@article{584c28d8e5284e0eb682a596db7e45a7,
title = "Baddeleyite as a widespread and sensitive indicator of meteorite bombardment in planetary crusts",
abstract = "Constraining the timing and intensity of Solar System bombardment is critical to understanding planetary formation, evolution and habitability. However, the identification and dating of shock-metamorphic events in the mafic igneous lithologies that dominate planetary materials remains highly challenging, particularly at relatively modest shock pressures. The accessory mineral baddeleyite (monoclinic-ZrO2) is abundant in these mafic crustal rocks, though the microstructural response of this mineral to shock-loading is currently unconstrained. Here we show that baddeleyite yields a predictable sequence of microstructures in the shock pressure range of 5 to ~20 GPa, based on analysis of mafic rocks collected along a well-constrained shock-pressure gradient in the crystalline bedrock of the Sudbury impact structure, Canada. High-resolution electron backscatter diffraction mapping of baddeleyite grains exposed to < 20 GPa of shock loading reveals a range of microstructures including complex orthogonally-related crystalline subgrains, amorphous domains and crystal plasic deformation. Evidence that the observed microstructures are controlled by the transition to and subsequent reversion from the high-pressure (experimentally constrained to > 5 GPa) orthorhombic-ZrO2 polymorph is provided by phase-heritage reconstruction using relationships between reverted monoclinic orientations. Our results demonstrate that baddeleyite is a sensitive shock indicator and barometer over low pressure ranges largely inaccessible with other minerals, augmenting ongoing studies with other mafic minerals into the intensity of inner Solar System bombardmen",
keywords = "Planetary geology, mineralogy, meteorite, geochemistry, zirconia, materials",
author = "White, {Lee Francis} and James Darling and Moser, {D. E.} and C. Cayron and Barker, {Ivan R.} and Joseph Dunlop and Tait, {Kim T.}",
year = "2018",
month = aug,
day = "1",
doi = "10.1130/G45008.1",
language = "English",
volume = "46",
pages = "719--722",
journal = "Geology",
issn = "0091-7613",
publisher = "Geological Society of America",
number = "8",
}