Journal Article

IMPULSE-2023-00136

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Mantle fragmentation and incomplete core merging of colliding planetesimals as evidenced by pallasites

Walte, N. P. (Corresponding author)MLZ* ; Howard, C. M. (Collaboration author)MLZ* ; Golabek, G. J. (Collaboration author)

2023
Elsevier Amsterdam [u.a.]

Please use a persistent id in citations: doi:10.1016/j.epsl.2023.118247

Abstract: Main group pallasites were likely formed by the collision of their parent body with a smaller impactor that caused a mixing of mantle and core material from the target and impactor, respectively. In order to better constrain the collision, we present particle size distribution (PSD) analyses of olivines in seven main group pallasites and of the Eagle station pallasite. The PSDs of two fragmental pallasites (Admire and Huckitta) contain linear segments in bi-logarithmic particle number versus size diagrams that are similar to terrestrial cataclasites or impact-related rocks. On the other hand, the PSDs of four angular pallasites only display linear segments above their respective average grain sizes. We argue that fragmental pallasites record brittle rock deformation close to the impact site of the collision, while angular pallasites represent deeper-lying mantle rocks of the target body that were disintegrated by the downward percolation of core metal from the impactor. High strain-rate deformation experiments with the system olivine – FeS melt ± Au melt produced microstructures and PSDs that are broadly similar to these two textural groups. The experiments also suggest that de-localized metal melt percolation and concomitant mantle disintegration as evidenced in angular pallasites is facilitated by weak grain boundaries caused by a small fraction of previously present metal melt in the mantle as opposed to localized diking that is dominant in a melt-free mantle. The former mechanism is expected to prevent efficient core-merging and instead causes mantle-impregnation with metal melt, which could be active when planetesimal mantles were still warm due to short-lived radiogenic heating. In addition to the parent body of the PMG, asteroid 16 Psyche may be an example of this inefficient core-merging mechanism.

Keyword(s): Earth, Environment and Cultural Heritage (1st) ; Geosciences (2nd)

Note: BMBF Projekt Nr. 05K19WCA "Aufbau einer Hochdruckpresse vom Multi-Anvil-Typ an der Forschungsneutronenquelle FRM II in Garching", konnte nicht im "grant name" Feld eingegeben werden.Der hochgeladene reprint ist nicht open access! Ich habe den Abstract eingefügt, da der auf der Journal Webseite (EPSL Elsevier) auch immer frei zu lesen ist, weiß aber nicht, ob das OK ist.

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Contributing Institute(s):

1. SAPHIR (SAPHIR)

Experiment(s):

1. SAPHiR : Six Anvil Press for High pressure Radiography and diffraction (SR5a)

Appears in the scientific report 2023

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection ; Zoological Record

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