Geophysical anomalies and quartz microstructures, Eastern Warburton Basin, North-east South Australia: Tectonic or impact shock metamorphic origin?

Glikson, Andrew Y., Uysal, I. Tonguç, Gerald, John D. Fitz and Saygin, Erdinc (2013) Geophysical anomalies and quartz microstructures, Eastern Warburton Basin, North-east South Australia: Tectonic or impact shock metamorphic origin?. Tectonophysics, 589 57-76. doi:10.1016/j.tecto.2012.12.036


Author Glikson, Andrew Y.
Uysal, I. Tonguç
Gerald, John D. Fitz
Saygin, Erdinc
Title Geophysical anomalies and quartz microstructures, Eastern Warburton Basin, North-east South Australia: Tectonic or impact shock metamorphic origin?
Journal name Tectonophysics   Check publisher's open access policy
ISSN 0040-1951
Publication date 2013-03-18
Sub-type Article (original research)
DOI 10.1016/j.tecto.2012.12.036
Volume 589
Start page 57
End page 76
Total pages 20
Place of publication Netherlands
Publisher Elsevier
Collection year 2014
Language eng
Formatted abstract
The Eastern Warburton Basin, Northeast South Australia, features major geophysical anomalies, including a magnetic high of near-200 nT centred on a ~ 25 km-wide magnetic low (< 100 nT), interpreted in terms of a magmatic body below 6 km depth. A distinct seismic tomographic low velocity anomaly may reflect its thick (9.5 km) sedimentary section, high temperatures and possible deep fracturing. Scanning electron microscope (SEM) analyses of granites resolves microbreccia veins consisting of micron-scale particles injected into resorbed quartz grains. Planar and sub-planar elements in quartz grains (Qz/PE) occur in granites, volcanics and sediments of the > 30,000 km-large Eastern Warburton Basin. The Qz/PE include multiple intersecting planar to curved sub-planar elements with relic lamellae less than 2 μm wide with spacing of 4–5 μm. Qz/PE are commonly re-deformed, displaying bent and wavy patterns accompanied with fluid inclusions. U-stage measurements of a total of 243 planar sets in 157 quartz grains indicate dominance of ∏{10–12}, ω{10–13} and subsidiary §{11–22}, {22–41}, m{10–11} and x{51–61} planes. Transmission Electron Microscopy (TEM) analysis displays relic narrow ≤ 1 μm-wide lamellae and relic non-sub grain boundaries where crystal segments maintain optical continuity. Extensive sericite alteration of feldspar suggests hydrothermal alteration to a depth of ~ 500 m below the unconformity which overlies the Qz/PE-bearing Warburton Basin terrain. The data are discussed in terms of (A) Tectonic–metamorphic deformation and (B) impact shock metamorphism producing planar deformation features (Qz/PDF). Deformed Qz/PE are compared to re-deformed Qz/PDFs in the Sudbury, Vredefort, Manicouagan and Charlevoix impact structures. A 4–5 km uplift of the Big Lake Granite Suite during ~ 298–295 Ma is consistent with missing of upper Ordovician to Devonian strata and possible impact rebound. The occurrence of circular seismic tomography anomalies below the east Warburton Basin, the Poolowana Basin and the Woodleigh impact structure signifies a potential diagnostic nature of circular tomographic anomalies.
Keyword Warburton Basin
Cooper Basin
Quartz planar microstructures
Magnetic anomaly
Tomography anomaly
Geothermal
Planar deformation features
Western-Australia
Carnarvon Basin
Vredefort structure
Bushveld complex
Wave tomography
Ambient noise
Africa
Woodleigh
Lamellae
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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