Speleothem stable isotope records for east-central Europe: resampling sedimentary proxy records to obtain evenly spaced time series with spectral guidance

Abstract

Abstract. Uneven spacing is a common feature of sedimentary paleoclimate records, in many cases causing difficulties in the application of classical statistical and time series methods. Although special statistical tools do exist to assess unevenly spaced data directly, the transformation of such data into a temporally equidistant time series which may then be examined using commonly employed statistical tools remains, however, an unachieved goal. The present paper, therefore, introduces an approach to obtain evenly spaced time series (using cubic spline fitting) from unevenly spaced speleothem records with the application of a spectral guidance to avoid the spectral bias caused by interpolation and retain the original spectral characteristics of the data. The methodology was applied to stable carbon and oxygen isotope records derived from two stalagmites from the Baradla Cave (NE Hungary) dating back to the late 18th century. To show the benefit of the equally spaced records to climate studies, their coherence with climate parameters is explored using wavelet transform coherence and discussed. The obtained equally spaced time series are available at https://doi.org/10.1594/PANGAEA.875917.

Speleothem Records from the Eastern Part of Europe and Turkey—Discussion on Stable Oxygen and Carbon Isotopes

“…are needed to improve our understanding on the environmental response of surface-and subsurface systems to climate changes. Lastly, it should be emphasized that speleothem derived paleoenvironmental data-typically unevenly spaced and associated with timescale error should be assessed using proper statistical tools [132,133] capable to provide more robust results in speleothem paleoclimatology than before.…”

Az ImaGeo magszkennelés módszerei egy Mecseki fúrás nagyfelbontású értelmezésének példáján

“…Ez a Lomb-Scargle periodogrambecslő eljárás (LOMB 1976, SCARGLE 1982, amely azon túl, hogy nem igényel ekvidisztáns mintavételezést, az eredményhez képes konfidencia intervallumot is konstruálni, mert ismert az eredményként kapott periodogram csúcsainak eloszlása (KO VÁCS et al 2004, KOVÁCS et al 2010. Ezzel csak a legnagyobb intenzitású csúcs szignifikanciája határozható meg (HATVANI et al 2018). Azonban egy módosított Lomb-Scargle-Fourier periodogrammmal (rLSP), melynek csúcsa it egy elsőrendű autoregresszív folyamathoz (AR[1]) viszonyítjuk, meghatározható minden csúcs szignifikan ci ája.…”

“…cseppkövek periodicitásvizs gálatánál alkalmazott beállításokkal (pl. HOLZKÄMPER et al 2004;HATVANI et al 2018).…”

Last deglaciation flooding events in the Southern Carpathians as revealed by the study of cave deposits from Muierilor Cave, Romania

“…Studies investigating cave deposits are increasingly becoming more relevant due to the value of the palaeoenvironmental archives they hold (Sasowsky and Mylorie 2007;Ford and Williams 2013;Bradley 2015). Karst archives include vertebrate remains, sediments, speleothems, and invertebrate fossil assemblages (Moldovan et al 2016;Winkler et al 2016;Lyman 2017;Hatvani et al 2018). These can be investigated through the use of various proxies and dating techniques that reveal stages of cave evolution connected to regional or global events.…”

“…Large mammal assemblages and micromammals are some of the oldest palaeontological records (Lyman 1994;Parmalee 2005) to indirectly determine the ages of cave sediments and the general climatic conditions for a particular region. Speleothems are the most used climatic archives in caves due to the potential for palaeoclimate reconstructions at regional scale that which can be accurately dated by using the U/Th method (McDermott 2004;Fairchild et al 2006;Obreht et al 2017;Hatvani et al 2018;Rossi et al 2018;Isola et al 2019). Clastic sediments found in caves are an important archive on the dynamics of the palaeohydrology of the underground settings (Sun et al 2017;Arriolabengoa et al 2018).…”