Authors / CoAuthors
Wyatt, B.W. | Yeates, A.N. | Tucker, D.H.
Abstract
Regional airborne magnetic and gravity data and field observations have been used to define four geophysical domains in the Lachlan Fold Belt of New South Wales. Each has a different pattern of anomaly trend and amplitude. Three domains correspond with provinces containing rocks of similar lithology and age; the other corresponds with the Darling Basin. The magnetic data highlight minor variation in magnetite abundance, chiefly in igneous rocks, and, across the region, reflect slight differences in magma composition, structural trends, and possibly also style of volcanism and sedimentation. The gravity data also delineate the same structural trends and some major lithological variations. The boundary of the Darling Basin is gradational. The other domain boundaries are sharp, but with no evidence of major faulting. Within the geophysical domains a classification of magnetic anomalies by length, width, and amplitude appears capable of distinguishing between the various sources, thereby providing a useful mapping tool in regions with surficial cover. Circular anomalies of largest extent occur over granitoids, the smallest over small pipes and veins, and the intermediate size over basic and ultrabasic stocks. Elliptical anomalies are associated with magnetic granitoids and some basic and ultrabasic bodies. Sources of narrow anomalies include basic dykes, steeply tilted Palaeozoic lavas, ignimbrites, and serpentinites. Sources of complex zones include Tertiary basalt flows, piles of basic and intermediate lavas surrounding small intrusions, and some inhomogeneous granitoids. The regional gravity data reflect features with very large dimensions or large density contrasts. A major north-northeast trending Bouguer anomaly low corresponds with the Eastern Highlands, a region of high relief, thick crust, and extensive granitoids. A narrower low corresponds to another belt of granitoids trending north-northwest from Holbrook to Cobar. Small-scale gravity features include the Coolac Serpentinite and its associated basic rocks, the Mid-Silurian to Mid-Devonian Hill End Trough, and numerous regions of Late Devonian quartzose sedimentary rocks.
Product Type
document
eCat Id
81052
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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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- NSW
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1980-01-01T00:00:00
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unknown
Topic Category
geoscientificInformation
Series Information
BMR Journal of Australian Geology and Geophysics 5:4:289-300
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Unknown
Parent Information
Extents
[-37.0, -29.0, 144.0, 151.5]
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