CL1.19

EDI
Speleothem and Continental Carbonate Archives of Modern and Palaeoenvironmental Change

Speleothems and continental carbonates (e.g. travertines, pedogenic, lacustrine, subglacial and cryogenic carbonates) are important terrestrial archives, which can provide precisely dated, high-resolution records of past environmental and climate changes. The field of carbonate-based paleoclimatology has seen (1) continuously improving analytical capacity, producing detailed records of climate variability integrating established as well as novel and innovative techniques. (2) Long-term monitoring campaigns facilitating the interpretation of high-resolution proxy time series from carbonate archives. (3) At the same time proxy-system models can help understanding the measured proxies, by describing processes such as water infiltration, CO2 and carbonate dissolution, and carbonate precipitation and diagenesis. Applied together, advancements in these cornerstones of carbonate related research pave the way towards developing highly reliable quantitative terrestrial climate reconstructions.
Here, we invite contributions that show progress in one of the three outlined domains. We especially welcome integrated and interdisciplinary studies, connecting these branches of carbonate related research in order to better understand the climate system on various time scales.

Co-organized by SSP1
Convener: Jens Fohlmeister | Co-conveners: Andrea Borsato, Gabriella KoltaiECSECS, Sophie WarkenECSECS, Andrea Columbu
vPICO presentations
| Thu, 29 Apr, 09:00–10:30 (CEST)

vPICO presentations: Thu, 29 Apr

Chairpersons: Jens Fohlmeister, Sophie Warken, Andrea Borsato
Monitoring
09:00–09:02
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EGU21-10629
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ECS
Marjan Temovski, Marianna Túri, Anikó Horváth, and László Palcsu

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.

09:02–09:04
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EGU21-7151
Virgil Dragusin, Vasile Ersek, Alvaro Fernandez, Roxana Ionete, Andreea Iordache, Nele Meckler, Ionut Mirea, and Ramona Zgavarogea

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.

09:04–09:06
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EGU21-790
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ECS
Ny Riavo G. Voarintsoa, Antsa Lal’Aina J. Ratovonanahary, Avotriniaina Z. M. Rakotovao, and Steven Bouillon

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, δ13CDIC, δ18Ow, δ2Hw, 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.

09:06–09:08
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EGU21-359
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ECS
Yoav Ben Dor, Tomer Flax, Itamar Levitan, Achim Brauer, Yehouda Enzel, and Yigal Erel

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, 2020.

Modelling and age control
09:08–09:10
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EGU21-9619
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ECS
Vanessa Skiba and Jens Fohlmeister

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.

09:10–09:12
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EGU21-5941
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ECS
Josefine Axelsson, Andreas Nilsson, and Jesper Sjolte

Due to age uncertainties and poor resolution in speleothems, age-depth modelling techniques are often implemented for cross-examinations. In this study, we use a variation of the analogue method to perform a pseudo-proxy reconstruction of the large-scale variability in Indian and East Asian monsoon precipitation using synthetic oxygen isotope records from speleothem sites and an isotope-enabled climate model.

We present a probabilistic approach to synchronize speleothems through oxygen isotope data and individual independent age constraints, achieved by co-estimating the regional δ18O variations through time. The δ18O variability is modelled using Gaussian processes, and an adaptation of BACON age-depth model is further used for the individual speleothem chronologies.

The method is tested using synthetic speleothem data generated from the ECHAM/MPI-OM climate model and corrupted through realistic noise from speleothems from the SISAL database.

By incorporating accurate and realistic depth-dependent age-uncertainties rather than shifting, stretching or compressing the time-series of oxygen isotope data, this modelling approach may lead to advancements of handling speleothem data for regional to global evaluations on variability between speleothems and timescales.

How to cite: Axelsson, J., Nilsson, A., and Sjolte, J.: A probabilistic approach to oxygen isotope modelling of speleothem data with age uncertainties, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5941, https://doi.org/10.5194/egusphere-egu21-5941, 2021.

09:12–09:14
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EGU21-3656
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ECS
Mohammadali Faraji, Andrea Borsato, Silvia Frisia, John C. Hellstrom, Andrew Lorrey, Adam Hartland, Alan Greig, and David P. Mattey

Climate and environmental events recorded by speleothems are accurately dated by radiometric techniques. However, speleothems from the Tropical Pacific are difficult to date by the U-series radiometric method due to low uranium content and/or multiple sources of 230Th. This is the case of stalagmites from Atiu, in the Southern Cook Islands Archipelago, which potentially record shifts of the South Pacific Convergence Zone through time and their impact on droughts and floods. Here we constrain the U-series-based chronology using synchrotron µXRF two-dimensional mapping of Sr concentrations coupled with growth laminae optical imaging constrained by in situ monitoring.

Chronology involving annual laminae counting has, to date, been focused on settings where strong temperature seasonality favours the formation of annual geochemical/physical cycles. In Atiu caves temperature is constant throughout the year (mean ∼23 °C), whereas precipitation exhibits a strong seasonality, with 70% of the mean Total Annual Rainfall (TAR = 1930±365 mm/yr) occurring from December to May. However, during the drier season (June through November) rainfall amounts are still substantial, which can lead to missing dry seasons in the speleothem record. Moreover, a shallow depth of the caves (5 -10 m) and limited soil cover enhance fast transmission of rain signal into the caves, possibly resulting in the formation of sub-annual growth bands. Thus, the concentration variability of Sr and Mg alone are not sufficient to identify an annual signal.

We integrated, in a multivariate analysis, high resolution (6µm) variations in trace elements analysed by LA-ICP-MS, with optically visible growth bands and two-dimensional Sr-concentration laminae as identified through synchrotron-radiation-based micro XRF mapping. Cycles of [Mg], [Sr], [Na], [Ba] and [P] concentration were counted for three independent transects in a modern stalagmite (Pu17) from Pouatea Cave. This included semi-automated counting of peak positions on individual elements, as well as on their principal components (PCA). The three independent analytical techniques produced 37 peak counting series, 20 of which were averaged and integrated into a single age model fitting into the uncertainty limits of U/Th dates. This master chronology was used to construct an age model that integrated laminae counting errors with the U/Th uncertainty. The average uncertainty of U–Th ages included in the age model is ca. 50%, whereas the initial lamina chronology has a maximum error of 15 years (4%), thus decreasing the uncertainty by at least 45%.

Our yearly resolved chronology was then tested against the local rainfall record by using hydrologically sensitive elements Mg, Na and P. High correlation coefficients for each element corroborated the reliability of the age model, paving the way to reconstruct seasonally resolved records from trace element variations in these tropical speleothems.

How to cite: Faraji, M., Borsato, A., Frisia, S., C. Hellstrom, J., Lorrey, A., Hartland, A., Greig, A., and P. Mattey, D.: Accurate dating of tropical South Pacific stalagmites using physical and chemical cycles, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3656, https://doi.org/10.5194/egusphere-egu21-3656, 2021.

Climate reconstruction
09:14–09:16
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EGU21-14642
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ECS
Anika Donner, Christoph Spötl, Paul Töchterle, Irka Hajdas, and Gina E. Moseley

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 (CCCfine), 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 CCCfine 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). CCCfine 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 CCCfine from caves at lower latitudes, the δ18O values are significantly lower and plot in the field of CCCcoarse (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 CCCfine 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.

09:16–09:18
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EGU21-14487
Miguel Bartolomé, Ana Moreno, Marc Luetscher, Christoph Spötl, Maria Leunda, Gerard Cazenave, Ánchel Belmonte, Cinta Osácar, Hai Cheng, Richard Lawrence Edwards, and Carlos Sancho

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.

09:18–09:20
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EGU21-12836
Caroline Welte, Jens Fohlmeister, Melina Wertnik, Lukas Wacker, Bodo Hattendorf, Tim Eglinton, and Christoph Spötl

Laser ablation coupled online to accelerator mass spectrometry [1] allows analyzing the radiocarbon (14C) concentration in carbonate samples in a fast and spatially resolved manner. This novel technique can provide 14C data at a spatial resolution comparable to that of stable carbon isotope measurements and, thus, can help to interpret δ13C signatures. In this work, we analyzed δ13C and 14C of a Holocene stalagmite from the high-alpine Spannagel Cave (Austria). Combined δ13C and 14C profiles allow identifying three growth periods : (i) the period > 8 ka BP exhibits relatively low δ13C values with small variability combined with a comparably high dead carbon fraction (dcf) of around 60%. This points towards C contributions of an old organic carbon reservoir in the karst potentially mobilized due to the warm climatic conditions of the early Holocene. (ii) Between 3.8 and 8 ka BP, a strong variability in δ13C with values from -8 to +1‰ and a generally lower dcf was observed. The δ13C variability was most likely caused by changes in gas exchange processes in the cave, which are induced by reduced drip rates as derived from lower stalagmite growth rates. Additionally, the lower dcf indicates that the OM reservoir contributed less to stalagmite growth in this period possibly as a result of reduced precipitation or because the OM reservoir became exhausted. (iii) In the youngest section between 2.4 and 3.8 ka BP, comparably stable and low δ13C values combined with an increasing dcf reaching up to 50% are again hinting towards a contribution of an aged organic carbon reservoir in the karst.

[1] C. Welte, et al., (2016). Anal. Chem., 88, 8570– 8576.

How to cite: Welte, C., Fohlmeister, J., Wertnik, M., Wacker, L., Hattendorf, B., Eglinton, T., and Spötl, C.: Climatic variations during the Holocene inferred from radiocarbon and stable carbon isotopes in a high-alpine cave, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12836, https://doi.org/10.5194/egusphere-egu21-12836, 2021.

09:20–09:22
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EGU21-15319
Dana Felicitas Christine Riechelmann, Klaus Peter Jochum, and Denis Scholz

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.

09:22–09:24
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EGU21-1356
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ECS
Ezgi Ünal İmer, İsmail Ömer Yılmaz, Mehmet Oruç Baykara, and Jian-Xin Zhao

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 (δ18OVSMOW = -7.8‰, δDVSMOW = -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 19th 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.

09:24–09:26
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EGU21-15846
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ECS
Nils Schorndorf, Norbert Frank, Sophie Warken, Julius Förstel, Andrea Schröder-Ritzrau, Jerónimo Avilés Olguín, and Wolfgang Stinnesbeck

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.

09:26–09:28
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EGU21-8066
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ECS
Marcela Eduarda Della Libera de Godoy, Valdir F. Novello, and Francisco William Cruz

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.

09:28–09:30
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EGU21-3040
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ECS
Sarah Parker, Sandy Harrison, and Laia Comas-Bru

Reconstruction of changes in interannual variability through the Holocene period can provide valuable insight into the sensitivity of internal modes of variability (e.g. ENSO, PDO) to external forcing. Coral and bivalve records are widely used examine past changes in short-term variability, however, far fewer reconstructions exist in the terrestrial realm. Here, we use the SISAL (Speleothem Isotopes Synthesis and AnaLysis) database to examine changes in the amplitude of interannual/short-term variability across the monsoon regions, recorded by speleothem δ18O standard deviation (δ18O s.d.). First, we identified and corrected for any confounding factors that may obscure interannual climate signals in the speleothem records, such as variable growth rate. We used a multiple linear regression model to constrain relationships between δ18O s.d. and growth rate and mean climate (represented by mean δ18O), then used these relationships to apply a correction. Second, corrected δ18O s.d. trends were combined into regional monsoon composites, representing changes in short-term variability across the Holocene. Trends are very similar between raw and corrected δ18O s.d., suggesting that confounding factors have a minimal effect. Trends differ amongst regions: the Indian monsoon shows gradually increasing δ18O s.d. through the Holocene, whilst the East Asian monsoon shows no significant changes through this period. The Indonesian-Australian monsoon shows higher than present δ18O s.d. during the mid- to early Holocene and the South American monsoon shows multi-centennial scale fluctuations between higher and lower δ18O s.d.

How to cite: Parker, S., Harrison, S., and Comas-Bru, L.: Speleothem records of interannual variability in the tropics during the Holocene, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3040, https://doi.org/10.5194/egusphere-egu21-3040, 2021.

09:30–09:32
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EGU21-12867
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Highlight
Russell Drysdale, Michael Griffiths, John Hellstrom, Ellen Corrick, Jon Woodhead, Kale Sniderman, Sune Rasmussen, Raimund Mueschler, and Emilie Capron

The end of the Younger Dryas (YD) was Earth’s last major abrupt climate event and is most vividly preserved in the water-isotope (ice δ18O), calcium (Ca2+) and methane-concentration (CH4) series of Greenland ice cores. Although numerous palaeoclimate records span this transition, surprisingly few have the dating precision necessary to test whether or not abrupt warming in Greenland was accompanied by synchronous climate changes beyond the Arctic. Speleothems, with their exceptional absolute chronologies, are well placed to conduct such a test.

Here we apply a change-point detection algorithm to new and published speleothem δ18O records of the YD from the Indo-Australian summer monsoon and Asian summer monsoon domains to compare the synchronicity of hydroclimate changes across the YD termination. The algorithm, which identifies the age (and its uncertainty) of a regime shift in a time series, was applied to the 13 - 11 ka interval of each speleothem record. The results yield an error-weighted mean YD-termination age of 11.55 ± 0.02 ka BP (2σ), supporting the hypothesis of a closely coupled monsoon seesaw. Analysis of the Greenland NGRIP ice-core δ18O and Ca2+ records on the GICC05 chronology for the same interval produces a YD-termination age of 11.63 ± 0.10 ka BP. Although the NGRIP and speleothem ages overlap within uncertainties, this hints at a possible Arctic lead over the tropics. However, if we apply a correction to the GICC05 chronology based on recent ice-core 10Be and tree-ring 14C synchronisation, the change-point analysis gives a NGRIP termination age of 11.57 ± 0.02 ka BP. This revised timing is consistent with the Cariaco Basin greyscale record (11.56 ± 0.02 ka BP). It also brings the NGRIP and Antarctic WAIS Divide ice-core CH4 records into perfect alignment across the transition. This assemblage of ages from geographically dispersed regions suggests that hydroclimate changes associated with the YD termination were synchronous, at least to within a couple of decades. It also calls for a revision to the onset age of the Greenlandian Stage (the Pleistocene-Holocene boundary).

How to cite: Drysdale, R., Griffiths, M., Hellstrom, J., Corrick, E., Woodhead, J., Sniderman, K., Rasmussen, S., Mueschler, R., and Capron, E.: Synchronous climate change between the Arctic and the Asian and Indo-Australian summer monsoon domains at the Younger Dryas termination, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12867, https://doi.org/10.5194/egusphere-egu21-12867, 2021.

09:32–09:34
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EGU21-10772
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ECS
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Highlight
Juan Luis Bernal Wormull, Ana Moreno Caballud, Yuri Dubliansky, Christoph Spötl, Carlos Pérez-Mejías, Miguel Bartolomé, Eneko Iriarte, Martin Arriolabengoa, Arantza Aranburu, Isabel Cacho, Hai Cheng, and R. Lawrence Edwards

The last deglaciation (from ≈19 kyr BP to the onset of the Holocene) is a time interval characterized by major and abrupt climate changes mostly caused by the Atlantic Meridional Overturning Circulation (AMOC) which is responsible for redistributing heat on a planetary scale, including the Iberian Peninsula. This study is focused in the Western Pyrenees, northern Spain, a southern European region key to understand Northern Hemisphere climate teleconnections associated to several warming and cooling events that took place abruptly. It is especially important to know when precisely these events occurred and what their amplitude was to better understand their causes and impacts on the regional environment.

The climatic events mentioned above are recorded in lake and marine sediments in the central and southern Europe denoting the importance of these records in the transitional zone between the Atlantic and the Mediterranean climatic realms. The glacial-interglacial transition was also identified in isotopic values of speleothems at this latitude, where differences and similarities with the patterns identified in the Greenland record during the last deglaciation are analysed. Even so, there is still no continental record of temperature reconstruction during part of the last deglaciation in the Iberian Peninsula that can be compared with the latest record of fluid inclusions in speleothems in central Europe (Affolter et al., 2019).

In this new study, three stalagmites from Ostolo Cave in the Western Pyrenees were analysed to identify and characterize the timing of the climate variability along the abrupt changes that punctuated the last deglaciation and subsequently generate a reconstruction of the past temperature with the help of fluid inclusion water isotopes. The samples were dated at high precision and cover almost continuously the same period (16.5-10 kyr BP) with a high degree of replication. The speleothem δ18O and fluid inclusion water isotopes (δD) records follow closely the well-known changes from high latitudes showing more negative values during GS-1 and H1, related to colder climates, while more positive values were reached during GI-1 and the Early Holocene, pointing towards warmer temperatures. Our Ostolo Cave fluid inclusion temperature record resembles Greenland and Mediterranean sea surface temperature trends and allows for the first time and from a continental record, a continuous reconstruction of temperature throughout the last deglaciation in southern Europe.

How to cite: Bernal Wormull, J. L., Moreno Caballud, A., Dubliansky, Y., Spötl, C., Pérez-Mejías, C., Bartolomé, M., Iriarte, E., Arriolabengoa, M., Aranburu, A., Cacho, I., Cheng, H., and Edwards, R. L.: Northern Spain temperature constrained by fluid inclusion water isotopes in speleothems during the abrupt oscillations of the last deglaciation period, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10772, https://doi.org/10.5194/egusphere-egu21-10772, 2021.

09:34–09:36
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EGU21-15940
Ana Moreno, Miguel Bartolomé, Carlos Sancho, Eneko Iriarte, Ánchel Belmonte, Isabel Cacho, Heather Stoll, Lawrence R. Edwards, and Hai Cheng

Paleoclimate records from the Pyrenees covering last glacial period are scarce since many lakes were covered by the glaciers, glacier deposits just provide discontinuous information and in very few caves we can find speleothem growth during that cold and generally dry time period. Las Gloces cave, located close to Ordesa and Monte Perdido National Park (Central Pyrenees, Iberian Peninsula) at 1240 m a.s.l., is one the few examples to study that time interval. Thus, for the first time, we present a speleothem in the Pyrenees that was growing during the Maximum Ice Extent in the last glacial period in a cave located just 3 km away from the glacier. Two speleothems from las Gloces were sampled, one covering the Holocene and last deglaciation (last 16.6 ka) and the other one growing from MIS4 (67.8 ka) to Mid-Holocene (4.7 ka), with two hiatuses at 50-47 ky and 30-21 ka coinciding with cold/dry periods. Both stalagmites were dated and analyzed for stable i sotopes and trace elements.

 

During MIS4, the lowest growth-rates correspond with Heinrich Stadial (HS) 6 while there is an increase in growth rate during MIS3 onset, reaching the maximum at Greenland Interstadial (GI)-14. After this, and corresponding with HS5, the growing stopped and it will reactivate again during GI-12, but with low growth rates. A new interruption took place 30 ka ago, with a second hiatus (30-21 ka), corresponding with an important retreat of Central Pyrenees glaciers and maximum regional aridity. During last glacial period, δ13C and δ18O records vary with rather small amplitude of change (4 ‰ and only 1‰, respectively) and showing low correlation between them indicating they were likely affected by different influences. At 21 ka BP, there is a new speleothem growth that will be characterized by the heaviest δ13C and δ18O values in the record (0‰ and -7‰, respectively) that occurred during the global LGM period.

 

Changes in the growth rate in those stalagmites could be related to precipitation oscillations during GS-GI cycles while the variation in δ13C could respond with changes in the temperature and rainfall on a glacial landscape with reduced vegetation cover. Differences in mean values of δ13C between MIS3 (-5‰) and Holocene (-9‰) represent a forest revegetation over the cave related with the climatic amelioration experienced during last deglaciation due to the increase in temperature and humidity. Drivers on δ18O change during MIS 3 are multiple and more complex but they may correspond to changes in amount of rainfall, temperature or moisture source. The drastic change in d18O during last deglaciation (from -10‰ at HS1 to -7 ‰ at the onset of the Holocene) could be additionally related to the well-known isotopic change of sea surface water due to the massive entrance of freshwater into the north Atlantic region.

How to cite: Moreno, A., Bartolomé, M., Sancho, C., Iriarte, E., Belmonte, Á., Cacho, I., Stoll, H., Edwards, L. R., and Cheng, H.: Centennial-scale climate variability inferred from Las Gloces cave in Central Pyrenees: evidences of rapid changes during last glacial cycle, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15940, https://doi.org/10.5194/egusphere-egu21-15940, 2021.

09:36–09:38
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EGU21-9696
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ECS
Mojgan Soleimani, Stacy Carolin, Alireza Nadimi, Gideon Henderson, and Christoph Spötl

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.

09:38–09:40
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EGU21-16120
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ECS
Calla Gould-Whaley, Russell Drysdale, Jan-Hendrick May, John Hellstrom, Hai Cheng, Jon Woodhead, Alan Greig, Ellen Corrick, and Timothy Cohen

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.

09:40–09:42
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EGU21-4488
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ECS
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Highlight
Rieneke Weij, Jon Woodhead, Liz Reed, Kale Sniderman, John Hellstrom, and Russell Drysdale

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.

09:42–10:30