CL1.19

Southeast Europe (i.e. Balkan Peninsula) is a climatologically interesting and complex area, located in a transient zone affected by both Mediterranean and continental atmospheric influences. Speleothem paleoclimate records are limited in this region, with only a few such records from the central parts. Furthermore, in the central parts, there are almost no existing data on cave monitoring, as well as on isotopic composition of precipitation.

For that purpose, a cave monitoring campaign was initiated in October 2018 at Drenska Peštera (southern parts of N. Macedonia) that followed a precipitation monitoring program initiated in the area in April 2018. The study site, located at 1150 m a.s.l., is an old fossil cave with a relatively simple morphology, and a total depth of ~40 m. The area has a mountain climate characterized as Dfb (cold with warm summer and no dry season) according to the Köppen-Geiger climate classification. Vadose speleothems are found throughout the cave, and few broken stalagmites were collected for paleoclimate study purposes. The cave monitoring initially included only monitoring of cave air temperatures, and was expanded in 2019 to include also monitoring of dripwater hydrology and geochemistry. Air temperatures were recorded at an hourly rate at three vertically distributed locations in the cave and at one location outside. Monthly collection of dripwater was initiated at two and later expanded to three dripping sites in the cave.

Preliminary results show that the local annual precipitation is generally in low amount (~400 mm), with maximum in Summer and Spring, and lowest in Winter. δ¹⁸O values of the precipitation show strong seasonality, with two distinct periods of higher (May-October) and lower (November-April) δ¹⁸O values, when average monthly temperatures are, respectively, above or below the local mean annual temperature. The local meteoric water line has slope that is close to the global meteoric water line with somewhat higher intercept indicating mixture of North Atlantic and Mediterranean atmospheric influences. Monthly variation of deuterium-excess indicates higher contribution of Mediterranean-sourced moisture in the cold period, likely related to Mediterranean cyclogenesis.

Cave air temperatures are stable (10.8±0.1 °C), reflecting the mean annual air temperature of the outside station (10.7 °C). Cave dripping is active mostly between December and July, and decreases (or completely stops) between August and November. Mean dripwater δ¹⁸O values (-11.1 ‰) are lower than the weighted-mean value of precipitation (-8.6 ‰), indicating bias towards cooler period infiltration. Dripwater δ¹⁸O values have smaller variation but still reflect the seasonal pattern of the precipitation, albeit with a seasonal shift, as the highest δ¹⁸O values are found in the winter period. The smallest variation in δ¹⁸O, dripping rate and temperature is found at the deepest station, reflecting better mixed aquifer, and most stable environment.

This research was funded by the GINOP-2.3.2-15-2016-00009 ‘ICER’ project. We would like to thank Dragan Temovski, Biljana Temovska, Stojan Mitreski, as well as Zlatko Angeleski and Darko Nedanoski from SK Zlatovrv, for their assistance with the cave and precipitation monitoring.

How to cite: Temovski, M., Túri, M., Horváth, A., and Palcsu, L.: Cave monitoring at Drenska Peštera (N. Macedonia) – preliminary results, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10629, https://doi.org/10.5194/egusphere-egu21-10629, 2021.

Ascunsă cave (Romania) is the subject of a monitoring program since 2012. While the cave air temperature was very stable around 7°C for most of the time, it experienced in 2019 a 3°C rise, and remained high until the present.

We present here δ¹⁸O, δ¹³C, and clumped isotope results from calcite farmed at two drip points inside the cave (POM X and POM 2). POM X has a slower drip rate than POM 2 and deposits calcite more continuously. Calcite deposition has been shown to depend on cave air CO₂ concentration, which controls the drip water pH and, further, the calcite saturation index.

In 2019, δ¹⁸O values at both sites quickly shifted to lower values as a response to the increase in temperature. At POM X, values were situated between approximately -7.2‰ and -7.6‰ before this transition, whereas in 2019 they shifted to -7.8‰ - -8.0‰. At POM 2, where values were generally lower, they shifted from -7.5‰ to -7.8‰ to -8.0‰.

Clumped isotope temperature estimates mostly agree, within measurement error, with measured cave temperature. This agreement is notable given that strong offsets are commonly observed in mid-latitude caves, reflecting kinetic fractionation effects. However, intervals with deviations from cave temperature are also observed, suggesting variations in isotopic disequilibrium conditions with time.

Here we will discuss these isotope changes in relation to cave air temperature and CO₂ concentration, drip water isotope values and elemental chemistry, as well as in relation to drip rates, in order to improve our understanding of calcite precipitation and isotope effects in caves.

How to cite: Dragusin, V., Ersek, V., Fernandez, A., Ionete, R., Iordache, A., Meckler, N., Mirea, I., and Zgavarogea, R.: Farmed calcite δ18O, δ13C, and Δ47 at Ascunsă cave, Romania, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7151, https://doi.org/10.5194/egusphere-egu21-7151, 2021.

Caves are an excellent natural laboratory for understanding the transfer processes of the region’s environmental signals to speleothems. At least eight speleothems have produced high resolution paleoclimate and paleoenvironment records from Anjohibe Cave, NW Madagascar. However, due to the remote and difficult access to many caves in Madagascar, no studies have yet been done to understand the transfer of climate and environmental changes of the region to the cave. This is the first monitoring study to understand the linkage between regional climatology and various responses in Anjohibe Cave. We monitored (1) the drip water pH, TDS, EC, temperature, δ¹³C_DIC, δ¹⁸O_w, δ²H_w, and elemental (Ca, Mg, Sr) composition, and (2) the cave atmosphere pCO₂, relative humidity and temperature. Results show that air-to-air transfer is fast, and the internal parameters closely vary with the regional climatology. In contrast, rainfall to drip signal transfer is not immediate, and it can take few months to one season for the signals to be detected in the drip water due to the “epikarst storage effect”. The deposition of CaCO₃ is inferred to occur late in the dry austral winter season, during which prior carbonate precipitation was also detected. Since the growth of speleothems is influenced by numerous cave-specific factors, this study, although preliminary, indicates that Anjohibe Cave drip waters are capable of registering changes in its surrounding environment. A longer monitoring study is expected in the future to constrain the timing and the mode of transfer.

How to cite: Voarintsoa, N. R. G., Ratovonanahary, A. L. J., Rakotovao, A. Z. M., and Bouillon, S.: Investigating cave responses to regional climate change: an approach to calibrate speleothem proxies in Madagascar, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-790, https://doi.org/10.5194/egusphere-egu21-790, 2021.

The sedimentary record of the endorheic Dead Sea and its precursors comprises aragonite laminae that make up an environmental archive extending into the Pleistocene, partially in annual resolution. Nevertheless, despite the importance of resolving the conditions that facilitate aragonite precipitation in the Dead Sea, contradictions exist between recent studies that utilized modern observations and the late Pleistocene geological record. The implications of aragonite precipitation in the Dead Sea and in its late Pleistocene predecessor Lake Lisan were investigated in this study by mixing natural and synthetic brines with a synthetic bicarbonate solution representing flood water entering the lake (4mM), with and without additions of extracellular polymeric substances (EPS). This was followed by measurements of aragonite precipitation incubation, rates, yields. Aragonite precipitation took place within days to few weeks after mixing of the brine with the synthetic bicarbonate solution and its incubation time was proportional to bicarbonate concentrations, while precipitation rates were also influenced by ionic strength. The addition of EPS inhibited aragonite precipitation for several months, which provides a reasonable explanation for the proposed summer-time precipitation of aragonite during the late Pleistocene glacials. We suggest that under increased inflow, increased biological activity would result in increased EPS production that could inhibit aragonite precipitation for several months. Finally, previous estimates of the freshwater inflow required to provide the carbonate for a uniform aragonite lamina of a typical thickness deposited during glacials are unreasonably high. This can be resolved by various processes: (1) Patchy aragonite deposition over limited segments of the lake’s floor; (2) Supply of additional carbonate to the lake from aeolian dust and recycled dust deposits; (3) Carbonate production through the oxidation of organic carbon by sulfate-reducing bacteria at the hypolimnion. Altogether, these results indicate that aragonite laminae thicknesses are insufficient to quantitatively reconstruct the hydrological balance for the entire lake, but may still be valuable for identifying climatic periodicities over a continuous record in a specific study site.

How to cite: Ben Dor, Y., Flax, T., Levitan, I., Brauer, A., Enzel, Y., and Erel, Y.: Using laboratory investigations to reveal the palaeohydrological implications of aragonite laminae deposition in the endorheic Dead Sea and its precursors under different climatic conditions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-359, https://doi.org/10.5194/egusphere-egu21-359, 2021.

Speleothems have been developed to be valuable climate archives. Albeit much progress has been made to understand speleothem proxies, it remains difficult to differentiate between a direct climate signal and variations, which occurred due to in-cave processes like prior calcite precipitation, CO₂ degassing or C exchange between dissolved inorganic C-species and cave air CO₂. Here, we analyse palaeoclimate proxies of contemporaneously growing speleothems, which were extracted from the SISALv2 database (Comas-Bru et al., 2020). We argue that differences in their stable O and C isotopic composition as well as in their growth rate can only arise by differences of drip site specific conditions as climate conditions for pairs of contemporaneously growing speleothems are similar. To better understand differences in the isotopic composition and growth rate of contemporaneously growing speleothems, we investigate the in-cave processes by applying a speleothem isotope and growth model. The model is based on a Rayleigh process, which includes CO₂ degassing and CaCO₃ precipitation, HCO₃^- <—> H₂O buffering as well as CO₂ exchange and is able to calculate growth rates. The model accounts for CaCO₃ deposition as prior calcite precipitation as well as CaCO₃ deposition at the speleothem. We find that C-exchange processes are necessary to explain the linked isotopic and growth rate differences in speleothems.

References

Comas-Bru, L., Atsawawaranunt, K., Harrison, S., SISAL working group members (2020): SISAL (Speleothem Isotopes Synthesis and AnaLysis Working Group) database version 2.0. University Of Reading.

How to cite: Skiba, V. and Fohlmeister, J.: Contemporaneously growing speleothems and their value to decipher in-cave processes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9619, https://doi.org/10.5194/egusphere-egu21-9619, 2021.

In recent years, cryogenic cave carbonates (CCC) have become the focus of studies tracking past climate change in periglacial environments. Two types of these speleothems occur, fine-grained CCC (CCC_fine), which form due to the rapid freezing of a thin water film on ice, and coarse-grained CCC whose origin is related to the slow freezing of water pockets inside cave ice. Here, we report for the first time the occurrence of CCC_fine from a cave in northeast Greenland, presently situated in continuous permafrost.

Eqik Qaarusussuaq (Cove Cave), located at 80.2° N, is a 103 m long, gently-dipping phreatic passage that was discovered during the 2019 Greenland Caves Project Expedition (www.greenlandcavesproject.org). CCC_fine were found in a dry chamber 65 m behind the entrance. The cave air temperature at the CCC site of -14.7 °C contrasts with outside air temperatures of up to +18.0 °C in July 2019. This, together with current dry conditions at the sampling site, indicates that water infiltration, necessary for CCC formation, is not possible under present-day climate conditions. This is further supported by a lack of ice found within the cave.

Stable isotope analyses of CCC show δ¹⁸O values ranging from -21.9 to -16.0 ‰ and δ¹³C values between 8.4 and 11.7 ‰ VPDB. While the δ¹³C values are consistent with published data of CCC_fine from caves at lower latitudes, the δ¹⁸O values are significantly lower and plot in the field of CCC_coarse (cf. Žák et al., 2018). This shift reflects the much lower δ¹⁸O values of meteoric precipitation in northeast Greenland compared to lower latitude sites.

Exploratory radiocarbon dating suggests that CCC_fine formed in this High Arctic cave as recent as during the end of the Little Ice Age.

Reference

Žák, K., Onac, B.P., Kadebskaya, O.I., Filippi, M., Dublyansky, Y., Luetscher, M., 2018. Cryogenic mineral formation in caves. In: Perşoiu, A., Lauritzen, S.-E. (Eds.), Ice caves. Elsevier, Amsterdam, Netherlands, pp. 123–162.

How to cite: Donner, A., Spötl, C., Töchterle, P., Hajdas, I., and Moseley, G. E.: First investigations of fine-grained cryogenic cave carbonates from a High-Arctic permafrost karst system in Greenland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14642, https://doi.org/10.5194/egusphere-egu21-14642, 2021.

Cryogenic cave carbonates (CCC) are rare speleothems that form when water freezes inside cave ice bodies. CCC have been used as an proxy for permafrost degradation, permafrost thickness, or subsurface ice formation. The presence of these minerals is usually attributed to warm periods of permafrost degradation. We found coarse crystalline CCC types within transparent, massive congelation ice in two Pyrenean ice caves in the Monte Perido Massif: Devaux, located on the north face at 2828 m a.s.l., and Sarrios 6, located in the south face at 2780 m a.s.l. The external mean annual air temperature (MAAT) at Devaux is ~ 0°C, while at Sarrios 6 is ~ 2.5°C. In the Monte Perdido massif discontinuous permafrost is currently present between 2750 and 2900 m a.s.l. and is more frequent above 2900 m a.s.l. in northern faces. In Devaux, air and rock temperatures, as well as the presence of hoarfrost and the absence of drip sites indicate a frozen host rock. Moreover, a river flows along the main gallery, and during winters the water freezes at the spring causing backflooding in the cave. In contrast, Sarrios 6 has several drip sites, although the gallery where CCC were collected is hydrologically inactive. This gallery opened in recent years due to ice retreat. During spring, water is present in the gallery due to the overflow of ponds forming beneath drips. CCC commonly formed as sub-millimeter-size spherulites, rhombohedrons and rafts. ²³⁰Th ages of the same CCC morphotype indicate that their formation took place at 1953±7, 1959±14, 1957±14, 1958±15, 1974±16 CE in Devaux, while in Sarrios 6 they formed at 1964±5, 1992±2, 1996±1 CE. The cumulative probability density function indicates that the most probable formation occurred 1957-1965 and 1992-1997. The instrumental temperature record at 2860 m a.s.l. indicates positive MAAT in 1964 (0.2°C) and 1997 (0.8°C). CCC formation could thus correspond with those two anomalously warm years. The massive and transparent ice would indicate a sudden ingress of water and subsequent slow freezing inside both caves during those years. Probably, CCC formation took place at a seasonal scale during the annual cycle.

How to cite: Bartolomé, M., Moreno, A., Luetscher, M., Spötl, C., Leunda, M., Cazenave, G., Belmonte, Á., Osácar, C., Cheng, H., Edwards, R. L., and Sancho, C.: Cryogenic cave carbonate formation during the Industrial Era in the Central Pyrenees (Iberian Peninsula), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14487, https://doi.org/10.5194/egusphere-egu21-14487, 2021.

Two stalagmites (B7-1 and B7-7) were sampled from B7-Cave in western Germany. B7-Cave is located very closely (100 m) to the extensively investigated Bunker Cave. Both B7-Cave stalagmites were previously dated and analysed for stable carbon and oxygen isotope composition at low resolution by Niggemann et al. (2003). Both stalagmites were now redated more precisely using the MC-ICP-MS methodology at the Max Planck Institute for Chemistry, Mainz, and Mainz University. Furthermore, the elemental concentrations of Mg, Sr, Ba, Al, P, Y, Zn, Th, and U were determined by laser ablation ICP-MS (MPIC Mainz) at high resolution. Additionally, thin sections of both stalagmites were anaylsed for their calcite fabrics and detection of detrital layers.

The dating showed a growth phase from 10.9 to 6.6 ka BP for stalagmite B7-1 and three growth phases for stalagmite B7-7 from 11.2 to 6.3 ka BP, 3.2 to 2.9 ka BP, and 1.3 to 1.2 ka BP. This is improved to the dating from Niggemmann et al. (2003), who only detected one hiatus in stalagmite B7-7. Stalagmites B7-1 and B7-7 have a substantial overlapping period. During this period, both stalagmites contain frequent detrital layers, which probably represent short growth stops. However, these growth stops are too short and contain too much detrital material to resolve their timing and duration by ²³⁰Th/U dating.

Phosphorus, Y, and Zn are correlated in both stalagmites and during all growth phases. These three elements are interpreted as proxies for vegetation activity. Magnesium, Sr, and Ba are difficult to interpret due to several factors potentially influencing them, such as prior calcite precipitation, growth rate, and soil processes. Furthermore, the detrital layers in stalagmite B7-1 and the oldest growth phase of B7-7 are indicated by high Al concentrations.

Niggemann, S., Mangini, A., Richter, D. K., Wurth, G., 2003. A paleoclimate record of the last 17,600 years in stalagmites from the B7 cave, Sauerland, Germany. Quaternary Science Reviews 22, 555-567.

How to cite: Riechelmann, D. F. C., Jochum, K. P., and Scholz, D.: Elemental concentrations in two stalagmites from B7-Cave indicating environmental changes during the Holocene, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15319, https://doi.org/10.5194/egusphere-egu21-15319, 2021.

Turkey lies along the transition zone between northerly and southerly climate regimes such that it provides opportunity for a good understanding of Holocene climate that impacted ancient Eastern Mediterranean civilizations. Within the scope of the EU-funded SPELEOTOLIA project, 7 caves from western and southwestern Anatolia were visited and several stalagmite samples were collected. Detailed mineralogical and geochemical analyses performed on samples from one of the target caves, the Sırtlanini Cave (Karacasu, Aydın), helps to reconstruct the regional Holocene climate and gives insights on living conditions of Anatolian civilizations, mainly including Roman and Ottoman Empires.   

The 450 m-long Sırtlanini Cave (max. depth of ~40 m; ~1060 m a.s.l.) developed within the Mesozoic marbles of the Menderes Massif. We focus on the first set of U-series age, stable and radiogenic isotope (C, O, and Sr) and mineralogical data performed on the stalagmite (SRT-5) from this cave. The drip water isotope data (δ¹⁸O_VSMOW = -7.8‰, δD_VSMOW = -41.6‰) indicated depletions in O and H isotopes compared to other cave waters in the region. The U-series age results of SRT-5 show that the 423 mm-long stalagmite was deposited fast (0.25 mm/y) between 0.111±0.034 kyr and 1.825±0.421 kyr (BP) spanning the Roman, Byzantine and Ottoman periods. SRT-5 seems to have grown intermittently with at least two possible hiatuses (at around 291 and 401 years BP) based on mineralogical studies. It is mainly composed of fine- to medium-grained columnar calcite, with occasional dendritic fabric and visible annual layering, particularly at the older bottom section of the stalagmite. Stable isotope profiles (δ¹³C: -10.5 to -8‰ VPDB, δ¹⁸O: -7 to -5.5‰ VPDB) constructed using 423 sub-sample analyses along the stalagmite demonstrate significant hydroclimatic variability through the Little Ice Age and Medieval Warm Period between 195 and 1909 CE. This variation correlates well with previously documented drought and related famine and migration events in western Anatolia primarily in the 19^th century. Further investigations (e.g., high-resolution LA-ICPMS trace element analyses) will be performed specifically to constrain the anthropogenic sources and distinguish these from recent Aegean or possible global (e.g., southeast Asian) volcanogenic signals. 

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No: 842403.

How to cite: Ünal İmer, E., Yılmaz, İ. Ö., Baykara, M. O., and Zhao, J.-X.: Late Holocene climate record from Sırtlanini Cave (central west Anatolia) stalagmite: implications from U-series dating, mineralogy and isotope data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1356, https://doi.org/10.5194/egusphere-egu21-1356, 2021.

The unsteady cultural evolution and final collapse of Maya civilization in Mesoamerica are heavily debated issues and discussion includes the impact of both natural (e.g., droughts, hurricanes, volcanic eruptions) and social disasters (e.g., warfare and unsustainable economy). An increasing number of records point to recurrent multi-year droughts coinciding with hiatuses in construction, periods of temporary urban abandonment and population collapse. Previous reconstructions indicate that environmental conditions and precipitation on the Yucatán Peninsula were distributed very heterogeneously in space and time and the duration and chronology of events remains uncertain. High resolution environmental reconstructions are, however, mainly based on archives from sites on the southern Yucatán Peninsula.

We have now recovered several stalagmites from Estrella Cave, northern Yucatán Peninsula, spanning the entire Maya era and reaching even to historical times (−1100 to 1780 AD). The high precision ²³⁰Th/U ages obtained so far from these stalagmites indicate growth rates of up to 160 µm per year, thus offering the potential for annual to decadal climate proxy reconstruction. Here we present ²³⁰Th/U based preliminary age models for some of these stalagmites. Based on growth rates, petrographic observations, and trace element to calcium ratios we draw first conclusions on the timing of (recurrent) dry periods around key episodes of Maya cultural evolution, such as the Terminal Classic Period (~800–1000 AD). Furthermore, these first results show that the incorporation of certain trace elements (Mg, Sr, Ba, P, …) in these speleothems is strongly related to recharge and hence precipitation above the cave. Moreover, the site also contains unique remains of the Mayan culture, such as paintings, pottery, constructions and even buried skeletons, thus highlighting its significance not only for regional climate reconstruction but also for local archaeology.

How to cite: Schorndorf, N., Frank, N., Warken, S., Förstel, J., Schröder-Ritzrau, A., Avilés Olguín, J., and Stinnesbeck, W.: Speleothems as recorders of local climate variability and its implications for Maya cultural evolution from a unique cave site on the northern Yucatán Peninsula, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15846, https://doi.org/10.5194/egusphere-egu21-15846, 2021.

South American Monsoon System (SAMS) and its main feature, the South American Convergence Zone (SACZ) are responsible for the major distribution of moisture in South America. The current work presents a novel high-resolution oxygen isotope record (δ¹⁸O) based on speleothems from southwest Amazon basin (Brazil), right at SAMS' core region and SACZ onset, where there is still a gap of high resolution paleoclimate records. The novel δ¹⁸O record presents an average of 3 year-resolution, composed by 1344 stable isotope analysis performed in two speleothems with a well-resolved chronology (37 U/Th ages) with average errors <1%. This work aims to describe the rainfall variability of the core region of the South American monsoon for the last 3k years and to take a broader look at precipitation patterns over Amazon basin. The Rondônia δ18O record shows three main stages throughout this time period. The first is from -1000 to ~400 CE, where it’s in accordance with most of other paleorecords from the Amazon basin. the second segment  is from ~400 to 1200 CE, when there is a continuous increase in the δ18O record until it reaches its highest values around 850 CE during the MCA (800-1200 CE), which is in accordance with western Amazon records, whilst the record in eastern Amazon presents an opposite trend. Thus, a precipitation dipole over Amazon emerges from ~400 CE onwards, majorly triggered by anomalous climate changes such as MCA, where western (eastern) Amazon is drier (wetter). During LIA (1450-1800 CE), on the other hand, Rondônia record presents its lowest values, also agreeing with western records and with records under the influence of SACZ whilst on eastern Amazon a drier period is established. Therefore, with this novel paleoclimate record located at the core region of SAMS, it's possible to evidence the dynamics of the precipitation dipole over the Amazon region, as well as understand the SACZ intensity variations.

How to cite: Della Libera de Godoy, M. E., Novello, V. F., and Cruz, F. W.: Reconstruction of the last three millennia South American Monsoon variability over the Amazon basin using speleothem isotope records, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8066, https://doi.org/10.5194/egusphere-egu21-8066, 2021.

Records of paleoclimate in the Middle East are particularly sparse in comparison with other regions around the world. In order to better resolve how Middle East climate responded to large global climate and environmental changes in the past, here we present the first glacial record of southwestern Iran climate constructed using speleothem climate proxies. We analyzed two stalagmites collected from a cave on the western side of the Zagros mountains, ~100 km north of the Persian Gulf. The average annual precipitation and temperature close to the cave site are ~350 mm and ~21.6 °C, respectively. Our data yield continuous δ¹⁸O and δ¹³C records from 45-35 kyr and 25-10 kyr BP, which show prominent millennial-scale events during the last glacial period and Termination I. The timing of these events is in agreement with North Atlantic Heinrich events and Greenland Daansgard-Oeschger events, within the respective records’ age errors. Moreover, unlike the generally stable NGRIP δ¹⁸O record, a proxy for high-latitude Northern Hemisphere temperatures, the stalagmite δ¹⁸O and δ¹³C records reveal clearly evident periodic variations during the Last Glacial Maximum. δ¹⁸O values are consistently heavier than eastern Mediterranean stalagmite δ¹⁸O values during both the glacial period and throughout Termination I, suggesting at least one source of moisture to the southwestern Iran site in addition to the westerlies.

How to cite: Soleimani, M., Carolin, S., Nadimi, A., Henderson, G., and Spötl, C.: Glacial climate variations in southwestern Iran, 50 to 10 ka, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9696, https://doi.org/10.5194/egusphere-egu21-9696, 2021.

Australia is the driest continent outside of Antarctica yet relatively little is known about its long-term moisture history. Many local palaeoclimate archives suffer preservation problems, particularly in the arid centre of the continent, where weathering and erosion leave behind an incomplete record. In an attempt to redress the paucity of arid-zone palaeoclimate records, we investigate ‘pendulites’, subaqueous speleothems that grow episodically according to fluctuations in local groundwater levels. At Mairs Cave (central Flinders Ranges, South Australia), pendulites have formed around stalactites. During the first sustained episode of drowning, the stalactite is veneered by subaqueous calcite, sealing it and preventing further stalactitic growth after water levels fall. Once sealed, the pendulites only record periods of persistent drowning, assumed to correspond to major pluvial episodes.

Age data from two pendulite samples collected from close to the ceiling where the highest water levels have reached reveal two main groundwater ‘high-stand’ phases centred on ~67 and ~48 ka, coincident with Southern Hemisphere summer insolation maxima. This suggests that precession-driven southward migration of the ITCZ resulted in regular and persistent incursions of tropical air masses to the central Flinders Ranges. Trace element, stable isotope and growth-rate changes reveal that these orbitally controlled growth intervals are superimposed by regional climate responses to Dansgaard-Oeschger and Heinrich events. The results from Mairs Cave shed new light on the moisture history of central Australia, in particular the competing influences of tropical and middle-latitude circulation systems. This provides a precisely dated regional palaeoclimate template for reconstructing ecosystem changes, understanding human migration/dispersal patterns of the first Australians, and the progressive demise of megafauna. We also highlight the utility of subaqueous speleothems more generally as important archives for investigating arid-zone palaeoclimate.

How to cite: Gould-Whaley, C., Drysdale, R., May, J.-H., Hellstrom, J., Cheng, H., Woodhead, J., Greig, A., Corrick, E., and Cohen, T.: Subaqueous speleothems from the Flinders Ranges, South Australia, as palaeohydrological archives for the arid zone, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16120, https://doi.org/10.5194/egusphere-egu21-16120, 2021.

Under the current rapid global warming, studying how environments responded to past climate change becomes increasingly important to better understand what impact climate variability has on regional flora and fauna. Our new multi-proxy study to the World Heritage Naracoorte Caves in southern Australia provides a unique window into the past climate as they are heavily decorated with speleothems but also contain in-fill deposits rich in Pleistocene vertebrate fossils including the extinct Australian megafauna. Until now, these speleothems have been dated using U-Th series and the fossil-bearing sediments with Optical Stimulated Luminescence and Electro Spin Resonance techniques, but only up to ca. 500 ka. We have U-Pb dated speleothems from the Naracoorte Caves for the first time and extended the record beyond 500 ka. We combined precise chronology with analyses of pollen and charcoal within the speleothems which allows us to better understand how southern Australia’s climate and its vegetation changed during the Quaternary. It also provides a unique insight into the timing and extent of cave opening with important potential for much older vertebrate fossil deposits than previously thought.

How to cite: Weij, R., Woodhead, J., Reed, L., Sniderman, K., Hellstrom, J., and Drysdale, R.: The World Heritage Naracoorte Caves beyond 500 ka: U-Pb dating and charcoal analysis from speleothems with implications for Pleistocene vertebrate fossil deposits, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4488, https://doi.org/10.5194/egusphere-egu21-4488, 2021.