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The sedimentary sequence in Scladina Cave (Belgium) is well-known for its rich Middle Paleolithic assemblages and its numerous faunal remains. Of particular interest is the presence of a nearly complete mandible of a Neandertal child. To place all these finds in the correct chronostratigraphic context, various dating techniques have been applied over the past decades. This resulted in a reasonably well-constrained age model, roughly spanning the last glacial cycle. Age constraints of the lower part of the Scladina sequence as well as from the underlying Sous-Saint-Paul Cave were however absent until now. Previous attempts to date several speleothem layers in Scladina Cave, using U-Th dating were only partly successful, presumably because diagenetic alteration of speleothem material compromised the ages. In the present study we re-assessed U-Th dating of various speleothem levels in Scladina Cave, applying state-of-the-art U-Th dating, and carefully selecting material that experienced little to no diagenetic alteration. The new results constitute a robust age framework for the Scladina sequence, which provides precisely dated stratigraphic anchor points that improve the previous age model. Furthermore, new U-Th analyses, for speleothems from the lower part of the Scladina sequence and from the Sous-Saint-Paul sequence, document Middle Pleistocene ages, making this one of the longer fossil-rich cave sedimentary sequences in NW Europe. The new data confirm that speleothem deposition predominantly took place in periods of warmer climate, while siliciclastic sediments characterize the colder intervals. New speleothem ages further suggest that the Neandertal mandible found in the sequence, and previously placed in Marine Isotope Stage 5a or 5b, could potentially be as old as Marine Isotope Stage 5d. [ABSTRACT FROM AUTHOR]

We present a 500‐year precipitation‐sensitive record based on co‐varying speleothem δ18O values and Mg/Ca ratios from Larga cave in Puerto Rico. This multi‐proxy record shows that the evolution of rainfall in the northeastern Caribbean was characterized by alternating centennial dry and wet phases corresponding to reduced versus enhanced convective activity. These phases occurred synchronous with relatively cool and warm tropical Atlantic sea‐surface temperatures (SSTs), respectively. While the observed pattern suggests a close link of northeastern Caribbean rainfall to the Atlantic Multidecadal Variability, a regional comparison reveals intermittent regional heterogeneity especially on decadal timescales, which may be related to a superimposing influence of the Pacific and Atlantic basins. Furthermore, the speleothem‐based hydroclimate reconstruction indicates a significant volcanic impact during the past two centuries, and further reveals a potential solar signal in the preceding three centuries. We posit that the forcing likely shifted from solar to volcanic during the eighteenth century in being an important source of multidecadal to centennial Caribbean rainfall variability. The link between convective rainfall and natural forcing may be explained through a modulation of SST variations in the tropical Atlantic and Pacific oceans. Plain Language Summary: Climate change is expected to affect rainfall throughout the Caribbean and Central America, where over 200 million people are heavily dependent upon rain as their main source of freshwater. We have looked at how the amount of rainfall in the Caribbean has changed through time, and possible reasons for these changes, to inform predictions of future rainfall patterns for the region. Cave mineral deposits, also known as speleothems, can be used to assess the amount of regional rainfall in the past by looking at their slight changes over time in the mineral's chemical composition. We created a record of Caribbean rainfall spanning the last five centuries using a speleothem from Puerto Rico. Our results indicate that rainfall changes since the sixteenth century were strongly influenced by changes in temperatures of the surface waters of the Atlantic Ocean. We further found that changes in the sun's brightness and volcanic eruptions may alter Atlantic Ocean sea‐surface temperature, which in turn affect the overall changes in Caribbean rainfall patterns. Key Points: Speleothem‐based Puerto Rican rainfall reconstruction shows prominent multidecadal‐to‐centennial variability during the past five centuriesPuerto Rican rainfall fluctuations are linked to solar variations before the eighteenth century and volcanic forcing thereafterCaribbean Sea‐surface temperature anomalies as part of the Atlantic Multidecadal Variability emerge as robust precursor of rainfall amounts [ABSTRACT FROM AUTHOR]

A speleothem collected from Palco Cave (Puerto Rico) spans the 8.2 ka event, a time interval associated with fluctuations of Atlantic Ocean circulation and possible drying in the Caribbean region. While stalagmite δ18O, δ13C, and Mg/Ca data do not show a sustained change in mean state over the 8.2 ka event, the proxies provide robust evidence for three abrupt fluctuations toward drier conditions in rapid succession, each lasting less than two decades, occurring at 8.20, 8.14, and 8.02 ka BP. A cave monitoring program at Palco Cave supports the interpretation of the speleothem proxy records. Because changes in the position of the Intertropical Convergence Zone (ITCZ) are directly coupled to sea-surface temperature variations in the North Atlantic, we hypothesize that cold events in the North Atlantic temporarily limited the northward migration of the ITCZ and tropical rain belt in boreal summer during these abrupt drying periods. The speleothem record suggests that the 8.2 ka event was associated with rapid rainfall fluctuations in the northern Caribbean followed by a comparably warm and wet phase after the 8.2 ka event. This enhanced variability during the transitional period of the deglaciation appears to be linked to a fast coupling between interacting oceanic and atmospheric processes. This involves, in particular, the Atlantic Meridional Overturning Circulation in modulating interhemispheric heat transport. [ABSTRACT FROM AUTHOR]

On glacial‐interglacial time scales, changes in the Earth's orbital configuration control climate seasonality and mean conditions. Tropical coral skeletons can be sampled at a sufficient resolution to reconstruct past seasonality. Here, last deglacial Porites skeletons from Integrated Ocean Drilling Program Expedition 310 to Tahiti are investigated and, supported by a modern calibration, monthly resolved time series in geochemical proxies (Sr/Ca, δ18O, δ13C) are constructed. For most of the deglaciation, Sr/Ca seasonality was similar to modern (0.139 ± 0.010 mmol mol−1; 2.8 ± 0.2°C) reflecting the small change in insolation seasonality. However, during the Younger Dryas, high values in Sr/Ca seasonality (0.171 ± 0.017 mmol mol−1; 3.4 ± 0.3°C) suggest a reduced mixed layer depth and enhanced influence of the South Pacific Subtropical Gyre due to South Pacific Convergence Zone (SPCZ) inactivity. Furthermore, high amplitudes in Younger Dryas skeletal δ18O (0.40 ± 0.22 ‰) and δ13C (0.86 ± 0.22 ‰) seasonality compared to modern (δ18O = 0.29 ± 0.08 ‰; δ13C = 0.27 ± 0.08 ‰) point to elevated winter‐summer discrepancies in rainfall and runoff. Mean coral Sr/Ca variability suggests an influence of Northern Hemisphere climate events, such as the Younger Dryas cooling (+0.134 ± 0.012 mmol mol−1;−2.6 ± 0.2°C), or the Bølling–Allerød warming (+0.032 ± 0.040 mmol mol−1; −0.6 ± 0.4°C). Deglacial mean coral Δδ18O (δ18Oseawater contribution to skeletal δ18O), corrected for the ice volume effect, was elevated pointing to more saline, thus dryer conditions, likely due to a northward migration of the SPCZ. Seasonal cycles in coral δ13C were likely caused by variations in linear extension rates that were reduced during the last deglaciation (1.00 ± 0.6 cm year−1) compared to today (1.6 ± 0.3 cm year−1). Plain Language Summary: Changes in the Earth's movement around the sun are the primary cause of changes in the annual cycle and annual mean of environmental conditions during the last glacial‐interglacial periods. Distinct from most climate archives, the annual bands of coral skeletons can be sampled at a monthly resolution that allows for reconstructions of past seasonal cycles. In this study, the chemical composition of coral skeletons from the genus Porites that grew during the last deglaciation at Tahiti (∼15,000–9,000 years ago) was analyzed to infer seasonal variations and mean conditions in past sea surface temperature and salinity. Prior to application, the methods were successfully calibrated using modern coral skeletons from Tahiti. Results showed that sea surface temperature seasonality was similar to today during most of the deglaciation. However, for the Younger Dryas, a particular cold interval, a marked increase in sea surface temperature seasonality suggests that Tahiti was at that time located outside the South Pacific Convergence Zone, a rain band extending across the tropical Southwest Pacific. Furthermore, coral reconstructions revealed that, although distant, North Atlantic last deglacial climate events influenced mean climate conditions at Tahiti. In addition, we show that last‐deglacial coral growth rates were reduced compared to today. Key Points: Last deglacial changes in Tahiti coral Sr/Ca suggest an influence of Northern‐Hemisphere climate events on the tropical South PacificVariations in last deglacial Tahitian climate were modulated by meridional migrations of the South Pacific Convergence ZoneLast deglacial Porites corals revealed reduced linear extension rates (1.0 ± 0.6 cm year−1) compared to today (1.6 ± 0.3 cm year−1) [ABSTRACT FROM AUTHOR]

The carbon isotopic signature inherited from soil and epikarst processes may be modified by degassing and prior calcite precipitation (PCP) before its imprint on speleothem calcite. Despite laboratory demonstration of PCP effects on carbon isotopes and increasingly sophisticated models of the governing processes, to date, there has been limited effort to deconvolve the dual PCP and soil–epikarst components in measured speleothem isotopic time series. In this contribution, we explore the feasibility, advantages, and disadvantages of using trace element ratios and δ44 Ca to remove the overprinting effect of PCP on measured δ13 C to infer the temporal variations in the initial δ13 C of drip water prior to degassing and PCP. In nine examined stalagmites, the most widely utilized PCP indicators Mg/Ca and δ44 Ca covary as expected. However, Sr / Ca does not show consistent relationships with δ44 Ca so PCP is not the dominant control on Sr / Ca. From δ44 Ca and Mg/Ca , our calculation of PCP as fCa , the fraction of initial Ca remaining in solution at the time the stalagmite layer is deposited, yields multiple viable solutions depending on the assumed δ44 Ca fractionation factor and inferred variation in DMg. Uncertainty in the effective fractionation of δ13 C during degassing and precipitation contributes to uncertainty in the absolute value of estimated initial δ13 C. Nonetheless, the trends in initial δ13 C are less sensitive to these uncertainties. In coeval stalagmites from the same cave spanning the 94 to 82 ka interval, trends in calculated initial δ13 C are more similar than those in measured δ13 C and reveal a common positive-anomaly initial δ13 C during a stadial cooling event. During deglaciations, calculated initial δ13 C implies a trend of greater respiration rates and higher soil CO 2 , although the higher interglacial drip water saturation favors more extensive PCP. Initial δ13 C can be estimated for active and fossil speleothems from a range of settings, wherever there is confidence that Mg/Ca and/or δ44 Ca provides a quantitative indication of past changes in PCP. Further study of Mg partitioning in speleothems will improve the robustness of Mg/Ca as a PCP proxy. [ABSTRACT FROM AUTHOR]

The Kurai Fault Zone (KFZ) is one of the most hazardous seismogenic structures in the Gorny Altai (Russia), which bounds the largest Kurai and Chuya intermontane basins from the north. Trenching studies, radiocarbon dating of colluvial wedge deposits, and 230Th-U dating of seismogenic travertine of the Meshtuyaryk field showed that the fault scarp in the northwestern part of the Chuya Depression was formed by earthquakes that occurred ca. 9.5, 7.7, 5.8, and 4.8–3.4 ka BP. The last two palaeoearthquakes are younger than 3.2 ka BP. The parameters of seismogenic ruptures, as well as the distances between coeval seismogenic travertines along the KFZ, yielded estimates of the Mw of the four oldest palaeoearthquakes as 6.8–7.6 and ESI 2007 shaking intensities of VIII–XI. The results of 230Th-U dating suggest that deposition of the Meshtuyaryk travertines was triggered by three strong palaeoearthquakes at ca. 9.5, 7.7, and 4.8–3.4 ka BP, which activated faults and caused a rapid rise along them of ambient-temperature bicarbonate groundwaters previously sealed in deep-seated limestone aquifers. [ABSTRACT FROM AUTHOR]

Hells Bells are underwater secondary carbonates discovered in sinkholes (cenotes) southeast of Cancun on the north-eastern Yucatán peninsula, Mexico. These authigenic calcite precipitates, reaching a length of up to 4 m, most likely grow in the pelagic redoxcline. Here we report on detailed 230Th/U-dating and in-depth geochemical and stable isotope analyses of specimens from cenotes El Zapote, Maravilla and Tortugas. Hells Bells developed since at least ~ 8000 years ago, with active growth until present day. Initial (234U/238U) activity ratios (δ234U0) in Hells Bells calcite decreas from 55 to 15‰ as sea level converges toward its present state. The temporal evolution of the geochemistry and isotope composition of Hells Bells calcites thus appears to be closely linked to sea-level rise and reflects changing hydrological conditions (desalinization) of the aquifer. We suggest that decelerated leaching of excess 234U from the previously unsaturated bedrock traces Holocene relative sea-level rise. Considering this proxy, the resulting mean sea-level reconstruction contains half as much scatter, i.e. improves by a factor of two, when compared to previously published work for the period between 8 and 4 ky BP. [ABSTRACT FROM AUTHOR]

The south-eastern Gorny Altai is one of the most hazardous seismogenic area in the north of Central Asia. We present a synthesis of field, 230Th-U geochronological, mineralogical and geochemical data collected on seven Quaternary travertines. All travertines occur within the zones of active faults that border the Chuya and Kurai intermontane basins. Travertine cement mainly comprises calcite (with minor amounts of aragonite), which cements alluvial, alluvial fan, and colluvial deposits. The results of 230Th-U dating suggest that deposition of the travertines was triggered by large paleoearthquakes in the last eight thousand years. Several stages of travertine formation with ages 9–11 ka BP correspond to the known period of strong paleoseismicity in the region (8–16 ka BP). The 123 ka BP travertine resulted from a slip triggered by the Middle Pleistocene deglaciation, while that of 400 ka BP represents seismic motions likely associated with the main Cenozoic orogenic phase. All travertine forming events fall within warm and wet climatic phases (interglacials). Large earthquakes activated faults and caused a rapid rise along them of ambient-temperature bicarbonate groundwater, which was previously sealed in deep-seated Upper Neoproterozoic–Paleozoic limestone-dolostone aquifers. Rapid CO2 degassing of the spring water was the most important control of calcite or aragonite precipitation. Such travertines represent an important tool for paleoseismological research in seismically active regions. [ABSTRACT FROM AUTHOR]

The Late Cretaceous orogeny followed by the Eocene collision of the Adriatic with the European plate dissected the Northern Calcareous Alps (NCA) by a number of well-studied strike-slip fault systems accommodating N-S shortening and E-W stretching. However, the post-Miocene fault activity is poorly constrained due to lack of Neogene faulted sediments, and glacial erosion of geomorphic indicators. Using the protected environment of caves, we fill the knowledge gap in the post-Miocene evolution of the NCA by paleostress analysis of 172 reactivated faults that offset passages in 28 caves near major faults. Constrained maximum age of caves, our results indicate that the NCA have been subjected to N to NE trending compression since Pliocene. Faulted speleothems dated with 230Th/U method, indicate that the recorded present-day stress state did not significantly change during the last 0.5 Ma. In contrast to the previously proposed post-Miocene N-S extension of NCA, but in agreement with what was observed in Vienna and Pannonian basins, we conclude that the eastward extrusion resulting from N-S convergence has continued despite a distinct slowdown of plate tectonic velocities in the late Miocene. The N-S extension affected only the Alpine front during Pliocene Molasse basin inversion, while at the scale of the Alpine orogen the NCA underwent successive N-S shortening and E-W stretching. [ABSTRACT FROM AUTHOR]

The carbon isotopic signature inherited from soil/epikarst processes may be modified by degassing and prior calcite precipitation (PCP) before its imprint on speleothem calcite. Despite laboratory demonstration of PCP effects on carbon isotopes and increasingly sophisticated models of the governing processes, to date, there has been limited effort to deconvolve the dual PCP and soil/epikarst components in measured speleothem isotopic time series. In this contribution, we explore the feasibility, advantages, and disadvantages of using trace element ratios and δ44Ca to remove the overprinting effect of PCP on measured δ13C to infer the temporal variations in the initial δ13C of dripwater. In 8 examined stalagmites, the most widely utilized PCP indicators Mg/Ca and δ44Ca covary as expected. However, Sr/Ca does not show consistent relationships with δ44Ca so PCP is not universally the dominant control on Sr/Ca. From δ44Ca and Mg/Ca, our calculation of PCP as fCa, fraction of initial Ca remaining at the deposition of the stalagmite layer, yields multiple viable solutions depending on the assumed δ44Ca fractionation factor and inferred variation in DMg. Uncertainty in the effective fractionation of δ13C during degassing and precipitation contributes to uncertainty in the absolute value of estimated initial δ13C. Nonetheless, the trends in initial δ13C are less sensitive to these uncertainties. In coeval stalagmites from the same cave spanning 94 to 82 ka interval, trends in calculated initial δ13C are more similar than those in measured δ13C, and reveal a common positive anomaly initial δ13C during a stadial cooling event. During deglaciations, the trend of greater respiration rates and higher soil CO2 is captured in the calculated initial δ13C, despite the tendency of higher interglacial dripwater situation to favor more extensive PCP. [ABSTRACT FROM AUTHOR]

Rationale: The first‐row transition metals Cu, Ni, and Co show a strong binding affinity to natural organic matter. Compared to dissolved elements and stable water isotopes, they may be transported rapidly through the soil and host rock into caves in response to infiltration events. This study aims to assess the potential of transition metal ratios as indicators for infiltration changes in response to the seasonal and/or event‐based rainfall variation. Methods: We developed a protocol to analyze Cu, Ni, and Co in the cave drip water using collision cell ICP‐QMS without extensive sample pretreatment. The high Ca matrix leads to significant isobaric interferences on all isotope masses. Our method includes a correction of these matrix effects and yields results with comparable accuracy and reproducibility to other published methods. We applied this protocol to drip water samples from Larga Cave (Puerto Rico) covering at least two full annual cycles between 2014 and 2019 on a bimonthly scale. Results: The analysis of external reference materials yielded a reproducibility between 4.7% and 9.2% (relative standard deviation), validating the accuracy of the matrix correction method. The limit of detection is <0.04 ppb for Cu, <0.02 ppb for Ni, and <0.008 ppb for Co. The analysis of drip water samples from Larga Cave reveals pronounced changes of several orders of magnitude in all Element (El) to Ca, Cu/Ni, and Cu/Co ratios in response to seasonal infiltration changes. In addition, we observe a partly even stronger response after major tropical storms and heavy precipitation events of the period of record, for example, tropical storm "Bertha" (2014) and the category 5 hurricanes "Irma" and "Maria" (both 2017). Conclusions: Transition metal ratios can be accurately measured in cave drip waters with high Ca matrix. At our tropical site, these are promising tracers of infiltration changes in response to changes in the amount of rainfall, providing the first step toward tropical cyclone reconstruction using trace elements in speleothems. [ABSTRACT FROM AUTHOR]

Here, we report on the first radiometric dating of pre-Quaternary sinters covering the ENE–WSW striking vertical faults filled with Upper Badenian sands (neptunian dykes) in Mesozoic carbonates of the Devín quarry in the Malé Karpaty Mountains. The 238U/206Pb age of 13.98±0.56 Ma fits well with the former age prediction based on biostratigraphic evidence. Our results provide fault opening age, refine the age of sediments and fossils preserved in the neptunian dykes, and constrain the onset of Badenian sea transgression. [ABSTRACT FROM AUTHOR]

Here we present an electrochemical method for the anodic oxidation and subsequent degradation of lignin in speleothems to utilize the resulting lignin oxidation products (LOPs) as paleo‐vegetation markers. LOPs were analyzed using an ultra‐high performance liquid chromatography (UHPLC) system coupled to a high‐resolution mass spectrometer (HRMS). The method presented here achieved comparable or even higher LOP concentrations than established CuO and CuSO4 oxidation methods. The method represents a new tool for the analysis and reconstruction of paleo‐vegetation and has the potential to be applied to other climate archives. [ABSTRACT FROM AUTHOR]

We present speleothem fluid inclusion δ18 O f and δ2 H f values from Larga Cave, Puerto Rico, that cover the interval between 46.2 and 15.3 ka on the millennial scale, including the Last Glacial Maximum (LGM) and several stadial and interstadial cycles. The data set can be divided in two main clusters of stable isotope compositions of the fluid inclusion water with respect to the global meteoric water line (GMWL), which coincide with strong variations in the water content of the stalagmite. In particular, this clustering is found to be climate related, where one cluster comprises samples from cold and dry periods, such as the Heinrich and Greenland stadials (HSs and GSs), as well as parts of the LGM, which exhibit very high δ18 O f and δ2 H f values. We interpret this enrichment as being caused by evaporation inside the cave due to enhanced cave ventilation during these colder and drier times. In contrast, in most samples corresponding to warmer and wetter Greenland interstadials (GIs), but also for some from HS 2 and 3, the δ18 O f and δ2 H f values plot on the meteoric water line and modification of fluid inclusion water due to "in-cave" evaporation are found to be negligible. Consequently, variations of recent glacial hydro-climate and temperatures in the western tropical Atlantic can be constrained. In general, δ18 O f values from fluid inclusions are up to 3 ‰ higher than those of modern drip water, which is interpreted as a weaker atmospheric convective activity during the last glacial period. In addition, reconstructed temperatures suggest an average cooling of 2–3 ∘ C during the LGM compared to modern cave temperatures. Reconstructed cave temperatures yield an average cooling of - 1.4 ± 2.8 ∘ C for HS 2 and - 3.6 ± 2.2 ∘ C for HS 3. Higher δ18 O f values of these samples further suggest that the drip water was dominated by orographic rainfall and/or cold fronts, along with weak or even absent convective activity. In contrast, during interstadial phases, reconstructed temperatures reached nearly modern values, and convective activity was comparable to or only slightly weaker than today. [ABSTRACT FROM AUTHOR]

Lignin oxidation products (LOPs) are widely used as vegetation proxies in climate archives, such as sediment and peat cores. The total LOP concentration, Σ 8, provides information on the abundance of vegetation, while the ratios C/V and S/V of the different LOP groups also provide information on the type of vegetation. Recently, LOP analysis has been successfully applied to speleothem archives. However, there are many open questions concerning the transport and microbial degradation of LOPs on their way from the soil into the cave system. These processes could potentially alter the original source-dependent LOP signals, in particular the C/V and S/V ratios, and thus complicate their interpretation in terms of past vegetation changes. We analyzed LOPs in leaf litter and different soil horizons as well as dripwater and flowstone samples from four different cave sites from different vegetation zones in New Zealand using ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry. We test whether the original source-dependent LOP signal of the overlying vegetation is preserved and can be recovered from flowstone samples and investigate how the signal is altered by the transport from the soil to the cave. The LOP concentrations range from mg g -1 in the soil to ng g -1 in the flowstones. Our results demonstrate that, from the soil to the flowstone, the C/V and S/V ratios both increase, while the total lignin content, Σ 8, strongly decreases. This shows that the LOP signal is strongly influenced by both transport and degradation processes. Nevertheless, the relative LOP signal from the overlying soil at the different cave sites is preserved in the flowstone. We emphasize that for the interpretation of C/V and S/V ratios in terms of past vegetation changes, it is important to compare only samples of the same type (e.g., speleothem, dripwater or soil) and to evaluate only relative variations. [ABSTRACT FROM AUTHOR]

The paleoenvironmental and tectonic history at the southwestern end of the Malé Karpaty Mountains was reconstructed using sediment analysis, mineralogy, and dating. Numerical ages using 26Al/10Be burial age dating, 230Th/U ages and luminescence age dating are combined to infer the Pliocene and Pleistocene development of the Hainburg Hills region. This study investigates sediments from two caves separated by a height difference of 92 m as well as aeolian cover sands from a fissure. The cave deposits are very unlike as one is a carbonate precipitate and the other sediment infill, but both preserve information on the uplift/incision at the Alpine-Carpathian border. Emplacement of coarsegrained fluvial deposits from the upper cave was dated to 4.1-4.6 Ma using terrestrial cosmogenic 26Al and 10Be in selected quartz cobbles. Calcite precipitates from the lower cave were 230Th/U dated on three morphologically slightly different cave rafts. Ages calculated from pristine calcite are least prone to alteration and give a time of formation at ~0.31-0.34 Ma. Vertical offset rates calculated from ages and positions above the recent streambed of the Danube vary between 36-42 m/Ma for the higher position and 162 m/Ma at maximum for the lower cave and point to increased uplift/incision that has been described from other areas in the Eastern Alps and the Pannonian Basin System. Deposition of aeolian sand cover was constrained to 13.6 -15.6 ka (pIRIR225 signal) and the presence of sand as opposed to its transport/erosion suggests a change in wind velocities at the Hainburg Gate. This can possibly be correlated to the termination of a cold phase with decreasing continentality accompanied by decreasing atmospheric pressure gradients. Minerals such as hematite and smectite as well as traces of poorly crystallized iron oxides found in the matrix of the upper (older) cave, were formed during warm and humid climate conditions facilitating lateritic soil formation. This is a remnant from the late Miocene or Early Pliocene soil that formed in a subtropical climate. [ABSTRACT FROM AUTHOR]

Lignin oxidation products (LOPs) are widely used as vegetation proxies in climate archives, such as sediment and peat cores. The total LOP concentration, S8, provides information on the abundance of vegetation, while the ratios C / V and S / V of the different LOP groups also provide information on the type of vegetation. Recently, LOP analysis has been successfully applied to speleothem archives. However, there are many open questions concerning the transport and microbial degradation of LOPs on their way from the soil into the cave system. These processes could potentially alter the original source-dependent LOP signals, in particular the C / V and S / V ratios, and thus complicate their interpretation in terms of past vegetation changes. We analyzed LOPs in leaf litter and different soil horizons as well as dripwater and flowstone samples from four different cave sites from different vegetation zones in New Zealand using ultrahigh performance liquid chromatography coupled to high resolution mass spectrometry. We test whether the original source-dependent LOP signal of the overlying vegetation is preserved and can be recovered from flowstone samples and investigate how the signal is altered by the transport from the soil to the cave. The LOP concentrations range from mg/g in the soil to ng/g in the flowstones. Our results demonstrate that, from the soil to the flowstone, the C / V and S / V ratios both increase, while the total lignin content, S8, strongly decreases. This shows that the LOP signal is strongly influenced by both transport and degradation processes. Nevertheless, the relative LOP signal from the overlying soil at the different cave sites is preserved in the flowstone. We emphasize that for the interpretation of C / V and S / V ratios in terms of past vegetation changes, it is important to compare only samples of the same type (e.g., speleothem, dripwater or soil) and to evaluate only relative variations. [ABSTRACT FROM AUTHOR]

The sensitivity of tropical Atlantic precipitation patterns to the mean position of the Intertropical Convergence Zone (ITCZ) at different time scales is well‐known. However, recent research suggests a more complex behavior of the northern hemispheric tropical rain belt related to the ITCZ in the western tropical Atlantic. Here we present a precisely dated speleothem multi‐proxy record from a well‐monitored cave in Puerto Rico, covering the period between 46.2 and 15.3 ka. The stable isotope and trace element records document a pronounced response of regional rainfall to abrupt climatic excursions in the North Atlantic across the Last Glacial such as Heinrich stadials and Dansgaard/Oeschger events. The annual to multidecadal resolution of the proxy time series allows substructural investigations of the recorded events. Spectral analysis suggests that multidecadal to centennial variability persisted in the regional hydroclimate mainly during interstadial conditions but also during the Last Glacial Maximum. In particular, we observe a strong agreement between the speleothem proxy data and the strength of the Atlantic meridional overturning circulation, supporting a persistent link of oceanic forcing to regional precipitation. Comparison to other paleo‐precipitation records enables the reconstruction of past changes in position, strength, and extent of the ITCZ in the western tropical Atlantic in response to millennial‐ and orbital‐scale global climate change. Plain Language Summary: It is important to understand the climatic circumstances of how rainfall in the western tropical Atlantic varies under a changing climate to better manage the water supply for millions of people. However, it is not well understood how rainfall varied in the past, especially during the Last Glacial period, a time of strong climate variability and abrupt climate changes. Here, we use a stalagmite from Puerto Rico to create a new record of past changes in rainfall in this region. For this purpose, we analyzed proxy data that reveal a series of wet and dry periods during the Last Glacial corresponding to rapid global climate shifts. Our rainfall‐sensitive stalagmite record captured changes of the tropical rain belt on various timescales and shows that this variability in rainfall is closely connected to changes in the strength of the ocean circulation. This suggests that the link between the ocean and the atmosphere is more robust than previously assumed. The comparison of our record with other rainfall‐sensitive records from Central America and the northern Caribbean allows for a detailed reconstruction of the spatial and temporal changes of the western tropical Atlantic rain belt. Key Points: Puerto Rican speleothem record documents multidecadal to millennial‐scale precipitation variability between 46.2 and 15.3 kaClimate proxies show a distinct rainfall response to abrupt North Atlantic climate change including Heinrich and Dansgaard/Oeschger eventsCompilation of regional precipitation records allows to reconstruct past changes in ITCZ patterns in the western tropical Atlantic [ABSTRACT FROM AUTHOR]

Surface temperature is a fundamental parameter of Earth's climate. Its evolution through time is commonly reconstructed using the oxygen isotope and the clumped isotope compositions of carbonate archives. However, reaction kinetics involved in the precipitation of carbonates can introduce inaccuracies in the derived temperatures. Here, we show that dual clumped isotope analyses, i.e., simultaneous ∆47 and ∆48 measurements on the single carbonate phase, can identify the origin and quantify the extent of these kinetic biases. Our results verify theoretical predictions and evidence that the isotopic disequilibrium commonly observed in speleothems and scleractinian coral skeletons is inherited from the dissolved inorganic carbon pool of their parent solutions. Further, we show that dual clumped isotope thermometry can achieve reliable palaeotemperature reconstructions, devoid of kinetic bias. Analysis of a belemnite rostrum implies that it precipitated near isotopic equilibrium and confirms the warmer-than-present temperatures during the Early Cretaceous at southern high latitudes. Some palaeotemperature proxies suffer from inaccuracies related to kinetic fractionations occurring during carbonate mineral growth. Here, the authors show that dual clumped isotope thermometry can identify the origin of these kinetic biases and allows for the reconstruction of accurate environmental temperatures. [ABSTRACT FROM AUTHOR]

Two small annually laminated stalagmites from Zoolithencave (southeastern Germany) grew between CE 1821 and 1970 (Zoo‐rez‐1) and CE 1835 and 1970 (Zoo‐rez‐2), respectively. Trace element concentrations were determined by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA‐ICP‐MS). Samples for δ13C and δ18O analyses were micromilled on annual and subannual resolution. Soil and host rock samples were analyzed by X‐Ray Diffraction (XRD) and their elemental concentrations determined via inductively coupled plasma optical emission spectrometer (ICP‐OES). Trace element concentrations in the stalagmites show two groups in the principal component analyses: one with Mg, Ba, and Sr and another with Y, P, and Al, respectively. The second group reflects the content of detrital material. Increased weathering of soil minerals seems to have a strong influence on the silicate/carbonate weathering ratio controlling the variability of Mg, Ba, and Sr. Meteorological and Global Network of Isotopes in Precipitation (GNIP) station data were used to calculate the δ18O values of the drip water (infiltration‐weighted, mean annual, and the mean of the winter precipitation δ18O values) as well as the corresponding speleothem calcite. The δ18O values calculated by the infiltration‐weighted model show similar patterns and amplitudes as the measured δ18O values of the two stalagmites. This suggests that the δ18O values of speleothem calcite reflect the δ18O values of infiltration‐weighted annual precipitation, which zis related to mean annual temperature, resulting in a significant correlation between mean annual temperature and the measured δ18O values of stalagmite Zoo‐rez‐2. This relationship could potentially be used for quantitative climate reconstruction in the future by extending the time series back in time with further stalagmites from Zoolithencave. Key Points: Silicate versus carbonate weathering has an influence on speleothem trace elementsYttrium, phosphorus, and aluminum reflect detrital content of the speleothemsδ18O values of the stalagmites are a proxy for mean annual temperature [ABSTRACT FROM AUTHOR]

The societal and cultural development during the Bronze Age and the subsequent Iron Age was enormous in Greece, however interrupted by two significant transformations around 4200 years b2k (Early Helladic II/III; b2k refers to years before 2000 CE) and 3200 years b2k (end of Late Helladic III). Artefacts and building remains provide some insights into the cultural evolution, but only little is known about environmental and climatic changes on a detailed temporal and spatial scale. Here we present a 4000-year long stalagmite record (GH17-05) from Hermes Cave, Greece, located on Mount Ziria in the close vicinity of the Late Bronze Age citadel of Mycenae and the Classical-Hellenistic polis of Corinth. The cave was used in ancient times, as indicated by ceramic fragments in the entrance area and a pronounced soot layer in the stalagmite. 230Th-U dating provides age constraints for the growth of the stalagmite (continuous between ~ 800 and ~ 5300 years b2k) and the formation of a soot layer (2.5+0.5-0.65 ka b2k). Speleothem δ18O and δ13C values together with clumped isotopes and elemental ratios provide a detailed paleoclimate record of the Northern Peloponnese. The proxy data suggest significant centennial scale climate variability (i.e., wet vs. dry). Furthermore, carbonate δ18O values, calculated drip water δ18O values, 234U/238U activity ratios and elemental ratios suggest a long-term trend towards drier conditions from ca 3.7 to ~ 2.0 ka b2k. From 2.0 ka b2k towards growth stop of the stalagmite, a trend towards wetter conditions is observed. A high degree of correlation was found for isotope trends of different speleothems from the Peloponnese and partially with climate records from the Eastern Mediterranean, whereas speleothems and lake records with a larger distance to the Peloponnese show little correlation or even opposing trends. [ABSTRACT FROM AUTHOR]

The in situ measurement of Sr isotopes in carbonates by MC‐ICP‐MS is limited by the availability of suitable microanalytical reference materials (RMs), which match the samples of interest. Whereas several well‐characterised carbonate reference materials for Sr mass fractions > 1000 µg g−1 are available, there is a lack of well‐characterised carbonate microanalytical RMs with lower Sr mass fractions. Here, we present a new synthetic carbonate nanopowder RM with a Sr mass fraction of ca. 500 µg g−1 suitable for microanalytical Sr isotope research ('NanoSr'). NanoSr was analysed by both solution‐based and in situ techniques. Element mass fractions were determined using EPMA (Ca mass fraction), as well as laser ablation and solution ICP‐MS in different laboratories. The 87Sr/86Sr ratio was determined by well‐established bulk methods for Sr isotope measurements and is 0.70756 ± 0.00003 (2s). The Sr isotope microhomogeneity of the material was determined by LA‐MC‐ICP‐MS, which resulted in 87Sr/86Sr ratios of 0.70753 ± 0.00007 (2s) and 0.70757 ± 0.00006 (2s), respectively, in agreement with the solution data within uncertainties. Thus, this new reference material is well suited to monitor and correct microanalytical Sr isotope measurements of low‐Sr, low‐REE carbonate samples. NanoSr is available from the corresponding author. [ABSTRACT FROM AUTHOR]

The climate of the western Mediterranean was characterized by a strong precipitation gradient during the Holocene driven by atmospheric circulation patterns. The scarcity of terrestrial paleoclimate archives has precluded exploring this hydroclimate pattern during Marine Isotope Stages 5 to 3. Here we present stable carbon and oxygen isotope records from three flowstones from southeast Iberia, which show that Dansgaard/Oeschger events were associated with more humid conditions. This is in agreement with other records from the Iberian Peninsula, the Mediterranean, and western Europe, which all responded in a similar way to millennial‐scale climate variability in Greenland. This general increase in precipitation during Dansgaard/Oeschger events cannot be explained by any present‐day or Holocene winter atmospheric circulation pattern. Instead, we suggest that changes in sea surface temperature played a dominant role in determining precipitation amounts in the western Mediterranean. Plain Language Summary: Climate events characterized by a sudden temperature increase of up to 10 °C occurring in less than a few decades during the last glacial are recorded in Greenland ice cores. These abrupt warmings, the Dansgaard/Oeschger events, affected large regions of the Northern Hemisphere. The understanding of the regional response in precipitation during these climate shifts is limited for the western Mediterranean, due to the restricted number of terrestrial climate records that cover the last glacial period at sufficient resolution. Speleothems and their stable isotope compositions allow to trace changes in climate and vegetation based on an accurate chronological framework. Here we present a speleothem stable isotope record that shows that the Dansgaard/Oeschger events were associated with increased rainfall and a denser vegetation in the western Mediterranean. A similar pattern was observed for western Europe and other parts of the Mediterranean, and we propose that this was related to generally higher sea surface temperatures of the surrounding oceans rather than a reorganization of atmospheric circulation. Key Points: Western Mediterranean precipitation responded to Greenland interstadials and stadials in a coherent mannerDansgaard/Oeschger interstadials were accompanied by humid climate conditions over the western MediterraneanAtmospheric circulation patterns did not induce spatial differences in precipitation during the last glacial as they did during the Holocene [ABSTRACT FROM AUTHOR]

The cave bear was a prominent member of the Upper Pleistocene fauna in Eurasia. While breakthroughs were recently achieved with respect to its phylogeny using ancient DNA techniques, it is still challenging to date cave bear fossils beyond the radiocarbon age range. Without an accurate and precise chronological framework, however, key questions regarding the palaeoecology cannot be addressed, such as the extent to which large climate swings during the last glacial affected the habitat and possibly even conditioned the final extinction of this mammal. Key to constraining the age of cave bear fossils older than the lower limit of radiocarbon dating is to date interlayered speleothems using 230Th/U. Here we report new results from one such site in the Eastern European Alps (Schwabenreith Cave), which yielded the highest density of bones of cave bear (Ursus spelaeus eremus). Although dating of the flowstones overlying this fossiliferous succession was partly compromised by diagenetic alteration, the 230Th/U dates indicate that the bear hibernated in this cave after about 113 ka and before about 109 ka. This time interval coincides with the equivalent of Greenland Stadial 25, suggesting possible climate control on the cave bear's habitat and behaviour. © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd [ABSTRACT FROM AUTHOR]

South-eastern Spain is one of the driest regions in Europe and thus, prone to drought. Terrestrial climate records covering the late Glacial and Holocene from this area are sparse. Here, we present a flowstone record from Cueva Victoria, south-eastern Spain, which covers the late Glacial (15 ka) to the mid-Holocene (7 ka) including the Younger Dryas (YD). Between the onset of the Bølling/Allerød (B/A) and the early Holocene, flowstone δ18O values progressively decrease in accordance with sea-surface temperatures in the Alboran Sea, indicating an increase in precipitation in south-eastern Spain and a supra-regional signal of North Atlantic temperature change. At the same time, decreasing δ13C values suggest progressively increasing precipitation and vegetation density. This trend is interrupted by both colder and drier conditions during the YD. Between 9.7 ± 0.3 and 7.8 ± 0.2 ka, a large positive excursion of the δ13C values indicates a strong reduction in vegetation density, probably as a consequence of very dry spring/summer conditions. In combination with the continuously low speleothem δ18O values and a nearly unchanged growth rate, this suggests increased seasonality (i.e. drier spring/summer conditions, but not a strong reduction in annual precipitation). This is consistent with several other climate records from the Western Mediterranean region, showing that the Western Mediterranean realm (Spain, Italy) experienced pronounced spring/summer drought during this time interval. Interestingly, the timing of this dry period coincided with the African Humid Period. This may be part of a teleconnection with the North African Monsoon via the Hadley cell circulation. [ABSTRACT FROM AUTHOR]

Here, we present the first quantitative speleothem record of lignin oxidation products (LOPs), which has been determined in a Holocene stalagmite from the Herbstlabyrinth Cave in central Germany. In addition, we present LOP results from 16 months of drip water monitoring. Lignin is only produced by vascular plants and therefore has the potential to be an unambiguous vegetation proxy and to complement other vegetation and climate proxies in speleothems. We compare our results with stable isotope and trace element data from the same sample. In the stalagmite, LOP concentrations show a similar behavior to P, Ba and U concentrations, which have previously been interpreted as vegetation proxies. The LOP S/V and C/V ratios, which are usually used to differentiate between angiosperm and gymnosperm and woody and non-woody vegetation, show complex patterns suggesting additional influencing factors, such as transport and microbiological effects. The drip water from a fast drip site shows a seasonal pattern of LOPs with low LOP concentrations in winter and higher LOP concentrations in summer. These results indicate the potential of LOPs as a new proxy for vegetational and environmental changes in speleothems but also demonstrate the complexity and the current limitations of our understanding of the transport of lignin from the soil into the cave and the speleothems. [ABSTRACT FROM AUTHOR]

Here we present the first quantitative record of lignin oxidation products (LOPs) in a Holocene stalagmite from the Herbstlabyrinth Cave in central Germany, as well as LOP results from 16 months of drip water monitoring. Lignin is only produced by vascular plants and is therefore an unambiguous vegetation proxy, which can help to better interpret other vegetation and climate proxies in speleothems. We compared our results with stable isotope and trace element data from the same samples. The drip water monitoring reveals a seasonal pattern of LOPs in a fast drip site with low LOP concentrations in winter and higher LOP concentrations in summer, which is opposite to the behaviour of the drip rate, Mg2+ and PO3-4 concentrations. In the stalagmite, LOP concentrations are correlated or show a similar behaviour to P, Ba and U concentrations. The LOP ratios C/V and S/V, which are usually used to differentiate between angiosperm and gymnosperm and woody and non-woody lignin sources, are anticorrelated to the LOP concentrations and show a similar behaviour to δ13C and Mg concentrations. These results highlight the potential of LOPs as a new, highly specific vegetation proxy in speleothems, but also demonstrate current limitations in our understanding of the transport of lignin from the soil into the cave and the speleothems. [ABSTRACT FROM AUTHOR]

Here we present a sensitive method to analyze lignin oxidation products (LOPs) in speleothems and cave drip water to provide a new tool for paleo-vegetation reconstruction. Speleothems are valuable climate archives. However, compared to other terrestrial climate archives, such as lake sediments, speleothems contain very little organic matter. Therefore, very few studies on organic biomarkers in speleothems are available. Our new sensitive method allows us to use LOPs as vegetation biomarkers in speleothems. Our method consists of acid digestion of the speleothem sample followed by solid-phase extraction (SPE) of the organic matter. The extracted polymeric lignin is degraded in a microwave-assisted alkaline CuO oxidation step to yield monomeric LOPs. The LOPs are extracted via SPE and finally analyzed via ultrahigh-performance liquid chromatography (UHPLC) coupled to electrospray ionization (ESI) and high-resolution Orbitrap mass spectrometry (HRMS). The method was applied to stalagmite samples with a sample size of 3-5 g and cave drip water samples with a sample size of 100-200mL from the Herbstlabyrinth-Advent Cave in Germany. In addition, fresh plant samples, soil water, and powdered lignin samples were analyzed for comparison. The concentration of the sum of eight LOPs (68) was in the range of 20-84 ngg -1 for the stalagmite samples and 230-440 ngL -1 for the cave drip water samples. The limits of quantification for the individual LOPs ranged from 0.3- 8.2 ng per sample or 1.5-41.0 ngmL -1 of the final sample solution. Our method represents a new and powerful analytical tool for paleo-vegetation studies and has great potential to identify the pathways of lignin incorporation into speleothems. [ABSTRACT FROM AUTHOR]

Abstract: A flight of marine terraces along the Cuban coast records Quaternary sea‐level highstands and a general slowly uplifting trend during the Pleistocene. U/Th dating of these limestone terraces is difficult because fossil reef corals have been affected by open system conditions. Terrace ages are thus often based on geological and geomorphological observations. In contrast, the minimum age of the terraces can be constrained by dating speleothems from coastal mixing (flank margin) caves formed during past sea‐level highstands and carving the marine limestones. Speleothems in Santa Catalina Cave have ages >360 ka and show various cycles of subaerial–subaqueous corrosion and speleothem growth. This suggests that the cave was carved during the MIS 11 sea‐level highstand or earlier. Some stalagmites grew during MIS 11 through MIS 8 and were submerged twice, once at the end of MIS 11 and then during MIS 9. Phreatic overgrowths (POS) covering the speleothems suggest anchialine conditions in the cave during MIS 5e. Their altitude at 16 m above present sea level indicates a late Pleistocene uplift rate of <0.1 mm/ka, but modelling also shows uplift to have been insignificant over a long timespan during the middle Pleistocene since the cave was carved. Our study shows that some flank margin caves in the region of Matanzas are older than commonly believed (i.e. MIS 11 rather than MIS 5). These caves not only can be preserved but are good markers of interglacial sea‐level highstands, more reliable than marine abrasion surfaces. Copyright © 2018 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Diagenetic alteration of fossil reef corals may have severe effects on the reliability of 230Th/U-ages. The widely applied criteria introduced to test for the reliability of coral 230Th/U-ages are often not sufficient to identify all altered ages. The combination of 230Th/U- with 231Pa/U-dating has been suggested as a promising method to identify altered ages. Furthermore, 226Ra/230Th ratios can provide information about the diagenetic history during the last 10 000 years. Here we present a method to chemically separate U, Th, Pa and Ra from the same aliquot of a carbonate sample. The isotope ratios of our mixed U–Th–Pa–Ra spike are calibrated using a secular equilibrium material treated in the same way as the samples during chemical separation and mass spectrometric analysis. This approach does not only circumvent corrections for the radioactive decay of the short-lived 233Pa spike, but also enables us to estimate the reproducibility of the spike calibration. The relative standard deviation (RSD) of the spike ratios is 0.27% for 229Th/236U, 4.2% for 228Ra/236U and between 0.6 and 4.0% for 233Pa/236U. The RSDs of the final ratios are 1.2% for 231Pa/235U and 3.4% for 226Ra/230Th. We assess the individual sources of uncertainty (e.g., mass spectrometric corrections, counting statistics, and spike calibration) in detail and quantify their contribution to the total uncertainties of the final isotope ratios. Most corrections contribute only moderately to the final uncertainties. However, in the case of a large abundance of natural isotopes in the spike, this correction can have a large influence on both the ratios and their uncertainties. Another parameter affecting the final uncertainties and the reproducibility of the method is the sample size and, thus, the concentration of the natural isotopes. This discussion provides useful guidelines for future applications and can be adjusted to the individual requirements of a specific user. [ABSTRACT FROM AUTHOR]

Here we present a sensitive method to analyse lignin oxidation products (LOPs) in speleothems and cave drip water to provide a new tool for paleo vegetation reconstruction. Speleothems are valuable climate archives. However, compared to other terrestrial climate archives, such as lake sediments, speleothems contain very little organic matter. Therefore, very few studies on organic biomarkers in speleothems are available. Our new sensitive method allows to use LOPs as vegetation biomarkers in speleothems. Our method consists of acid digestion of the speleothem sample followed by solid phase extraction (SPE) of the organic matter. The extracted polymeric lignin is degraded in a microwave assisted alkaline CuO oxidation step to yield monomeric LOPs. The LOPs are extracted via SPE and finally analysed via ultrahigh-performance liquid chromatography (UHPLC) coupled to electrospray ionisation (ESI) and high-resolution orbitrap mass spectrometry (HRMS). The method was applied to stalagmite samples with a sample size of 3-5 g and cave drip water samples with a sample size of 100-200 mL from the Herbstlabyrinth-Advent-Cave in Germany. In addition, fresh plant samples, soil water and powdered lignin samples were analysed for comparison. The concentration of the sum of eight LOPs (Σ8) was in the range of 20-84 ng g-1 for the stalagmite samples and 230-440 ng L-1 for the cave drip water samples. The limits of quantification for the individual LOPs ranged from 0.3-8.2 ng per sample. Our method represents a new and powerful analytical tool for paleo vegetation studies and has great potential to identify the pathways of lignin incorporation into speleothems. [ABSTRACT FROM AUTHOR]

Abstract: Hurricane‐induced rainfall over Puerto Rico has characteristic δ18O values which are more negative than local rainfall events. Thus, hurricanes may be recorded in speleothems from Larga cave, Puerto Rico, as characteristic oxygen isotope excursions. Samples of 84 local rainfall events between 2012 and 2013 ranged from −6.2 to +0.3‰, whereas nine rainfall samples belonging to a rainband of hurricane Isaac (23–24 August 2012) ranged from −11.8 to −7.1‰. Cave monitoring covered the hurricane season of 2014 and investigated the impact of hurricane rainfall on drip water chemistry. δ18O values were measured in cumulative monthly rainwater samples above the cave. Inside the cave, δ18O values of instantaneous drip water samples were analyzed and drip rates were recorded at six drip sites. Most effective recharge appears to occur during the wet months (April–May and August–November). δ18O values of instantaneous drip water samples ranged from −3.5 to −2.4‰. In April 2014 and April 2015 some drip sites showed more negative δ18O values than the effective rainfall (−2.9‰), implying an influence of hurricane rainfall reaching the cave via stratified seepage flow months to years after the event. Speleothems from these drip sites in Larga cave have a high potential for paleotempestology studies. [ABSTRACT FROM AUTHOR]

In situ laser ablation analyses rely on the microanalytical homogeneity of reference materials (RMs) and a similar matrix and mass fraction between unknown samples and RMs to obtain reliable results. Suitable carbonate and phosphate RMs for determination of Sr isotope ratios in such materials are limited. Thus, we determined 87Sr/86Sr ratios of several carbonate (JCt‐1, JCp‐1, MACS‐1, MACS‐3) and phosphate (MAPS‐4, MAPS‐5, NIST SRM 1400, NIST SRM 1486) international RMs using dissolved samples and two different multi‐collector inductively coupled plasma‐mass spectrometers (MC‐ICP‐MS). Our Sr isotope data are in agreement with published data and have an improved measurement precision for some RMs. For MACS‐1, we present the first 87Sr/86Sr value. We tested the suitability of these materials for microanalytical analyses by LA‐MC‐ICP‐MS, with two different laser ablation systems: a conventional nanosecond laser and a state‐of‐the‐art femtosecond laser. We investigated the RMs micro‐homogeneity and compared the data with our solution data. Both laser ablation systems yielded identical 87Sr/86Sr ratios within uncertainty to the solution data for RMs with low interferences of REEs. Therefore, these carbonate and phosphate RMs can be used to achieve accurate and precise results for in situ Sr isotope investigations by LA‐MC‐ICP‐MS of similar materials. [ABSTRACT FROM AUTHOR]

Their amenability to radiometric dating (U-series) makes speleothems (secondary cave carbonate deposits) a key archive of past climatic and environmental changes. However, incorporation of non-radiogenic thorium can hamper U-series dating, and samples older than ca. 600 ka remain out-of-reach for UTh dating. Our aim is to develop isothermal thermoluminescence (ITL) dating as an alternative approach for otherwise undatable samples. The calcite thermoluminescence (TL) signal (280 °C peak) saturates at very high doses (saturation dose up to 5000 Gy) [1,2], which shows great potential to extend the dating limit to several millions of years. However, a spurious TL signal occurring in the high temperature range so far hindered its application [3,4]. The conventional multiple-aliquot additive-dose (MAAD) protocol used for TL dating applies extrapolation for equivalent dose (De) estimation, which is also associated with large uncertainties. ITL dating with the single-aliquot regenerative-dose (SAR) protocol [5,6] might be a promising way to circumvent these issues as it reduces the influence of the spurious TL signal and it applies interpolation to obtain the De. However, this protocol has not been tested yet on samples with independent age control. Here we test the ITL SAR dating protocol on a speleothem sample from Bleßberg cave, Germany, which has been accurately dated by the 230Th/U-method (425.6±3.9 ka to 321.6±2.0 ka, based on 17 dates). An ITL measurement at 235 °C for 200 s can remove the 280 °C TL peak completely without TL contribution from the higher temperature range. The ITL De shows a plateau in the ITL temperature range between 230 °C and 240 °C. Peak shifting and isothermal annealing tests indicate that the 280 °C TL peak and the ITL signal at 235 °C have lifetimes of tens of millions of years at 10 °C, which is sufficiently stable considering the age range of this speleothem sample. The accurate alpha efficiency (a-value) and the U and Th distribution within the sample are measured to estimate the dose rate. The time-dependent dose rate variation due to U-series disequilibrium is corrected for. The ITL ages are compared with the 230Th/U ages to evaluate the performance of the ITL SAR dating protocol. [ABSTRACT FROM AUTHOR]

RATIONALE: High spatial resolution Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) determination of trace element concentrations is of great interest for geological and environmental studies. Data reduction is a very important aspect of LA-ICP-MS, and several commercial programs for handling LA-ICPMS trace element data are available. Each of these software packages has its specific advantages and disadvantages. METHODS: Here we present TERMITE, an R script for the reduction of LA-ICPMS data, which can reduce both spot and line scan measurements. Several parameters can be adjusted by the user, who does not necessarily need prior knowledge in R. Currently, ten reference materials with different matrices for calibration of LA-ICPMS data are implemented, and additional reference materials can be added by the user. TERMITE also provides an optional outlier test, and the results are provided graphically (as a pdf file) as well as numerically (as a csv file). RESULTS: As an example, we apply TERMITE to a speleothem sample and compare the results with those obtained using the commercial software GLITTER. The two programs give similar results. TERMITE is particularly useful for samples that are homogeneous with respect to their major element composition (in particular for the element used as an internal standard) and when many measurements are performed using the same analytical parameters. In this case, data evaluation using TERMITE is much faster than with all other available software, and the concentrations of more than 100 single spot measurements can be calculated in less than a minute. CONCLUSIONS: TERMITE is an open-source software for the reduction of LA-ICPMS data, which is particularly useful for the fast, reproducible evaluation of large datasets of samples that are homogeneous with respect to their major element composition. [ABSTRACT FROM AUTHOR]

Here, we present high-resolution trace element and stable isotope records from three coeval Holocene stalagmites from the Herbstlabyrinth cave system, Central Germany. All stalagmites were precisely dated using MC-ICPMS 230Th/U-dating. One stalagmite started to grow at 13.62 ± 0.13 ka BP, covering the late Glacial; the other two speleothems started to grow at 11.13 ± 0.08 and 10.26 ± 0.08 ka BP, respectively. The combined record covers the entire Holocene. The interpretation of the different climate proxies is supported by data from a detailed cave monitoring programme. Cold conditions during the Younger Dryas are reflected by intermittent stalagmite growth at the Herbstlabyrinth. The δ18O records are in general agreement with the NGRIP δ18O record on millennial time scales indicating that speleothem δ18O values at the Herbstlabyrinth reflect large-scale climate variability in the North Atlantic area. The 8.2 ka event is clearly visible as a pronounced negative excursion in the δ18O records. In all other proxies, it is not reflected as a major excursion. Correlation and principal component analysis enable us to disentangle the various processes affecting the stable isotope and trace element signals. Phases with higher P, Ba and U concentrations and more negative δ13C values are interpreted as reflecting more productive vegetation above the cave. The negative correlation of Mg with P, Ba and U and the positive correlation with δ13C indicate more recharge during phases of more productive vegetation, probably because of increased rainfall. The majority of the observed phases of reduced vegetation productivity and drier climate coincide with cooler periods in the polar North Atlantic as reflected by a higher abundance of hematite-stained grains (i.e. the Bond events), suggesting a close relationship between terrestrial climate in Central Europe and the polar North Atlantic. [ABSTRACT FROM AUTHOR]

An arrangement of three stalagmites from Zoolithencave (southern Germany) was analysed for different types of annual laminae using both microscopic and geochemical methods. The speleothems show visible laminae (consisting of a clear and a brownish, pigmented layer pair) as well as fluorescent and elemental laminae. The age of the speleothems was constrained to 1800 to 1970 AD by 14C-dating of a charcoal piece below the speleothems, detection of the 14C bomb peak, as well as counting of annual laminae. Dating by the 230Th/U-method was impossible due to detrital contamination. On the annual time-scale, the variability of Mg, Ba, and Sr is controlled by Prior Calcite Precipitation (PCP) resulting in lower values during the wet season (autumn/winter) and vice versa. Yttrium and P are proxies for soil activity and are enriched in the brownish, pigmented layers. However, Y and P are also influenced by detrital content superimposing the soil activity signal. Aluminium and Mn are proxies for detrital content. Lamina thickness shows a significant correlation with the amount of precipitation of previous December and current January, February, March, April, May, and December (DJFMAMD) recorded at the nearby meteorological station Bamberg. Thus lamina thickness is a proxy for past precipitation, which is confirmed by the good agreement with a precipitation reconstruction based on tree-ring width from the Bavarian forest. This highlights the potential of these speleothems for climate reconstruction at annual resolution. [ABSTRACT FROM AUTHOR]

We present cave monitoring data and two drip water δO models for the Herbstlabyrinth-Adventhöhle (HL) cave system, Germany. Winter climate of the cave region is influenced by the North Atlantic Oscillation (NAO), as documented by the positive correlations between winter temperature, winter rainfall δO values and the winter NAO index. Cave monitoring data show that recharge of the aquifer at the HL cave system mainly occurs during winter months, confirming our drip water model, which calculates recharge as the difference between precipitation and potential evapo-transpiration. Cave drip water from the HL cave system should, thus, be a sensitive proxy for reconstruction of the NAO. The infiltration models accounting for mixing effects occurring in the karst aquifer show a very good agreement with the monitoring data. Comparison of the modelled and the monitored drip water δO values suggests a mean residence time of the water in the aquifer of 12 months and a transmission time of 10 months. Using these parameters, a long-term dataset from the nearby meteorological station Frankfurt am Main and the rainfall δO data from our monitoring program, we model the δO values of the cave drip water for the last 144 years. Despite of the favourable conditions of the HL cave system for NAO reconstruction, the modelled drip water δO time series only shows a moderate correlation with the winter NAO index (r = 0.33). The major reason for the relatively low correlation is the substantial contribution of precipitation from the remaining seasons to the drip water, for instance, due to heavy precipitation events occurring during summer. These rainfall events bias the seasonality of infiltration and weaken the winter NAO signal recorded in the drip water δO values. Reconstruction of the NAO from speleothems is, thus, challenging, in particular considering further complications arising from chronological uncertainties and calcite precipitation under conditions deviating from isotopic equilibrium. These problems may, at least in part, be avoided by multi-proxy studies of annually laminated stalagmites. [ABSTRACT FROM AUTHOR]

The connection between climatic change and social response is complex because change articulates a number of inter-related factors. Human decisions are filtered by social buffers – including social memory, risk perception, and cultural priorities – and the rate and scale of climate change is usually much larger than the scale of human decision-making. In this article, we provide information on climate change based on precisely dated speleothems with the response evident in archaeological sites that have radiocarbon date ranges within the same time frame. A stalagmite recovered from within the catchment area for aquifer recharge of the Pre-Arawak site of Angostura in Barceloneta, Puerto Rico, shows that a significant wet period occurred between 3.9 and 3.1 ka (primarily centered at 3.5 ka). We investigate the effect that this increase in precipitation had on the earliest occupations on the island in the context of palaeoenvironmental, geoarchaeological, and archaeological records from Angostura, Maruca, and Paso del Indio. Our analysis suggests the presence of two different adaptation strategies: settlement relocation and microlandscape modification. Our study concludes that the social response to change cannot be seen as monolithic given that human behavior, even within the same period, addresses the needs of individual groups with different priorities. This multiplicity of responses can indeed enhance resilience as social support can continue through alliances and exchanges, strengthening social bonds that can help buffer catastrophes. The results can help shed light on the range of adaptation strategies to change encompassed within the manifestations of social resilience or vulnerability. [ABSTRACT FROM PUBLISHER]

ABSTRACT Tischoferhöhle and Pendling-Bärenhöhle near Kufstein, Tyrol, are among the only locations where remains of cave bear, Ursus spelaeus-group, were found in the western part of Austria. One sample from each site was radiocarbon-dated four decades ago to ca. 28 14C ka BP. Here we report that attempts to date additional samples from Pendling-Bärenhöhle have failed due to the lack of collagen, casting doubts on the validity of the original measurement. We also unsuccessfully tried to date flowstone clasts embedded in the bone-bearing sediment to provide maximum constraints on the age of this sediment. Ten cave bear bones from Tischoferhöhle showing good collagen preservation were radiocarbon-dated to 31.1-39.9 14C ka BP, again pointing towards an age underestimation by the original radiocarbon-dated sample from this site. These new dates from Tischoferhöhle are therefore currently the only reliable cave bear dates in western Austria and constrain the interval of cave occupation to 44.3-33.5 cal ka BP. We re-calibrate and re-evaluate dates of alpine cave bear samples in the context of available palaeoclimate information from the greater alpine region covering the transition into the Last Glacial Maximum, eventually leading to the demise of this megafauna. [ABSTRACT FROM AUTHOR]

RATIONALE Milling of wood samples is a widely applied preparation method for pooling tree-rings from different trees or periods of several years for determination of δ13C and δ18O values. In this study, whole wood samples were milled using different procedures in order to evaluate potential effects of this preparation method on δ13C and δ18O values. METHODS Subsamples of a 5 cm3 wood piece of a single tree-ring from a lowland white fir were used. The samples were milled with different setups: (i) two and three stainless-steel balls, (ii) 3, 5 and 8 min milling time, and (iii) discontinuous and continuous milling. The δ13C values were measured using an elemental analyser connected to an IsoPrime mass spectrometer and δ18O values using a Thermo Scientific MAT 253 mass spectrometer and a TC/EA connected by a ConFlo IV. RESULTS The results show that varying the milling procedure does not alter the δ13C and δ18O values in comparison to non-milled blank samples. For shorter milling times, an increased variance of δ18O values is recorded, probably caused by isotopic gradient between early- and latewood portions of the tree-ring and thereby biasing the insufficiently homogenised samples. No overheating effects on the δ13C and δ18O values were detected. CONCLUSIONS Milling of wood samples for carbon and oxygen isotope analyses is an appropriate preparation method. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study presents a novel method for the analysis of low molecular weight (LMW) fatty acids in cave drip water and speleothems. The method development included optimization of sample preparation procedures, e.g., blank reduction, solid phase extraction, concentration of extracts as well as liquid chromatography coupled to electrospray ion-trap mass spectrometry (HPLC-ESI-IT/MS) measurement parameters. Retention times for five analytes (lauric acid, myristic acid, palmitic acid, stearic acid and arachidic acid) were between 5 and 13.5 min. Spiking experiments were performed to accomplish external calibrations which ranged from 12.5 to 75 ng per spiked water sample. The correlation coefficient ranged from 0.9558 to 0.9989. Inter-batch precision, expressed as the relative standard deviation of three replicates, was <7 %. Limits of detection ranged from 0.77 to 55.97 ng for the diverse analytes; obtained recoveries varied from 30 to 103 %. For a first application, cave drip water and stalagmite samples from Herbstlabyrinth-Adventhöhle cave system were analyzed. Concentrations ranged from 38.37 to 9,982.54 ng L for water samples and 2.52 to 1,344.96 ng g for the stalagmite. Thereby, the different fatty acids showed a distinctive variation. Whereas shorter-chained fatty acids exhibited similarities, arachidic acid showed opposite trends. Diverse correlations were found, which could improve the understanding of different organic sources of the lipids transported by drip water and preserved in speleothems. This new method provides a more selective extraction process, particularly adjusted to LMW fatty acids and therefore reduces the required sample size. Furthermore, it is applicable to stalagmite as well as cave drip water samples. [ABSTRACT FROM AUTHOR]

Cover Feature: Development of a Method for Anodic Degradation of Lignin for the Analysis of Paleo-Vegetation Proxies in Speleothems (ChemElectroChem 6/2022) Anode, Electrochemistry, Lignin, Oxidation, Speleothem Keywords: Anode; Electrochemistry; Lignin; Oxidation; Speleothem EN Anode Electrochemistry Lignin Oxidation Speleothem 1 1 1 03/31/22 20220329 NES 220329 B The Cover Feature b illustrates the pathway of lignin from the plant into a stalagmite and to the electrochemically generated monomeric analytes. [Extracted from the article]

Here we present the first high-resolution δ18O record of a stalagmite from western Cuba. The record reflects precipitation variability in the northwestern Caribbean during the last 1.3 ka and exhibits a correlation to the Atlantic Multidecadal Oscillation (AMO). This suggests a relationship between Caribbean rainfall intensity and North Atlantic sea-surface temperature (SST) anomalies. A potential mechanism for this relationship may be the strength of the Thermohaline Circulation (THC). For a weaker THC, lower SSTs in the North Atlantic possibly lead to a southward shift of the Intertropical Convergence Zone and drier conditions in Cuba. Thus, this Cuban stalagmite records drier conditions during cold phases in the North Atlantic such as the ‘Little Ice Age’. This study contributes to the understanding of teleconnections between North Atlantic SSTs and northern Caribbean climate variability during the past 1.3 ka. [ABSTRACT FROM AUTHOR]

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An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

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