The morphology and concentrations of trace elements and rare earth elements REE of zircon from a transitional layer of bentonite ash at the Paleocene#x2013;Eocene boundary at a locality north of Salzburg in the Eastern Alps suggest a magmatic genesis of the zircon, and data on the REE distribution in the mineral testify to an oceanic nature of the magmas. A more reliable criterion of the nature of the magmatic source is data on the Li concentrations; the latter in some of the zircon grains are much lower than the minimum values typical of the continental crust. It is hypothesized that a zircon type exists that is related to plume magmatism.
Zircon, Paleocene and Eocene bentonite, geochemistry, Eastern Alps
1. Bottazzi, An accurate procedure for the quantification of rare earth elements in silicates, SIMS IX Proceedings eds. A. Benninghoven, Y. Nihei, R. Shimizu and H. W. Werner, 1994.
2. Carley, Studies of the evolution of felsic magma systems: I. Zircon in historic eruptions, Iceland; II.~Modeling magma chamber evolution leading to the peach spring tuff supereruption, Arizona, Nevada and California, 2010.
3. Christidis, Geological aspects and genesis of bentonites, Elements, 2009., doi:https://doi.org/10.2113/gselements.5.2.93
4. Clayton, The implications of reworking on the mineralogy and chemistry of Lower Carboniferous K-bentonites, Clay Minerals, 1996., doi:https://doi.org/10.1180/claymin.1996.031.3.08
5. Compston, Zircon U--Pb ages for the Early Cambrian time-scale, J. Geol. Soc. London, 1992., doi:https://doi.org/10.1144/gsjgs.149.2.0171
6. Egger, Gigantic volcanic eruptions and climatic change in the early Eocene, Int. J. Earth Sci. Geol. Rundsch, 2006., doi:https://doi.org/10.1007/s00531-006-0085-7
7. Egger, Early Eocene climatic, volcanic, and biotic events in the northwestern Tethyan Untersberg section, Austria, Palaeogeography, Palaeoclimatology, Palaeoecology, 2005., doi:https://doi.org/10.1016/j.palaeo.2004.12.006
8. Fedotova, Ion-microprobe zircon geochemistry as an indicator of mineral genesis during geochronological studies, Geochemistry International, 2008., doi:https://doi.org/10.1134/S001670290809005X
9. Fu, Ti-in-zircon thermometry: applications and limitations, Contrib. Mineral. Petrol., 2008., doi:https://doi.org/10.1007/s00410-008-0281-5
10. Grimes, The trace element chemistry of zircons from oceanic crust: a method for distinguishing detrital zircon provenance, Geology, 2007., doi:https://doi.org/10.1130/G23603A.1
11. Grimes, On the occurrence, trace element geochemistry, and crystallization history of zircon from in situ ocean lithosphere, Contrib. Mineral. Petrol., 2009., doi:https://doi.org/10.1007/s00410-009-0409-2
12. Hinton, The chemistry of zircon: variations within and between large crystals from syenite and alkali basalt xenoliths, Geochim. Cosmochim. Acta, 1991., doi:https://doi.org/10.1016/0016-70379190489-R
13. Hoskin, Trace-element composition of hydrothermal zircon and the alteration of Hadean zircon from the Jack Hills, Australia, Geochim. Cosmochim. Acta, 2005., doi:https://doi.org/10.1016/j.gca.2004.07.006
14. Hoskin, The composition of zircon and igneous and metamorphic petrogenesis, Rev. Mineral. Geochem., v. 53, 2003.
15. Huber, Geochemical study of lower Eocene volcanic ash layers from the Alpine Anthering Formation, Austria, Geochemical Journal, 2003., doi:https://doi.org/10.2343/geochemj.37.123
16. Jochum, The preparation and preliminary characterisation of eight geological MPI-DING reference glasses for in-situ microanalysis, Geost. Newslett., 2000., doi:https://doi.org/10.1111/j.1751-908X.2000.tb00590.x
17. Kennett, Abrupt deep-sea warming, paleoceanographic changes, and benthic extinctions and the end of the Paleocene, Nature, 1991., doi:https://doi.org/10.1038/353225a0
18. Larsen, Paleogene volcanic ash layers in the Danish Basin: compositions and source areas in the North Atlantic Igneous Province, Lithos, 2003., doi:https://doi.org/10.1016/j.lithos.2003.07.001
19. Li, Geochronology and geochemistry of single-grain zircons: Simultaneous in-situ analysis of U-Pb age and trace elements by LAM-ICP-MS, Eur. J. Mineral., v. 12, 2000.
20. McDounough, The composition of the Earth, Chem. Geol., 1995., doi:https://doi.org/10.1016/0009-25419400140-4
21. Nosova, Minor elements in clinopyroxene from Paleozoic volcanics of the Tagil Island Arc in the Central Urals, Geokhimiya, v. 40, 2002.
22. Schmitt, Rapid cooling rates at an active mid-ocean ridge from zircon thermochronology, Earth and Planet. Sci. Lett., 2011., doi:https://doi.org/10.1016/j.epsl.2010.12.022
23. Seifert, Typology, chemistry and origin of zircon from alkali basalts of SE Saxony Germany, Neues Jahrbuch fur Mineralogie Abhandlungen, 2008., doi:https://doi.org/10.1127/0077-7757/2008/0102
24. Smirnov, Quantitative SIMS analysis of melt inclusions and host minerals for trace elements and H$_2$O, EOS Trans. Spring Meet. Suppl., AGU, v. 17, 1995.
25. Spicuzza, Li concentration and isotope ratio in lunar zircons: Li-enriched and depleted magmas on the Moon, 43rd Lunar and Planetary Science Conference, 2012.
26. Thurow, Bentonites as tracers of earliest Cretaceous post-breakup volcanism off northwestern Australia, Gradstein F. M., Ludden, J. N., et al., Proceedings of the Ocean Drilling Program, Scientific Results, 123, 1992.
27. Ushikubo, Lithium in Jack Hills zircons: Evidence for extensiveweathering of Earth's earliest crust, Earth Planet. Sci. Lett., 2008., doi:https://doi.org/10.1016/j.epsl.2008.05.032
28. Vasquez, Trace elements and oxygen isotope composition of Hawaiian hotspot zircon, Am. Geoph. Un., Fall Meeting, V41B-2275, 2010.
29. Watson, Crystallization thermometers for zircon and rutile, Contribs Miner. Petrol., 2006., doi:https://doi.org/10.1007/s00410-006-0068-5
30. Zachos, Rapid acidification of the ocean during the Paleocene--Eocene thermal maximum, Science, 2005., doi:https://doi.org/10.1126/science.1109004
31. Zinger, Influence of Plastic Deformations in Zircon on its Chemical Composition: Evidence From Gabbroids of the Spreading Zone of the Mid-Atlantic Ridge, Markov Trough, 6\hbox $^\circ $N, Doklady Akademii Nauk, Earth Sciences, v. 433, 2010.
