Authors / CoAuthors
Mackenzie, D.E.
Abstract
Volcanic and intrusive rocks of Permian age, ranging from basalt and andesite through granodiorite and dacite to rhyolite, are sparsely but non-randomly distributed in the western Georgetown Inlier, including newly recognised areas in the Croydon region. The basaltic to andesitic rocks are typical intra-plate transitional alkaline rocks, apparently genetically unrelated to the granodiorite/dacite to rhyolite group, which are a suite of fractionated I-type (and possibly A-type) rocks, lower in alkalis, derived from evolved (old) crustal source rocks. The Permian magmatism appears to have been controlled by northwest-trending, and some north-trending, major fractures. Carboniferous igneous rocks in the same region, although only slightly different in chemistry, include a much greater proportion of felsic ignimbrites relative to more mafic extrusive rocks, and are related to north-south aligned and/or elongated sag-type cauldron structures. Total volumes, relative proportions of mafic and felsic rocks, and, to some extent, their compositions, appear to be related to tectonic style.
Product Type
document
eCat Id
81209
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
-
- GA PublicationJournal
-
- QLD
- Australian and New Zealand Standard Research Classification (ANZSRC)
-
- Earth Sciences
-
- Published_External
Publication Date
1987-01-01T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
unknown
Topic Category
geoscientificInformation
Series Information
BMR Journal of Australian Geology and Geophysics 10:2:109-120
Lineage
Unknown
Parent Information
Extents
[-20.38, -16.8, 141.28, 145.76]
Reference System
Spatial Resolution
Service Information
Associations
Source Information
Source data not available.