Search

To explore the main controlling mechanism of hydroclimatic conditions during the last deglaciation on eastern Tibetan Plateau (TP), clay mineral records in Xinmocun lacustrine sediments were analyzed. The results indicate that high illite + chlorite contents (>92%) in the section represent the primary product of strong physical weathering in a tectonically active area. The chemical weathering index (IC) was used to monitor hydrological changes in the section. Under the transition from glacial to interglacial periods, the fluctuation amplitude of IC during humid periods was greater than that during dry periods. The IC demonstrates changes in hydrological conditions on a millennial scale. From 18.7 to 16.8 ka, high values of IC and illite crystallinity suggest strong hydrolysis in humid conditions. From 16.8 to 11.7 ka, low IC values suggest weak hydrolysis during a five-millennium long dry period, which was followed by a more humid period from 11.7 to 10.5 ka. The overall arid hydrological conditions during the last deglaciation on eastern TP probably resulted from northward shift of the intertropical convergence zone driven by enhanced insolation, leading to the extension of the Indian monsoon to the interior of East Asia. Our findings suggest that the Indian summer monsoon has dominated hydrological conditions on eastern TP since the onset of deglaciation at approximately 16.8 ka. [ABSTRACT FROM AUTHOR]

A flowstone section in the Račiška pečina Cave (Classical Karst, SW Slovenia) records multiple chronostratigraphic and palaeoclimatic proxies that can be correlated with other records on the global scale (Mediterranean region, Japan). Its upper part has an excellent record of the Matuyama/Brunhes (M/B) magnetic reversal. The M/B reversal zone, which is 6 mm in thickness, was detected by a high-resolution palaeomagnetic analysis of the sequence. An age model based on oxygen isotopic stratigraphy locates this quick transition in mid-MIS 19, between 777.9 and 777.2 ka, with the midpoint at 777.7 ka. The transition is marked by abrupt changes in stable isotopic compositions, trace element concentrations and flowstone fabrics that point to temperature and precipitation changes. Two distinct maxima in trace element concentrations at the beginning and the end of the M/B transition indicate two periods of higher precipitation, with increased washes of clay minerals into the cave. In addition, the stable isotopic (δ13C and δ18O) compositions indicate that significant cooling and high precipitation occurred during the M/B reversal within the generally warm MIS 19. [ABSTRACT FROM AUTHOR]

Investigations of the unconsolidated Upper Pleistocene – Holocene cave deposits of the Northern Urals resulted in detailed biostratigraphical and palaeoenvironmental data. The article summarizes data from important stratigraphical levels exposed in 19 cave localities, most part of which represent several layers dated to different periods. These data cover the period from the beginning of the Upper Pleistocene (MIS 5-4) to the end of the Upper Holocene. At the beginning of Marine Isotope Stage 3 (MIS 3), open woodlands were distributed, which at the end of MIS 3 were replaced by Forest–steppe landscapes. At the beginning of MIS 2 (LGM), Periglacial steppe landscape was distributed. At the end of MIS 2 and at the beginning of the Holocene (MIS 1), semi-open landscapes were common. At the beginning of the Middle Holocene, they were replaced by taiga landscapes. Fish were present in the fauna of the Northern Urals in the Upper Pleistocene and Holocene. Amphibians in the Upper Pleistocene as part of the fauna of the region appear only at its beginning (MIS 5-4) and end (Bølling – Allerød period). Since the beginning of the Holocene (MIS 1), they have been constantly present in the fauna of the Northern Urals. Reptiles appear in the fauna of the region only in the Middle Holocene. During the Upper Pleistocene, the avifauna and fauna of small mammals were dominated by species of open landscapes, and the fauna of large mammals was dominated by species of open and semi-open landscapes. At the beginning of the Holocene, the avifauna and theriofauna increased the number of species associated with tree and shrub vegetation and near-aquatic species. Since the beginning of the Middle Holocene, the avifauna and theriofauna have been dominated by species of taiga landscapes. Palynological data and data on the fauna of small and large mammals allow us to separate the deposits of the Upper Pleistocene and Holocene. These data also allow us to separate the deposits of the beginning (MIS 5-4), middle (MIS 3), end (MIS 2)) of the Upper Pleistocene, Lower, Middle and Upper Holocene (MIS 1). [ABSTRACT FROM AUTHOR]

Understanding supra-regional climate variability such as the changes in the North Atlantic realm is important to identify the drivers of the climate system. In this study maar lake sediments from the Eifel (western Germany) were analysed with a multi-proxy approach and compared to central and western European speleothem growth phases. C org (chlorins) and the pollen assemblage were analysed from two sediment cores of the Hoher List infilled maar lake. To generate C org (chlorins) and pollen records covering the entire last 130,000 yr b2k (years before year 2000 CE), the data from this study were stacked with published data from other Eifel maar lake sediment cores (Sirocko et al., 2013, 2021, 2022). The sediment cores from Hoher List infilled maar lake were dated by marker tephra layers giving chronological anchor points and the precise dating of the sediment cores was performed by the tuning of the C org (chlorins) records to the NGRIP δ18O record (Rasmussen et al., 2014). The speleothems, whose growth phases are compared to the lake sediment proxy records, were compiled from the literature as well as speleothems from Dechencave (western Germany) dated by the 230Th/U-method in this study. The C org (chlorins) variability shows the bioproductivity in the maar lake, which is related to water temperature and corresponds to the Greenland Interstadials (GIs) in the NGRIP δ18O record indicates its dependence on supra-regional climate variations in the North Atlantic. The pollen record shows three periods of forest with temperate forest species, during the Eemian, early Marine Isotope Stage (MIS) 3, and the Holocene. Speleothem growth in four caves in central and western Europe (Dechencave, Spannagel Cave, Hölloch Cave, Villars Cave) is predominantly sensitive to cold periods with glaciers and/or permafrost conditions above the caves inhibiting speleothem growth. The forested phases and phases of high bioproductivity in the Eifel correspond well with phases of speleothem growth indicating three warm phases in central Europe during the last glacial cycle. [ABSTRACT FROM AUTHOR]

Speleothems, particularly stalagmites are extensively used to reconstruct paleoclimatic and paleomonsoon changes by using stable oxygen and carbon isotopes along the growth profile of a stalagmite sample. Trace and rare earth elements (REEs) variations in stalagmites are widely recognized as indicators of past precipitation and local hydrology. The amalgamation of isotopic and trace element proxies in speleothems has been regarded as an important tool to infer past climate and hydro-chemical fluctuations. Current advancements in geochemical techniques have enabled us to generate high-resolution paleo-records of almost all trace and REEs from stalagmites. However, their assessment is dependent on numerous factors that control the formation of a stalagmite. Here we present a geochemical record from a well dated stalagmite (VSPM1) from a cave located in the southern India. The stalagmite grew between 15,610 and 13,160 yr BP as revealed by its StalAge modelled ages from eight U–Th dates. This study demonstrates significant variations in trace and REEs during the last deglacial time interval of 2100 years and suggests variations in drip water chemistry. The relative amount of trace elements in colloidal solutions originating from the soil organics and weathered particles of host dolomitic rock may have altered with climatic changes. It appears that trace and REEs of VSPM1 stalagmite have responded to fluctuations in Indian Summer Monsoon (ISM) intensity during the time interval of this study. [ABSTRACT FROM AUTHOR]

In this paper, we described fossils from six mammal taxa (Coendou magnus Cuvier, 1823; Nothrotherium maquinense (Lund, 1839); Tamandua tetradactyla (Linnaeus, 1758); Leopardus wiedii (Schinz, 1821); Didelphis sp.; and Dicotyles tajacu (Linnaeus, 1758)) found in Toca da Barriguda cave (Campo Formoso, Bahia, Brazil). To better understand the isotopic paleoecology of these taxa, AMS radiocarbon dating and carbon and oxygen isotopic analyses were performed. The radiocarbon ages indicate the occurrence of Condou magnus at 33,171–33,765 Cal yr BP, Tamandua tetradactyla at 43,944–44,496 Cal yr BP, Leopardus wiedii at 45,475–46,157 Cal yr BP, and Didelphis sp. at ∼50,227 cal yr BP. Of these taxa, five were carnivorous/omnivorous, only Coendou magnus was herbivorous and lived in low-density forest and arboreal savanna habitats (δ 13C = −12.8‰ to −8.4‰; p i C 3 = 80–90%) during the late Pleistocene. An increase in a dry climate in the region between 50 cal kyr BP (δ 18O = 27.1‰) and 27 cal kyr BP (δ 18O = 34.0‰) was suggested based on the oxygen isotopic values found in the mammalian bone fossils, which presents similarity and good correlation with the oxygen isotopic values recorded in stalagmites from two caves in Brazil. [ABSTRACT FROM AUTHOR]

Speleothem deposits in nowadays arid environments are important climate archives, as they indicate phases of enhanced precipitation and can precisely be dated by uranium-series dating. So far only very few of such archives have been found in the today hyper-arid Saharo-Arabian Desert (SAD). Therefore, the study at hand fills a gap that exists for speleothem climate archives in Northeast Africa. A new record from Saqia Cave (Central Eastern Desert, Egypt) documents for the first-time speleothem growth in Egypt for all sub-stages of MIS 5 and singular phases during MIS 6. Most important growth phases occur during periods of strong increase and maximum orbitally-forced northern hemisphere insolation, but also during phases of low insolation, which are in general attributed to aridity in North Africa. Here, at least semi-arid climate conditions are proposed for periods of low insolation during stadials of MIS 5. This suggests an impact of different possible sources of precipitation, apart from large scale shifts of the African monsoon, such as Red Sea Troughs, tropical plums and a larger spatial extent of the Mediterranean winter-rainfall zone. Concerning the spatial rainfall pattern in Egypt, we propose a considerable east to west rainfall gradient in Egypt for the Last Interglacial and suggest a stronger impact of variable moisture sources in the Eastern Desert near the Mediterranean and Red Sea in comparison to the more continental Western Desert of Egypt. This reveals more favorable pre-conditions for an enhanced land use potential in the past. Therefore, the more sustaining wetter climate in the Eastern Desert point to a recurring feasible dispersal corridor for Homo sapiens from the tropical climate into the temperate climate regime throughout MIS 5. Such a more humid climate provided an ideal basis for long-term, favorable environmental conditions east of the Nile Valley, creating a kind of contiguous landscape corridor that may have been attractive to humans and wildlife alike, linking the East African tropical climate regime with that of the temperate zone in Northeast Africa and Eurasia. [ABSTRACT FROM AUTHOR]

Indian summer monsoon (ISM) variability in the late Holocene (last 4000 years) is of great interest as the arid phase of ISM and cultivation of kharif (rainy season) crops started in this period. The present study aims to revisit the available speleothem records to study ISM rainfall variations and possible controlling factors in different Indian regions viz., core monsoon zone (CMZ), peninsular, the Himalaya, and the Bay of Bengal in the last 4000 years. The late Holocene encompasses notable global warm periods viz., Medieval Climate Anomaly, Roman Warm Period (RWP) & Minoan Warm Period, and cold periods viz., Dark Age cold period and Little Ice Age (LIA). ISM rainfall declines until the middle of RWP in all the regions. The decline is linked with the southward migration of the Intertropical convergence zone caused by the northern Hemisphere summer insolation. Though the Solar insolation follows the same trend, all the records show large variability with the disappearance of the declining trend around the middle of RWP. This change coincided with the reversal in the north Atlantic Sea surface temperature (SST) trend, northern hemisphere temperature, and abrupt changes in the southeastern Indian Ocean SST. This period also witnessed high El-Nino Southern Oscillation activities. This synergy of ISM variations in the characterized zones falls apart during the pre-LIA with a slight increasing (decreasing) trend in CMZ and Bay of Bengal (peninsular and Himalayan). The spatially variable response of ISM rainfall in recent centuries might be caused by the interaction between internal variability and external forcing and also by anthropogenic-induced warming and aerosol forcing. [ABSTRACT FROM AUTHOR]

Speleothem isotope records have been widely used in the forefront of paleoclimate researches. Although the oxygen isotope (δ18O) records of speleothems remain the most commonly used hydroclimate proxy, the carbon isotope (δ13C) and trace element records of speleothem have also shown their unique advantages in charactering regional-local hydroclimate variations. In this study, we present two high-resolution (seasonal-monthly) and precisely dated speleothem δ13C records (NB2 and NB3) over the past 120 years from Niubi cave in Southeast China. Our analyses show that hydroclimate-induced changes in the regional vegetation coverage appear to be the primary control on the speleothem δ13C values over the past 120 years. However, during the late 1950s to early 1960s, a large high δ13C excursion is observed in the NB record, which is apparently linked to a special human activity in China's modern history, the so-called "Great Leap Forward in Iron and Steel". We suggest that the large degree of damages to regional vegetation occurred during the time period resulted in the observed high speleothem δ13C values, as the local precipitation remained in an ordinary state inferred from δ18O and trace element data. The persistent decreasing trend in the NB δ13C record during the 1980–2018 CE may be attributed to the increased vegetation effect via increases in precipitation, temperature and atmosphere CO 2 , as well as the decrease of δ13C of atmospheric CO 2. [ABSTRACT FROM AUTHOR]

In recent years, many researchers have studied spatial variation of summer monsoon precipitation pattern in eastern China during the last 50 years by using instrumental data. However, precisely dated high-resolution reconstructed records spanning over more than a hundred years are still sparse. Here, we present a seasonally-resolved speleothem multi-proxy (Mg/Ca, δ18O c and δ13C) record spanning 1824–2009 CE from E'mei cave, Jiangxi Province, Southeast China. For the last 180 years, the δ13C record shows similar variation to the Mg/Ca record, and both are consistent with local precipitation, but δ18O c record shows a unique variation different from δ13C and Mg/Ca records. We suggest that both δ13C and Mg/Ca can reflect changes in local precipitation while δ18O c is mainly influenced by large-scale monsoon circulation on the long-term trend. Comparison of the Mg/Ca record between E'mei and Shihua caves indicates that the variation of summer monsoon precipitation in the lower reaches of the Yangtze River is opposite to that in northern China during the last ∼150 years, consistent with the pattern of the "northern drought and southern flood" in eastern China observed in instrumental data. • Speleothem δ13C and Mg/Ca can be used to reflect changes in local precipitation. • Speleothem δ18O c is dominantly influenced by large-scale circulation different from δ13C and Mg/Ca for the last 180 years. • The "northern drought and southern flood" pattern inferred from speleothem is consistent with modern observations. [ABSTRACT FROM AUTHOR]

We review the archaeological, chronological, and biological data from multiple karst caves in southern China that date to the late-Paleolithic to early-Neolithic transition. Our review shows that the radiocarbon dates, although having a large quantity, do not align with the known cultural sequences correlated among the cave sites (based on the degree of sophistication of artefact manufacturing) and they conflict with the corresponding paleoclimatic conditions revealed by the biological data. Most of these radiocarbon dates are older than expected, and their samples probably incorporate dead carbon through the reaction with groundwater. We argue that, when correlated with global paleoclimate records, the chronological framework provided by the biological datasets provides a more robust chronology than the available radiocarbon dates. Accordingly, all the Neolithic layers reviewed, with their plentiful biological remains of tropical/subtropical and aquatic/water-loving species, are likely to have been deposited in Holocene, and the Paleolithic cultural layers likely date to the Younger Dryas or the Bølling-Allerød. Our review suggests that the late-to-postglacial climate change helped initiate the development of Neolithic cultures in East Asia. We attribute this development to the growth of creeks/wetlands and their associated ecosystems (including the spreading of wild rice) during the period of climate warming and wetting, which greatly increased accessible food, water, and mud resources, providing opportunities for ancient peoples to recognize wild rice and to invent polishing stone tools and making pinched earthenware. [ABSTRACT FROM AUTHOR]

The 230Th dating (238U–234U–230Th dating method) has become one of the most important dating methods for Quaternary research. However, the 230Th/232Th ratio of 4.4 ± 2.2ⅹ10−6 is widely used for age correction in 230Th dating method. Here, we collected active speleothems with exactly known age and zero-year-old calcium carbonate from caves and dated them by 230Th dating. Our data indicated that the initial 230Th/232Th ratio can be one order of magnitude higher than the ratio of 4.4 ± 2.2 × 10−6. High initial 230Th/232Th ratio may result in false and comparatively old calculated age than the real age of young samples with low 238U concentration. So, the accurate initial 230Th/232Th ratio of active speleothem deposited in the same cave, instead of the general initial 230Th/232Th ratio, is essential for the precise age correction of young speleothem samples of low 238U concentration. Finally, we proposed a procedure to correlate modern observation and speleothem based paleoclimate reconstruction, on the basis of precise 230Th age which corrected by the true initial 230Th/232Th ratio. [ABSTRACT FROM AUTHOR]

This work highlights the potential significance of palaeoclimate model outputs in explaining the physical processes and mechanisms to better understand the speleothem-based proxy records of the precipitation and temperature signals during the Indian northeast and southwest monsoon from 850 to 2000AD. Thus, discussion is mainly focused on this conception by providing insights for aligning modeling preferences with the proxy records. δ18O speleothem values show that precipitation over northeast India (NEI) remained constantly higher than that over the summer core monsoon zone (CMZ) from 850-2000AD. Based on the dynamical numerical coupled model (CSIRO-Mk3L-1–2) outputs, the data are in alignment with the presence of four proxy-based major extreme climatic events: Dry Century (DC), Medieval Climatic Anomaly (MCA), Extreme Dry Century (EDC) and Little Ice Age (LIA) during the last millennia. In these extremes a significant trend in diurnal temperature range (DTR), in particular, is correspondingly observed. These extremes and associated mechanisms are examined using surface energetics and corresponding atmospheric-oceanic coupled processes. The analysis of downward radiative (shortwave and longwave), latent and sensible heat fluxes provided better rationale and understanding of associated physical processes and mechanisms. It is found that the latent and sensible heat fluxes were balanced by downward radiative fluxes and the remaining part of energy was anomalously trapped inside the surface, thus reflecting anomalous climatic behavior during these extremes. [ABSTRACT FROM AUTHOR]

On the Iberian Peninsula, abrupt climate shifts during the Late Pleistocene impacted human and natural systems. Our knowledge of human adaptive responses to these climatic perturbations has improved in recent years with the development of new radiocarbon techniques that have increased the temporal resolution of cultural chronologies. At the same time, new high-resolution paleoclimatic records from Greenland ice cores, deep-sea sediment cores, speleothems, and microfaunal assemblages have permitted detailed paleoenvironmental reconstructions. Combined with the archaeological record of culture change, these data sets allow for a better understanding of the nature of human socio-ecological systems during the Late Pleistocene. Here we present new data on the Gravettian occupations at Lapa do Picareiro, a cave site in Portugal with a long continuous stratigraphic sequence spanning MIS 3 and 2. The ongoing excavation of Lapa do Picareiro has revealed at least three Gravettian levels with very different patterns of raw material use and technological reduction. The Early Gravettian levels contain a quartzite flake assemblage with several refitting clusters and a small chert assemblage with nosed endscrapers and bladelet technology. The Late or Terminal Gravettian level contains carinated endscraper/core-bladelet technology, mainly quartz, with chert blade production, and a few bone tools. The faunal assemblages also have a different character. Both contain a similar range of medium and large ungulates but the earlier Gravettian has a much richer and more diverse assemblage of small animals. These combined archaeological data sets provide a new perspective on Gravettian human adaptations in response to climate shifts, especially Heinrich Event 3 and Greenland Interstadials 4 and 3. [ABSTRACT FROM AUTHOR]

Societal concerns about future hydroclimate changes urge a thorough understanding of the governing processes. Here, an analysis of Middle and Late Holocene speleothem-based hydroclimate reconstructions and paleoclimate model simulations reveals sub-millennial fluctuations in the spatiotemporal variability of precipitation in the European and Mediterranean regions, that complements previous dendrochronological and pollen-based reconstructions with an improved temporal resolution. Although insolation forcing is the primary driver of Holocene hydroclimate changes in Europe on a multimillennial scale, the evaluation of the principal component analysis of speleothem records and correlations with sea surface temperature data indicates that North Atlantic ocean circulation played a significant role in the sub-millennial variation of continental moisture transport, with an increasing importance during the Late Holocene. The combined evaluation of speleothem-based data, climate simulations and sea surface temperature records therefore advances our understanding of the governing processes of Holocene hydroclimate changes in the European and Mediterranean regions. [ABSTRACT FROM AUTHOR]

Studies of the abrupt climate events that punctuated the warm Holocene epoch allow us to understand the climate system, forecast future climate change, and interpret the cultural transformations. Paleoclimate records around the world show manifestations of prominent climate anomalies between 6000 and 5000 calibrated years before present (cal BP). However, a comprehensive review of these anomalies remains unavailable in China. In this article, we collected, compiled, and analyzed proxy climate evidence from 49 sites recorded by a variety of natural archives, including lacustrine sequences, speleothems, peat profiles, an ice core, and marine sediments, to document these changes. Our synthesis results indicate that pronounced climatic anomalies generally characterized by cold and dry conditions occurred during 6000–5000 cal BP, which were associated with weakening of the Asian summer monsoon. However, these anomalies show a lack of absolute synchronicity or equality by various proxy records because of the different proxy sensitivities and/or dating uncertainties. Such 6000–5000 cal BP climatic anomalies also have possible equivalents in proxy records from various regions around the world. Comparison of paleoclimate records with climate forcing time series suggests that both the reduced solar activity and a long-term trend of orbitally-driven insolation change are the main driving mechanisms for these short-lived climate changes. More quantitative and higher-resolution palaeoclimatic reconstructions are needed to fully capture the magnitude, timing, and mechanism of the 6000–5000 cal BP climatic anomalies. [ABSTRACT FROM AUTHOR]

High-resolution proxy records help to understand natural forcing of climate variability and improving our capability to predict climate variability on decadal to centennial time scales. Present study from the Mawmluh cave, northeastern India shows sudden shifts in speleothem oxygen isotope values, indicating several abrupt changes in the Indian summer monsoon (ISM) during ~212 BCE to 1986 CE. Moderate ISM conditions prevailed during ~212 BCE to 400 CE punctuated with weak intervals, strong ISM during 400 and 500 CE and from 640 to 1060 CE, whereas weak ISM conditions prevailed during 520–540 CE, 820–850 CE and 940–980 CE and after 1060 CE. The interval from 1060 to 1986 CE witnessed decreased precipitation than the previous millennium. The latter phase of the Medieval Climate Anomaly (MCA; 1060 to 1200 CE) was quite drier in contrast to the earlier intervals. The ISM was generally weak during the Little Ice Age (LIA; 1350 to 1850 CE) with short-term pulses of high precipitation when sun-spot activity was high. The data shows the weakest ISM condition during 1640–1740 CE (Maunder Minimum) of the last two millennia. Variations in extra-tropical northern hemisphere temperatures due to volcanic activity and solar insolation, and accompanying northward/southward shifting of the Inter-Tropical Convergence Zone played a pivotal role in modulating the strength of the ISM during the past two millennia. [ABSTRACT FROM AUTHOR]

The most commonly used paleoclimatic proxies in speleothem studies are the carbon and oxygen stable isotopes and the trace elements of calcite. However, assessing the incorporation of other components, such as organic matter, may also be of interest in interpreting and reconstructing the climate during speleothem growth. In this work, the incorporation of humic and fulvic acids derived from overlying soils is proposed as the cause of the red coloration of speleothems from the Goikoetxe Cave (Busturia, Bizkaia). Through the application of petrological studies combined with X-ray fluorescence, UV luminescence, Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) analysis, it has been possible to correlate a variation of organic content in the overlying soils and the red coloration, being this stain a main proxy to study and reconstruct the seasonal paleoclimatic parameters during the speleothem formation. [ABSTRACT FROM AUTHOR]

In Guangxi Zhuang Autonomous Region, southern China, Quaternary mammalian assemblages, commonly known as " Stegodon - Ailuropoda fauna", are well documented in the central and southwest parts of the region. Unfortunately, our knowledge of Quaternary biogeographic variation in other areas of Guangxi is poor due to limited systematic investigations. Here, we report the faunal remains from the newly discovered Diaozhongyan ("DZY") cave site in northeast Guangxi. Our initial excavation in autumn 2016 resulted in the removal of 10 square meters of sediment and the discovery of 304 pieces of large mammal teeth. Biostratigraphic correlations indicate a late Middle Pleistocene age and in situ fossil teeth and calcites were Uranium-series dated to ~210 ka. The DZY faunal assemblage consists of many typical components of the traditional " Ailuropoda - Stegodon " fauna representative of southern China. Interestingly, giant pandas, identified as Ailuropoda melanoleuca baconi , are one of the dominant components of the DZY fauna (15% of the entire assemblage). However, giant pandas rarely dominate Quaternary faunal assemblages in southern China. In addition, fossil orangutan (Pongo weidenreichi), one of the most common species in central and south Guangxi during the Middle Pleistocene, is absent in DZY in northeast Guangxi. Further, fossil orangutans have not been reported from other sites in Hunan or Hubei province. We hypothesize that the Nanling Mountains served as a geographic barrier for this species. Fossil orangutans are present southwest of this biogeographic line, but are absent northeast of the line. This biogeographic boundary needs to be further evaluated with additional studies. [ABSTRACT FROM AUTHOR]

The interpretations of late Quaternary climate variation in the Kalahari are controversial. Only few speleothem humidity records do exist and reconstruction of aridity periods using aeolian sediments is challenged by considerable dating uncertainties. On the other hand studies on the large structural lake basins of the Kalahari have to cope with tectonics and the active catchment being far in the north, in a different climate zone. Thus hydrological signals from such palaeolakes may not or only partly reflect Kalahari palaeoclimate. The sediments of a regional drainage basin, west of the Tsodilo Hills, northern Kalahari, archive hydrological signals not superimposed by remote river catchment and tectonics. A ca. 3 m thick sediment profile near the palaeoshore of the former lake exhibits two lake highstands dated to MIS 3b and LGM. Geomorphological studies, fossil aquatic assemblages, their comparison to modern analogues and geochemical analyses, including sclerochronological stable isotope patterns from gastropod shells, suggest relatively deep, freshwater to oligohaline, open-basin lake periods. The data indicates that the climate was more humid than today, with two intra-annual rainfall maxima during the LGM, but likely under temperature regimes similar to modern times. The lake highstands were probably in phase with an inter-hemispheric Atlantic climate seesaw, which may imply that the main moisture source was rather the southern Atlantic than the Indian Ocean. [ABSTRACT FROM AUTHOR]

Loess-based proxies have been widely used to infer glacial-interglacial to millennial-scale changes of the East Asian monsoon. However, the characteristic of millennial-scale variability is still unclear during glacial-interglacial cycles in loess-palaeosol sequence. Here, we present high-resolution (5-cm) elemental results of a 96.7-m thick Mangshan loess-palaeosol sequence on the southeastern Chinese Loess Plateau to emphasize millennial monsoon changes. We explore time series of loess proxies (magnetic susceptibility, CaCO 3 content, Ca/K, Fe/K, and Rb/Sr ratios) and speleothem δ18O records and decompose these proxies into intrinsic components using the ensemble empirical mode decomposition method. Synthesized signals of low- and high-frequency components can track the monsoon variability at glacial-interglcial and millennial timescales, respectively. The proportions of millennial components of the loess proxies vary from 9.4%~13.4%, less than that in Chinese speleothem δ18O record (~24.4%). Among five loess proxies, Fe/K ratio is the most sensitive indicator of millennial-scale summer monsoon oscillations, exhibiting abrupt changes similar to that of the Chinese speleothem δ18O record. The amplitude of abrupt monsoon changes recorded in Mangshan is larger during interglacials than glacials, which is in line with Gulang records, implying the lower sensitivity of loess proxies to weak weathering during glacilals and an interglacial amplification of abrupt summer monsoon changes. [ABSTRACT FROM AUTHOR]

This paper summarizes the current state of knowledge about the millennial scale climate variability characterizing Marine Isotope Stage 3 (MIS 3) in S-Europe and the Mediterranean area and its effects on terrestrial ecosystems. The sequence of Dansgaard-Oeschger events, as recorded by Greenland ice cores and recognizable in isotope profiles from speleothems and high-resolution palaeoecological records, led to dramatic variations in glacier extent and sea level configuration with major impacts on the physiography and vegetation patterns, both latitudinally and altitudinally. The recurrent succession of (open) woodlands, including temperate taxa, and grasslands with xerophytic elements, have been tentatively correlated to GIs in Greenland ice cores. Concerning colder phases, the Greenland Stadials (GSs) related to Heinrich events (HEs) appear to have a more pronounced effect than other GSs on woodland withdrawal and xerophytes expansion. Notably, GS 9-HE4 phase corresponds to the most severe reduction of tree cover in a number of Mediterranean records. On a long-term scale, a reduction/opening of forests throughout MIS 3 started from Greenland Interstadials (GIs) 14/13 (ca. 55–48 ka), which show a maximum in woodland density. At that time, natural environments were favourable for Anatomically Modern Humans (AMHs) to migrate from Africa into Europe as documented by industries associated with modern hominin remains in the Levant. Afterwards, a variety of early Upper Palaeolithic cultures emerged (e.g., Uluzzian and Proto-Aurignacian). In this chronostratigraphic framework, attention is paid to the Campanian Ignimbrite tephra marker, as a pivotal tool for deciphering and correlating several temporal-spatial issues crucial for understanding the interaction between AMHs and Neandertals at the time of the Middle to Upper Palaeolithic transition. [ABSTRACT FROM AUTHOR]

The speleothem stable carbon isotope (δ13C) is an important proxy for paleoclimate reconstruction. Understanding the stable carbon isotope composition of dissolved inorganic carbon (δ13C DIC) in drip water is crucial for the interpretation of speleothem δ13C signals. In this study, we present two years of drip water δ13C DIC data and its hydrogeochemistry variables (e.g. P C O 2 , Ca2+, Mg/Ca, SO 4 2−, pH, drip rate, saturation index of calcite, electrical conductivity) in the Shawan Cave. We also conducted continuous in situ monitoring of P C O 2 in the atmosphere, soil air, and cave air and microenvironmental factors. The results show that cave air CO 2 primarily originates from soil air CO 2 , but there is an unsynchronous seasonal variation between cave air CO 2 and soil air CO 2 , which is likely caused by cave ventilation. Cave ventilation is also responsible for seasonal variations in drip water δ13C DIC and speleothem growth. Cave air exchange leads to higher drip water δ13C DIC and rapid speleothem growth in the spring and summer seasons, and cave air stagnation results in lower drip water δ13C DIC and slow speleothem growth. The impact of isotopically light CO 2 of soil air on drip water δ13C DIC during spring and summer seasons is more than during autumn and winter seasons, where the more isotopically light CO 2 of soil air is enriched by drip water under cave air exchange conditions. Since speleothems growth is rapid in the spring and summer seasons, the speleothems δ13C of the Shawan Cave have the potential to record climate information for the spring and summer seasons. Additionally, by comparing the speleothem δ13C values of eleven caves, we found that paleoclimate signals recorded by speleothem δ13C revealed different seasonal biases under different ventilation types. Therefore, it is necessary to determine the cave ventilation type in order to understand how speleothem δ13C responds to climate change in a ventilated cave. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Non-marine carbonates such as travertine, tufa and speleothem are quite sensitive for climatic fluctuations. This study presents the new dating and the first pollen records from Afyon (Sarıkavak) tufas, SW-Turkey, together with lithofacies descriptions, geochemical and petrographic results obtained from drilling cores (SL-2, SL-6 and SL-7). The data extensively provides insight into palaeoenvironmental and palaeoclimatic changes during the Middle-Late Pleistocene period. According to core samples, these fluvial tufa occurrences formed in high-gradient and stepped fluvial conditions have been defined as barrage-dammed and terraced-slope systems in the investigated area. The depositional lithofacies are moss tufa included macrophytes, bryophytes and vertical stems, phytoclastic tufa, peloidal tufa, micritic tufa, microbial tufa, intraclastic tufa, extra-formational tufa, lime-muddy clay and paleosol level, in respectively. The new U/Th radiometric dating and stable isotopes are evaluated together with previously published results. In regard to new radiometric data, tufa deposits occurred predominantly during the Marine Isotopic Stages, at 313.3 ± 21 (MIS 9), 295.8 ± 63 (MIS 8-9), 230.8 ± 42 (MIS 7d-e), 228.8 ± 12 (MIS 7d), 215.7 ± 17 (MIS 7c) and 188.2 ± 16 (MIS 6-7a) ka, respectively. The climatic changes occurring between glacial and interglacial periods (such as during the Middle –Late Pleistocene) might probably influenced the precipitation of tufas in the area. In addition, the less negative and the more positive carbon isotopic values (between −0.8 and + 1.3‰ V-PDB) could be related to the progressive downstream CO 2 degassing from host rocks, enhanced by high-velocity current conditions, changes in the soil-CO 2 contribution and photosynthesis. The changes of δ18O values (between −8.3 and −10.1‰ V-PDB) are most probably related to variable effects of evaporation in depositional environment. Palynofloral data, gives important clues about the paleovegetation and paleoclimate of the region. This field survey has been conducted the first time in this area. Both carbon values and palynological findings show that drought conditions were dominantly present in the Pleistocene period, but in some processes drought conditions decreased depending on the amount of rainfall. The increasing amount of gymnosperm pollens is more likely to appear in more humid conditions due to the decreasing of drought condition in this time interval. [ABSTRACT FROM AUTHOR]

In tropical Southern Hemisphere South America, late Quaternary marine core and speleothem records provide different proxies and accurate chronologies correlating millennial-scale intervals of increased precipitation with southward shifts of the Intertropical Convergence Zone (ITCZ). However, the climatic effect of these intervals on coastal landforms is poorly understood. Here we investigated the response of abrupt and long-lasting climate events during the Marine Isotope Stages 3 and 2 in a 13.8-m thick sand succession located in a large-scale coastal eolian system, the Lençóis Maranhenses Dunefield, NE Brazil, where winds and precipitation are anti-phased and controlled by the single action of the ITCZ. A chronology of the sediment overburden determined by optically stimulated luminescence (OSL) dating of 14 sediment samples obtained at 1-m intervals showed ages between 132.2 ± 7.0 and 12.9 ± 0.6 thousand years ago in stratigraphic order. A multi-proxy approach based on grain size, surface grain texture, heavy minerals, thermoluminescence (TL) sensitivity, inorganic geochemistry, reflectance, and magnetic parameters from 268 sediment samples collected at 5-cm intervals indicated periods of dune building and stabilization. Significant stabilization periods are synchronous with Heinrich Stadials 6, 4, 3, 2, and 1, and Greenland Stadial 4, within age model uncertainties. Heavy mineral analysis indicated a steady sand source to the dune succession, while TL sensitivity analysis of quartz grains showed the input allochthonous sediments during stadials. The preservation of peak dune activity during the Last Glacial Maximum is attributed to the enduring precipitation brought by the subsequent Heinrich Stadial 1 event. • A 13.8-m stabilized eolian deposit in the Lençóis Maranhenses Dunefield was investigated. • A multi-proxy approach was essential in determining periods of dune-building and stabilization. • Periods of dune stabilization are synchronous with stadial events of MIS3–MIS2. [ABSTRACT FROM AUTHOR]

Coímbre cave (Peñamellera Alta, Asturias) is an Upper Palaeolithic site in Northern Spain, spanning an occupation sequence from the Gravettian to the Magdalenian periods. The upper layers -layer I and II-, corresponding to the Upper Magdalenian, register the highest intensity of human activity. In this paper, we analyse raw material functionality at the site through the study of cut-marks found on bone remains. At Coímbre, we have documented mainly quartzite, followed by flint; other raw materials are found in very low frequencies. There are several types of local quartzite that appear mainly as flaking debitage and stone tools such as burins and scrappers. On the other hand, flint is mainly knapped to elaborate blades and bladelets, as well as specialised implements, such as different types of side scrappers. Retouched flakes on flint are relatively more abundant than those made on quartzite. In this paper we employ the use of photogrammetry, geometric morphometrics and statistics to analyse the cut-marks from the Upper Magdalenian assemblage of Coímbre cave. Our aim is to determine the lithic raw material preferentially used for carcass processing at the site. [ABSTRACT FROM AUTHOR]

A stalagmitic flowstone deposit from the Béke Cave (called Nagy-tufa deposit), East-Central Europe is characterized by complex, climate related textural and geochemical records as documented from a drill core (BNT-2 core) covering the period of 4 to 1 ka cal BP. The core location was monitored in an earlier study. Based on monitoring, textural and chemical relationships, it has been hypothesized that the stable carbon isotope signal of the flowstone deposit is a regional humidity record, indicating wet periods 3.8 to 3.4, 3.0 to 2.8 and 2.0 to 1.6 ka cal BP, and a prominent dry period between 2.1 and 2.7 ka cal BP. Furthermore, stable H isotope data of inclusion-hosted water were used to reconstruct the atmospheric temperatures that fit independent regional paleotemperature records, indicating warm conditions around 2.7 ka BP and a relatively cold period between 2.5 and 1.5 ka BP. Comparisons with regional speleothem records and reconstructed North Atlantic Oscillation data indicate that the Late Holocene paleohumidity changes recorded by the BNT-2 stable carbon isotope record can be detected in the entire Western-Central European region with further links to the North Atlantic realm. [ABSTRACT FROM AUTHOR]

In the study we present results of stable isotope analysis (δ18O, δ13C) of two stalagmites (SPD-1 and SPD-2) from Strašna peć Cave, situated on Dugi otok Island in the Central Adriatic region. The growth interval of the speleothems based on U-Th dating covers the period from 4.4 ka to 1.5 ka. Both speleothems show frequent δ18O and δ13C fluctuations with similar average values (δ18O value of -4‰ for both speleothems; and average value of δ13C-8.5‰ and −8.8‰, respectively). In order to reconstruct the Holocene climatic conditions in the Eastern Adriatic, the speleothem isotopic record is discussed and compared with other Holocene records. They reveal periods of drought which occurred at 4.3–4 ka and around 3.5 ka, with relatively wet phases between. From 3 ka, there is a general trend towards dryness as evidentiated by the relatively high δ18O values of -3.5‰ to -2.5‰ recorded in speleothem SPD-1. There is distinct trend of drying during the Roman Warm Period and further toward the Dark Age Cold Period (DACP) with shorter periods of wetter conditions. These changes coincide well with the other records, thus revealing regional events along the Eastern Adriatic. [ABSTRACT FROM AUTHOR]

Abstract A study of pollen, fossil mammals and lithology (including grain-size analysis) of the terrigenous deposits in the Bukovynka Cave enables the reconstruction of the environments of several geochronologic subdivisions of the Middle Pleniglacial, Late Glacial and Holocene. A comparison of pollen assemblages in surface samples from the cave deposits and from the soils prove the importance of cave palynology for palaeovegetation reconstruction. The same patterns were shown by a comparison of pollen from hyaena coprolites in the cave and their enclosing sediments. In the Trapeznyi Chamber record, the two interstadials and one stadial identified are correlated with those of the Moershoofd interval, and the following stadial (after 41,000 yrs BP) is compared with the Hosselo stadial of Western Europe. In the Sukhyi Chamber record, Late Glacial times (around 10,700 yrs BP) differed from the Holocene in having a much harsher climate (with the spread of boreal forest). During the Holocene, a relatively wet phase, transitional from Atlantic to Early Subboreal, was separated from the similar phase of the Late Subboreal (2800 yrs BP) by a drier Middle Subboreal (with the disappearance of water-loving trees and the existence of steppe rodents). The Subatlantic was the wettest time, with culmination of a broad-leaved flora in the Roman (2300–1800 yrs BP) and Medieval (1000 yrs BP) Warm Periods. The cultivation of Cerealia started from 2800 yrs BP, and forest clearances increased after the Medieval Warm Period. [ABSTRACT FROM AUTHOR]

Abstract Determining the processes and conditions that control and affect the precipitation of carbonates in cave environments is essential to correctly interpret speleothem-based proxies and reconstruct past climate and environmental changes. Therefore, two cave systems rich in speleothems and that are located at different distances from the Adriatic Sea were selected to conduct cave monitoring during 2013–2014: 1) the Barać caves (Lower and Upper) situated in the inner part of Croatia; 2) the Lower Cerovačka Cave located on the northern slope of the southeastern part of Velebit Mountain, closer to the Adriatic coast. The monitoring included microclimate measurements, analyses of the elemental and stable isotope composition of drip water and precipitation, as well as stable isotope and 14C measurement of modern calcite precipitates formed on light bulbs. The stable isotope composition of drip waters in the Barać caves shows systematically lower values than those found in amount-weighted annual precipitation, which indicates that the source of the infiltrating water dominantly derives from winter precipitation. In contrast, the δD and δ18O values of the drip waters in the Lower Cerovačka Cave show similar or more positive values compared with those in the amount-weighted annual precipitation, which suggests more contribution from summer precipitation. All of the studied drip sites (except one) were characterized by stable δD and δ18O values during the whole monitoring period, which implies that the karst water above these sites is well mixed and the residence time of the groundwater is more than one year. Thus, it is likely that the speleothems from these sites could preserve the multiannual isotopic changes of precipitation. The deuterium-excess values of the drip waters and precipitation show systematically higher values than 10‰ suggesting significant contribution from moisture originated in the Mediterranean Basin. Although temperature time series do not cover a whole year, it seems that the Lower and Upper Barać caves display different calcite-water fractionation. These findings emphasize the importance of measurements on the carbonate precipitates from each site, even within the same cave system, before using speleothems for past climate reconstruction. [ABSTRACT FROM AUTHOR]

Abstract The Bokanjačko blato karst polje (field) is a typical depression along the eastern Adriatic coast that is filled with lake sediments. This large-scale structure is also an hydrologically important region as wells in southern part of the karst polje comprise the water supply for surrounding towns and villages. The evolution of this polje, however, remains poorly understood. A 7.8 m long sediment core from the south-eastern part of the karst polje is utilized in this study to enable a multiproxy approach to the reconstruction of depositional processes that have occurred over the last 10.3 ka cal BP. The sedimentological, mineralogical and geochemical characteristics, as well as palynological analyses of this core indicate that the whole sediment sequence consists of lake sediments alongside a variable amount of carbonates and silicates. The lake existed for approximately 10,300 years before it was drained for agricultural purposes in the 1960s. Depositional changes are also evident throughout the core; between 10.3 and 4.2 ka cal BP, a higher values of magnetic susceptibility (MS) and concentrations of lithogenic elements indicate increased erosion and input of material from the catchment and therefore wetter climatic condition. Deposition of siliciclastic detrital material gradually decreased from 4.2 ka cal BP onwards, replaced by carbonate sedimentation alongside minimal input of the former. The carbonate-based sandy silt sedimentation remains until hydromelioration of the depression. The results of this study show that the lake level gradually increased between 4.2 and 2.9 ka cal BP, evidenced by a higher carbonate content and a lower proportion of detrital material, reaching a maximum between 2.9 and 1.6 ka cal BP. Data also show that at 1.6 ka cal BP, the lake level was likely lowered due to higher nutrient content, including sulfur (S) and phosphorus (P), as well as organic compound levels, prior to human intervention and hydromelioration for agriculture. High concentrations of the nutrient elements, lead (Pb), copper (Cu), and zinc (Zn) in the upper 40 cm of this sequence are indicative of the influence of agricultural activities across the karst polje as well as anthropogenic atmospheric pollution. Geochemical and sedimentological proxies illustrate centennial-scale variability in carbonate deposition and erosional runoff processes comparable with the natural climatic and anthropogenic factors that are known to influence the evolution of Holocene karst poljes across the central Mediterranean. [ABSTRACT FROM AUTHOR]

Abstract Quaternary palaeo-environmental changes that have taken place in Croatia are likely to be recorded in speleothems – secondary carbonate deposits precipitated in caves. Confident interpretation of well dated speleothem proxy records relies on modern monitoring programs, which we provided in three regionally different caves. Parallel monitoring of the surface and cave air temperature and relative humidity, precipitation and cave drip intensity, as well as stable isotope modification of meteoric and drip water was carried out in order to estimate the most reliable stalagmites for the interpretation of Quaternary landscape history. In all three caves, Nova Grgosova (239 m a.s.l.; T cave = 11.2 °C) in central Croatia, Lokvarka (780 m a.s.l.; T cave = 7.5 °C) in the mountainous part of Croatia, and Modrič (32 m a.s.l.; T cave = 16.6 °C) in coastal Croatia, we selected the parts of the caves where the ambient cave conditions appeared to be appropriate for equilibrium deposition of calcite in terms of constant air temperature (seasonal amplitudes of 0.73, 0.38 and 0.45 °C, respectively) and relative humidity (100%). Both Atlantic and Mediterranean moisture influences were detected in all three caves, but of different intensities. Cave hydrological settings governed by karst aquifer properties were resolved by the comparison of the precipitation intensities and drip site responses to the rain events, and generally, seasonal rainwater isotopic signal was almost completely attenuated, except for one drip site. Such homogenized drip water and stable cave environmental settings give confidence for calcite deposition under equilibrium conditions, especially for Modrič and Nova Grgosova caves where speleothems' inner structures also look promising for potentially quality dating results and stable isotopic profiles. The fracture-flow drip regime of selected drip sites in Lokvarka Cave, and uncompleted homogenization of the water in the epikarst might point to speleothem samples that are unsuitable for resolving multi-annual Quaternary climate changes. This view is supported by the high porosity internal structure of some Lokvarka speleothems, so further monitoring, sampling and the thorough speleothem examination is therefore necessary for adequate interpretations of palaeo-environmental changes. [ABSTRACT FROM AUTHOR]

Speleothems, as secondary carbonate deposits, precipitate in the cave environment from the water originally sourced from the ocean, transferred via atmosphere through soil and epikarst into the cave system. As such, they archive valuable information on the ongoing changes in the atmosphere, biosphere, hydrosphere and lithosphere which may be used for palaeoenvironmental reconstructions, especially for the Quaternary Period. Speleothem-based Quaternary research in Croatia started in the 1960's with the utilization of the flowstone and speleothems whose radiometric ages ( 14 C and U-Th) provided constrained chronological framework for underlying fossils or archaeological material, mainly without any further palaeoenvironmental interpretations. Since the 1990's, several studies have used speleothems for the reconstruction of particular phases of speleogenesis, while in the early 2000's investigation on submerged speleothems started, with the aim to reconstruct Quaternary relative sea-level changes along the eastern Adriatic coast. Only after that, thorough research on subaerial speleothems from the different regions of the Croatian karst has been initiated, usually associated with monitoring programs. This paper gathers the most important speleothem-based studies, displaying potential of this still understudied, but promising area in the terms of palaeoclimate and palaeoenvironmental changes in a wider European and global context. [ABSTRACT FROM AUTHOR]

Soot traces are witnesses of past human activities. They can sometimes be noticed on the walls and vaults of caves and rock shelters, sometimes also inside speleothems. These deposits resulting from anthropogenic fires prove to be a suitable material for micro-chronological studies. The microscopic analysis of parietal carbonated crusts of various ages, from Grotte Mandrin (Middle Palaeolithic from about 100 ka till early Upper Palaeolithic around 42 ka BP) and from the Balma de la Margineda (late Upper Palaeolithic) shows that they have preserved the trace of multiple occupations. These latter can be linked to the archaeological units recognised on excavation field. The MNO (Minimum Number of Occupations) recorded at high temporal resolution for each archaeological level are usually high. These attest the cumulative nature of archaeological units and invite to rethink the following concepts of “archaeological floor” and “palimpsest” vis-à-vis spatial studies in caves and rock shelters. Each unit records a different number of occupations and shows its own rhythmicity in the succession of occupations. By retracing occupations chronicles of each archaeological level, possibility for studying mobility of passed human groups can also be raised. [ABSTRACT FROM AUTHOR]

This research aims to elucidate the Holocene sea level (SL) variability on Minami Daito Island, Japan, where no previous such research has been done due to the apparent absence of any SL indicators. Here we use phreatic overgrowths on speleothems (POS) in a cave as an alternative SL indicator. The relationship between the highest modern groundwater fluctuation level (GWFL) and the highest POS level was studied, and the oldest POS calcite was dated using the radiocarbon method considering the dead carbon proportion (the “reservoir effect”). The results show that SL reached its Holocene maximum between ca. 5.1 and 4.6 ka cal BP, after which it remained more or less stable till the present day, with a possible minor sea-level drawdown of ca. 30–35 cm. Although the timing of the maximum Holocene SL coincides with mid-Holocene SL highstand observed across the tropical and subtropical Indo-Pacific, the relative stability of the SL after reaching its peak is not expected in the given subtropical setting. The SL on Minami Daito did not have a distinct highstand in the Holocene and instead followed closely the eustatic sea-level change. These findings are important in better understanding the mechanisms that control local relative SL variability and show the high value of POS as precise SL indicator. [ABSTRACT FROM AUTHOR]

Records of Asia Summer Monsoon (ASM) from the Chinese loess and the speleothem display distinct features. The very different proxies that were applied to the two archives may be responsible for this discrepancy. A direct comparison between the speleothem and the loess records under the same proxy system of rainwater δ 18 O may help to resolve this puzzle. Here we show that the calcified microcodium in the loess deposits may record the oxygen isotopic composition of the summer rainwater. A microcodium based δ 18 O record covering the past 140 kyrs was generated, which shows similar magnitude of the overall variation to that of the speleothem records. However, much weaker precession variability was registered in the microcodium record during the last interglacial period. Instead, the microcodium δ 18 O record is more consistent with the widely used summer monsoon proxy of magnetic susceptibility in the loess deposits with clear glacial-interglacial pattern. This similarity may originate from the low sedimentation rate of the interglacial paleosol layer that preferentially record the peak ASM signals on the precession band. It is also possible that the orbital variability of ASM between the North China and South China is inherently different with more ice-volume related influence in the north. A longer microcodium δ 18 O record in sequences of higher sedimentation rate and a reliable record of summer rainfall may help to resolve these possibilities. [ABSTRACT FROM AUTHOR]

Stable isotopic measurements on the upper 168 cm of stalagmite DG24 from southern China, which is annually-laminated above 74.8 cm (∼11.8 ka), reconstruct a history of detailed Asian summer monsoon (ASM) variability and soil processes between 14.8 and 10.3 ka. The climate sequence of Bølling-Younger Dryas (YD)-Preboreal events is evident in δ 18 O record. In the Preboreal, four-year-resolution and annually-counted δ 18 O record reveals that the ASM strengthening can be divided into three phases, with a prominent and persistent rise initiated at about 11.2 ± 0.3 ka, likely in response to interactions between ocean, atmosphere, and ice sheets. In contrast, the long-term δ 18 O depletion is absent in the δ 13 C and annual layer records, which characterize persistent centennial oscillations and likely represent relative humidity of the soil. At multi-decadal scale, prominent ASM failures are generally consistent with periods of δ 13 C enrichment and decreased layer thickness. When compared with solar proxies, centennial-scale δ 13 C changes match well with solar activity regardless of the observed disparity between ASM and solar records, and common cycles of 130 and 300 years are identified in both the atmospheric Δ 14 C and speleothem δ 13 C records. This implicates that during the Preboreal local soil humidity budget and CO 2 production, indicated by the δ 13 C and annual layer records, is more sensitive to changes in solar output than the regional hydroclimate variability recorded by the δ 18 O signal. [ABSTRACT FROM AUTHOR]

Although the variations in δ 18 O and δ 13 C and the U/Th dating in the speleothems are considered as key proxies, improved dating with better quality resolution as well as composition of stalagmites and growth rate along with the cave monitoring are equally important for understanding the high resolution precipitation variability in the past. With a total of six dates on a 11.5 cm long stalagmite, we re-interpret the decadal to century scale climatic changes with multi-year droughts from the Indian Central Himalaya between ca. 1622 and 1950 AD. The sample is composed of aragonite (both compact sub-layers and porous sub-layers). Although, the age model of this young speleothem may be within age uncertainty owing to the high 230 Th/ 23 2 Th isotope ratios, yet the distinction of this study lies in recording various historical drought events which are otherwise never reported from the Himalayan foothills. Additionally, the sample consists of reasonable amount of U (>2 ppm), thus the age correction requirement may be minimum. The higher growth rate and comparatively lower values of δ 18 O and δ 13 C are observed during the Little Ice Age (LIA) until ca. 1820 AD, indicating its being wet in the Himalayan foothills in contrast to the Peninsular India and other regions which are solely influenced by the Indian Summer Monsoon (ISM). This is mainly because the monsoon trough moves from the plains to the Himalayan foothills during break-monsoon conditions and provides more orographic precipitation in form of the Westerlies in the south facing Himalayan slopes. The post-LIA period from ca. 1820 AD onwards is interpreted as comparatively drier than the LIA. [ABSTRACT FROM AUTHOR]

Subaqueous flowstones have been studied in two resurgence caves in Slovak Karst (southern Slovakia), namely Krásnohorská and Drienovská Caves. The flowstones litter streambeds within the distance of several hundred meters upstream from resurgences. They form laminated crusts within channels of the underground streams flowing through the caves. Layers composed of columnar sparry calcite alternate with those composed of microcrystalline calcite. The latter are enriched in fine, detrital, non-carbonate components, which resulted in crystallization of microcrystalline calcite instead of sparry calcite. The growth rate of the studied flowstones reaches 0.96 mg/cm 2 /day, which corresponds to ca. 0.3 mm per year. Seasonal observations conducted between November 2010 and September 2012 reveal that deposition of subaqueous flowstones in the studied caves significantly depends on the local hydrological conditions. During the periods of low flow, SI calc. values of underground stream increase and columnar sparry calcite grows. Conversely, during peak flow periods SI calc. values decrease and subaqueous flowstones are subjected to destruction, both by mechanical erosion and corrosion. The decreasing discharge, just after peak flows, causes deposition of fine-grained particles, which results in precipitation of microcrystalline layers. Subaqueous flowstones grow in complete darkness and in atmosphere with elevated CO 2 content, similarly to typical speleothems, but they are fed with turbulent stream water, similarly to calcareous tufas. Their growth rate is higher than those of ‘normal’ flowstones fed with a film of water seeping down; it falls within a range of growth rate of calcareous tufas, though near the lower limit of this range. Therefore, subaqueous flowstones represent an intermediate link between other speleothems and tufas deposited outside the cave environment. [ABSTRACT FROM AUTHOR]

Zhiren Cave in southern China is an important site for the study of the origin and the environmental background of early modern humans. The combination of Elephas kiangnanensis , Elephas maximus , and Megatapirus augustus , indicates an early representative of the typical Asian elephant fauna. Previous U-series dating of flowstone calcite has pinpointed an upper age limit for the fossils of about 100 ka. In order to achieve a better comprehension of the chronology of the modern human and contemporaneous faunal assemblage, paleomagnetic, stratigraphic, and optically stimulated luminescence (OSL) dating methods have been applied to the cave sediments. Paleomagnetic analyses reveal that there is a reversed polarity excursion below the fossiliferous layer. This excursion can be regarded as the Blake excursion event, given the U-series ages of the overlying flowstone calcite, the OSL measurements, the virtual geomagnetic pole (VGP) path of the excursion, the two reverse polarity zones within this excursion event, and the characteristic of the fauna assemblage. The human remains and mammalian fauna assemblage can be bracketed to 116–106 ka. Application of OSL dating leads to erroneous ages, largely due to the uncertainty associated with the estimation on the dose rates. [ABSTRACT FROM AUTHOR]

Two hominin teeth and an abundance of faunal remains were recovered from Panlong Cave in Guangdong Province, southern China in 1987. The site has remained largely unknown to the prehistoric community mainly for the lack of reliable chronological constraints. This paper reports high-precision mass spectrometric U-series dating of eight calcite samples from the extant cross-section. Based on the dates on the overlying flowstone layers, the hominin teeth should be definitely older than 292 ± 10 ka. Furthermore, as indicated by the U-series ages on the secondary calcite formations the fossiliferous deposits should be older than 441 ± 18 ka. These dates support the paleontological inference that Panlong Cave may predate the nearby Maba hominin site. The hominin specimens from the site may thus represent an early member of the Ailuropoda-Stegodon fauna and one of the oldest non- erectus Middle Pleistocene hominin fossils in southern China. [ABSTRACT FROM AUTHOR]

Despite the fact Java Island is a volcanic area, it has been challenging to build a chronological framework of its early human settlements, from the oldest Lower Pleistocene Homo erectus up to the dispersals that followed the Last Glacial Maximum (LGM). Various dating methods are implemented on volcanic effluents, sedimentary deposits, speleothems and also on fossils (including direct analyses on human remains), thanks to radiometric and palaeodosimetric grounded techniques as well as to magnetostratigraphy. However, a number of results must be considered with caution, in order to identify specific bias originating from reworking of volcanic effluents or post-depositional geochemical evolution. Such bias might well explain apparent contradictions between absolute dating results and other chronologically significant proxies (e.g. biostratigraphy). Converging age estimates resulting from the implementation of several dating methods, though being sometimes less precise, seem to have a higher reliability. [ABSTRACT FROM AUTHOR]

The issue of diagenetic alteration of carbonate deposits in caves (speleothems) has gained increasing importance in recent years, as this process has serious consequences for speleothem-based paleoclimate studies. In this study stable hydrogen and oxygen isotope data of water trapped in fluid inclusions were collected for recently forming stalagmites and flowstones in order to determine how dripwater compositions are reflected and preserved in the inclusion water compositions. Hydrogen isotope compositions were found to reflect dripwater values, whereas the oxygen isotope data were increasingly shifted from the local dripwater compositions with the time elapsed after deposition. The δ 18 O data are correlated with X-Ray diffraction full width at half maximum values (related to crystal domain size and lattice strain), suggesting that the oxygen isotope shift is related to recrystallization of calcite. Transmission electron microscope analyses detected the presence of nanocrystalline (<50 nm) calcite, whose crystallization to coarser-grained calcite crystals (>200 nm) may have induced re-equilibration between the carbonate and the trapped inclusion water. The Ostwald ripening process provides an explanation for unexpectedly low oxygen isotope compositions in the inclusion water. The detected diagenetic alteration and its isotopic effects should be taken into consideration during sampling strategies and data evaluation as speleothems containing nanocrystalline calcite during their deposition are prone to late-stage oxygen isotope water-carbonate re-equilibration, which may shift the oxygen isotope composition of the inclusion water to more depleted values while the hydrogen isotope composition remains intact. [ABSTRACT FROM AUTHOR]