¹R. J. Macke,¹C. P. Opeil,¹D. T. Britt,¹G. J. Consolmagno,¹A. Irving
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14171]
¹Vatican Observatory, Vatican City-State, Vatican
²Department of Physics, Boston College, Chestnut Hill, Massachusetts, USA
³Department of Physics, University of Central Florida, Orlando, Florida, USA
⁴Center for Lunar and Asteroid Surface Science, Orlando, Florida, USA
⁵University of Washington Earth & Space Sciences, Seattle, Washington, USA
Published by arrangement with John Wiley & Sons

Lunar meteorites are the most diverse and readily available specimens for the direct laboratory study of lunar surface materials. In addition to informing us about the composition and heterogeneity of lunar material, measurements of their thermo-physical properties provide data necessary to inform the models of the thermal evolution of the lunar surface and provide data on fundamental physical properties of the surface material for the design of exploration and resource extraction hardware. Low-temperature data are particularly important for the exploration of low-temperature environments of the lunar poles and permanently shadowed regions. We report low-temperature-specific heat capacity, thermal conductivity, and linear thermal expansion for six lunar meteorites: Northwest Africa [NWA] 5000, NWA 6950, NWA 8687, NWA 10678, NWA 11421, and NWA 11474, over the range 5 ≤ T ≤ 300 K. From these, we calculate thermal inertia and thermal diffusivity as functions of temperature. Additionally, heat capacities were measured for 15 other lunar meteorites, from which we calculate their Debye temperature and effective molar mass.

^1,2,3,4L.F. White,⁵D.E. Moser,³J.R. Darling,⁴B.G. Rider-Stokes,^1,2,5B. Hyde,^1,2K.T. Tait,⁶K. Chamberlain,^7,8A.K. Schmitt,³J. Dunlop,⁴M.Anand
Earth and Planetary Science Letters 636, 118694 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2024.118694]
¹Department of Natural History, Royal Ontario Museum, Toronto, Ontario, M5S 2C6, Canada
²Department of Earth Sciences, University of Toronto, Toronto, Ontario, M5S 3B1, Canada
³School of Earth and Environmental Science, University of Portsmouth, Portsmouth, PO1 3QL, UK
⁴School of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK
⁵Western University, London, Ontario, Canada N6A 3KL
⁶Department of Geology and Geophysics, University of Wyoming, 1000 E. University Ave, Laramie, Wyoming 82071-3006, USA
⁷Institute of Earth Sciences, Ruprecht-Karls-Universitat Heidelberg, Im Neuenheimer Feld 236, D-69120 Heidelberg, Germany
⁸John de Laeter Centre, Curtin University, Bentley. WA 6102, Australia
Copyright Elsevier

A long-standing paradigm in planetary science is that the inner Solar System experienced a period of intense and sustained bombardment between 4.2 and 3.9 Ga. Evidence of this period, termed the Late Heavy Bombardment is provided by the 40Ar/39Ar isotope systematics of returned Apollo samples, lunar meteorites, and asteroidal meteorites. However, it has been largely unsupported by more recent and robust isotopic age data, such as isotopic age data obtained using the U-Pb system. Here we conduct careful microstructural characterisation of baddeleyite, zircon, and apatite in six different eucrites prior to conducting SIMS and LA-ICP-MS measurement of U, Th, and Pb isotopic ratios and radiometric dating. Baddeleyite, displaying complex internal twinning linked to reversion from a high symmetry polymorph in two samples, records the formation of the parent body (4554 ± 3 Ma 2σ; n = 8), while structurally simple zircon records a tight spread of ages representing metamorphism between 4574 ± 14 Ma and 4487 ± 31 Ma (n = 6). Apatite, a more readily reset shock chronometer, records crystallisation ages of ∼4509 Ma (n = 6), with structurally deformed grains (attributed to impact events) yielding U-Pb ages of 4228 Ma (n = 12). In concert, there is no evidence within the measured U-Pb systematics or microstructural record of the eucrites examined in this study to support a period of late heavy bombardment between 4.2 and 3.9 Ga.