1Alex M. Ruzicka, 2,3Jon M. Friedrich, 1Richard C. Hugo, 4Robert J. Macke, 1Daniel Sheikh, 1Melinda Hutson
Meteoritics & Planetary Science, (in Press), 1–36
Open Source Link to Article [DOI: 10.1111/maps.70246]
1Cascadia Meteorite Laboratory, Portland State University, School of Earth, Environment and Society—Earth and Planetary Sciences Academic Area, Portland, Oregon, USA
2Department of Chemistry, Fordham University, Bronx, New York, USA
3Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
4Vatican Observatory, Vatican City State
Published by arrangement with John Wiley & Sons
Eight different H, L, and LL chondrites with 11 lithologies were studied and showgood evidence for progressive shock effects and compaction. In weakly shocked chondrites(Baszkόwka, Bjurb ¨ole, Saratov, NWA 7298 Lithology A and C), silicates were dominantlyfractured, troilite and metal were more deformed than olivine and fluidized, and estimatedstresses were 4–7 GPa. In strongly shocked chondrites (NWA 7298 Lithology B, NWA11315 Lithology A and B, Alfianello, NWA 8709, NWA 4860), olivine grains display moreplastic deformation than in weakly shocked chondrites and were ultimately recrystallized;troilite, some metal, and some bulk areas were melted; and estimated stresses were >7 GPa.Three settings for lithification are inferred: (A) initial lithification during accretion of warmchondrule aggregates, (B) later lithification in warm, metamorphosing parent bodies thatwere being affected by mainly low-velocity collisions, and (C) final lithification in cool parentbodies after the waning of metamorphic heat that were being affected by higher velocitycollisions. Thus, collisions together with heat of different types (accretionary, metamorphic,and shock-related) were probably the main ways in which unmelted planetesimals werelithified. Impact-fluidized metal and troilite may have acted as important lithification bindingagents even in weak shock events.
