Three-dimensional petrography of metal phases in equilibrated L chondrites: Effects of shock loading and dynamic compaction

Journal Article · Mon Oct 20 00:00:00 EDT 2008 · Earth and Planetary Science Letters

DOI:https://doi.org/10.1016/j.epsl.2008.08.024· OSTI ID:1006902

Friedrich, J M; Wignarajah, D P; Chaudhary, S; Rivers, M L; Nehru, C E; Ebel, D S ^[1]

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1. AMNH

To examine the role of impacts in the evolution of asteroids as seen through their chondritic offspring, we have performed a quantitative three dimensional (3D) study of metal grains in a suite of increasingly shocked L chondrites with synchrotron X-ray microtomography (XMT). Our data allow rigorous quantification of size-number distributions and collective morphology of Fe(Ni) metal phases in chondritic meteorites. At the resolution of our XMT measurements (8.4--17.9 {mu}m/voxel), the number of metal particles increase with higher degrees of petrographically identified shock loading, indicating a coalescing of Fe-Ni metal at or below this scale. Our results demonstrate that collective degrees of metal grain preferred orientation increase with greater degrees of impact-related compaction and shock loading. Ductile metal grains in L chondrites begin to show foliation at peak shock pressures < 5 GPa, pressures great enough to compact and indurate loosely bound chondritic material, and our results constitute evidence for multiple generations of impact events acting on the L parent body or bodies.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: USDOE
• OSTI ID: 1006902
• Journal Information: Earth and Planetary Science Letters, Vol. 275, Issue (1-2) ; 10, 2008; ISSN 0012-821X
• Publisher: Elsevier
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ASTEROIDS
CHONDRITES
COMPACTING
DISTRIBUTION
DYNAMIC LOADS
GRAIN ORIENTATION
GRAIN SIZE
IMPACT TESTS
IRON
LOADING
METALS
METEORITES
MORPHOLOGY
NICKEL
PETROGRAPHY
PRESSURE RANGE GIGA PA
RESOLUTION
SHOCK WAVES
THREE-DIMENSIONAL CALCULATIONS
TOMOGRAPHY
X RADIATION