Towards identifying the origin of metamorphic components in Austrian loess: insights from detrital rutile chemistry, thermometry and UePb geochronology Gábor Újvári a, * , Urs Klötzli b , Franz Kiraly b , Theodoros Ntaflos b a Geodetic and Geophysical Institute, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, H-9400 Sopron, Csatkai E. u. 6-8., Hungary b Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria article info Article history: Received 12 March 2013 Received in revised form 4 June 2013 Accepted 9 June 2013 Available online Keywords: Detrital rutile Loess provenance Quaternary Zr-in-rutile thermometry Rutile UePb ages abstract Trace element (Cr, Nb, Zr) geochemistry and UePb geochronology of detrital rutile grains provide con- straints on the nature of potential metamorphic sources of loess in Austria. Cr and Nb compositions reveal rutile sources with a predominance of metapelitic lithologies for all three loess samples. By contrast, Zr-in-rutile geothermometry indicates that formation temperatures for loess rutiles around Krems (at the Bohemian Massif ¼ BM) proved to be ca 100e125  C higher (T median ¼ 717 and 737  C for two samples from Stratzing and Krems) than those at Wels (close to the Eastern Alps ¼ EA; T median ¼ 612  C), implying that rutiles in loess at Wels were derived from Alpine lower amphibolite- grade rocks, while those in loess around Krems from rocks formed under upper amphibolite to granulite-grade conditions. Metamorphic temperatures recorded in rutiles from loess at the BM closely match the ‘two-reaction’ thermobarometry estimates of the last high-T overprint (7e11 kbar and 700 e800  C) of rocks making up the Varied series and Gföhl units around Krems. This event dated at 340 to 350 Ma is believed to be captured by the detrital rutile UePb data as well (e.g. 349  21 and 352  32 Ma). All these data demonstrate the significance of proximal BM sources (Varied series and Gföhl unit drained by the Danube) in loess formation around Krems. Fluvial transport is believed to have played a substantial role in entraining and accumulating rutiles for subsequent aeolian deflation for loess near Wels. While the ultimate sources of these grains are likely to be in the Eastern Alps, the recycling of these rutiles from the flysch zone of the EA cannot be ruled out. Despite the uncertainties of CreNb-based source discriminations in some cases and the potential decoupling of Zr- and UePb systematics recognized in rutiles, this study demonstrates that rutiles may provide unique details on the nature and metamorphic history of their parent rocks, if used with caution and by knowing its limitations under certain conditions. It is anticipated that, beyond zircon, rutile geochemistry will become a powerful provenance tracer in loess studies too. This seems to be particularly important to gain a better understanding on the erosion and rutile fertility of different metamorphic ter- rains and their contributions to loess material, issues that have not been adequately addressed thus far. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Any insights into aeolian transport of dust provided by prove- nance analyses of Quaternary loess deposits allow to further constrain regional scale atmospheric circulation patterns recon- structed from model simulations (e.g. Mahowald et al., 2006; Aleinikoff et al., 2008; Stevens et al., 2010; Újvári et al., 2010, 2012). Thus, linking sources and sediments by gaining insight into the origin of particles making up loess deposits is of crucial importance in understanding paleo-transport processes and Qua- ternary paleogeography. In general, most loess provenance studies are based on the mineralogical and geochemical (major and trace element) analyses of bulk sediments (Gallet et al., 1998; Sun et al., 2007; Buggle et al., 2008; Muhs et al., 2008; Újvári et al., 2008) or grain size separates (Qingyu et al., 2008; Hao et al., 2010; Ferrat et al., 2011; Kim et al., 2011), and SreNd isotopes (Gallet et al., 1998; Sun, 2002; Smith et al., 2003; Honda et al., 2004; Yokoo et al., 2004; Chen et al., 2007). At the same time, the use of single grain techniques, such as zircon UePb geochronology has just started in the recent past (Aleinikoff et al., 1999, 2008; Stevens * Corresponding author. E-mail addresses: ujvari@ggki.hu, ujvari.gabor@csfk.mta.hu (G. Újvári). Contents lists available at SciVerse ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev 0277-3791/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.quascirev.2013.06.002 Quaternary Science Reviews 75 (2013) 132e142