A Late Glacial Paleolake Record from an Up-Dammed River Valley in Northern Transylvania, Romania

• Published in: Quaternary International
• Main Authors: Lascu, Ioan, Wohlfarth, Barbara, Onac, Bogdan P, Björck, Svante, Kromer, Bernd
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Digital Commons @ University of South Florida 2015
• Subjects: Romania; Late Glacial; Lake sediments; Mineral magnetism; Paleoenvironment; Vegetation dynamics; Earth Sciences; Glacial Lake; Greenland
• Online Access: https://digitalcommons.usf.edu/geo_facpub/1900; https://doi.org/10.1016/j.quaint.2014.11.041

Lake sediments from the Măgheruş Valley in the lowlands of northern Transylvania provide new evidence of paleoenvironmental development in Romania during the Late Glacial. The studied sediments were deposited as a result of the damming of a small river valley following a series of mass wasting events that occurred during the deglaciation period. A continuous sedimentary sequence belonging to the former lake is preserved in the banks of the stream, and contains evidence of paleoenvironmental changes associated with the Late Glacial Interstadial (Bølling–Allerød or Greenland Interstadial 1, GI-1) and the Late Glacial Stadial (Younger Dryas or Greenland Stadial 1, GS-1), implying that the hallmark climatic episodes of northwestern Europe are also expressed in Eastern Europe. We employ a multiproxy approach based on the analysis of sediment composition and texture, mineral magnetism, organic macrofossils, and radiocarbon dating. The reconstructed paleoenvironmental evolution at the site captures the warm and humid conditions associated with GI-1, as well as the subsequent cooling concomitant with the onset of GS-1. These climatic events are paralleled by vegetation shifts in the region, as deduced from comparisons with pollen sequences from Măgheruş and neighboring locations in Transylvania and the Carpathians. The Late Glacial Interstadial was warmer and wetter, as evidenced by increased organic matter content in the lake, decreased erosion in the catchment, development of palustrine plant communities in the proximity of the lake, and expansion of spruce during the Allerød (GI-1c-a). The Late Glacial Stadial was colder and dryer, as indicated by low sedimentary organic matter content, an increase in erosion markers, and the decline of spruce and its replacement by birch. The landscape was more open, as herbs and grasses also expanded during this time. These fluctuations imply that Late Glacial climatic events are well expressed not only in upland areas of Romania, but also in lowland regions such as the ...