@article{c1af44c24b9c400aa286706169555648,
title = "Timing of geological events in the lunar highlands recorded in shocked zircon-bearing clasts from Apollo 16: Shocked zircon from Apollo 16",
abstract = " Apollo 16 soil-like regolith breccia 65745,7 contains two zircon-bearing clasts. One of these clasts is a thermally annealed silica-rich rock, which mineralogically has affinities with the High Alkali Suite (Clast 1), and yields zircon dates ranging from 4.08 to 3.38 Ga. The other clast is a KREEP-rich impact melt breccia (Clast 2) and yields zircon dates ranging from 3.97 to 3.91 Ga. The crystalline cores of both grains, which yield dates of ca 3.9 Ga, have undergone shock pressure modification at less than 20 GPa. We interpret that the U-Pb chronometer in these zircon grains has been partially reset by the Imbrium basin-forming event when the clasts were incorporated into the Cayley Plains ejecta blanket deposit. The zircon grains in Clast 1 have been partially decomposed, resulting in a breakdown polymineralic texture, with elevated U, Pb and Th abundances compared with those in the crystalline zircon. These decomposed areas exhibit younger dates around 3.4 Ga, suggesting a secondary high-pressure, high-temperature event, probably caused by an impact in the local Apollo 16 highlands area. ",
keywords = "Apollo 16, Pb-Pb age dating, lunar samples, regolith breccias, shock-zircon, zircon",
author = "Joy, {K. H.} and Snape, {J. F.} and Nemchin, {A. A.} and R. Tart{\`e}se and Martin, {D. M.} and Whitehouse, {M. J.} and V. Vishnyakov and Pernet-Fisher, {J. F.} and Kring, {D. A.}",
note = "Funding Information: Data accessibility. Data have been uploaded as part of the electronic supplementary material. Authors{\textquoteright} contributions. K.H.J. conceived the study and wrote the manuscript. J.F.S., A.A.N. and M.J.W. undertook the SIMS analysis. D.M.M. and J.F.P.-F. assisted with the FTIR data collection and interpretation. R.T. assisted with NanoSIMS data collection. V.V. assisted with the CL data acquisition. D.A.K. supported the regolith breccia research. All authors have read and have contributed to the final manuscript. Competing interests. We declare we have no competing interests. Funding. This research was facilitated by STFC (PhD studentship to Dayl Martin, and grant nos. ST/M001253/1, ST/ P005225/1 and ST/L002957/1) and the Royal Society (grant no. RS/UF140190) funding. K.H.J. acknowledges NASA Lunar Science Institute contract NNA09DB33A to D.A.K., which supported the JSC EMP analyses and thin section mapping. This is LPI Contribution number 2366. A.A.N. and M.J.W. were co-PI{\textquoteright}s on the Knut and Alice Wallenberg Foundation grant no. 2012.0097 and Swedish Research Council grant no. 2012–04370, and the NordSIMS laboratory was funded under Swedish Research Council grant no. 2014–06375; this is NordSIMS contribution number 640. J.F.S. acknowledges funding from the European Commission Horizon 2020 Research and Innovation programme (Marie Sk{\l}odowska-Curie Actions Fellowship grant no. 794287). At The University of Manchester, the NanoSIMS was funded by UK Research Partnership Investment Funding (UKRPIF) Manchester RPIF Round 2. Acknowledgements. K.H.J. would like to thank the LPI library staff for digitizing the Warner et al. Apollo 16 technical report, and George Rossman at the Caltech Mineral Spectroscopy Server and Ming Zhang for their help locating zircon FTIR data. Also thanks to NASA JSC ARES staff for Roger Harrington for help with the thin section. We also thank Dr Marc Norman and two anonymous reviewers for their helpful comments on the manuscript. Publisher Copyright: {\textcopyright} 2020 The Authors.",
year = "2020",
month = jun,
day = "3",
doi = "10.1098/rsos.200236rsos200236",
language = "English",
volume = "7",
pages = "200236",
journal = "Royal Society Open Science",
issn = "2054-5703",
publisher = "The Royal Society Publishing",
number = "6",
}