Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

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Session Overview
Session
5.3 Advances in terrestrial and marine carbonate archives – novel proxies and innovative techniques to decipher past climate variability
Time:
Thursday, 23/Sept/2021:
1:30pm - 3:00pm

Session Chair: Dana Felicitas Christine Riechelmann, Johannes Gutenberg University Mainz
Session Chair: Maximilian Hansen, Johannes Gutenberg-Universität Mainz
Session Chair: Sophie Warken, Heidelberg University
Session Chair: Michael Weber, Johannes Gutenberg Universität Mainz

Session Abstract

The use of carbonate-based paleoclimate archives has gained increasing importance to obtain reliable and detailed information on past climate and environmental variability in order to better understand the modern climate regime and the influence of anthropogenically induced global warming. In the last decades, the diversity of geochemical proxies available in carbonate palaeoclimate archives have emerged rapidly and significantly. Trace elements and traditional stable isotopes of oxygen and carbon have been supplemented with numerous non-traditional stable isotope systems such as B, Li, Ba, Mg, Ca, Sr, U, N, Δ17O, Δ47.In addition, the study of organic matter in carbonaceous archives and investigation of different biomarkers has massively expanded over the last years. Most importantly, recent developments in analytical techniques allow for improved precision, unprecedented resolution or smallest sample amounts. Furthermore, sophisticated isotope enabled diffusion-reaction models as well as high resolution experimental approaches significantly improved our understanding of the underlying fractionation processes. All these novel geochemical proxies and innovative methods open new advances towards qualitative and quantitative reconstruction in terrestrial and marine palaeoclimate studies and allow for multi-proxy approaches at different spatial and temporal scales.This session aims to bring together researchers from different fields of palaeoclimate research to share their knowledge, and allow inter-disciplinary exchange in order to apply these proxies to other palaeoclimate archives. We especially invite early career researcher to submit their abstracts to this interdisciplinary session. This will inspire both young researcher as well as senior scientists to apply new multi-proxy research approaches to study past climate variability. 


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Presentations
1:30pm - 2:00pm
Session Keynote

An archive of many hats: speleothems for coupled climate and ecosystem reconstructions

Franziska Anna Lechleitner

Department of Chemistry, Biochemistry and Pharmaceutical Sciences & Oeschger Centre for Climate Change Research, University of Bern

Speleothems are secondary cave carbonate deposits and an established terrestrial paleoclimate archive. Moreover, they have the potential to record conditions in the ecosystem overlying the cave, particularly the vegetation and soil. Coupled records of paleoclimate and -ecological information from a single speleothem would be an invaluable source of information to understand the past and future sensitivity of terrestrial ecosystems to climate change, particularly under the lens of anthropogenic forcing. In order to develop proxies that record unambiguous and quantifiable ecosystem processes, it is necessary to i) understand and characterize how processes in the soil-karst-cave system will affect geochemical tracers that may be sensitive to ecosystem conditions, and ii) develop transfer functions and frameworks that allow the interpretation of such tracers in speleothems over time periods longer than observations.

In this talk, I will discuss ways to approach these problems using different methods. I will show how combining multiple proxy measurements and forward modeling can be used to quantify the temperature sensitivity of soil respiration in the past from speleothem δ13C records. Finally, I will discuss the potential of speleothem organic carbon isotopes (δ13C and 14C) as direct tracers for surface ecosystem conditions, and the challenges and opportunities associated with these measurements.



2:00pm - 2:15pm

No warming in the eastern Gulf of Mexico since 1845 recorded by a Siderastrea siderea coral from Cuba

Marie Harbott1, Henry C. Wu1, Henning Kuhnert2, Simone Kasemann2, Anette Meixner2, Carlos Jimenez3, Patricia González-Díaz4, Tim Rixen1,5

1Leibniz Center for Tropical Marine Research, Fahrenheitstraße 6, 28359 Bremen,Germany; 2Marum-Faculty of Geoscience & Center for Marine Environmental Sciences, University of Bremen, Leobener Str. 8, 28359 Bremen, Germany; 3The Cyprus Institute. 20 Konstantinou Kavafi St, 2121 Aglantzia. Nicosia, Cyprus; 4Centro de Investigaciones Marinas Universidad de La Habana, Calle 16 no.114 e/ 1ra y 3ra, Miramar. Playa, Ciudad de La Habana, Cuba; 5Institute of Geology, University of Hamburg, Bundesstrasse 55, 20148 Hamburg, Germany

Changes in the surface ocean pH and temperature caused by the uptake of anthropogenic CO2 are posing a threat to calcifying marine organisms. Recent studies have observed significant impacts on coral reef ecosystems with impaired carbonate skeletal growth and decreased calcification due to acidifying oceans. The current coverage of observations for the northwestern Cuban coastal waters provides an incomplete picture of natural climate variability over interannual to interdecadal timescales, showing the need for high resolution climate archives. Cuba is situated between densely populated landmasses of North and South America offering a unique environment to study multiple aspects of anthropogenic activity across the region as well as their interconnectivity. Sub-seasonally resolved sea surface temperature (SST), δ18O of seawater, and carbonate chemistry parameters were reconstructed from a massive Siderastrea siderea coral from Cuba’s northwestern coast through a multi-proxy approach since the preindustrial era. Trace element ratios as proxies of SST indicate no significant increase in temperature over the past 160 years since 1845. Over the same time period, coral skeletal δ11B ratio decreased by ca. 1.6 ‰, translating into a decrease of 0.1 on the pH scale, reflecting the acidification of the northwestern Cuban coastal waters. Furthermore, an accelerating depletion of coral δ13C from the 1850s to 2005 of 1.5 ‰ demonstrates the changes in seawater CO2 with an anthropogenic imprint due to increased fossil fuel combustion. Further investigation and the comparison to trace elements indicate possible baseline shifts in regional seawater carbonate chemistry that has been affected by anthropogenic activity.



2:15pm - 2:30pm

Comparison of high-resolution SIMS profiles with maximum resolution IRMS stable isotope data

Tobias Kluge1,2, Philipp Holz1, Elisabeth Eiche1, Thomas Neumann3, Alexander Land4,5, Maximilian Schuh2,6, Mario Trieloff2,7, Axel K. Schmitt2,7

1Institute of Applied Geosciences, Karlsruhe Institute of Technology, Germany; 2Heidelberg Center for the Environment, Heidelberg University, Germany; 3Institute of Applied Geosciences, Technische Universität Berlin, Germany; 4Institute of Biology (190a), University of Hohenheim, Germany; 5Silviculture & Forest Growth and Yield, University of Applied Forest Sciences, Germany; 6Medieval History, Department of History and Cultural Studies, FU Berlin, Germany; 7Institute of Earth Sciences, Heidelberg University, Germany

High-resolution speleothem paleoclimate records with annual to seasonal resolution are helpful for detailed analysis of climatic changes with limited duration (e.g., volcanic climate impacts), but also for longer-duration events (e.g., at 8.2 ka or 4.2 ka). A high resolution paleoclimate data set is also mandatory for meaningful comparison with archaeological or historical records.

Low stalagmite growth rates could impede the acquisition of high-resolution isotope data with the classical micro-milling approach and isotope ratio mass spectrometry (IRMS) analysis. We therefore compared secondary ionization mass spectrometry (SIMS) stable isotope measurements at 7-15 µm resolution with the lower-resolution micro-milling results at 90 µm steps. For the investigated stalagmite from Kleine Teufelshöhle (Frankonia, Germany) the SIMS resolution corresponds to annual resolution, whereas IRMS only reaches a 4-13 year resolution.

Albeit a constant offset, SIMS and IRMS δ18O data match very well (r = 0.61, p < 0.001, n = 84). This significant correspondence suggests that SIMS stable isotope analysis could be a promising alternative for high-resolution carbonate studies. An adjacent second δ18O SIMS profile reproduced high-resolution features (r=0.59, p < 0.001, n = 982) and allows a detailed assessment of paleoclimate variability on an annual scale and a comparison with independent climate records, e.g., weather information from historical documents or tree rings.

Stalagmite δ18O trends closely follow the low-frequency fluctuations of a regional tree-ring record (Land et al., 2019), additionally constraining the stalagmite chronology. The different climate sensitivities of both records enable a more robust and detailed discussion of paleoclimatic variations.



2:30pm - 2:45pm

Cave monitoring of La Vallina Cave (NISA): Imprint of seasonality on δ13CDIC, δ18O and trace elements and the implications for speleothems

Oliver Kost1, Saul Gonzalez Lemos2, Laura Endres1, Heather Stoll1

1ETH Zurich, Switzerland; 2ASCIEM Consulting S.L.P.

A cave monitoring sets the basis of speleothem studies. It helps to understand changing cave conditions on seasonal scale and site-specific geochemical differences such as hydrological conditions and heterogeneities in bedrock respectively. Here we present a set of parameters measured in La Vallina Cave (NW Iberian Speleothem Archive, NISA). Over the course of 16 months cave air conditions (pCO2 and δ13C) were examined to understand calcite precipitation, ventilation processes and mixing of soil air and atmospheric air. From stalactitic soda straws the δ13CDIC of dripwater was determined to learn about the carbon cycle in the overlaying soil and karst driven by seasonal vegetation and microbial degradation changes. We capture seasonal changes in δ13CDIC independent of degassing/PCP effects. Further, the δ18O and δD composition of dripwater and hydrology help to understand water reservoir and recharge processes related to precipitation. Finally, the elemental geochemistry of dripwater was investigated by analyzing 16 elements. We present data of commonly used elements such as Mg, Sr, Ca or Ba but also elements sparsely reported in cave dripwater monitoring studies such as Y, Na or As. Controlling factors are related to bedrock leaching, particulate import and potentially redox conditions.



2:45pm - 3:00pm

Combined Fluorescence Imaging and LA-ICP-MS Trace Element Mapping ofStalagmites: Microfabric identification and interpretation

Jakub Sliwinski1, Heather Stoll2

1University of St Andrews, United Kingdom; 2ETH Zurich

Here, we map a series of stalagmites from Asturias, Spain, by laser ablation inductively-coupled-plasma mass spectrometry and confocal laser scanning (fluorescence) microscopy and discuss the origins of trace element and fluorescence variations. Seasonal banding is evident with both methods and may be attributed to lignins/humic acids based on fluorescence absorption and emission characteristics.
Some lateral variations in fluorescence present as saw-tooth “spires” and demonstrate disruptions of seasonal banding, corroborated by trace element variations (most prominently Mg and Na). Such features likely reflect the differential partitioning of trace elements by sectoral zoning as a result of low supersaturation and/or high organic matter load, combined with the effects of dissolved organic matter on the calcite growth surface and the association of each element with colloidal organic matter. The lateral variability of trace elements demonstrates the pitfalls of obtaining trace element information from one-dimensional transects without prior reconnaissance mapping. It is, however, possible that traditional drilling with ~1 mm holes homogenizes these features and provides reliable trace element estimates.



 
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