title: Pressure-temperature evolution of primordial solar system solids during impact-induced compaction.
abstract: Prior to becoming chondritic meteorites, primordial solids were a poorly consolidated mix of mm-scale igneous inclusions (chondrules) and high-porosity sub-μm dust (matrix). We used high-resolution numerical simulations to track the effect of impact-induced compaction on these materials. Here we show that impact velocities as low as 1.5 km s(-1) were capable of heating the matrix to >1,000 K, with pressure-temperature varying by >10 GPa and >1,000 K over ~100 μm. Chondrules were unaffected, acting as heat-sinks: matrix temperature excursions were brief. As impact-induced compaction was a primary and ubiquitous process, our new understanding of its effects requires that key aspects of the chondrite record be re-evaluated: palaeomagnetism, petrography and variability in shock level across meteorite groups. Our data suggest a lithification mechanism for meteorites, and provide a 'speed limit' constraint on major compressive impacts that is inconsistent with recent models of solar system orbital architecture that require an early, rapid phase of main-belt collisional evolution.
authors.affiliation: Department of Applied Geology, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: P A
authors.initials: PA
authors.lastname: Bland
authors.affiliation: Impacts &Astromaterials Research Centre (IARC), Department of Earth Science &Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: G S
authors.initials: GS
authors.lastname: Collins
authors.affiliation: Impacts &Astromaterials Research Centre (IARC), Department of Earth Science &Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: T M
authors.initials: TM
authors.lastname: Davison
authors.affiliation: Earth Science Program, Pennsylvania State University-Du Bois Campus, Du Bois, Pennsylvania 15801, USA.
authors.forename: N M
authors.initials: NM
authors.lastname: Abreu
authors.affiliation: Department of Geophysical Science, University of Chicago, 5734 South Ellis Avenue, Chicago, Illinois 60430, USA.
authors.forename: F J
authors.initials: FJ
authors.lastname: Ciesla
authors.affiliation: Impacts &Astromaterials Research Centre (IARC), Department of Earth Science &Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: A R
authors.initials: AR
authors.lastname: Muxworthy
authors.affiliation: Impacts &Astromaterials Research Centre (IARC), Department of Earth Science &Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: J
authors.initials: J
authors.lastname: Moore