Classification of mafic clasts from mesosiderites: Implications for endogenous igneous processes

Journal Article · Sat Feb 01 00:00:00 EST 1992 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(92)90101-N· OSTI ID:5195317

Rubin, A E ^[1]; Mittlefehldt, D W ^[2]

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1. Univ. of California, Los Angeles (United States)
2. Lockheed Engineering and Science Co., Houston, TX (United States)

The authors have analyzed thirteen igneous pebbles from the Vaca Muerta, EET87500, and Bondoc mesosiderites by electron microprobe and instrumental neutron activation and combined these data with literature data for forty-three analyzed mesosiderite clasts. They classify these well-characterized clasts into the following five principal groups: (1) Polygenic and monogenic cumulates (39%) are coarse-grained gabbros that are highly depleted in incompatible elements (relative to H chondrites); they formed at moderate depth either as residues of low-degree partial melting of pre-existing cumulate eucrites or as cumulates from parent melts similar to cumulate eucrites. (2) Polygenic basalts (30%) are finer-grained rocks with positive europium anomalies, La/Lu ratios < 1, and lower rare earth element abundances than basaltic eucrites. It seems likely that these rocks were formed near their parent body surface by remelting mixtures of major amounts of basaltic eucrites and lesser amounts of cumulate eucrites. (3) Quench-textured rocks comprise two compositional groups, (a) those which resemble basaltic eucrites (5%), and (b) those which resemble cumulate eucrites (2%). The quench-textured rocks are probably monogenic; they formed most likely when small-scale impacts at their parent body surface totally melted small amounts of basaltic or cumulate eucrite material. (4) Monogenic basalts (11%) resemble basaltic eucrites and formed by endogenous igneous processes on the mesosiderite parent body (MPB). (5) Ultramafic rocks are cumulates consisting mainly of large crystals of orthopyroxene (9%) or olivine (4%). Orthopyroxenite clasts closely resemble diogenites and were formed most likely by endogenous igneous processes.

• OSTI ID: 5195317
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 56:2; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
BASALT
CHEMICAL COMPOSITION
CLASSIFICATION
GABBROS
METEORITES
ELECTRON MICROPROBE ANALYSIS
ELEMENT ABUNDANCE
MINERALOGY
NEUTRON ACTIVATION ANALYSIS
OLIVINE
PETROCHEMISTRY
PETROGENESIS
PETROLOGY
QUANTITY RATIO
RARE EARTHS
ABUNDANCE
ACTIVATION ANALYSIS
CHEMICAL ANALYSIS
ELEMENTS
GEOLOGY
IGNEOUS ROCKS
METALS
MICROANALYSIS
MINERALS
NONDESTRUCTIVE ANALYSIS
PLUTONIC ROCKS
ROCKS
SILICATE MINERALS
VOLCANIC ROCKS
580000* - Geosciences