Warm period growth of travertine during the last interglaciation in southern Germany

Late-Quaternary travertine at two sites near Stuttgart formed entirely during interglacial periods. The travertine contains structures from growth induced by bacteria, and such structures have been dated by Th-230/U mass spectrometry, The resulting ages from both sites imply growth episodes of short duration, with growth rates up to 5 mm yr(-1), at 99,800 +/- 1300 pr B,P. (2 sigma; n = 8) and 105,900 +/- 1300 yr B.P. (2 sigma; n = 7). These episodes were likely part of marine isotope stage (MIS) 5.3. Deposition of silt interrupted travertine growth at one of the sites similar to 105,000 yr B.P. Likely correlatives of this silt are the St. Germain I-B stade recorded in the Grand Pile peat bog and a cold episode similar to 1000 pr long recorded by delta(18)O values in the GRIP ice core, Travertine also formed during stage 5.5 (similar to 115,000 yr) and during the early Holocene, We found no evidence for travertine accumulation in stages 2, 3, 4, and 5.1. At both sites, the Sr/U ratio and the initial U-234/U-238 activity ratio resemble those of modern spring water. However, the sites differ in the chemical composition of spring water and in stratigraphic sequence of travertine accumulation. (C) 2000 University of Washington.