Comment on "Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia"

Glikson, Andrew Y.

doi:10.1126/science.1100404

Cited by 30 publications

(13 citation statements)

References 9 publications

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“…1994; Surenian 1988 versus Leroux and Doukhan 1993; Ernstson and Fiebag 1992 versus Langenhorst and Deutsch 1996; Becker et al. 2004 versus Glikson 2004; Retallack et al. 1998 versus Langenhorst et al.…”

Section: Introductionmentioning

confidence: 99%

Scanning electron microscope‐cathodoluminescence (SEM‐CL) imaging of planar deformation features and tectonic deformation lamellae in quartz

Hamers¹,

Drury

2011

Meteorit & Planetary Scien

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Abstract-Planar deformation features (PDFs) in quartz are essential proof for the correct identification of meteorite impact structures and related ejecta layers, but can be confused with tectonic deformation lamellae. The only completely reliable method to demonstrate the shock origin of suspected (sub-) planar microstructures, transmission electron microscope (TEM) observations, is costly and time consuming. We have used a cathodoluminescence (CL) detector attached to a scanning electron microscope (SEM) to image both PDFs and tectonic deformation lamellae in quartz to demonstrate the potential of a simple method to identify PDFs and define characteristics that allow their distinction from tectonic deformation lamellae. In both limited wavelength grayscale and composite color SEM-CL images, PDFs are easily identified. They are straight, narrow, well-defined features, whereas tectonic deformation lamellae are thicker, slightly curved, and there is often no clear boundary between lamella and host quartz. Composite color images reveal two types of CL behavior in PDFs: either they emit a red to infrared CL signal or they are nonluminescent. The color of the CL signal emitted by tectonic deformation lamellae ranges from blue to red. For comparison, we also imaged several shocked quartz grains at cryogenic temperature. In most cases, the PDF characteristics in cryo-CL images do not differ significantly from those in images recorded at room temperature. We conclude that SEM-CL imaging, especially when color composites are used, provides a promising, practical, low cost, and nondestructive method to distinguish between PDFs and tectonic lamellae, even when the simplest CL techniques available are used.

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Section: Introductionmentioning

confidence: 99%

Scanning electron microscope‐cathodoluminescence (SEM‐CL) imaging of planar deformation features and tectonic deformation lamellae in quartz

Hamers¹,

Drury

2011

Meteorit & Planetary Scien

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“…40 Ar/ 39 Ar dating of feldspar from the breccia in Lagrange 1 gives an age of 251.1 + 4 Ma, approximately coincident with the Permian -Triassic boundary ). However, from independent analysis of Bedout 1 core samples, Glikson (2004b) found no evidence of shock metamorphism and reinterpreted the purported impact breccia as an altered mafic volcanic breccia. Renne et al (2004) also disputed the presented evidence for shock metamorphism and the dating methodology, and considered that the geophysical data are not consistent with a large impact structure.…”

Section: Bedout Western Australia (188s 1198e)mentioning

confidence: 88%

Impact cratering and distal ejecta: the Australian record

Haines¹

2005

Australian Journal of Earth Sciences

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“…Some argue that the PT boundary extinction was rapid, perhaps resulting from some combination of volcanically induced climate change (e.g., Courtillot et al, 1999;Courtillot and Renne, 2003;Renne et al, 1995), oceanic anoxia due to deepwater overturn (Wignall and Twitchett, 1996), hypercapnia (Knoll et al, 2007), melting of gas hydrates (Krull and Retallack, 2000;Ryskin, 2003), large-scale marine regression and/or transgression (Hallam and Wignall, 1999), and/or bolide impact (Becker et al, 2001;Hagstrum, 2005;Kaiho et al, 2001;Rampino, 1992;Xu and Yan, 1993), although evidence for the later is scarce (Farley et al, 2005;Glikson, 2004;Müller et al, 2005;Renne et al, 2004a;Wignall et al, 2004). The close coincidence of the PT mass extinction with the eruption of the Siberian Traps (the main pulse of volcanism is constrained by 40 Ar/ 39 Ar to an age of 250 Ma; Reichow et al, 2002;Renne, 1995) is perhaps the most compelling argument for volcanism as a direct causal mechanism for the PT biotic crisis.…”

Section: Causes For Pt Mass Extinctionsmentioning

confidence: 97%

Magnetostratigraphic correlations of Permian–Triassic marine-to-terrestrial sections from China

Glen

Nomade

Lyons

et al. 2009

Journal of Asian Earth Sciences

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Comment on "Bedout: A Possible End-Permian Impact Crater Offshore of Northwestern Australia"

Cited by 30 publications

References 9 publications

Scanning electron microscope‐cathodoluminescence (SEM‐CL) imaging of planar deformation features and tectonic deformation lamellae in quartz

Scanning electron microscope‐cathodoluminescence (SEM‐CL) imaging of planar deformation features and tectonic deformation lamellae in quartz

Impact cratering and distal ejecta: the Australian record

Magnetostratigraphic correlations of Permian–Triassic marine-to-terrestrial sections from China

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