Detrital garnet Lu-Hf and U-Pb geochronometry coupled with compositional analysis: Possibilities and limitations as a sediment provenance indicator
- 1Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden (chris.mark@nrm.se)
- 2Institute of Applied Geosciences, Technische Universität Darmstadt, Darmstadt, Germany
- 3Department of Earth and Environmental Sciences, Università di Milano-Bicocca, Milan, Italy
- 4School of Earth Sciences, University College Dublin, Dublin, Ireland
- 5Department of Earth Sciences, The University of Adelaide, Adelaide, Australia
Detrital geochronology is a powerful tool to interrogate the sedimentary archive of (paleo-)hinterland tectonic, metamorphic, and climatic processes, and can also be applied to modern river sediment as a first-pass tool to establish regional bedrock ages. The popular zircon U-Pb detrital geochronometer has seen widespread adoption for these tasks (3,626/4,471 results for the search term detrital geochronology also contain the term zircon U-Pb; Clarivate Analytics Web of Science). However, zircon fertility is strongly biased to intermediate to felsic source rocks. Moreover, zircon crystallization is volumetrically limited in metamorphic terranes which do not achieve anataxis (e.g., Moecher & Samson, 2006), and is typically restricted to rim overgrowths which are vulnerable to mechanical destruction during fluvial transport, and which are challenging to detect and analyse (e.g., Campbell et al., 2005).
Therefore, it is desirable to develop complementary provenance tools for metamorphic settings. Garnet group minerals are rock-forming in several common metamorphic lithologies, and garnet is therefore a common constituent of clastic detritus from orogens. Moreover, single-grain in-situ dating of garnet by LA-ICPMS is possible using the U-Pb (e.g., Seman et al., 2017) and, by use of an online reaction cell, the Lu-Hf radioisotope systems (Simpson et al., 2021).
Here, we present results from U-Pb and Lu-Hf double-dating, acquired by LA-ICPMS for detrital garnet recovered from the Oligo-Miocene pro-foreland basin of the European Alps, as well as modern Alpine river sediment. We integrate these data with compositional data acquired by Raman spectroscopy, and energy and wavelength-dispersive X-ray spectroscopy (Stutenbecker et al., 2019). We discuss the implications for Alpine tectonics and metamorphism, and future scope of detrital garnet geochronometry.
Campbell, I., et al., 2005. Earth Planet. Sci. Lett. 237, 402-432, doi: 10.1016/j.epsl.2005.06.043
Moecher, D., & Samson, S., 2006, Earth Planet. Sci. Lett. 247, 252–266, doi: 10.1016/j.epsl.2006.04.035
Seman, S., et al., 2017. Chem. Geol. 460, 106–116. doi: 10.1016/j.chemgeo.2017.04.020
Simpson, A., et al., 2021. Chem. Geol. 577, 120299. doi: 10.1016/j.chemgeo.2021.120299
Stutenbecker, L., et al., 2019, Solid Earth 10, 1581–1595, doi: 10.5194/se-10-1581-2019
How to cite: Mark, C., Stutenbecker, L., Andò, S., Barbarano, M., O'Sullivan, G., Glorie, S., Simpson, A., and Daly, J. S.: Detrital garnet Lu-Hf and U-Pb geochronometry coupled with compositional analysis: Possibilities and limitations as a sediment provenance indicator, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6405, https://doi.org/10.5194/egusphere-egu22-6405, 2022.
