The petrology of an adamellite-porphyrite from the New England Bathylith (New South Wales)

J. F G Wilkinson*, R. H. Vernon, S. E. Shaw

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The paper presents an account of the occurrence, petrography, mineralogy, and geochemistry of several intrusions of adamellite-porphyrite, an early member of the New England Bathylith (N.S.W.). The rock is composed of phenocrysts of quartz, andesine, hornblende, biotite, augite (and minor orthopyroxene) which are set in a fine-grained quartzofeldspathic groundmass. Compositions of silicate phenocrysts (which reveal widespread evidence of cataclasis) accord with coexisting phases of an assemblage appropriate to intermediate rocks. Xenolith mineralogy is similar to equivalent minerals occurring as phenocrysts. The recalculated bulk composition of a rock represented by the modal andesine, hornblende, biotite, augite, and magnetite of the adamellite-porphyrite is similar to the composition of a biotite-diorite; the composition of the quartzo-feldspathic groundmass plots in the low-melting region of the NaAISi 3O 8-KAISi 3O 8-SiO 2-H 2O system. Evidence is presented to indicate a hybrid origin for the adamellite-porphyrite whereby disrupted biotite-diorite was invaded and mixed with low-melting silicic alkalic liquid.

Original languageEnglish
Pages (from-to)461-488
Number of pages28
JournalJournal of Petrology
Volume5
Issue number3
DOIs
Publication statusPublished - 1964
Externally publishedYes

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