^1,2Timothy T. BARROWS,³John MAGEE,⁴Gifford MILLER,⁵L. Keith FIFIELD
Meteoritics & Planetary Society (in Press) Link to Article [doi: 10.1111/maps.13378]
¹School of Earth and Environmental Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia
²Department of Geography, University of Portsmouth, Portsmouth PO1 2UP, UK
³Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia
⁴INSTAAR and Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309, USA
⁵Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra,Australian Capital Territory 2601, Australia
Published by arrangement with John Wiley & Sons

Wolfe Creek crater lies in northwestern Australia at the edge of the Great SandyDesert. Together with Meteor Crater, it is one of the two largest craters on Earth fromwhich meteorite fragments have been recovered. The age of the impact is poorly constrainedand unpublished data places the event at about 300,000 years ago. In comparison, MeteorCrater is well constrained by exposure dating. In this paper, we present new ages for WolfeCreek Crater from exposure dating using the cosmogenic nuclides10Be and26Al, togetherwith optically stimulated luminescence ages (OSL) on sand from a site created by theimpact. We also present a new topographic survey of the crater using photogrammetry. Theexposure ages range from~86 to 128 ka. The OSL ages indicate that the age of the impactis most likely to be~120 ka with a maximum age of 137 ka. Considering the geomorphicsetting, the most likely age of the crater is 1209 ka. Last, we review the age of MeteorCrater in Arizona. Changes in production rates and scaling factors since the original datingwork revise the impact age to 61.14.8 ka, or~20% older than previously reported.

¹Haruka ONO,^2,3Atsushi TAKENOUCHI,⁴Takashi MIKOUCHI,³Akira YAMAGUCHI
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13384]
¹Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
²Department of Basic Science, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
³National Institute of Polar Research (NIPR), 10-3 Midori-cho, Tachikawa, Tokyo 190-8518, Japan
⁴The University Museum, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Published by arrangement with John Wiley & Sons

Some eucrites contain up to 10 vol% silica minerals; however, silica minerals havenot been studied in detail so far. We performed a mineralogical study of silica minerals inthree cumulate eucrites (Moore County, Moama, and Yamato [Y] 980433). Monoclinictridymite was common in all three samples. Moama contained orthorhombic tridymite aslamellae within monoclinic tridymite grains. Y 980433 included quartz around an impactmelt vein. The presence of orthorhombic tridymite in Moama indicates that Moama cooledmore rapidly than the other two samples at low temperatures (<400°C). This result isdifferent from the slower cooling rates of Moama (≳0.0004°Cyr1) than that of MooreCounty (>0.3°Cyr1, after the shock event) at high temperatures (>500°C) estimated fromcompositional profiles of pyroxene exsolution lamellae. The difference of the cooling ratesmay reflect their geological settings. Y 980433 cooled slowly at low temperature, as didMoore County. Quartz in Y 980433 could be a local product transformed from monoclinictridymite by a shock event. We suggest that silica minerals in meteorites record thermalhistories at low temperatures and shock events.