DOI: 10.1016/j.quascirev.2013.06.002
Scopus记录号: 2-s2.0-84880151261
论文题名: Towards identifying the origin of metamorphic components in Austrian loess: Insights from detrital rutile chemistry, thermometry and U-Pb geochronology
作者: Újvári G. ; Klötzli U. ; Kiraly F. ; Ntaflos T.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2013
卷: 75 起始页码: 132
结束页码: 142
语种: 英语
英文关键词: Detrital rutile
; Loess provenance
; Quaternary
; Rutile U-Pb ages
; Zr-in-rutile thermometry
Scopus关键词: Detrital rutile
; Loess provenances
; Quaternary
; U-Pb ages
; Zr-in-rutile thermometry
; Geochemistry
; Lead
; Metamorphic rocks
; Rocks
; Sediments
; Silicate minerals
; Thermometers
; Uranium
; Zirconium
; Oxide minerals
; amphibolite
; detrital deposit
; flysch
; geochronology
; geothermometry
; loess
; metapelite
; Quaternary
; rutile
; uranium-lead dating
; zircon
; Alps
; Austria
; Bohemian Massif
; Eastern Alps
英文摘要: Trace element (Cr, Nb, Zr) geochemistry and U-Pb geochronology of detrital rutile grains provide constraints 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=BM) proved to be ca 100-125°C higher (Tmedian=717 and 737°C for two samples from Stratzing and Krems) than those at Wels (close to the Eastern Alps=EA; Tmedian=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 (7-11kbar and 700-800°C) of rocks making up the Varied series and Gföhl units around Krems. This event dated at 340 to 350Ma is believed to be captured by the detrital rutile U-Pb 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 Cr-Nb-based source discriminations in some cases and the potential decoupling of Zr- and U-Pb 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 terrains and their contributions to loess material, issues that have not been adequately addressed thus far. © 2013 Elsevier Ltd. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/60557
Appears in Collections: 过去全球变化的重建
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作者单位: Geodetic and Geophysical Institute, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Csatkai E. u. 6-8, H-9400 Sopron, Hungary; Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
Recommended Citation:
Újvári G.,Klötzli U.,Kiraly F.,et al. Towards identifying the origin of metamorphic components in Austrian loess: Insights from detrital rutile chemistry, thermometry and U-Pb geochronology[J]. Quaternary Science Reviews,2013-01-01,75