Age Determination of Obsidian Source Samples from North Queensland and New South Wales, Australia

Bonetti, R.; Guglielmetti, A.; Malerba, F.; Migliorini, E.; Oddone, Massimo; Bird, Roger

doi:10.1007/978-94-015-9133-1_19

Cited by 5 publications

(5 citation statements)

References 3 publications

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“…1 was reached after 3 days and 1 day, respectively. Another remarkable result has been reported by Bonetti et al (1998). These authors practiced a step-heating treatment at 140°C for 60 h on an old Australian obsidian.…”

Section: Relative Age Method: Rock Varnishmentioning

confidence: 63%

Fission‐track dating of a tephra layer related to Poti‐Malal and Seguro drifts in the Río Grande basin, Mendoza, Argentina

Espizua

Bigazzi

Iunes

et al. 2002

J Quaternary Science

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Two old drift units called Poti-Malal and Seguro have been differentiated in the Río Grande basin based on relative-age criteria, stratigraphical relationships, morphology and fission-track dating. A tephra dated at 0.226 ± 0.025 Ma was deposited on the Poti-Malal drift and underlies the Seguro outwash, which is inferred to equate with marine oxygen isotope stage 6. The stratigraphical position and age suggest that the tephra post-dates the Poti-Malal glaciation and that it is older than the Seguro drift. The Poti-Malal glaciation must be at least as old as Early-Middle Pleistocene, and the Seguro glaciation is assigned to the penultimate glaciation. The tephra unit may have been deposited during marine oxygen isotope stage 7.

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Section: Relative Age Method: Rock Varnishmentioning

confidence: 63%

Fission‐track dating of a tephra layer related to Poti‐Malal and Seguro drifts in the Río Grande basin, Mendoza, Argentina

Espizua

Bigazzi

Iunes

et al. 2002

J Quaternary Science

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“…Implicitly, the high Na/K glasses were considered to form another tektite or impact glass strewn field, despite the lack of a detailed study able to exclude a volcanic origin. In fact, the documented occurrence of volcanic glasses in Australia (e.g., Bonetti et al., 1998; Smith, 1996) has been overlooked. Volcanic glasses could have been dispersed naturally or by Aboriginal Australians in the tektite strewn field.…”

Section: Discussionmentioning

confidence: 99%

Obsidian and mafic volcanic glasses from the Philippines and Vietnam found in the Paris Museum Australasian tektite collection

Rochette

Bezaeva

Beck

et al. 2022

Meteorit & Planetary Scien

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During the systematic magnetic susceptibility survey of the Paris Museum Australasian tektite collection, we identified three previously overlooked occurrences of volcanic glass that resembles tektites, based on anomalous magnetic properties, high water content, the presence of microcrystals, and anomalous chemical composition. These occurrences are from the Phu Yen province in south‐central Vietnam (two rhyolitic glass fragments) and from the Philippines: one from northern Luzon Island (a basaltic rounded etched glass), one from Santa Mesa near Manilla (a dozen small rounded rhyolitic gravels). The two occurrences in the Philippines are quite similar to previously described volcanic glasses from the nearby Pagudpod and Nagcarlan localities, respectively. The rhyolitic glass specimens from the Phu Yen province are the first documentation of a geological occurrence of obsidian in Vietnam. This work is a warning note that glass samples with anomalous properties found among tektite collections may correspond to volcanic pseudotektites instead of real tektites with anomalous composition. The basaltic glass sample from the Philippines locally shows microcrystalline quench textures previously unknown in natural samples. These findings may also be of interest for archeologists involved in glass artifacts sourcing.

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“…If PTF has occurred, this ratio will be too low. An excellent example is the work of Bonetti et al (1998) on an Australian obsidian (Figure 8). The value of r s /r i at this plateau level is used to give an FT age corrected for PTF.…”

Section: Plateau Correction Methodsmentioning

confidence: 99%

Fission-Track Dating

Westgate¹,

Naeser²,

Alloway³

2013

Encyclopedia of Quaternary Science

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IntroductionA fission track is a linear region of intense radiation damage formed by the passage of an energetic, charged nuclear particle through an insulating solid. According to a popular hypothesis, known as the 'ion explosion spike' model (Fleischer et al., 1975), the charged particle collides with atoms in its path, displaces them and removes their electrons, producing a narrow zone rich in positive ions, which repulse each other into interstitial positions and form vacancies. An elastic adjustment of the crystal or glass then occurs, straining the undamaged matrix (Fleischer, 2004). Another idea, called the 'thermal spike' model, sees the fast-moving fission fragment producing intense heat along its trajectory. After passage of the charged particle, the track core is quenched by heat loss to the adjacent lattice, leaving it in a disordered state. According to Chadderton (2003), it is likely that both mechanisms are involved in track formation. Maximum density damage exists at the site of fission and decreases to the track termini. This damaged zone persists in the solid after the fission fragment has come to a rest and is called a latent track. Its length is equal to the sum of the range of the two charged particles formed by nuclear fission, each moving in opposite directions. 238 U fission events form latent tracks that are 6-10 nm wide and 10-20 mm long and account for most tracks in natural, terrestrial materials. Latent tracks can only be observed with a transmission electron microscope but can be made visible by chemical etching (Young, 1958) and readily seen under an optical microscope. Etching takes place by rapid dissolution of the disordered region of the track core, which exists in a state of higher free energy than the undamaged material. As can be seen in Figure 1, the shape of the etched fission tracks varies in different materials, due mainly to differences in symmetry and magnitude of the difference between the track and bulk etch rates. Fission tracks in glass are relatively wide, conical pits due to its isotropic properties and a track etch rate that is not much greater than the bulk etch rate. Micas have diamond-shaped tracks, whereas tracks in zircon and apatite are needle-like because of the large difference between track and bulk etch rates, the former being much greater.Fission tracks have varied uses ranging from applications in the fields of engineering, medicine, nuclear physics, and space sciences to the earth sciences (Fleischer, 1998). The most important applications in the earth sciences are thermochronology (Reiners and Ehlers, 2005) and geochronology. Thermochronology -the more active field at present -focuses on understanding the thermal history of rocks and duration and rates of geological processes, such as crustal uplift. 643Geochronology, on the other hand, is primarily concerned with formation age, the topic of interest to us here.Zircon and glass are the most suitable phases for dating Quaternary deposits by fission-track (FT) methods, although apatite and sphene may ...

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Age Determination of Obsidian Source Samples from North Queensland and New South Wales, Australia

Cited by 5 publications

References 3 publications

Fission‐track dating of a tephra layer related to Poti‐Malal and Seguro drifts in the Río Grande basin, Mendoza, Argentina

Fission‐track dating of a tephra layer related to Poti‐Malal and Seguro drifts in the Río Grande basin, Mendoza, Argentina

Obsidian and mafic volcanic glasses from the Philippines and Vietnam found in the Paris Museum Australasian tektite collection

Fission-Track Dating

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