Esk Trough—Yarraman Block contact, an unconformity: Its nature and implications for regional tectonics

Willey, Edwin Clayton (2000) Esk Trough—Yarraman Block contact, an unconformity: Its nature and implications for regional tectonics. Australian Journal of Earth Sciences, 47 (1). pp. 139-152. ISSN 0812-0099


Abstract

Detailed field study in southeast Queensland has resulted in the interpretation of an unconformity at the base of the Esk Trough sequence at its contact with the Yarraman Block (Maronghi Creek beds and associated intrusions). Previously this contact had been considered to be faulted. The nature
of the unconformity is very variable with the Esk Formation resting on freshly eroded surfaces, on mature palaeosols and on an immature palaeosol. Immediately above the unconformity, the Esk Formation variably comprises scree breccia, fluvial conglomerate and arenite, and alluvial fan
conglomerate and arenite. North-northwest–south-southeast-striking faults are associated with the unconformity. Where the unconformity parallels these faults, it retains a relatively constant character, but where it is cut by these faults, it shows greater variability, a relationship interpreted to result from contemporaneous tectonism. The Glen Howden Fault extends into structurally disturbed areas previously described as ‘fractured anticlines’ and ‘complex anticlines’, which are here interpreted as flower structures and associated features. The south-southeast extension of the Glen Howden Fault strikes obliquely across the Esk Trough to finally pass into the South Moreton Anticline previously interpreted as a positive flower structure, and resolves structural and stratigraphic observations that previously appeared anomalous. Inferred strike-slip movement in the Esk Trough resulted from Early to Middle Triassic north-northwest–south-southeast oblique transtension followed by Late Triassic transpression, and similar tectonism probably affected adjacent portions of the Yarraman Block.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Sciences - Department of Biological and Physical Sciences (Up to 30 Jun 2013)
Faculty/School / Institute/Centre: Historic - Faculty of Sciences - Department of Biological and Physical Sciences (Up to 30 Jun 2013)
Date Deposited: 03 Dec 2021 02:06
Last Modified: 03 Dec 2021 02:37
Uncontrolled Keywords: Esk Trough; Queensland; transpression; transtension; Yarraman Block
Fields of Research (2008): 04 Earth Sciences > 0403 Geology > 040399 Geology not elsewhere classified
Fields of Research (2020): 37 EARTH SCIENCES > 3705 Geology > 370599 Geology not elsewhere classified
Identification Number or DOI: https://doi.org/10.1046/j.1440-0952.2000.00771.x
URI: http://eprints.usq.edu.au/id/eprint/44140

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