an alluvial deposit that has been displaced by Quaternary movement along a cross-cutting fault. Unfortunately, many Quaternary dating techniques are hindered by uncertainties inherent to individual geochronometers. Such uncertainties can be minimised by combining multiple independent techniques. In this study, we combine 10Be exposure dating of boulder tops and U-series dating of layered pedogenic carbonate cements accumulated on the underside of clasts from two separate alluvial surfaces. These surfaces are both displaced by the active Ölgiy strike-slip fault in the Mongolian Altay Mountains. We date individual layers of pedogenic carbonate, and for the first time apply a Bayesian statistical analysis to the results to develop a history of carbonate accumulation. Our approach to the U-series dating provides an age of initiation of carbonate cement formation and avoids the problem of averaging contributions from younger layers within the carbonate. The U-series ages make it possible to distinguish 10Be samples that have anomalously young exposure ages and have hence been subject to the effects of post-depositional erosion or exhumation. The combination of 10Be and U-series dating methods provides better constrained age estimates than using either method in isolation and allows us to bracket the abandonment ages of the two surfaces as 18.0–28.1 kyr and 38.4–76.4 kyr. Our ages, combined with measurements of the displacement of the surfaces, yield a right-lateral slip-rate for the Ölgiy fault of 0.3–1.3 mm yr−1, showing that it is a relatively important structure within the active tectonics of Mongolia and that it constitutes a substantial hazard to local populations.

Metric and geometric morphometric analysis of new hominin fossils from Maba (Guangdong, China)

We present an analysis of a set of previously unreported hominin fossils from Maba (Guangdong, China), a cave site that is best known for the presence of a partial hominin cranium currently assigned as mid-Pleistocene Homo and that has been traditionally dated to around the Middle-Late Pleistocene transition. A more recent set of Uranium series dates indicate that the Maba travertine may date to >237 ka (thousands of years ago), as opposed to the original U-series date, which placed Maba at 135–129 ka. The fossils under study include five upper first and second molars and a partial left mandible with a socketed m3, all recovered from different parts of the site than the cranium or the dated sediments. The results of our metric and 2D geometric morphometric (‘GM’) study suggest that the upper first molars are likely from modern humans, suggesting a more recent origin. The upper second molars align more closely with modern humans, though the minimum spanning tree from the 2D GM analysis also connects Maba to Homo neanderthalensis. The patterning in the M2s is not as clear as with the M1s. The m3 and partial mandible are morphometrically intermediate between Holocene modern humans and older Homo sapiens. However, a minimum spanning tree indicates that both the partial mandible and m3 align most closely with Holocene modern humans, and they also may be substantially younger than the cranium. Because questions exist regarding the context and the relationship of the dated travertine with the hominin fossils, we suggest caution is warranted in interpreting the Maba specimens.

Age of Maba hominin site in southern China: Evidence from U-series dating of Southern Branch Cave

Maba hominin, one of the key representatives of archaic Homo sapiens in China, was originally attributed to around the Middle-Late Pleistocene transition (∼130 ka) based on biostratigraphic correlation and alpha-spectrometric U-series dating of fossil teeth. This paper reports mass-spectrometric U-series dates on speleothem samples intercalated with the deposits in Southern Branch Cave. Also presented here is a new survey of the entire Second Level Caves, which provides evidence that the so-called Southern Branch Cave is in fact the front section of the main corridor, and its obstruction marked the end of depositional processes throughout the caves at this level. Accordingly, the capping flowstone in Southern Branch Cave marks the minimum age of all fossiliferous deposits of the site. Maba hominin should thus be at least 230 ± 5 ka (2σ) old, most probably older than 278 ± 4 ka (2σ). This is consistent with an earlier interface between H. erectus and archaic H. sapiens, and would allow for an earlier presence of modern H. sapiens in eastern Asia.

The Middle–Upper Pleistocene Fronte Section (Taranto, Italy): An exceptionally preserved marine record of the Last Interglacial

The Fronte Section, a well-exposed stratigraphic succession from southern Italy (Taranto area), provides an uninterrupted marine sedimentary record of MIS 5e. At this location, a highly expanded (8.5m thick) stratigraphic succession, unconformably overlying Middle Pleistocene marine clay deposits, provides evidence for sea-level fluctuations during the Last Interglacial. An integrated study of Fronte Section, including facies analysis, detailed macrofaunal and meiofaunal characterization, and sequence stratigraphy, is presented. The occurrence of Persististrombus latus (=Strombus bubonius) and other warm-water indicators (“Senegalaise” – “Senegalian” – guests of Gignoux, 1913), together with the presence of the dinocyst Polysphaeridium zoharyi and ten U-series dates on Cladocora caespitosa samples, permit an unequivocal MIS 5e age assignment to the upper part of the study succession. Above a stratigraphic unconformity marked by the boring coastal-lagoonal bivalve Pholas dactylus, the MIS 5e succession displays a first transgressive suite of brackish to shallow-marine deposits. These latter include highly fossiliferous muds rich in C. caespitosa, overlain by a fossil-rich calcarenite, 2m-thick, yielding warm-water “Senegalian” mollusks. Above this prominent stratigraphic marker (regionally called panchina), which is interpreted to represent a short-lived phase of sea-level stillstand or gentle fall during MIS 5e, renewed transgression took place, leading to the accumulation of middle-outer shelf muds, about 5m thick. The maximum flooding zone is clearly identified on the basis of the turnaround from a deepening-up to a shallowing-up trend. The upper part of Fronte Section records a second fossil-rich, sublittoral calcarenite containing warm-water mollusks, which is interpreted to reflect the subsequent phase of sea-level highstand, likely correlative with the MIS 5e plateau.