Evidence for early fragmentation-reassembly of ordinary chondrite (H, L, and LL) parent bodies from REE-in-two-pyroxene thermometry

Thermochemical evolution of the acapulcoite–lodranite parent body: Evidence for fragmentation‐disrupted partial differentiation

“…In all samples, light through heavy REEs + Y in cpx are above detection limits and replicate analyses show good reproducibility (Table 3). The lack of data above detection limits for light REEs in opx does not preclude the application of the REE‐in‐two‐pyroxene thermometer as temperatures are determined from heavy REEs and Y (e.g., Lucas et al., 2020; see REE‐in‐Two‐Pyroxene Thermometry ( T REE ) section of this study).…”

“…These samples cooled slowly and exhibit T REE ≫ T BKN , and plot far to the left of the 1:1 line. The relationship between T REE and T BKN makes it possible to discriminate between possible asteroidal thermal histories by evaluating Δ T values, whereas large positive Δ T s imply slow cooling after radiogenic heating, small positive Δ T s imply fast cooling after a fragmentation event (e.g., Lucas et al., 2020), and negative ΔT s may imply short‐lived heating, or that chemical equilibrium has been disturbed by secondary or metasomatic processes.…”

“…In all samples, light through heavy REEs + Y in cpx are above detection limits and replicate analyses show good reproducibility (Table 3). The lack of data above detection limits for light REEs in opx does not preclude Literature EPMA data; REE data (Floss, 2000) Literature EPMA data (Keil and McCoy, 2018) NWA 5488 the application of the REE-in-two-pyroxene thermometer as temperatures are determined from heavy REEs and Y (e.g., Lucas et al, 2020; see REE-in-Two-Pyroxene Thermometry (T REE ) section of this study). Chondrite-normalized (Anders & Grevesse, 1989) REE + Y abundances are shown for opx (dotted lines) and cpx (solid lines) in Fig.…”

“…S6-S8 in supporting information) yields T REE. Further details on this method are provided in Liang et al (2013) and Lucas et al (2020).…”

Porosity Evolution in Metallic Asteroids: Implications for the Origin and Thermal History of Asteroid 16 Psyche

“…The hit-and-run collisions described by Asphaug et al (2006) occur during the accretion phase of planetary formation, which lasts until approximately 1.5 Myr post-CAI formation (Yang et al, 2007). Alternatively, the catastrophic impacts that disrupted parent bodies of ordinary chondrites occur at or near-peak temperatures for the bodies (Lucas et al, 2020), which are expected to be reached prior to 10 Myr post-CAI formation (Bouvier et al, 2007). As the cooling timescale required by a pure iron Psyche to retain a bulk porosity of ∼52 vol% extends beyond the hit-and-run collision and catastrophic impact epochs of the early solar system, a collision scenario for the formation of a highly porous, pure iron Psyche is not likely.…”