Search

This research was carried out in north-central Poland, which was occupied by the ice sheet of the Saalian (Marine Isotope Stage [MIS] 6) and Upper Stadial of the Weichselian (MIS 2) glaciation. The application of the anisotropy of magnetic susceptibility (AMS) method supported by a digital elevation model (DEM) analysis of the orientation of glacial landforms allowed for the reconstruction of ice-sheet extent and ice movement directions of these two Pleistocene glaciations. The research used an innovative method of collecting AMS till samples from the glacial plateau areas. Based on the research, it was found that during the general recession of the ice sheet of the Saalian glaciation, a previously undescribed glacial transgression occurred, characterized by a different direction of ice-sheet movement. On the basis of detailed geomorphological studies of the area of terminal moraines, previously described in fragments, the maximum extent of the ice sheet during the Weichselian glaciation was clarified. The recession of the ice sheet of the Weichselian glaciation from the area of north-central Poland took place in four regressive or transgressive–regressive stages with variable directions of ice-sheet movement. The results obtained indicate the great potential of the AMS method in paleoenvironmental studies of glaciated areas. [ABSTRACT FROM AUTHOR]

The Lagoa Salgada is located in the Paraíba do Sul river delta plain on the coast of Rio de Janeiro state, Brazil, and is one of the few lagoons in the world that have well-developed recent stromatolites. Lagoa Salgada is a hypersaline lagoon formed in a very complex environmental system subjected to terrestrial and oceanic influences under different sea level regimes and climate variations. In addition, sediment and stromatolites are characterized by unusually positive inorganic δ13C VPDB values. For this reason, it has been the target of several geological and paleoenvironmental studies, which, in their great majority, require a geochronological technique in order to determine the changes in the environment over time. When radiocarbon (14C) dating is used, it is necessary to consider some details as the source of 14C in the environment and perform 14C ages calibration accordingly. In the present paper, a bibliographic survey was carried out in order to review the data treatment and improve the environmental evolution discussion based on accurate calibration. Using the Marine20 curve and an undetermined ΔR, we generated growth and depositional models to establish an overview of the formation of this lagoon. [ABSTRACT FROM AUTHOR]

Sedimentary records from the Kumtag (also known as Kumtagh) Desert (KMD) in northwestern China are investigated to better understand Late Quaternary paleoenvironmental changes in this hyper-arid region. Presented here are the results of probably the first systematic survey of sedimentary sequences from the KMD, with the chronology determined by the optically stimulated luminescence dating. The variation of sedimentary facies, supported by granular and geochemical paleoenvironmental proxies, is used to decipher the history of Late Quaternary environment changes. The results demonstrate that a constantly dry condition characterized the eastern KMD since the last glacial maximum, but with occurrences of wetter periods. From ca. 17 to 15 ka, fluvial activity was probably triggered by melting of glaciers in mountains located south of the KMD. A distinctly drier stage (ca. 13–7 ka) was recognized due to the prominent occurrence of aeolian sands. A wetter environment likely persisted between ca. 4.4 and 2.2 ka, consistent with evidence of human activities. While the causes of paleoenvironmental changes in the eastern KMD are still a matter of debate, the melting of glaciers in the Altyn-Tagh Mountains in the south must be considered as an important factor. [ABSTRACT FROM AUTHOR]

Ditch cuttings (69 samples) from a section of Awaizombe-1well located in the Northern Depobelt of the eastern Niger Delta Basin were used for this study. The lithology of the studied interval 1373–1812 m (439 m thick) consists of fissile grey shale and mudstone units. The scid method of sample preparation for palynormorphs' recovery was adopted. Analysis recorded a well-preserved and diverse assemblage of palynomorphs, rich in pollen, spores and dinoflagellate cysts (dinocysts). First and last occurrences of marker and age diagnostic species were used for palynostratigraphic interpretation. Four palynostratigraphic interval range zones were established: Psilatriporites sp.– Racemonocolpites hians Zone; early Oligocene (Rupelian age), Praedapollis africanus–Doualaidites laevigatus Zone; late Eocene (Priabonian age), middle Eocene (Lutetian and Bartonian ages), Doualaidites laevigatus – Praedapollis flexibilies Zone; and early Eocene (Ypresian age), Verrucatosporites usmensis – Retitricolpites ituensis Zone. The first downhole occurrence of D. laevigatus at the 1482 m marks the late Eocene/early Oligocene boundary. Established zones are useful for inter and intra basins correlation. Lithology and age of the studied section are suggestive of the lower Agbada Formation. Palaeoenvironmental interpretations using diagnostic species revealed two environments: brackish and inner neritic to upper bathyal (0–600 m) under relatively warm-water marine condition indicated by thermophilic dinocyst taxa, such as Lingulodinium machaerophorum , Polysphaeridium zoharyi and Homotryblium spp. The lithology and these types of environments are good sites for hydrocarbon generation. [ABSTRACT FROM AUTHOR]

We conducted the first taphonomic and paleoenvironmental study based on late Pleistocene–Holocene small mammal remains recovered from the famous Mylodon Cave (Cerro Benítez area, Última Esperanza, Chile). Most of the analyzed material came from the extensive excavations made by Earl Saxon in 1976. We also studied late Holocene small mammal samples of the neighboring rock shelter Dos Herraduras 1. Analyzed remains were mostly produced by owls, probably living inside the caves. In Mylodon Cave, the higher values of girdle bones are consistent with a windblown litter. We recorded nine species of rodents, seven cricetids, and two caviomorphs; almost all the identified taxa integrate recent local communities. Late Pleistocene–Holocene assemblages are characterized by the chinchilla rat Euneomys, indicating unforested areas around the caves under cold and moist climatic conditions. Middle Holocene amelioration is reflected by incremental rodent species richness, including the first record of taxa clearly associated with forest (e.g., Abrothrix lanosa). Late Holocene assemblages are markedly stable, indicating local conditions similar to the current (historical) environment. Quaternary rodents from Cerro Benítez area do not indicate abrupt environmental changes during middle–late Holocene, but a progressive trend towards forest increase. [ABSTRACT FROM AUTHOR]

The fourth millennium b.p. in the Maya lowlands provides an interesting case, with mobile, aceramic peoples documented, while ceramic-using villagers lived in other parts of Mesoamerica. Rather than ask why ceramic containers and village life took so long to reach the Maya lowlands, the question can be inverted to posit that a mixed horticultural-foraging adaptation was so effective that it persisted longer than elsewhere. I propose that the so-called 4.2 ka b.p. event was the ultimate cause of increased sedentism and the first adoption of ceramic containers in a limited number of regions of Mesoamerica. My musings are grounded in the comparisons of data from the Soconusco region of southern Mexico and evidence from northern Belize at Colha and Pulltrouser Swamp, as well as the Freshwater Creek drainage. I assume that proximate behavior must account for local adaptations and different rates of change in each region of Mesoamerica. Therefore, regional adaptation in northern Belize during the Late Archaic period provides the evidence with which to reconstruct local adaptation. Excavations and regional reconnaissance document a distinctive orange soil horizon at Progresso Lagoon associated with patinated chert tools and an absence of ceramics. Stone tool assemblages from the preceramic components of three sites in the region indicate a spatial separation of tool use and resharpening at island versus shore. Starch grains recovered from these stone tools indicate that preceramic peoples in northern Belize harvested maize and several other domesticated plant species. These data are consistent with local paleoenvironmental studies that document an extended period of horticultural activity during the fifth and fourth millennia b.p. prior to the adoption of ceramics. Lithic assemblages and associated dietary information from multiple sites provide glimpses of the data necessary to reconstruct Late Archaic period adaptation from a single locale. Such data will be required to understand the proximate causes for the transition to a more settled, village life. [ABSTRACT FROM AUTHOR]

This article discusses recent developments in the field of speleothem paleoclimate and paleoenvironmental science. Speleothems, such as stalagmites and stalactites, have been used to reconstruct past climate and environmental conditions using methods like U-Th absolute dating and stable isotope analysis. The article highlights the use of new techniques, such as U-Pb dating and the analysis of trace elements, clumped isotopes, and fluid inclusions, to extend the time range of speleothem-based paleoclimate reconstructions. The special issue includes a range of studies from different regions and time periods, covering topics such as hydroclimate variability, stalagmite formations, rainfall dynamics, and Holocene climate features. Additionally, the article introduces a web-based tool called the SISAL webApp, which aims to increase accessibility to the Speleothem Isotope Synthesis and AnaLysis (SISAL) database. Overall, these studies contribute to a comprehensive understanding of past climate variations. [Extracted from the article]

Marine mollusk shells have been extensively used to provide radiocarbon (14C)-based chronologies in paleoenvironmental and archaeological studies, however uncertainties in age measurements are introduced because secondary factors such as vital effects and diet may influence 14C incorporation into these shells. Deep burrowing and deposit feeding mollusks, in particular, may incorporate "old" carbon resulting in apparently older ages than their contemporary environment. In this study, we present paired 14C and stable isotope (δ13C and δ18O) measurements for nine species of known-age bivalves having different feeding strategies and collected in six localities around the NE Atlantic. We exclude potential "old" carbon contamination in these known-age mollusk shells, acquire a better understanding of local ecology and provide an improved context for the environmental interpretation of 14C ages. Our results indicate that, in the NE Atlantic, marine mollusk-derived 14C ages provide a reliable basis for environmental and archaeological investigation, independently of vital effects and differences in microhabitats, feeding strategies and sample location—all of which are apparent from stable isotopes. [ABSTRACT FROM AUTHOR]

To investigate the relationship between paleoenvironmental changes and marine reservoir effects, the radiocarbon ages of marine bioclasts and terrestrial plants from the same horizons of a sediment core in the Holocene Epoch were measured. This core, with a length of approximately 9 m, was obtained from the southern part of the Miyazaki Plain southeast of Kyushu Island, which faces the Kuroshio warm current. This drilling site is located in an uplift area associated with the subduction of the Philippine Sea Plate. Based on analyses of lithology, molluscan and foraminifera assemblages, and radiocarbon dating, we interpreted four sedimentary units in order of age: tidal flat, inner bay, Kikai-Akahoya volcanic ash, and delta plain. These paleoenvironmental changes were mainly associated with the sea-level rise during the deglacial period. The reservoir ages of nine pairs from the tidal flat to inner bay facies were found to be from the time span of 7300–8200 cal BP. The chronological changes in the reservoir effect are correlated with those seen in Holocene sediments of the other coastal area in East Asia. [ABSTRACT FROM AUTHOR]

Understanding the properties of time averaging (age mixing) in a stratigraphic layer is essential for properly interpreting the paleofauna preserved in the geologic record. This work assesses the age and quantifies the scale and structure of time averaging of land snail-rich colluvial sediments from the Madeira Archipelago (Portugal) by dating individual shells using amino acid racemization calibrated with graphite-target and carbonate-target accelerator mass spectrometry radiocarbon methods. Gastropod shells of Actinella nitidiuscula were collected from seven sites on the volcanic islands of Bugio and Deserta Grande (Desertas Islands), where snail shells are abundant and well preserved in Quaternary colluvial deposits. Results show that the shells ranged in age from modern to ~48 cal ka BP (calibrated radiocarbon age), covering the last glacial and present interglacial periods. Snail shells retrieved from two of the colluvial sites exhibit multimillennial age mixing (>6 ka), which significantly exceeds the analytical error from dating methods and calibration. The observed multimillennial mixing of these assemblages should be taking into consideration in upcoming paleoenvironmental and paleoecological studies in the region. The extent of age mixing may also inform about the time span of colluvial deposition, which can be useful in future geomorphological studies. In addition, this study presents the first carbonate-target radiocarbon results for land snail shells and suggests that this novel, rapid, and more affordable dating method offers reliable age estimates for small land snail shells younger than ~20 cal ka BP. [ABSTRACT FROM AUTHOR]

Peatland development and carbon accumulation on the Pacific coast of Canada have received little attention in paleoecological studies, despite wetlands being common landscape features. Here, we present a multi–proxy paleoenvironmental study of an ombrotrophic bog in coastal British Columbia. Following decreases in relative sea level, the wetland was isolated from marine waters by 13,300 cal yr BP. Peat composition, non-pollen palynomorph, and C and N analyses demonstrate terrestrialization from an oligotrophic lake to a marsh by 11,600 cal yr BP, followed by development of a poor fen, and then a drier ombrotrophic bog by 8700 cal yr BP. Maximum carbon accumulation occurred during the early Holocene fen stage, when seasonal differences in insolation were amplified. This highlights the importance of seasonality in constraining peatland carbon sequestration by enhancing productivity during summer and reducing decomposition during winter. Pollen analysis shows that Pinus contorta dominated regional forests by 14,000 cal yr BP. Warm and relatively dry summers in the early Holocene allowed Pseudotsuga menziesii to dominate lowland forests 11,200–7000 cal yr BP. Tsuga heterophylla and P. menziesii formed coniferous forest in the mid- and late Holocene. Tephra matching the mid-Holocene Glacier Peak–Dusty Creek assemblage provides evidence of its most northwesterly occurrence to date. [ABSTRACT FROM AUTHOR]

In the hinterland of the desert, valuable archives of paleoenvironmental evolution are scarce. Calcareous root tubes (CRTs) have a strong potential for reconstructing paleoenvironmental conditions. It is still unclear, however, whether chemical elements in the CRTs can provide insights into paleoenvironmental conditions. In this study, the major- and trace-element composition of 32 CRT samples from the Alashan Desert were analyzed by X-ray fluorescence spectrometry. Results showed that the elemental composition and content change were controlled by the parent material and climatic conditions at the time of CRT formation. Ca, Mg, and Sr were significantly affected by climate, whereas the enrichment of P is likely related to the growth of plants. Higher (lower) Mg/Ca and Sr/Ca ratios corresponded to higher (lower) effective moisture and a higher (lower) Mg/Sr ratio indicated a higher (lower) temperature during the middle Holocene (8–5 cal ka BP). The reconstruction results for effective moisture were consistent with those in the Asian monsoon margin of northwestern China, which were caused by higher monsoon precipitation and lower evaporation. Therefore, chemical elements in the CRTs can reflect changes in paleo-effective moisture and paleotemperature at a millennial resolution in this area. [ABSTRACT FROM AUTHOR]

The multi-layered settlement of Turganik in the Tok River valley (steppe region west of the Urals) has been studied using paleopedological and microbiomorphical methods. Early humans lived in the settlement during the Eneolithic epoch (the fifth millennium BC) and in the Early Bronze Age (the fourth millennium BC). The cultural layers attributable to the Atlantic period of the Holocene developed under conditions of a rather dry climate, with the landscapes being dominated by the grass and herb steppe. The settlement area was above the flood water level and was suitable for habitation. The soils in its vicinity were Kastanozems (Endosalic Protosodic). The final stages of the cultural layer formation bear traces of strong (though short-term) floods, with the deposits of the latter partly concealed traces of the preceding long-term arid phase. Maximum aridity was during the final interval of the Atlantic period. The Subboreal and Subatlantic periods were noted for meadow-chernozem soil formation (Luvic Chernozems [Stagnic]) and an increasing proportion of arboreal species in the pollen assemblages. Some phytoliths of aquatic plants were found in the assemblages dominated by those of meadow grasses. The climate was more humid and cool, although short episodes of aridity were possible. [ABSTRACT FROM AUTHOR]

Banwari Trace, a well-stratified shell midden located in southeastern Trinidad, provides the oldest known archaeological evidence of human settlement in the West Indies and has been crucial to our understanding of the initial peopling of the greater Caribbean region. Detailed excavation profile descriptions, soil and faunal analyses, accelerator mass spectrometry radiocarbon and optically stimulated luminescence dating, and stable carbon isotope analyses provide an accurate chronology and paleoenvironmental framework for the natural and anthropogenic depositional history of this significant archaeological site. Our findings support the recognition of three Middle Holocene strata at Banwari Trace, which represent significant periods of midden deposition and environmental change at: ~7800-7900 cal BP (Level 3); ~6900-7400 cal BP (Level 2); and ~5500-6200 cal BP (Level 1). Stable carbon isotope analyses show the landscape was dominated by C3 vegetation throughout the Middle Holocene with a possible drying episode near the end of the Middle Holocene climatic optimum. Cedrosan potsherds discovered in the uppermost 25 cm (Level 0) suggest that a Late Holocene radiocarbon age of ~2770-2200 cal BP for charcoal from this stratum is valid and possibly contemporary with an apparently intrusive human burial recovered in 1971 at a depth of ~20 cm. [ABSTRACT FROM AUTHOR]

Bison antiquus Leidy, 1852 was one of the largest and most widely distributed megafaunal species during the Late Pleistocene in North America, giving rise to the modern plains bison in the middle Holocene. Despite the importance of the ancient bison, little is known about its feeding ecology. We employed a combination of extended mesowear, and mesowear III to infer the dietary preference and habitat use of three Mexican samples of B. antiquus. These included two northern samples—La Piedad-Santa Ana and La Cinta-Portalitos—from the Transmexican Volcanic Belt morphotectonic Province, as well as one southern sample—Viko Vijin—from the Sierra Madre del Sur morphotectonic province. We found that the northern Mexican samples were primarily nonstrict grazers, whereas the southern sample displays a pattern consistent with mixed feeding habits. This suggests variability among the diets of the bison from these samples, caused by different paleoenvironments. This evidence complements the paleoenvironmental reconstructions in the studied localities; for the northern samples, open prairies composed of patches of woodland or shrubland and, for the southern locality, a fluvial floodplain with short-lived vegetation. In both scenarios, grasses (Poaceae) were nondominant. The dietary habits of our samples of ancient bison in Mexico are the southernmost dietary inference for the species in North America and expand our knowledge of the dietary habits of B. antiquus during the Late Pleistocene. [ABSTRACT FROM AUTHOR]

A new ichnogenus and ichnospecies, Spirolites radwanskii, is a spiral boring recognized in large limestone clasts deposited in a Miocene cliff-foot ramp. It is characterized by a semi-circular or inverted Ω-shaped cross section, gradually increasing width, gradual entrenching in the rock from the narrower side, consistent coiling direction, steep margin from the wider side, two-order annuli, and occasional truncation of the narrower side by the wider part. It is interpreted as a boring of vermetid gastropods, similar to the recent Dendropoma. Spirolites co-occurs with the bivalve borings Gastrochaenolites, mostly G. torpedo, sponge borings Entobia, and the spionid polychaete boring Caulostrepsis, which are typical of the Entobia ichnofacies. Spirolites was produced in very shallow, clean and warm sea waters. [ABSTRACT FROM AUTHOR]

Here we report a new find of abundant woody debris and cones in stratum of two sections located to the east of the Qinghai Lake basin in China. Analysis of the anatomical structure of the wood and cones confirmed that they are Picea crassifolia Kom. The results of accelerator mass spectrometry 14C dating indicate that the buried Qinghai spruce grew during 9.7–4.2 ka, and the ages of the large trunks or branches are mainly concentrated within the interval 7.5–6.5 ka. This finding gives direct evidence at the species level about the presence of coniferous forest in the early–middle Holocene in Qinghai lake basin. In addition, the buried cones suggest that the early-middle Holocene environment was suitable for the propagation of Picea crassifolia Kom. The variations in the occurrence of Qinghai spruce forest in the Holocene probably reflect changes in humidity/moisture. The humid early-middle Holocene was suitable for the growth and reproduction of Qinghai spruce forest, while a shift toward an increasingly arid climate during the late Holocene resulted in the disappearance of Picea crassifolia Kom. from the Qinghai Lake basin, although human activities may also have contributed to the environmental change. [ABSTRACT FROM AUTHOR]

The Sahara was wetter and greener during multiple interglacial periods of the Quaternary, when some have suggested it featured very large (mega) lakes, ranging in surface area from 30,000 to 350,000 km2. In this paper, we review the physical and biological evidence for these large lakes, especially during the African Humid Period (AHP) 11–5 ka. Megalake systems from around the world provide a checklist of diagnostic features, such as multiple well-defined shoreline benches, wave-rounded beach gravels where coarse material is present, landscape smoothing by lacustrine sediment, large-scale deltaic deposits, and in places, tufas encrusting shorelines. Our survey reveals no clear evidence of these features in the Sahara, except in the Chad basin. Hydrologic modeling of the proposed megalakes requires mean annual rainfall ≥1.2 m/yr and a northward displacement of tropical rainfall belts by ≥1000 km. Such a profound displacement is not supported by other paleo-climate proxies and comprehensive climate models, challenging the existence of megalakes in the Sahara. Rather than megalakes, isolated wetlands and small lakes are more consistent with the Sahelo-Sudanian paleoenvironment that prevailed in the Sahara during the AHP. A pale-green and discontinuously wet Sahara is the likelier context for human migrations out of Africa during the late Quaternary. [ABSTRACT FROM AUTHOR]

We present a paleoenvironmental and paleoclimatic reconstruction based on microfaunal assemblages preserved at Lezetxiki II Cave (Arrasate, Basque Country, Iberian Peninsula) and synthesize previously published and new chronological work from the cave to better understand the environmental history of the region. The stratigraphic sequence of this short gallery ranges from the end of the middle Pleistocene to the middle Holocene and has great micropaleontological relevance for the Iberian Peninsula, especially because it contains the most ancient small vertebrate remains found in the Cantabrian region, likely deposited during Marine Oxygen Isotope Stage 7–6. Thirty-two small vertebrate taxa, including two extinct species, were identified. Environmental reconstruction based on small vertebrates suggests an open landscape at the base of the sequence (three lower levels) that progressively changed to woodland in the upper levels. Other paleoenvironmental data suggest a similar interpretation of the environmental history of the region, and although some uncertainty in the environmental reconstruction and chronology still exists, our data provide a richly detailed record of small vertebrates from an area that likely represented an important late Quaternary migration corridor for species traveling between the Iberian Peninsula and European continent. [ABSTRACT FROM AUTHOR]

This paper reports a previously unidentified paleoenvironmental record found in sand dunes of the Atacama Desert, Chile. Long-term aeolian deflation by prevailing onshore winds has resulted in the deposition of sand on the irregular surface of a Miocene-aged anhydrite outcrop. Two deposits ~25 km apart, along the prevailing wind trajectory, were hand excavated then analyzed for vertical (and temporal) changes in physical and chemical composition. Radiocarbon ages of organic matter embedded within the deposits show that rapid accumulation of sediment began at the last glacial maximum and slowed considerably after the Pacific Ocean attained its present post-glacial level. Over this time period, grain sizes are seen to increase while accumulation rates simultaneously decrease, suggesting greater wind speeds and/or a change or decrease in sediment supply. Changes in δ34S values of sulfate in the sediment beginning ~10 ka indicate an increase in marine sources. Similarly, δ2H values from palmitic acid show a steady increase at ~10 ka, likely resulting from aridification of the region during the Holocene. Due to the extreme aridity in the region, these sand dunes retain a well-preserved chemical record that reflects changes in elevation and coastal proximity after the last glacial maximum. [ABSTRACT FROM AUTHOR]

The first systematic research on the funerary record at the Río Bote 1 (RB1) rockshelter, located next to the Bote River, a tributary of the Santa Cruz River in southern Patagonia, has revealed at least three human burial events dating to the very early Late Holocene and one dating to the middle Late Holocene. The RB1 site appears to have been used for both subsistence and inhumation activities. All of the burials uncovered postdate the deposition of a prominent volcanic ash layer. Technological information indicates that RB1 was used by groups that were also using spaces to the west and south. Mortuary evidence indicates connections with groups living in areas extending from the Última Esperanza region to the Pali Aike volcanic field, at least at the beginning of the Late Holocene. The selection of the same place for multiple burials may explain why so few human burials are known in southern Patagonia from the beginning of the Late Holocene and earlier periods, as it is possible that sites like RB1 are yet to be discovered. [ABSTRACT FROM AUTHOR]

Three gravity cores (LZK1, ZKA4, and CSJA6) from the incised Yangtze paleo-valley comprise a thick sequence of the post-glacial deposit. Nineteen genera (26 species) of the benthic foraminifers are described from these cores, with detailed down-core foraminiferal variations to investigate their paleoenvironmental implications. Three foraminiferal assemblages are recognized for the lower, middle, and upper parts of the cores respectively. The lower part is dominated by Ammonia beccarii var. and Florilus decorus with lower abundance and diversity. In the middle part, the foraminifers are abundant and diverse, dominated by both Ammonia beccarii var. and Elphidium advenum. Cavarotalia annectens, Pararotalia nipponica, and porcellaneous benthic foraminiferal forms are always present, sometimes abundant. The upper part is characterized by the Ammonia beccarii-Elphidium magellanicum assemblage, except for the Core ZKA4, which is barren of foraminifers in this interval. AMS 14C dates and foraminiferal assemblages both confirm that the transgression-regression sequence in these cores belongs to the "Ammonia transgression" during the Holocene. In addition to documenting the post-glacial sea-level fluctuations, the benthic foraminifers also reflect a warmer climate during the early-middle Holocene. The foraminiferal differences among the three cores can be used to interpret the influence of seawater during the post-glacial sea-level fluctuations. The area in the vicinity of Core ZKA4 was affected by marine water only during the middle Holocene, which was much shorter than the areas of the other cores. [ABSTRACT FROM AUTHOR]

Wonderwerk Cave has yielded one of the longest and most complete Holocene Later Stone Age (LSA) records for the arid interior of South Africa. This paper presents the results of a new radiocarbon dating program for Excavation 1 that is explored within a Bayesian model of all existing Wonderwerk Cave radiocarbon (14C) dates for the Holocene. The proposed model, using Phases within an OxCal Sequence model, provides robust age estimates for changes in the technological and paleoenvironmental record at the site. The more precise dates allow a comparison of the timing of climate shifts across the interior of southern Africa and begin to allow us to identify whether hiatuses in human occupation, or cultural shifts, are synchronous across broader areas of the subcontinent, or not. [ABSTRACT FROM AUTHOR]

Vitória Bay is located in the south-central part of the State of Espírito Santo (SES). Multiproxy analyses were performed on samples from a 490-cm-long sediment core collected at the coordinates 40°18′23′′W and 20°14′48′′S. The objective of this study was to identify and integrate the multiproxy data to determine the environmental dynamics during the Holocene. The material was subsampled every 10 m and submitted to standard methodological processing. The sediment core was dated to two depths: the oldest age was between 9396 and 9520 cal yr BP at a 480-cm depth, and the youngest age was from 7423 to 7511 cal yr BP at a 304-cm depth. The integrated analysis revealed evidence of three major environmental changes in Vitória Bay. The first phase had a fluvial influence (depth of 490–480 cm; 9396–9520 cal yr BP). This was followed by a transitional period (depth of 480–290 cm; 7423–7511 cal yr BP) with a salt influence due to the Last Marine Transgression (LMT). Later, the environmental stability was similar to that of today (290 cm to the core top). This was a reflection of the Last Marine Regression (LMR) in the Holocene. [ABSTRACT FROM AUTHOR]

Application of the glass fission-track dating method to Chester Bluff tephra (CBt), exposed in loess deposits at Chester Bluff along the Yukon River in east-central Alaska, has clarified the age of the immediately underlying fossiliferous interglacial bed. Surprise Creek tephra (SZt), at site CRH47 in the northern Old Crow basin of the Yukon Territory, is a correlative of CBt so that the new age information on CBt can also be applied to the interglacial sediments below SZt. Two independent age determinations were obtained on CBt, 243 ±28 ka and 249 ±26 ka, giving a weighted mean age and error of 246 ±19 ka. Therefore, the closely associated interglacial bed belongs to the early part of Marine Oxygen Isotope Stage (MIS) 7. The stratigraphy and paleoenvironmental setting of SZt show that deposition of the tephra occurred soon after interglacial conditions, when the climate became colder, probably between MIS 7.5 and 7.4, that is, slightly younger than the mean fission-track age, but within the 1σ uncertainty. This result tightly constrains the age of the rich mammalian faunal assemblage found at and just below SZt at the CRH47 site. [ABSTRACT FROM AUTHOR]

A new spinicaudatan species, Estherites? jocelynae new species, is described from more than fiftyspecimens collected from the Medicine Lodge Formation (early Oligocene) of the Beaverhead Basin in southwestern Montana, USA. This is the first spinicaudatan species reported from Cenozoic strata of North America and is the second-youngest fossil clam shrimp described globally. The new species extends the range of the superfamily Estheriteoidea into the Paleogene. Carapaces of E.? jocelynae n. sp. are preserved as a calcium carbonate replacement of the original chitin-calcium-phosphate structure, which is an uncommon style of preservation for spinicaudatans. The unique preservation coupled with the range extension suggests that the sparse Cenozoic fossil record of spinicaudatans may be partly attributable to preservation bias related to geochemical conditions rather than exclusively to diversity decline following the end-Cretaceous mass extinction. The presence of E.? jocelynae n. sp. in the Medicine Lodge Formation indicates that lakes in the Beaverhead Basin experienced seasonality and fluctuating lake levels with at least some drying at the lake margins. The ecological inferences support previous paleoenvironmental interpretations based on paleobotanical and other faunal evidence. [ABSTRACT FROM AUTHOR]

A megaslump at Batagaika, in northern Yakutia, exposes a remarkable stratigraphic sequence of permafrost deposits ~50–80 m thick. To determine their potential for answering key questions about Quaternary environmental and climatic change in northeast Siberia, we carried out a reconnaissance study of their cryostratigraphy and paleoecology, supported by four rangefinder 14C ages. The sequence includes two ice complexes separated by a unit of fine sand containing narrow syngenetic ice wedges and multiple paleosols. Overall, the sequence developed as permafrost grew syngenetically through an eolian sand sheet aggrading on a hillslope. Wood remains occur in two forest beds, each associated with a reddened weathering horizon. The lower bed contains high amounts of Larix pollen (>20%), plus small amounts of Picea and Pinus pumila, and is attributed to interglacial conditions. Pollen from the overlying sequence is dominated by herbaceous taxa (~70%–80%) attributed to an open tundra landscape during interstadial climatic conditions. Of three hypothetical age schemes considered, we tentatively attribute much of the Batagaika sequence to Marine Oxygen Isotope Stage (MIS) 3. The upper and lower forest beds may represent a mid–MIS 3 optimum and MIS 5, respectively, although we cannot discount alternative attributions to MIS 5 and 7. [ABSTRACT FROM AUTHOR]

Fruit carbonate of Buglossoides arvensis (syn. Lithospermum arvense) is a valuable dating and paleoenvironmental proxy for late Quaternary deposits and cultural layers because CaCO3 in fruit is assumed to be accumulated from photosynthetic carbon (C). However, considering the uptake of HCO3– by roots from soil solution, the estimated age could be too old depending on the source of HCO3– allocated in fruit carbonate. Until now, no studies have assessed the contributions of photosynthetic and soil C to the fruit carbonate. To evaluate this, the allocation of photo-assimilated carbon and root uptake of HCO3– was examined by radiocarbon (14C) labeling and tracing. B. arvensis was grown in carbonate-free and carbonate-containing soils (sand and loess, respectively), where 14C was provided as (1) 14CO2 in the atmosphere (5 times shoot pulse labeling), or (2) Na214CO3 in soil solution (root-labeling; 5 times by injecting labeled solution into the soil) during one month of fruit development. Distinctly different patterns of 14C distribution in plant organs after root- and shoot labeling showed the ability of B. arvensis to take up HCO3– from soil solution. The highest 14C activity from root labeling was recovered in roots, followed by shoots, fruit organics, and fruit carbonate. In contrast, 14C activity after shoot labeling was the highest in shoots, followed by fruit organics, roots and fruit carbonate. Total photo-assimilated C incorporated via shoot labeling in loess-grown plants was 1.51 mg lower than in sand, reflecting the presence of dissolved carbonate (i.e. CaCO3) in loess. Loess carbonate dissolution and root-respired CO2 in soil solution are both sources of HCO3– for root uptake. Considering this dilution effect by carbonates, the total incorporated HCO3– comprised 0.15% of C in fruit carbonate after 10 hr of shoot labeling. However, if the incorporated HCO3– during 10 hr of shoot labeling is extrapolated for the whole month of fruit development (i.e. 420-hr photoperiod), fruit carbonate in loess-grown plants incorporated approximately 6.3% more HCO3– than in sand. Therefore, fruit carbonates from plants grown on calcareous soils may yield overestimated 14C ages around 500 yr because of a few percentage uptake of HCO3– by roots. However, the age overestimation because of HCO3– uptake becomes insignificant in fruits older than approximately 11,000 yr due to increasing uncertainties in age determination. [ABSTRACT FROM PUBLISHER]

New samples of fusulinids collected in the Tengchong Block, western Yunnan, China, are systematically studied and presented here. The fusulinid fauna from the Xishancun section in the Shanmutang area is dominated by Chusenella and Nankinella, whereas that from the Shuangheyan area is composed mainly of Chusenella and Schwagerina. Both faunas are dated as Roadian–Capitanian (middle Permian). These new findings are integrated with fusulinid taxa reported earlier from the block to demonstrate the taxonomic features and paleogeographic significance of Permian fusulinids. The low generic diversity through early and middle Permian and the paucity of middle Permian neoschwagerinids and verbeekinids in the block confirm its Gondwana-affinity attributes. Moreover, the Permian fusulinids of the Tengchong Block are depauperate; i.e., consisting of a limited number of species with abundant individuals. This particular feature commonly suggests an inhospitable environment, and carbonates of varied facies containing these faunas in the Tengchong Block suggest a facies-independent factor as the reason, most likely the relatively low temperature of seawater. [ABSTRACT FROM PUBLISHER]

Numerous researchers discuss of the collapse of civilizations in response to abrupt climate change in the Mediterranean region. The period between 6500 and 5000 cal yr BP is one of the least studied episodes of rapid climate change at the end of the Late Neolithic. This period is characterized by a dramatic decline in settlement and a cultural break in the Balkans. High-resolution paleoenvironmental proxy data obtained in the Lower Angitis Valley enables an examination of the societal responses to rapid climatic change in Greece. Development of a lasting fluvio-lacustrine environment followed by enhanced fluvial activity is evident from 6000 cal yr BP. Paleoecological data show a succession of dry events at 5800–5700, 5450 and 5000–4900 cal yr BP. These events correspond to incursion of cold air masses to the eastern Mediterranean, confirming the climatic instability of the middle Holocene climate transition. Two periods with farming and pastural activities (6300–5600 and 5100–4700 cal BP) are evident. The intervening period is marked by environmental changes, but the continuous occurrence of anthropogenic taxa suggests the persistence of human activities despite the absence of archaeological evidence. The environmental factors alone were not sufficient to trigger the observed societal changes. [ABSTRACT FROM AUTHOR]

The discovery of the fully developed Formative sites of Cotocallao (ca. 3750-2350 cal. B.P.) in the Quito Basin and La Chimba (ca. 2650-1700 cal. B.P.) in the northern highlands of Ecuador has raised questions about their cultural antecedents, which have not been resolved despite decades of archaeological work in the region. Paleoenvironmental corin g investigations were conducted at Lake San Pablo in northern highland Ecuador to determine the date for the onset of prehistoric maize farming in the temperate highland valleys of this region. The investigations included analysis of lake sediments for pollen, phytoliths, diatoms, and tephra. Maize pollen was identified as early as 4900 cal. B.P., while maize phytoliths dated even earlier, to 6200 or 6600 cal. B.P. These results demonstrate a long history of maize farming in valleys around Lake San Pablo, but in the context of a punctuated record of major and minor volcanic eruptions. It is concluded that early horticultural sites predating Cotocallao and La Chimba must exist, but to find such sites, archaeologists will have to locate and study deeply buried A-horizon soils. [ABSTRACT FROM AUTHOR]

Paleosols record paleoclimatic processes in the Earth's Critical Zone and are archives of ancient landscapes associated with archeological sites. Detailed field, micromorphologic, and bulk geochemical analysis of paleosols were conducted near four sites at Olduvai Gorge, Tanzania within the same stratigraphic horizon as the Zinjanthropus ( Paranthropus ) boisei archeological site. Paleosols are thin (< 35 cm), smectitic, and exhibit Vertisol shrink–swell features. Traced across the paleolandscape over 1 km and just beneath Tuff IC (1.845 Ma), the paleosols record a paleocatena in which soil moisture at the four sites was supplemented by seepage additions from adjacent springs, and soil development was enhanced by this additional moisture. Field evidence revealed an abrupt lateral transition in paleosol composition at the PTK site (< 1.5 m apart) in which paleosol B, formed nearest the spring system, is highly siliceous, vs. paleosol A, formed in smectitic clay. Thin-section investigations combined with mass-balance geochemistry, using Chapati Tuff as parent material and assuming immobile Ti, show moderately intense weathering. Pedotransfer functions indicate a fertile soil system, but sodicity may have limited some plant growth. Paleosol bulk geochemical proxies used to estimate paleoprecipitation (733–944 mm/yr), are higher than published estimates of 250–700 mm/yr using δD values of lipid biomarkers. [ABSTRACT FROM AUTHOR]

Holocene climatic variability and human impact on vegetation are reconstructed from a region in central European Russia, which lies at an important ecotone between broadleaf forest and steppe. For the first time in this region we adopt a multi-proxy approach that combines analysis of local mire conditions from plant macrofossil and testate amoeba analyses with pollen-based quantitative climate reconstruction. The proxies indicate a long-term warming trend from 9700 to 7500 cal yr BP, interrupted by a series of short-term cold events. From 7500 to 5000 cal yr BP the results imply a relatively stable climate, warmer and drier than present, spanning the Holocene Thermal Maximum. Since 5000 cal yr BP the data suggest a change to cooler climate, but with centennial-scale variability. This shift at around 5000 cal yr BP is supported by extensive evidence from other sites. In the early Holocene, the region was occupied mainly by pine and birch forests. Broad-leafed forests of oak, lime and elm expanded after 7800 cal yr BP and remained dominant until the last few centuries. During the historical period, vegetation changes have been driven mainly by human activities. [ABSTRACT FROM AUTHOR]

Trochotomidae is a small but distinctive extinct family of pleurotomarioidean gastropods characterized by trochiform shells with an elliptical trema. Two new species of trochotomids are described from Pliensbachian deposits in the Neuquén Basin, Argentina. The new genus-group name Placotoma is proposed to replace the pre-occupied name Discotoma Haber non Mulsant. The record of Trochotoma (Trochotoma) protonotialis new species and Trochotoma (Placotoma) neuquensis new species in the early Jurassic of Argentina extends the paleobiogeographical distribution of the genus (and the family) to the Southern Hemisphere. The new taxa reported here represent a component of the pleurotomarioidean adaptive radiation that took place in the Tethyan region during the earliest Jurassic. They are related to local patch coral reefs of shallow, open-marine paleoenvironments, agreeing with the known habitat of most species of this family. The group was well represented in the Tethyan region during the Mesozoic, especially during the Jurassic, and the new species represent its southernmost occurrence. [ABSTRACT FROM PUBLISHER]

Using a combination of pollen, non-pollen palynomorphs (NPPs) and charcoal particle stratigraphies from sediment cores from two sites, along with historical records, we reconstructed paleoenvironmental change in mid-coastal California. The San Antonio Creek section contains a discontinuous, Holocene-length record, while Mod Pond includes a continuous late Holocene record. Together the records allow for interpretation of most of the present interglacial. The longer record documents coastal sage scrub and chaparral dominated by woodland elements early in the Holocene to about 9000 yr ago, a potential decline in woodland communities with drying conditions during the middle Holocene to about 4800 yr ago, and an expansion of coastal sage scrub with grassland during the late Holocene. Evidence for climatic fluctuations during the last 1000 yr at Mod Pond is equivocal, suggesting that the Medieval Climate Anomaly–Little Ice Age had modest impact on the Mod Pond environment. However, evidence of significant environmental change associated with cultural transitions in the 18th–19th centuries is stark. Introduction of non-native plants, establishment of cattle and sheep grazing, missionization of the native population, changes in burning practices during the Spanish period and enhanced cropping activities during North American settlement worked together to substantially modify the mid-California coastal landscape in about a century's time. [ABSTRACT FROM AUTHOR]

The Ziegler Reservoir fossil site near Snowmass Village, Colorado (USA), provides a unique opportunity to reconstruct high-altitude paleoenvironmental conditions in the Rocky Mountains during the Last Interglacial Period. We used four different techniques to establish a chronological framework for the site. Radiocarbon dating of lake organics, bone collagen, and shell carbonate, and in situ cosmogenic 10 Be and 26 Al ages on a boulder on the crest of a moraine that impounded the lake suggest that the ages of the sediments that hosted the fossils are between ~ 140 ka and > 45 ka. Uranium-series ages of vertebrate remains generally fall within these bounds, but extremely low uranium concentrations and evidence of open-system behavior limit their utility. Optically stimulated luminescence (OSL) ages (n = 18) obtained from fine-grained quartz maintain stratigraphic order, were replicable, and provide reliable ages for the lake sediments. Analysis of the equivalent dose (D E ) dispersion of the OSL samples showed that the sediments were fully bleached prior to deposition and low scatter suggests that eolian processes were likely the dominant transport mechanism for fine-grained sediments into the lake. The resulting ages show that the fossil-bearing sediments span the latest part of Marine Oxygen Isotope Stage (MIS) 6, all of MIS 5 and MIS 4, and the earliest part of MIS 3. [ABSTRACT FROM AUTHOR]

Paleoecological studies from Rocky Mountain (USA) high elevations encompassing the previous interglacial (MIS 5e) are rare. The ~ 10-m composite profile from the Ziegler Reservoir fossil site (2705 m asl) of central Colorado allows us to determine paleoenvironments from Marine Oxygen Isotope Stages (MIS) 6– 4 using pollen zones that are approximately equivalent to marine oxygen isotope stages. During Pollen Zone (PZ) 6 time, pollen assemblages dominated by Artemisia (sagebrush) suggest that alpine tundra or steppe occurred nearby. The transition to PZ 5e was characterized by a rapid increase in tree pollen, initially Picea (spruce) and Pinus (pine) but also Quercus (oak) and Pseudotsuga menziesii (Douglas-fir). Non-arboreal pollen (NAP) types increased during PZ 5d, while Abies (fir) and Juniperus (juniper) increased during PZ 5c. Pollen evidence suggests that temperatures during PZ 5b were as cold as during PZ 6, with the site again surrounded by alpine tundra. Picea dominated during PZ 5a before the onset of cooler conditions during PZ 4. The MIS 6–MIS 5e transition here was similar to the MIS 2–MIS 1 transition at other Rocky Mountain sites. However, the Ziegler Reservoir pollen record contains evidence suggesting unexpected climatic trends at this site, including a warmer-than-expected MIS 5d and cooler-than-expected MIS 5b. [ABSTRACT FROM AUTHOR]

A total of 272 oak (Quercus sp.) samples have been collected from large subfossil trees dredged from sediment deposited by the Sava and various tributary rivers in the Zagreb region of northwestern Croatia, and in northern Bosnia and Herzegovina. Measurement series of tree-ring widths from these samples produced 12 groups, totaling 3456 years of floating tree-ring chronologies spread through the last ca. 8000 years. This work represents the first step in creating a new, high-resolution resource for dating and paleoenvironmental reconstruction in the Balkan region and potentially a means to bridge between the floating tree-ring chronologies of the wider Mediterranean region and the continuous long chronologies from central Europe. [ABSTRACT FROM AUTHOR]

We present detailed biostratigraphy based on conodonts and palaeoenvironmental trends deduced from microfacies and conodont abundance through the Famennian (Late Devonian) at Col des Tribes (Montagne Noire, France). The succession is characterized by micritic limestones deposited in settings oscillating between mid to outer ramp. Facies contain poor fauna, widely dominated by nektonic organisms. This section is complete and one of the most conodont-rich for the Famennian of the north Gondwana-related area. The Upper Kellwasser event (Frasnian–Famennian boundary) and the Hangenberg (Devonian–Carboniferous boundary) have been lithologically identified. They are characterized by decimetre-thick black dysoxic to anoxic argillaceous sediments. The Condroz and annulata events, although not materialized by lithological changes, have been positioned due to the precise stratigraphy. The first event occurred during the deposition of condensed ferruginous facies (griotte limestones) and the second event during the deposition of micrites barren of benthic fauna. The combination of information from both facies and conodont biofacies changes allows a general sea-level curve through the entire Famennian for north Gondwana to be proposed for the first time. At Col des Tribes, the general trend is a slight deepening upwards from triangularis to trachytera zones, then a pronounced shallowing-upwards trend from upper trachytera to praesulcata zones. This curve correlates with the well-known reference curve from Euramerica concerning the late Famennian (trachytera to praesulcata Zones). There are some discrepancies in minor cycles which can be explained by tectonical phenomena at the onset of the edification of the Variscan belt in Europe. [ABSTRACT FROM AUTHOR]

We report high-resolution macroscopic charcoal, pollen and sedimentological data for Agua Caliente, a freshwater lagoon located in southern Belize, and infer a late Holocene record of human land-use/climate interactions for the nearby prehistoric Maya center of Uxbenká. Land-use activities spanning the initial clearance of forests for agriculture through the drought-linked Maya collapse and continuing into the historic recolonization of the region are all reflected in the record. Human land alteration in association with swidden agriculture is evident early in the record during the Middle Preclassic starting ca. 2600calyrBP. Fire slowly tapered off during the Late and Terminal Classic, consistent with the gradual political demise and depopulation of the Uxbenká polity sometime between ca. 1150 and 950calyrBP, during a period of multiple droughts evident in a nearby speleothem record. Fire activity was at its lowest during the Maya Postclassic ca. 950-430calyrBP, but rose consistent with increasing recolonization of the region between ca. 430calyrBP and present. These data suggest that this environmental record provides both a proxy for 2800years of cultural change, including colonization, growth, decline, and reorganization of regional populations, and an independent confirmation of recent paleoclimate reconstructions from the same region. [ABSTRACT FROM AUTHOR]

The article discusses the radiocarbon dates of the megafauna and botanical remain from Central Alberta, Canada. The research focuses on the factors of geological, paleontological and paleoenvironmental recond of the western North America. The research study outlines the importance of depositional context for preservatoin of significant paleontological resources in Western Canada. Also noted are the results of the research study.

Sum probability and Bayesian modeling of a substantial series of radiocarbon dates from a former extensive lake area in NW Belgium, known as the Moervaart area, allow important hydrological changes to be synchronized with Greenland Interstadial 1b (or Intra-Allerød Cold Period). It is postulated that the disappearance of nearly all open water systems (Moervaart lake, anastomosing gullies, and dune-slacks) in response to this short but abrupt cooling event was responsible for a nearly total retreat of hunter-gatherers already some centuries before the start of Greenland Stadial 1 (Younger Dryas). [ABSTRACT FROM AUTHOR]

A case study of the Neolithic comb ceramic site Pezmog 4 of the Kama culture presents a situation when results of radiocarbon dating change long-existing concepts concerning the development of archaeological events. Until the early 2000s, the chronology of the Kama culture, distributed mainly in the Kama and Vychegda River basins, has been based on comparative-typological analysis. Estimates of the age of this culture changed from the 3rd millennium BC in the 1950s to the 1st half of the 4th millennium BC by the 1990s. Research concerning the Pezmog 4 site in the central Vychegda River basin in 1999-2002 has abruptly changed this chronological understanding. The data obtained put the age of the early stage of Kama culture within the time range 5750-5620 cal BC and allowed us to propose the existence of another way of early pottery distribution in the forest zone of eastern Europe at the beginning of the 6th millennium BC. This innovation probably penetrated from the trans-Ural region. [ABSTRACT FROM AUTHOR]

A summary is presented of more than a decade-long study of direct radiocarbon dating for one of the most important human burials in Eurasia, the Sungir site in eastern Europe. Eighteen 14C dates were produced before early 2014 on three skeletons (Sungir 1-3), and there is still no consistency in the results. In the absence of other independent methods to establish the antiquity of Sungir, a careful analysis is performed of the site's stratigraphy, paleoenvironment, and 14C dates run on animal bones from the same layer as the burials. Although the conclusions of this work cannot be guaranteed to be absolutely correct, we suggest that at the present stage of research the age range of ~26,000-27,210 BP is the most probable time for the creation of the elaborate human burials at the Sungir site. [ABSTRACT FROM AUTHOR]

Accurate reconstruction of the paleo-Mojave River and pluvial lake (Harper, Manix, Cronese, and Mojave) system of southern California is critical to understanding paleoclimate and the North American polar jet stream position over the last 500ka. Previous studies inferred a polar jet stream south of 35°N at 18ka and at ~40°N at 17–14ka. Highstand sediments of Harper Lake, the upstream-most pluvial lake along the Mojave River, have yielded uncalibrated radiocarbon ages ranging from 24,000 to >30,000 14CyrBP. Based on geologic mapping, radiocarbon and optically stimulated luminescence dating, we infer a ~45–40ka age for the Harper Lake highstand sediments. Combining the Harper Lake highstand with other Great Basin pluvial lake/spring and marine climate records, we infer that the North American polar jet stream was south of 35°N about 45–40ka, but shifted to 40°N by ~35ka. Ostracodes (Limnocythere ceriotuberosa) from Harper Lake highstand sediments are consistent with an alkaline lake environment that received seasonal inflow from the Mojave River, thus confirming the lake was fed by the Mojave River. The ~45–40ka highstand at Harper Lake coincides with a shallowing interval at downstream Lake Manix. [ABSTRACT FROM AUTHOR]

Abstract: To evaluate the potential of using surficial shell accumulations for paleoenvironmental studies, an extensive time series of individually dated specimens of the marine infaunal bivalve mollusk Semele casali was assembled using amino acid racemization (AAR) ratios (n=270) calibrated against radiocarbon ages (n=32). The shells were collected from surface sediments at multiple sites across a sediment-starved shelf in the shallow sub-tropical São Paulo Bight (São Paulo State, Brazil). The resulting 14C-calibrated AAR time series, one of the largest AAR datasets compiled to date, ranges from modern to 10,307calyr BP, is right skewed, and represents a remarkably complete time series: the completeness of the Holocene record is 66% at 250-yr binning resolution and 81% at 500-yr binning resolution. Extensive time-averaging is observed for all sites across the sampled bathymetric range indicating long water depth-invariant survival of carbonate shells at the sediment surface with low net sedimentation rates. Benthic organisms collected from active depositional surfaces can provide multi-millennial time series of biomineral records and serve as a source of geochemical proxy data for reconstructing environmental and climatic trends throughout the Holocene at centennial resolution. Surface sediments can contain time-rich shell accumulations that record the entire Holocene, not just the present. [Copyright &y& Elsevier]

Recent estimates of when Hawai'i was colonized by Polynesians display considerable variability, with dates ranging from about A.D. 800 to 1250. Using high resolution paleoenvironmental coring data and a carefully defined set of archaeological radiocarbon dates, a Bayesian model for initial settlement was constructed. The pollen and charcoal assemblages of the core record made it possible to identify and date the prehuman period and also the start of human settlement using a simple depositional model. The archaeological and paleoenvironmental estimates of the colonization date show a striking convergence, indicating that initial settlement occurred at A.D. 940-1130 at a 95 percent highest posterior density region (HPD), and most probably between A.D. 1000 to 1100, using a 67 percent HPD. This analysis highlights problems that may occur when paleoenvironmental core chronologies are based on bulk soil dates. Further research on the dating of the bones of Rattus exulans, a Polynesian introduction, may refine the dating model, as would archaeological investigations focused on potential early site locations. [ABSTRACT FROM AUTHOR]

Abstract: Slope deposits in semiarid regions are known to be very sensitive environments, especially those that occurred during the minor fluctuations of the late Holocene. In this paper we analyse Holocene colluvium genesis, composition, and paleoenvironmental meaning through the study of slope deposits in NE Spain. Two cumulative slope stages are described during this period. In the study area, both slope accumulations are superimposed and this has enabled an excellent preservation of the aggregative sequence and the paleosols corresponding to stabilisation stages. 14C and TL dating, as well as archaeological remains, provide considerable chronological precision for this sequence. The origin of the accumulation of the lower unit is placed around 4295–4083calyr BP/2346–2134calyr BC (late Chalcolithic) and it developed until the Iron Age in a cooler and wetter climate (Cold Iron Age). Under favourable conditions, a soil A-horizon was formed on top of this unit. A new slope accumulation was formed during the Little Ice Age. Within the slope two morphogenetic periods ending with A-horizons are distinguished and related with two main cold–wet climatic events. The study of these slopes provides a great amount of data for the paleoenvironmental and geoarchaeological reconstruction of the late Holocene in NE Spain. [Copyright &y& Elsevier]

Radiocarbon accelerator mass spectrometry (AMS) techniques were used to date total organic carbon and plant seeds in the 1Fs core sequence (36°48'N, 100°08'E) from Qinghai Lake, China. This core was drilled ~18 m into Qinghai Lake sediments as part of an international cooperative research project, "Scientific Drilling at Qinghai Lake in the Northeastern Tibetan Plateau: High-Resolution Paleoenvironmental Records of Eastern Asia Linked to Global Change," which began in 2004. Based on the differences in lithology and total organic content (TOC) in core 1Fs, the core was divided into 3 sections for age-modeling purposes: the upper ~499 cm lacustrine silty clay to clay; the middle unit of silty clay with silt layers from 499-901 cm; and the lower 901-1861 cm silty clay, loess-like silt, and fine sand layers. Three different approaches are applied to the reservoir age problem. First, a simple linear regression gives an offset of 1342 yr. If the core is divided into three sections, linear regressions can be applied separately for the three segments, which results in an age estimate for the average hardwater effect of ~135 yr BP for the surface section up to 499 cm. If extrapolated for deeper sections, these results imply a higher reservoir offset for those two sections, which may be as much as 1143 and 2523 yr, but this assumes that there are no discontinuities in the core. A third approach using a wiggle-matching approach gave an offset of 196 yr. This study concludes that the reservoir age of Qinghai Lake is complex, but these new data add to our understanding of the 14C chronology of Qinghai Lake for the last 32 ka. [ABSTRACT FROM AUTHOR]