Review of dated Late Quaternary palaeolimnological records in the Carpathian region with special regard to diatom-based reconstructions

Transcription

1 PAGES Budapest november 18. Review of dated Late Quaternary palaeolimnological records in the Carpathian region with special regard to diatom-based reconstructions Krisztina Buczkó 1, Enikő Magyari 2, Mihály Braun 3, Miklós Bálint 4 Peter Bituśik 5, Agnieszka Wacnik 6 1 Hungarian Natural History Museum, Department of Botany, 1476 Budapest, P.O. Box 222, Hungary, Krisztina@buczko.eu 2 Hungarian Academy of Sciences-1Hungarian Natural History Museum, Palaeonthological Research Group, Hungarian Natural History Museum, 1476 Budapest, P.O. Box 222, Hungary 3 University of Debrecen, Department of Inorganic and Analytical Chemistry, H-4010 Debrecen, P.O. Box 21, Hungary 4 Babes-Bolyai University, Molecular Biology Center, Str. Treboniu Laurean 42, Cluj, Romania 5 Research Institute & Faculty of Science, Matthias Belius University, SK Banská Bystrica, Slovakia 6 Polish Academy of Sciences, W. Szafer Institute of Botany, Lubicz 46, Kraków, Poland

2 The Carpathian Region (including mountains and plains) has for a long time been lacking good palaeoenvironmental and especially palaeolimnological records, particularly for the Late Quaternary. In the last two decades many new sedimentary sequences were obtained and studied using a wide range of paleoproxies. We reviewed the results from 121 sequences in the Carpathian Region, all dated by radiometric methods. For more datails see: Buczkó M, Magyari E K, Bitušík P, Wacnik A Review of dated Late Quaternary palaeolimnological records in the Carpathian Region, east-central Europe. HYDROBIOLOGIA 631: Diatom analysis were carried out on 12 sequences in this region, but only 4 of them bear high-resolution, quantitative analyses: lake Przedni Staw, Zalavári lake, Lake Saint Anna, and the recently studied Taul dintre Brazi glacial lake. Site Name Details of locality of core Type Dating 14C age Calibrated deepest data (cal yr BP) Record Length Hiatus Lithololgy pollen Macrofossil Diatom Moll.(malacolog Cladocera Ostr. Geoch. Arch. Chironomid LOI testate amoebae Przedni y Staw Tatra Mts glacial lake ,000 BP 11,095-11, cm yes yes yes yes yes Temnosmrečinské y gpleso Tatra Mts glacial lake 210 Pb, 137 Cs 30 cm yes yes yes pleso Tatra Mts glacial lake 210 Pb, 137 Cs yes yes yes Nižné Terianske pleso Tatra Mts glacial lake 210 Pb, 137 Cs 1440 (rough estimate) 30 yes yes yes yes Balaton (Tó-22) Balaton shallow lake ca. 16,000 cal yr BP 14,223-15, cm yes yes yes yes Balaton (Tó-30) Balaton shallow lake ca cal yr BP) 12,550-13, yes yes yes yes Balaton (Tó-31) Balaton shallow lake ca cal yr BP 13,666-14, cm yes yes yes yes Zalavári 2 Balaton region shallow lake BP cm yes yes yes yes Garancsi-tó Tinnye shallow lake 137Cs ~100 yr 44 cm yes yes Taul dintre brazi Retezat Mts glacial lake 10 AMS 0-15,300 cal yr BP 10,914-11,183* 490 cm yes yes yes yes yes Taul Zanogutii Retezat Mts glacial lake 11 AMS 0-14,800 cal yr BP * 480(565 cm) yes yes yes yes Saint Anna Harghitei Mts crater lake 7 AMS cal BP cm yes yes yes yes yes yes yes

3 The lake sediment of Taul dintre Brazi (N 45o23 47 E22o m asl) was studied. The lake is located below the upper tree limit, in a Norway spruce (Picea abies) forest. Five-meter-long sediment core was taken in 2007 with Livingston piston corer from the deepest part of the shallow lake (1 meter average depth). Three zones were differentiated with 2-5 sub-zones on the basis of the generic level diatom analyses. The most characteristic changes were found at ca. 10,150 and 5800 cal yr BP. During the first part of the siliceous algae remain analysis the whole sequence was studied at low resolution (4-8 cm). In this phase 52 samples were counted, the diatoms were identified at generic level. As a second phase of the work, the deepest 1 meter long part vof the lake sediment was studied with high-resolution (Late Glacial Early Holocene part, 1 cm resolution).

4 Changes in dominant diatom taxa of Taul dinter Brazi during the Late Glacial (14,500-10,000 cal yr BP) Abrupt and characteristic changes of the diatom flora and vegetation were detected in the Late Glacial part of the sequence. Eight zones were distiguished, including the oldest part of the core. Here the diatom preservation is poor, mainly corroded valves were found. In the second zone also the poor (but better) preservation determine the assemblage, here the central parts of the Pinnularia taxa are dominant. Fragilaria venter and Stauroforma exugiformis alternate, but many other taxa including new, earlier unknown taxa are present. Scientific description of four new taxa is in progress. Abrupt changes were detected at 12,900, 12,500 and 10,500 cal yrs BP.

5 More than one hundred taxa were distinguished. The fragilaroid taxa (including Fragilaria, Pseudostaurosira, Stauroforma, Staurosira) were abundant in the older, Late Glacial and Early Holocene layers. Beside the common fragilaroid species, Stauroforma exiguiformis was dominant in several samples. In the last 10,000 cal yr BP Aulacoseira species gradually replaced fragilaroid taxa. 1-4 Aulacoseira alpigera 5-9. Stauroforma exiguiformis Aulacoseira valida Cavinula pseudocutiformis Aulacosiera spp. 20. Navicula seminuloides. 21. Pinnularia neomajor 22. Stauroneis sp. 23. Neidium amphigomphus Pinnularia hemiptera

6 The siliceous algae - including diatoms and chrysophyceaen cysts - provide a useful proxy for the reconstruction of the climate-driven environmental changes as well as human impact on lake sediments. This evidence is independent and characteristic for the water body. The aim of the multi-proxy analyses on the sediment of Taul dintre Brazi is to provide high-resolution environmental reconstruction for periods that show rapid climate change. On the basis of earlier published paleolimnological studies in this region, rapid climate changes are expected around 12,900; 11,500, 8,600-8,200 and 3,300-2,800 cal yr BP. The preliminary, genus-level diatom analyses verified the evidences of these boundaries. High-resolution, species level study of the Late Glacial diatom samples refine the envinronmental reconstruction. Species-level identification is fundamental for fine diatom-based environmental reconstruction (ph, trophy). The higher resolution analyses with species level identification promise high quality data set for the palaeoecological reconstruction of the southeast European region. Our results regarding the diatom flora and succession correlate well with the data of ~ 17,000 yr old Zănoguţa Sphagnum bog at 1840 m asl in the Retezat Mts (Péterfi 1974). The analogous changes can help in the better understanding of climate-driven events in the Retezat Mts.