C. T. Pillinger¹, J. M. Pillinger¹, D. Johnson¹, R. C. Greenwood¹, A. G. Tindle², A. J. T. Jull³, D. H. Allen⁴ and B. Cunliffe⁵

¹Planetary and Space Sciences, The Open University, Milton Keynes, UK
²CEPSAR, The Open University, Milton Keynes, UK
³NSF Arizona AMS Laboratory and Department of Geosciences, The University of Arizona, Tucson, Arizona, USA
⁴Arts and Museums Service, Hampshire County Council, Winchester, UK
⁵Institute of Archaeology, University of Oxford, Oxford, UK

What remains of a 30 g sample, first recognized as a meteorite in 1989 during characterization of metalworking debris from Danebury, an Iron Age hillfort, in Hampshire, England, has been classified as an H5 ordinary chondrite. Its arrival on Earth has been dated as 2350 ± 120 yr BP, making it contemporary with the period of maximum human activity at the recovery site. Despite its considerable terrestrial residence age, the interior of the specimen is remarkably fresh with a weathering index of W1/2. There is, however, no evidence of human intervention in its preservation. Its near-pristine state is explained in terms of its serendipitous burial during the back-fill of a pit dug into chalk by prehistoric people for the storage of grain. This chance discovery has interesting ramifications for the survival of meteorites in areas having a high pH because of a natural lime content arising as a result of the local geology.

Reference
Pillinger CT, Pillinger JM, Johnson D, Greenwood RC, Tindle AG, Jull AJT, Allen DH and Cunliffe B (in press) The Danebury Iron Age meteorite—An H5 ordinary chondrite “find” from Hampshire, England. Meteoritics & Planetary Science
[doi:10.1111/maps.12301]
Published by arrangement with John Wiley & Sons

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Shoko Oshigami¹, Shiho Watanabe², Yasushi Yamaguchi², Atsushi Yamaji³, Takao Kobayashi⁴, Atsushi Kumamoto⁵, Ken Ishiyama⁵ and Takayuki Ono⁵

¹National Astronomical Observatory of Japan, Oshu, Japan
²Graduate School of Environmental Studies, Nagoya University, Chikusa-ku, Japan
³Graduate School of Science, Kyoto University, Kyoto, Japan
⁴Geological Research Division, Korean Institute of Geoscience and Mineral Resources, Daejeon, South Korea
⁵Graduate School of Science, Tohoku University, Sendai, Japan

The Lunar Radar Sounder (LRS) onboard Kaguya (SELENE) detected widespread horizontal reflectors under some nearside maria. Previous studies estimated that the depths of the subsurface reflectors were up to several hundreds of meters and suggested that the reflectors were interfaces between mare basalt units. The comparison between the reflectors detected in the LRS data and surface age maps indicating the formation age of each basalt unit allows us to discuss the lower limit volume of each basalt unit and its space and time variation. We estimated volumes of basalt units in the ages of 2.7 Ga to 3.8 Ga in the nearside maria including Mare Crisium, Mare Humorum, Mare Imbrium, Mare Nectaris, Mare Serenitatis, Mare Smythii, and Oceanus Procellarum. The lower limit volumes of the geologic units estimated in this study were on the order of 10³ to 10⁴ km³. This volume range is consistent with the total amount of erupted lava flows derived from numerical simulations of thermal erosion models of lunar sinuous rille formation and is also comparable to the average flow volumes of continental flood basalt units formed after the Paleozoic and calculated flow volumes of Archean komatiite flows on the Earth. The lower limits of average eruption rates estimated from the unit volumes were on the order of 10⁻⁵ to 10⁻³ km³/yr. The estimated volumes of the geologic mare units and average eruption rate showed clear positive correlations with their ages within the same mare basin, while they vary among different maria compared within the same age range.

Reference
Oshigami S, Watanabe S, Yamaguchi Y, Yamaji A, Kobayashi T, Kumamoto A, Ishiyama K, and Ono T (in press) Mare volcanism: Reinterpretation based on Kaguya Lunar Radar Sounder data. Journal of Geophysical Research: Planets
[doi:10.1002/2013JE004568]
Published by arrangement with John Wiley & Sons

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Alan P. Boss and Sandra A. Keiser

Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road, NW, Washington, DC 20015-1305, USA

A key test of the supernova triggering and injection hypothesis for the origin of the solar system’s short-lived radioisotopes is to reproduce the inferred initial abundances of these isotopes. We present here the most detailed models to date of the shock wave triggering and injection process, where shock waves with varied properties strike fully three-dimensional, rotating, dense cloud cores. The models are calculated with the FLASH adaptive mesh hydrodynamics code. Three different outcomes can result: triggered collapse leading to fragmentation into a multiple protostar system; triggered collapse leading to a single protostar embedded in a protostellar disk; or failure to undergo dynamic collapse. Shock wave material is injected into the collapsing clouds through Rayleigh–Taylor fingers, resulting in initially inhomogeneous distributions in the protostars and protostellar disks. Cloud rotation about an axis aligned with the shock propagation direction does not increase the injection efficiency appreciably, as the shock parameters were chosen to be optimal for injection even in the absence of rotation. For a shock wave from a core-collapse supernova, the dilution factors for supernova material are in the range of ~10⁻⁴ to ~3 × 10⁻⁴, in agreement with recent laboratory estimates of the required amount of dilution for ⁶⁰Fe and ²⁶Al. We conclude that a type II supernova remains as a promising candidate for synthesizing the solar system’s short-lived radioisotopes shortly before their injection into the presolar cloud core by the supernova’s remnant shock wave.

Reference
Boss AP and Keiser SA (2014) Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-lived Radioisotopes with a Shock Wave. III. Rotating Three-dimensional Cloud Cores. The Astrophysical Journal 788:20.
[doi:10.1088/0004-637X/788/1/20]

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