The petrology of layered mafic-ultramafic intrusions of the Giles Complex, western Musgrave Block, Western Australia  

Authors / CoAuthors

Ballhaus, C. | Glikson, A.Y.

Abstract

The Musgrave Block hosts about twenty major layered intrusions and several generations of compositionally diverse sills and dykes collectively referred to as the Giles Igneous Complex. All were emplaced in middle Proterozoic intermediate to felsic granulites and amphibolites. On the basis of crystallisation sequences within the cumulates, we distinguish between (1) ultramafic olivine-clinopyroxene rich cumulate sequences, (2) mafic clinopyroxene-plagioclase-rich sequences, and (3) evolved troctolitic olivine-plagioclase ± magnetite-rich sequences. The layered igneous rocks are intruded by several generations of dykes, whose phenocryst assemblages resemble the crystallisation sequences in the cumulates. On this basis, at least three discrete parental melt compositions are identified, namely (1) a near-primitive olivine±clinopyroxene saturated melt, (2) a slightly fractionated olivine-( orthopyroxene )-clinopyroxene-plagioclase saturated melt, and (3) a strongly fractionated fayalitic olivine-plagioclase ± magnetite saturated melt. These magmas represent derivatives of a parental liquid that experienced various degrees of polybaric orthopyroxene-clinopyroxene ± olivine fractionation prior to emplacement, at depths significantly greater than the emplacement levels of the Giles intrusions and the dykes.

Product Type

document

eCat Id

81421

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Keywords

• GA PublicationJournal

• NTSAWA

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_External

Publication Date

1995-01-01T00:00:00

Creation Date

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Australian Government Security ClassificationSystem    

Classification - unclassified

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Creative Commons Attribution 4.0 International Licence    

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Use - license

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Purpose

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unknown

Topic Category

geoscientificInformation

Series Information

AGSO Journal of Australian Geology and Geophysics 16:1-2:69-89

Lineage

Unknown

Parent Information

Extents

[-28.0, -24.5, 126.5, 134.2]

Reference System

Spatial Resolution

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Journal article (pdf)  

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