Karen K. Serieyssol, Aude Beauger, Yannick Miras, Léo Chassiot, Victor Arricau, Emmanuel Chapron
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引用次数: 0
Abstract
Lake Pavin, a maar lake was formed approximately 7000 years ago by a phreatomagmatic explosion, leaving a deep central crater with shallow steep side slopes. PAV12 core, collected from the center of the lake, displayed two diatomite layers, separated by a 4-m thick unit of reworked sediments. Diatom diversity and zonation analyses registered six zones documenting the lake evolution. Asterionella formosa, Pantocsekiella ocellata and Discostella pseudostelligera (including f. diminuta) along with fragilariod taxa composed the basal unit (L-1, ~ 6900 to 6570 cal a BP). With increased mineralization of the lake waters, Stephanodiscus taxa became the major species (L-2, 6190–3800 cal a BP). A transition zone was noted between Zone L-2 and L-3 (3950–3700 BP) and related to a major change in diatom composition. Asterionella formosa and Nitzschia paleacea dominated Zone L-3 (3760–1470 cal a BP) with a large decrease in Stephanodiscus taxa. This major change has been related to soil erosion and the possible development of meromixis. Stephanodiscus parvus and Asterionella formosa dominated the upper diatomite zone L-4 (640–400 cal a BP) while zone L-5 (290–160 cal a BP) is dominated by Aulacoseira subarctica (including f. recta) and may be caused by the Little Ice Age. Zone L-6 (subrecent) saw a return to similar conditions as in zone L-4. The gradual opening of the diversified forest and appearance of regional agriculture appears to be related to the development of meromixis. Changes in the upper diatomite zone are related to agricultural activity, changes in incomplete overturn and climate. This study examines relationships between diatom changes and pollen and geochemical changes observed within the lake.
期刊介绍:
The realization that a historical perspective is often useful, if not essential, to the understanding of most limnological processes has resulted in the recent surge of interest in paleolimnology. The main aim of the Journal of Paleolimnology is the provision of a vehicle for the rapid dissemination of original scientific work dealing with the reconstruction of lake histories. Although the majority of papers deal with lakes, paleoenvironmental studies of river, wetland, peatland and estuary systems are also eligible for publication.
The Journal of Paleolimnology, like the subject itself, is multidisciplinary in nature, and papers are published that are concerned with all aspects (e.g. biological, chemical, physical, geological, etc.) of the reconstruction and interpretation of lake histories. Both applied and more theoretical papers are equally encouraged. The Journal of Paleolimnology will continue to be a major repository for papers dealing with climatic change, as well as other pressing topics, such as global environmental change, lake acidification, eutrophication, long-term monitoring, and other aspects of lake ontogeny. Taxonomic and methodological papers are also acceptable provided they are of relatively broad interest. New equipment designs are frequently featured. In addition to original data and ideas, the Journal of Paleolimnology also publishes review articles, commentaries and program announcements. A relevant Book Review Section is also featured.