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The occurrence of speleothems in New Zealand with reversed magnetism indicates that secondary calcite deposition in caves has occurred for more than 780 thousand years (ka). 394 uranium-series dates on 148 speleothems show that such deposition has taken place somewhere in the country with little interruption for more than 500 ka. A relative probability distribution of speleothem ages indicates that most growth occurred in mild, moist interglacial and interstadial intervals, a conclusion reinforced by comparing peaks and troughs in the distribution with time series curves of speleothem δ18O and δ13C values. The stable isotope time series were constructed using data from 15 speleothems from two different regions of the country. The greater the number of overlapping speleothem series (i.e. the greater the sample depth) for any one region, the more confidence is justified in considering the stacked record to be representative of the region. Revising and extending earlier work, composite records are produced for central-west North Island (CWNI) and north-west South Island (NWSI). Both demonstrate that over the last 15 ka the regions responded similarly to global climatic events, but that the North Island site was also influenced by the waxing and waning of regional subtropical marine influences that penetrated from the north but did not reach the higher latitudes of the South Island. Cooling marking the commencement of the last glacial maximum (LGM) was evident from about 28 ka. There was a mid-LGM interstadial at 23-21.7 ka and Termination 1 occurred around 18.1 ka. The glacial-interglacial transition was marked by a series of negative excursions in δ18O that coincide with dated recessional moraines in South Island glaciers. A late glacial cooling event, the NZ Late Glacial Reversal, occurred from 13.4-11.2 ka and this was followed by an early Holocene optimum at 10.8 ka. Comparison of δ18O records from NWSI and EPICA DML ice-core shows climatic events in New Zealand to lag those in Antarctica by several centuries to a thousand years. Waxing and waning of subantarctic and subtropical oceanic influences in the Tasman Sea are considered the immediate drivers of palaeoclimatic change.

High-resolution U-Th and 14C dating of two calcite flowstones (RTf: Last Interglacial; RTy: Late Holocene) from the Re Tiberio – Monte Tondo karst system (North Italy) is presented to investigate the palaeoclimate potential of speleothems from gypsum caves. To date, there is a lack of information regarding the dating potential of calcite speleothems that have grown in such gypsum karst environment (e.g. no pseudokarst). High-resolution U-Th dating, aimed at establishing if these speleothems can provide robust radiometric age sequences, is first presented. Although both samples show promise for reliable radiometric dating, about 20% of the ages in the RTf dataset were excluded from the age-model as outliers. These outliers are best explained by post-depositional diagenetic processes affecting the U-Th system rather than anything specific to gypsum karst environment conditions. In contrast, outliers were not detected in the RTy sample, but U-Th analysis was not able to constrain its relatively young age (∼600 years before present, B.P.). Consequently, radiocarbon measurements were undertaken, and combined with the U-Th ages to build an age-model. The latter allowed the estimation of "dead carbon fraction" (DCF), which yields a constant value through time, and a magnitude comparable to other sites where climate is similar to Monte Tondo. Soils were considered the main source of carbon, because bedrock dissolution acted predominantly under open-system conditions, and soil organic matter (SOM) turnover rate appears above average compared to sites studied elsewhere. [ABSTRACT FROM AUTHOR]

Abstract: This study aimed to further test the method, reported by , to develop robust chronologies of deposits in limestone caves through U/Th (Uranium/Thorium or U-Series) dating of soda straw stalactites. The chronology of fossil bearing deposits at Blanche Cave was further constrained with thermal ionisation mass spectrometry (TIMS) U/Th dating of 17 additional soda straw stalactite samples, and results were compared to recalibrated 14C ages of charcoal. The results support the assertion that soda straw stalactites can provide ages close to the time of sediment deposition and may be used as reliable chronological markers, particularly for periods reaching or beyond the radiocarbon dating limit. The application of an enhanced cleaning technique facilitated the reduction of detrital Th in samples, significantly increasing age accuracy and precision. Additionally U/Th age accuracy and precision was increased through the application of site-specific measured U/Th ratios to correct for the detrital 230Th component in samples. [Copyright &y& Elsevier]

Abstract: Although it was demonstrated 20 years ago that mass spectrometric U–Th methods are capable of high-precision dating of young corals, the use of this approach to decipher recent environmental, climatic and archaeological records is still restricted and its potential has not yet been widely recognised. U–Th methods are typically used to determine the ages of carbonate materials such as speleothem and coral. Dating young carbonates of this sort is challenging. Their extremely low 230Th content necessitates stricter instrumental and laboratory conditions than those required for dating older samples. Moreover, analyses must be corrected for the presence of non-radiogenic 230Th, which is proportionally far more significant than in older samples. Nevertheless, 2σ precisions of around ±1–10 years are readily achievable for pristine coral samples dating from the last 500 years. Although the range of analytical precisions for speleothems may vary more widely depending on U concentrations and levels of non-radiogenic 230Th correction, published studies reveal 2σ precisions of around ±10–80 years for typical speleothems. This paper demonstrates how the U–Th method may be applied to establish the causes of recent coral mortality, to determine the recurrence interval of extreme wave events, to investigate earthquake frequency and neotectonic uplift, to reconstruct recent climatic history, and to understand settlement patterns and sociopolitical changes in Polynesia prior to European contact. [Copyright &y& Elsevier]

Abstract: Uranium-series (U-series) dating of speleothems is frequently used for palaeoclimate studies but its archaeological and palaeontological applications are limited to stratigraphically significant speleothem formations, such as flowstones, to provide maximum and minimum temporal points. This study targeted soda straw stalactites for U-series dating. In contrast to other speleothem formations, soda straw stalactites are fragile, have typically short life spans (usually only years but rarely up to a few hundred years) and are frequently incorporated into cave deposits. Results of thermal ionisation mass spectrometry (TIMS) U-series dating of soda straw stalactites from palaeontological excavations at Blanche Cave, South Australia, show that small, dense, clean straws tend to yield ages closest to the time of stratigraphic deposition. A correlation between soda straw U-series ages and radiocarbon ages of charcoal from the site is shown. Multiple soda straw age determinations for a single stratigraphic unit are required in order to verify age concordance. In conjunction with other dating methods, U-series dating of soda straw stalactites may help to significantly constrain the age of stratigraphic units and associated archaeological and palaeontological deposits in order to provide more robust chronologies. Here we advocate the collection of soda straw stalactites at future excavations of limestone cave sites. [Copyright &y& Elsevier]

This paper reports U-series dates on speleothem samples from Locality 15 at Zhoukoudian, one of the richest Paleolithic sites in northern China. The age of the lower part of Layer 2 is securely bracketed between 155,000 and 284,000 yr. The underlying Layer 3 dates back at least 284,000 yr. Layer 4, further below, should be older still, possibly by a cycle on the SPECMAP time scale before 284,000 yr ago. These ages, much greater than the previous estimates of 110,000–140,000 yr from U-series and electron spin resonance dating of fossil teeth, suggest that Locality 15 was broadly contemporaneous with Locality 4 (New Cave) and with the uppermost strata of Locality 1 (Peking Man site). The physical evolution and cultural development evidenced by the timing of the Zhoukoudian localities are in line with the opinion of Chinese anthropologists for a regional transition from Homo erectus to archaic Homo sapiens. [Copyright &y& Elsevier]

A correction to the article "An 80 kyr-long continuous speleothem record from Dim Cave, SW Turkey with paleoclimatic implications for the Eastern Mediterranean" that was published online in the September 4, 2015 issue is presented.

Speleothem-based stable isotope records are valuable in sub-humid and semi-arid settings where many other terrestrial climate proxies are fragmentary. The Eastern Mediterranean is one such region. Here we present an 80-kyr-long precisely-dated (by U-series) and high-resolution oxygen (δ18O) and carbon (δ13C) records from Dim Cave (~36°N) in SW Turkey. The glacial-interglacial δ18O variations in the Dim Cave speleothem are best explained in terms of changes in the trajectories of winter westerly air masses. These are along a northerly (European) track (isotopically less depleted) during the early last glaciation but are gradually depressed southward closer to the modern westerly track along the North African coast (more depleted) after c.50 kyr and remain in the southern track through the Last Glacial Maximum. The southward displacement of the westerly track reflects growth of the Fennoscandian ice sheet and its impact on westerly wind fields. Changes in δ13C are interpreted as reflecting soil organic matter composition and/or thickness. δ13C values are significantly more negative in interglacials reflecting active carbonic acid production in the soil and less negative in glacial times reflecting carbonate rock values. Several Heinrich events are recorded in the Dim record indicating intensification of westerly flow across this part of the EM. [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]

Multiple climate-sensitive trace element/Ca and stable isotope (O and C) profiles derived from Dim Cave speleothems (S-SW Turkey) provide evidence of climatic changes and define a series of palaeohydrological conditions for the period ~10–90 kyr. Dim Cave speleothem Mg/Ca, Sr/Ca, U/Ca, Ba/Ca, and Y/Ca ratios demonstrate similar patterns over glacial–interglacial scales, in agreement with δ 18 O and δ 13 C records. Three episodes of more positive moisture balance (71–63 kyr, 51–40 kyr, and 18–10 kyr) were observed based on Y/Ca (and to a lesser extent Zr/Ca), 87 Sr/ 86 Sr ratios, calcite micromorphology, and growth rates. Increasing concentrations of Y, Zr (and U) and elevated 87 Sr/ 86 Sr ratios are attributed to enhanced levels of terrestrial input during these periods. Correlations between δ 13 C, δ 18 O and Mg/Ca during 40–18 kyr (corresponding with the lowest growth rate of ~ 0.8 mm/kyr), 63–51, and 80–71 kyr (relatively low growth rates), as well as co-varying and enhanced Mg/Ca, Sr/Ca, and to a lesser extent Ba/Ca, ratios point to the prior calcite precipitation, wall rock interaction, and preferential dolomite dissolution over calcite in the host dolomitic limestone during these periods. This relationship suggests that water–rock interactions are maximised during episodes of slower drip rates of water through the karst under drier conditions. Chondrite-normalised rare earth element and yttrium (REY) patterns of the stalagmites reveal seawater signatures closely linked to the dolomitic limestone. Excluding the aragonite formation during ~80–75 kyr, which is an autogenic effect, trace element/Ca ratios appear to respond to millennial scale global cooling periods such as Heinrich events. [ABSTRACT FROM AUTHOR]

Speleothem records of past environmental change provide an important opportunity to explore fire frequency and intensity in the past, and the antecedent climatic conditions leading to fire events. Here, fire sensitive geochemical signals in a stalagmite from Yonderup Cave, a shallow cave in Western Australia, are compared to well-documented wildfire events that occurred in recent decades. The results are extended to identify wildfires during the growth interval of the speleothem (1760 CE–2005 CE). Principal component analysis of the stalagmite time-series revealed distinct peaks in a combination of phosphorus and metal (aluminium, zinc, copper and lead) concentrations in response to known fire events, which are interpreted to have come from ash. Varying responses in the geochemical signal in the pre- and post-European colonisation period are likely linked to changes in land management, fire frequency and fire intensities. Of note is what we infer to be a particularly intense fire event concluded to have occurred in 1897 ± 5 CE, which climate sensitive proxies (δ18O and bedrock-derived elements) indicate was preceded by a multi-decadal dry period that began in the late 1860s. The intensity of the deduced fire event is supported by a peak in P that is 6.3 times higher than elsewhere in the speleothem, accompanied by a peak in Zn. It was also inferred that changes to the surface-cave hydrology occurred as a result of this event, indicated by increased input of colloidal organic material onto the stalagmite that was interpreted to be caused by shallow karst bedrock fracturing from the heat-induced deformation that is observed after intense fires. These findings show the potential for speleothems to provide dated records of fire intensity and recurrence intervals. Further development could lead to a better understanding of the climate-fire relationship and the effects of land-management practices on wildfire frequency and intensity. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the first stable isotope (δ18O and δ13C) data of a ∼400 years (1590–2006 AD) long annual to decadal-resolution speleothem record collected from the Indian Lesser Himalaya. The data show a variation from −2.7 to −5.9‰ in δ18O and −5.3 to −8.8‰ in δ13C. The isotopic analyses indicate that the climate during this period can be divided into two stages: a wet phase during the Little Ice Age (LIA) (1590–1850 AD) and comparatively dry phase during the post-LIA after 1850 AD. However, the record also documents the minor dry events during the LIA and a wet episode after the LIA. Within the age uncertainty, the dry spells during the LIA are linked with the historical drought events in the Indian subcontinent and similar latitudes. The isotopic record is consistent with a number of previous studies in the areas influenced by the Westerlies but appears to be conflicting to the regions, dominated by the Indian Summer Monsoon (ISM). This may be due to the possible changes in the strength of Westerlies in the study area and added by negative anomaly of North Atlantic Oscillation (NAO) during the LIA. [Copyright &y& Elsevier]

Abstract: A low-resolution strontium isotopic ratio (87Sr/86Sr) record coupled with a high-resolution Sr concentration profile covering the last deglacial period were obtained for a stalagmite, SJ3, collected from Songjia Cave, northeast Sichuan province, Central China. Both Sr and 87Sr/86Sr display significant variations during the period between 20 and 10ka, which correlate well with oxygen isotope records from Greenland ice cores and speleothems in the East Asian summer monsoon regime, with higher Sr and more radiogenic 87Sr/86Sr values occurring during cold-dry climatic phases and vice versa. The Sr in SJ3 shows a negative linear relationship between 87Sr/86Sr and 1/Sr, suggesting the binary mixing of two end-members, the host rock of Late Permian limestone with a relatively lower 87Sr/86Sr ratio (∼0.7071) and an exotic Sr source with a relatively radiogenic 87Sr/86Sr ratio (∼0.7109 deduced from the 87Sr/86Sr-1/Sr correlation). Atmospheric dust activity was suggested to be the most probable factor influencing the two indices. Because the carbonate fraction in wind-blown dust is enriched in Sr and has a more radiogenic 87Sr/86Sr ratio, enhanced atmospheric dust activity under stronger Asian winter monsoon which is associated with cold-dry climate would lead to higher Sr concentrations and more radiogenic 87Sr/86Sr ratios in SJ3 and vice versa. This interpretation is supported by the general parallelism of the two Sr indices to winter monsoon proxy from East Asia such as the dust flux and quartz median diameter in Luochuan loess profile during the same period. This study suggests that the speleothem 87Sr/86Sr ratio and Sr concentration, especially the former in northeastern Sichuan Province can be used to investigate the atmospheric dust activity and Asian winter monsoon. [Copyright &y& Elsevier]

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]

Previous studies have analysed the age distributions of stalagmites harvested from multiple caves and inferred important palaeoclimate changes that explain stalagmite growth phases. However, stalagmites may grow over tens of thousands of years; thus, they are irreplaceable. The value of speleothems to science must be weighed against their potential and current aesthetic and cultural value. In this study, we show that some palaeoclimate information can be extracted from a cave system without the removal of stalagmites. Our case study is based on basal U–Th dates for 77 individual stalagmites from thirteen caves located in and around Bantimurung-Bulusaraung National Park, southwest Sulawesi, Indonesia. The stalagmites grew during discrete intervals within the last ~ 530,000 years, and an analysis of their age distribution shows a first-order exponential decrease in the number of older stalagmites surviving to the present day. Further, this exponential relationship is observed in stalagmite populations around the world and is therefore likely to be a general cave phenomenon. Superimposed on the first-order exponential age distribution in southwest Sulawesi are positive anomalies in stalagmite growth frequency at 425–400, 385–370, 345–335, 330–315, 160–155, 75–70 and 10–5 ka, which are typically coincident with wet periods on Borneo. To explain this distribution, we present a simple model of stalagmite growth and attrition. A first-order trend is controlled by processes intrinsic to karst systems that govern the natural attrition of stalagmites. These processes are nearly constant over time and result in the observed exponential relationship of stalagmite basal ages. Second-order variation is controlled by changes in the rate of stalagmite generation caused by fluctuating climates, which is a well-known concept in the speleothem literature. Removal of the exponential baseline allows for better assessment of relative peak heights and basic palaeoclimate information to be inferred. Importantly, the first- and second-order growth frequency variations can be characterised using basal stalagmite ages only, without the removal of stalagmites, thereby helping reduce the impact of scientific sampling on the cave environment. [ABSTRACT FROM AUTHOR]

Results from terrestrial and marine palaeoclimate proxies are integrated to reconstruct palaeoclimate variations in New Zealand from the Last Interglacial to the global Last Glacial Maximum (gLGM). By combining data from 21 speleothems we have constructed composite O–C stable isotope sequences from 0 to 88.5 ka BP and from 107.8 to 128.2 ka BP. The gaps in the sequence (a 19.3 ka break in coverage in MIS 5b/c and a 2.97 ka gap in MIS 5a) preclude the construct of a continuous record; so data were referenced to a common scale by normalising individual records (subtracting means and dividing by standard deviation). Overlapping records were then merged chronologically. These records were compared to integrated summer insolation for 45°S and to terrestrial and marine environmental proxies available for the New Zealand region. The MIS 5e thermal maximum in New Zealand was around 128–122 kiloyears BP (ka BP) and therefore similar in timing to the Last Interglacial in Australia, southern Europe and Greenland. Temperatures in parts of the North Island may have been 2°–3 °C warmer than present and the sea rose 3–6 m above modern level. In MIS 5d and 5b cool conditions with glacial advances occurred in the South Island, but from about 87 to 73 ka in MIS 5a warmth within 2 °C of present characterised most of the interstadial (locally termed the Otamangakau Interstadial). Conditions then cooled rapidly and culminated in a MIS 4 glacial advance that was the greatest of the New Zealand Last Glacial Cycle (nzLGM). The climate was cool to cold and while wet in westerly windward locations may have been dry in the east. Combined Australian and New Zealand evidence suggests glacial culmination around 67–62 ka. This regional LGM coincided with severe cooling in Europe. During MIS 3 conditions were very variable. The climate in eastern North Island (Hawke Bay and the Bay of Plenty) at the start of MIS 3 was similar to the Holocene, and the period 61–43 ka was relatively mild overall and is termed the Aurora Interstadial, although it contained a short interval of mountain glacier expansion around 49–47 ka. After 43 ka conditions cooled again with a glacial advance from 42 to 38 ka, before a return to milder but still cool conditions during the Moerangi Interstadial from 37 to 31 ka. After this conditions deteriorated at the lead in to the gLGM. The maximum glacial advance occurred in late MIS 3 between 31 and 29 ka. The glacial onset was abrupt with Te Anau Glacier in Fiordland, one of the largest in the Southern Alps, taking only about 2000 years to achieve its maximum gLGM depth, probably because conditions were wet as well as cold. But stable isotope data suggest that the climate then became drier, while remaining cold, and the glacier progressively ablated such that its surface had lowered 390 m by the start of MIS 2 and by >600 m by ca 18 ka. The gLGM maximum in New Zealand may have led the terrestrial (ice-sheet) LGM in the Northern Hemisphere by a few thousand years, possibly because alpine glaciers respond more rapidly to climate change than continental ice sheets. The culmination of the gLGM in NZ occurred in MIS 3 about 12 000 years before global ice volume reached its peak as determined by the marine stable isotope record (the marine gLGM). By the time global ice volume was at a maximum (19 ka) glaciers had almost disappeared from major Fiordland valleys in New Zealand. Whereas polar ice sheet records have revealed a “bi-polar see-saw”, this is not so evident in the mid-latitudes, because some temperate zone inter-hemispheric climate events coincide closely in time. Perhaps the see-saw effect diminishes with distance from the poles? [ABSTRACT FROM AUTHOR]

Abstract: Little is known about the possible teleconnections between abrupt climatic changes originating in the North Atlantic and precipitation dynamics in the Australian–Indonesian summer monsoon (AISM) domain. We examine the climatic impacts of Heinrich stadial 3 (HS3) and Greenland interstadials 4 and 3 (GIS4/3) on AISM-associated precipitation through a high-resolution analysis of stable isotope (δ18O, δ13C) and trace element (Mg/Ca, P/Ca) ratios in a stalagmite from Liang Luar cave, Flores, Indonesia. Sixteen high precision 230Th dates indicate that stalagmite LR07-E1 grew rapidly (~0.3–1.0mm/yr) in two phases between ~31.5–30.1ka and ~27.8–25.6ka, separated by a ~2.3kyr unconformity. Temporally consistent abrupt responses occur in the Flores record during HS3 and GIS4, which are coherent with changes in stalagmite δ18O records from China and Brazil. The response of low-latitude precipitation to HS3 cooling and GIS4 warming, as demonstrated by the widely separated sites, comprises three distinct simplified phases: (1) a strong southward migration of the ITCZ during HS3 is associated with a decrease in rainfall at Liang Luar cave and in China, while wetter conditions are reconstructed from Brazil, (2) represents the peak of HS3 impacts and an extended hiatus begins in the Flores record and (3) where suggested dry conditions at Liang Luar throughout GIS4 form part of a coherent north–south anti-phasing in precipitation changes. The reconstructed changes are also broadly consistent with NASA GISS ModelE-R simulations of a Heinrich-like freshwater perturbation in the North Atlantic basin, which produces a southward shift in the ITCZ. The relationship between the palaeoclimate records indicates that atmospheric teleconnections rapidly propagate and synchronise climate change across the hemispheres during periods of abrupt climate change. Our findings augment recent proposals that large-scale atmospheric re-organisations during stadials and interstadials play a key role in driving changes in atmospheric CO2 concentration, air temperature and global climate change. [Copyright &y& Elsevier]

We have applied a new technique to analyze the oxygen (δ 18O) and hydrogen (δD) isotope ratios in speleothem fluid inclusions to reconstruct the temperature and rainfall history of southern Indonesia during the Younger Dryas (YD) event and the Holocene. The 12,640-year speleothem record, anchored by 33 uranium-series dates, shows that fluid-inclusion δ 18O values vary in phase with speleothem calcite δ 18O during the Holocene, suggesting that the speleothem calcite δ 18O primarily reflects variations in the δ 18O of local rainfall. Significant early to mid-Holocene decreases in both δ 18O series are interpreted as an intensification of Australian–Indonesian summer monsoon rainfall in response to deglacial eustatic sea-level rise and flooding of the Sunda Shelf. Cave drip-water temperatures reconstructed from coupled measurements of δ 18O in speleothem calcite and fluid inclusions remained relatively constant through the Holocene. This is consistent with reconstructions of Indo-Pacific sea-surface temperature (SST) based on analysis of Mg/Ca ratios in planktonic foraminifera. However, during the YD event, drip-water (i.e. cave) temperature was ∼5°C cooler than modern, which is substantially cooler than SSTs inferred from foraminiferal Mg/Ca, but consistent with coral Sr/Ca reconstructions of SST and terrestrial evidence for high-elevation snow-line depressions. Lower fluid-inclusion δ 18O values during the YD indicate that the cooling was accompanied by increased monsoon rainfall. Taken together, the results suggest that the southerly penetration of the intertropical convergence zone (ITCZ) was largely influenced by the cross-equatorial temperature gradient, rather than local SSTs (and air temperatures). Our results provide new evidence for a rapid cooling of deep tropical air temperatures and repositioning of the ITCZ during the YD event. [Copyright &y& Elsevier]

Abstract: Trace element and stable isotope ratios from an active stalagmite (LR06-B1) recovered from Liang Luar Cave on the island of Flores (eastern Indonesia) are used to reconstruct the position of the austral summer inter-tropical convergence zone and Australian-Indonesian summer monsoon variability during the Holocene. Uranium-series dating of the stalagmite shows that it commenced growth 12,640years ago, with hiatuses spanning 8,560 to 6,420 and 3,670 to 2,780years ago. Stalagmite Mg/Ca and Sr/Ca ratios correlate significantly with one another, and with δ 18O and δ 13C, throughout the record. This suggests that the Mg/Ca and Sr/Ca ratios are dominated by prior calcite precipitation, a process whereby degassing in the vadose zone during periods of low recharge causes deposition of calcite and disproportionate loss of Ca2+ ions (relative to Mg2+ and Sr2+) ‘upstream’ of the stalagmite. The degree of initial 234U/238U disequilibrium also appears to have been controlled by recharge to the overlying aquifer. Together with the Mg/Ca, Sr/Ca, and δ 18O values, the initial uranium isotope activity ratios ([234U/238U]I) imply a generally drier early Holocene, coincident with a lower sea level and lower Southern Hemisphere summer insolation. Comparison of speleothem δ 18O time-series from Flores and Borneo shows that they vary in unison for much of the Holocene. However, there is a significant decrease in the Borneo δ18O record ~6,000 to 4,000 years ago that does not occur in the Flores record. This anomaly may be related to a change in the Australian-Indonesian summer monsoon circulation in response to a protracted positive phase of the Indian Ocean Dipole. Under this scenario, stronger upwelling off of western Indonesia would, based on present-day effects, result in reduced summer convective activity over Flores and a subsequent northward shift of the intertropical convergence zone. [Copyright &y& Elsevier]

Abstract: The fossils of Chaoxian hominin, widely accepted as representing archaic Homo sapiens in eastern China, were recovered from the middle or slightly higher levels of Layer 2 deposits of a collapsed cave at Yinshan, Anhui Province. Results of mass spectrometric U-series dating of intercalated speleothem calcites are presented. Based mainly on four broadly coeval calcite samples, the hominin fossils should be bracketed in the range of 310–360ka or somewhat older. These ages are much older than the previous estimate at 160–200ka based on the U-series dating of fossil teeth and bones, and may be cited as supporting evidence for an earlier H. erectus–archaic H. sapiens interface in China. [Copyright &y& Elsevier]

The age structure and stable isotope composition of a stalagmite (CC1) from an upland cave in central-western Italy were studied to investigate regional response to global climatic changes. Four growth phases are constrained by 28 thermal ionization and multi-collector inductively coupled plasma mass spectrometry Th–U ages and reveal intermittent deposition through the period between Marine Isotope Stage (MIS) 11 and 3 (∼380 and ∼43 kyr). Most of the growth took place between ∼380 and ∼280 kyr, a period punctuated briefly by a hiatus in deposition through the glacial maximum of MIS 10. Growth was terminated abruptly at 280 kyr just prior to the MIS 8 glacial maximum. With a present-day chamber temperature of 7.5 °C, the timing of hiatuses close to these glacial maxima point to freezing conditions at the time. No deposition was recorded through the entirety of MIS 7 and most of MIS 6, whilst two minor growth phases occurred at ∼141–125 and ∼43 kyr. Growth at 141 kyr indicates temperatures >0 °C at a time when MIS 6 ice volumes were close to their maximum. High stable carbon isotope (δ13C) values (−2.8‰ to +3.1‰) throughout the stalagmite''s growth reflect a persistently low input of biogenic CO2, indicating that the steep, barren and alpine-like recharge area of today has been in existence for at least the last ∼380 kyr. During MIS 9, the lowest δ13C values occur well after maximum interglacial conditions, suggesting a lag in the development of post-glacial soils in this high-altitude karst. The stable oxygen isotope (δ18O) trends match the main structural features of the major climate proxy records (SPECMAP, Vostok and Devils Hole), suggesting that the δ18O of CC1 has responded to global-scale climate changes, whilst remarkable similarity exists between CC1 δ18O and regional sea-surface temperature reconstructions from North Atlantic core ODP980 and southwest Pacific marine core MD97-2120 through the most detailed part of the CC1 record, MIS 9–8. The results suggest that CC1 and other stalagmites from the cave have the potential to capture a long record of regional temperature trends, particularly in regards to the relative severity of Pleistocene glacial stages. [Copyright &y& Elsevier]

Crystallization pathways are at the core of incorporation of chemical species by calcium carbonate minerals. This is particularly important in speleothems where the classical equilibrium precipitation approach and the theoretical partition coefficient are not always applicable. In fact, in several speleothems non classical nucleation plays an active role and an empiric "speleothem enrichment factor" better describes the incorporation of different chemical species. Here we present the first attempt to calibrate chemical parameters on the base of speleothem fabrics for active and Late Holocene stalagmites taken from two caves in Atiu, Cook Islands. Our multi-proxy analysis integrates high-resolution petrography, trace element and stable isotope analysis of stalagmites characterised by growth rates ranging from 20 up to 1000 µm/yr, which have been dated by U-Th series and lamina counting. In-situ calcite farming experiments yielded calcite crystals of the order of ten nanometer from the slow drips, whereas colloidal calcite particulate (2-3 nm crystals) associated to organic and inorganic colloids formed from the fast drips. Fast/variable and slow/constant drip rate end members generate active forming stalagmite fabrics with fast growing opaque open/porous calcite and translucent compact columnar calcite respectively. In the compact fabric soluble species are incorporated within the calcite lattice, whilst OM colloids are expelled or isolated in the crystal defects. This allows using a partition coefficient for soluble elements, but not for elements adsorbed on colloids. In the open/porous fabric calcite crystals seem to grow by attachment of particles and there is a large number of sites where colloids, particulate and even solute elements can be adsorbed and incorporate outside the calcite lattice. This results in an enhanced incorporation of trace elements and thus, the theoretical partition coefficient cannot be utilized to reconstruct the original chemistry of the dripwater.In two Late Holocene stalagmites LA-ICP-MS analyses reveal specific patterns in the elemental distribution. Most of the solute elements (Mg, Sr, Ba, Na) show a positive covariance and can be potentially be utilized as palaeo-hydrological proxy. This is corroborated by the negative correlation with colloidally transported elements such as Y and P, and the general trend of δ13C that is consistent with Mg and Sr. During wet condition (low Mg and Sr), δ13C shifts toward more negative values (down to -11‰). In contrast, dry conditions are characterised by less negative δ13C and higher concentration of Mg and Sr suggesting the influence of kinetic effects and/or evapotranspiration. However, the higher incorporation of solute elements during dry phases is further enhanced in the open/porous fabric and a fabric-specific elemental enrichment factor has to be taken into account. [ABSTRACT FROM AUTHOR]