Authors / CoAuthors
Stewart, A.J.
Abstract
The Mount Aloysius massif comprises complexly folded high-pressure Mesoproterozoic granulites, typical of those making up much of the western Musgrave Block. The granulites host the well-studied mafic-ultramafic layered intrusions of the Giles Complex, but up to now have not been mapped in detail. Previous lithological mapping and airphoto interpretation produced conflicting synformal and antiformal interpretations of the structure of the massif. New mapping reported here resolves this conflict, and shows that the massif preserves four episodes of folding. The first formed small, initially recumbent (now reclined), F1 folds, which are earlier than any previously known in the massif. Two major episodes formed a large west-inclined isoclinal, gently doubly plunging, F2 antiform, which was subsequently folded early in D3 to a steeply doubly plunging antiform and then bent late in D3 to an arcuate shape. With each episode, the intensity of deformation decreased, from isoclinal F1 folds with a strong axial-plane granoblastic-textured foliation to open F4* folds with spaced axial-plane cleavage and local greenschist retrogression, reflecting decreasing ductility as the rocks cooled. Formation of the F2 antiform was helped by the presence of a stiff buttress of relatively massive granulite in the east of the massif, against which well-layered granulite to the west was squashed and flattened. Subsequently, the same near-massive granulite provided a stiff auge-like core, around which the well-layered granulite was wrapped during D3.
Product Type
document
eCat Id
81422
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- GA PublicationJournal
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- NTSAWA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1995-01-01T00:00:00
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Topic Category
geoscientificInformation
Series Information
AGSO Journal of Australian Geology and Geophysics 16:1-2:91-105
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Unknown
Parent Information
Extents
[-28.0, -24.5, 126.5, 134.2]
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Spatial Resolution
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