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The sedimentary history of the inner‐alpine Inn Valley, Austria: extending the Baumkirchen type section further back in time with new drilling
Author(s) -
Barrett Samuel,
Starnberger Reinhard,
Tjallingii Rik,
Brauer Achim,
Spötl Christoph
Publication year - 2017
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.2924
Subject(s) - geology , marine isotope stage , sedimentary rock , glacial period , silt , debris , paleontology , period (music) , drilling , quaternary , stratigraphy , sediment , hiatus , stage (stratigraphy) , geomorphology , interglacial , oceanography , mechanical engineering , engineering , physics , acoustics , tectonics
The Baumkirchen clay pit near Innsbruck, western Austria, is a well‐known site in Alpine Quaternary stratigraphy. Lacustrine sediments from the last glacial cycle from within the Alps provide a unique opportunity to investigate the regional palaeoclimate. Recent drilling has extended the known sequence to a total length of at least 250 m consisting of almost entirely well‐laminated clayey silt. Luminescence dating identified two lake sequences, separated by a hiatus of ca. 7000–15 000 years. Lake phase 1 spans the period ca. 77–55 ka, i.e. from about Marine Isotope Stage (MIS) 5/4 to the MIS 4/3 transition. Lake phase 2 extends from mid‐ to late MIS 3 between ca. 45 and 33 ka. Down‐core X‐ray fluorescence core scanning confirmed the presence of the lake phases in the sediment composition, suggesting different sediment sources and/or transport mechanisms during these two intervals. A unique section of exotic, angular, silt matrix‐supported gravel at the top of lake phase 1 is interpreted as ice‐rafted debris. Luminescence dating constrains this layer to ca. 55 ka, thus providing the first evidence of a late MIS 4 or early MIS 3 ice advance confined to the interior of the Eastern Alps. A conceptual model of the sedimentary history of the valley is presented.