Homogeneous magnetic susceptibilities of tektites: Implications for extreme homogenization of source material

Werner, Tomasz; Borradaile, Graham J.

doi:10.1016/s0031-9201(98)00098-3

Cited by 11 publications

(19 citation statements)

References 27 publications

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“…Werner and Boradaile [21] measured also susceptibility of tektites on large samples (1-10 g range) using a low field AC susceptibility bridge, on 152 australasites (mostly from Australia, with a mean χ at 82 ± 10 × 10 −9 m 3 /kg) and 15 moldavites. Contrary to previous studies, they reported M S in the 10 −3 -10 −2 Am 2 /kg range, using an AGFM magnetometer with few mg samples, and also large M RS .…”

Section: Early Studiesmentioning

confidence: 99%

“…Finally, Rochette et al [9] reported new measurements on all five tektite fields, as well as on LDG and five types of non tektite splash-form impact glasses (called tektoids). They also developed the study of the ferromagnetic contribution in their samples, and showed that the high M S reported in tektites in [21] were artifacts of the AGFM system (likely faulty sample holder subtraction). They also confirm M RS of tektites is of the order of 10 −6 Am 2 /kg.…”

Section: Early Studiesmentioning

confidence: 99%

“…To test the homogeneity of χon a single locality we measured 668 samples from a site in South China (Maoming) and obtained a very narrow range of χ: 87 ± 3 × 10 −9 m 3 /kg, i.e., with a standard deviation 3 times smaller than that from the database [21]. The only outlier (over twice the mean) appeared to be due to an inclusion of hardened oxide rich soil within a large bubble connected with the exterior.…”

Section: Essentially Paramagnetic Glass: Tektites and Darwin Glassmentioning

confidence: 99%

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Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

et al. 2019

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High velocity impacts produce melts that solidify as ejected or in-situ glasses. We provide a review of their peculiar magnetic properties, as well as a new detailed study of four glasses from Siberia: El’gygytgyn, Popigai, urengoites, and South-Ural glass (on a total of 24 different craters or strewn-fields). Two types of behavior appear: 1) purely paramagnetic with ferromagnetic impurities at most of the order of 10 ppm; this corresponds to the five tektite strewn-fields (including the new one from Belize), urengoites, and Darwin glass. Oxidation state, based in particular on X-ray spectroscopy, is mostly restricted to Fe2+; 2) variable and up to strong ferromagnetic component, up to the 1 wt % range, mostly due to substituted magnetite often in superparamagnetic state. Accordingly, bulk oxidation state is intermediate between Fe2+ and Fe3+, although metallic iron, hematite, and pyrrhotite are sometimes encountered. Various applications of these magnetic properties are reviewed in the field of paleomagnetism, magnetic anomalies, recognition of glass origin, and formation processes.

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Section: Early Studiesmentioning

confidence: 99%

Section: Early Studiesmentioning

confidence: 99%

Section: Essentially Paramagnetic Glass: Tektites and Darwin Glassmentioning

confidence: 99%

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Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

et al. 2019

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“…Alternatively, the same spherules will be ferromagnetic at high magnetic fields (above saturation). In a study of the lunar glass, Thorpe et al [1970] More recently, Werner and Borradaile [1998] have made ac magnetic susceptibility measurements in Australasian tektites and have observed very small amounts of ferromagnetism in the glass. deGasparis et al [1975] have shown that Muong Nong tektites have a small remanent magnetization which could be accounted for by the presence of small ferromagnetic iron spherules.…”

Section: Determination Of Fe 2+ Curie Constant Andmentioning

confidence: 99%

Magnetic measurements of glass from Tikal, Guatemala: Possible tektites

Senftle¹,

Thorpe²,

Grant³

et al. 2000

J. Geophys. Res.

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Abstract. Certain glass nodules found at the archeological site at Tikal, Guatemala, have been considered as possible tektites. To test this possibility, magnetic studies have been made on three of the glass specimens. These specimens are similar to tektites, both visually and also because they contain very little Fe 3+ as detected by M6ssbauer spectroscopy. The magnetic Curie constants are similar in magnitude to those found for normal tektites but show some variation from point to point in the same specimen. This variation reflects an inhomogeneity in the iron concentration. The Fe 2+ calculated from the Curie constants accounts for most of the iron. The temperature-independent component of the total dc magnetic susceptibility is several times higher than that found in tektites from other strewn fields. The high values can be explained if the glass contains metallic iron spherules with Fe in the parts per million range and/or a ferromagnetic component which does not saturate in a low magnetic field. The magnetic properties resemble those of Muong Nong type tektites and suggest that the Tikal glass specimens are tektites of the Muong Nong type. IntroductionEsserie et al. [1987] have reported microprobe analyses of 11 unworked nodules of olive-green vesicular glass found in the Mayan city of Tikal, Guatemala. Their analysis indicated that the glass had an andesitic composition. They suggested that because of the complete lack of crystallites these specimens would be highly anomalous if they were andesitic obsidians. Because it is unlikely, and surely unique, that these specimens were derived from andesitic obsidian, Esserie et al. [1987] further suggested that the specimens may be impactites from a terrestrial andesitic source rock. Later, Moholy-Nagy and Nelson [1990] reported on a study of some 30 obsidian artifacts from the same area. In an effort to trace the source of the obsidian they analyzed the specimens for 10 different elements using X-ray fluorescence. One of the specimens (their number 1589) was an unworked brownish-green glass nodule that had a composition distinctly different from the other obsidian artifacts. The Fe, Ti, and Sr concentrations were higher, and the Rb and Nb concentrations were lower than those determined for any of the other obsidian fragments. The obsidian fragments could all be related to known local quarries, while specimen 1589 was of unknown origin and from a source of more andesitic composition. The surface of the nodule was pitted, and the glass was remarkably free of crystallites. Because of these characteristics it was suggested that this specimen might We report here a magnetic study on three of the specimens described in the above studies and designated as 12T-451/79, 20M-97B/41 (same as Moholy-Nagy and Nelson [1990] specimen 1589), and 24F-26/11 (hereinafter referred to as 12T, 20M, and 24F) in an attempt to confirm them as true tektites. Senfile and Thorpe [1959] have shown that magnetic properties can be used to distinguish tektites from obsidian glass. Obsidians ...

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“…1999;Borradaile at al. 1993a, b) and hysteresis studies of tektites (Werner and Borradaile 1998). After returning to Poland he focused on the applicability of methods of magnetic fabrics (AMS, AARM) for tectonic problems for the Sudetes (Jeleńska et al 1996;Werner 1997;Jeleńska and Werner 1997;Jeleńska et al 2000;Jeleńska et al 2002a, b;Kądziałko-Hofmokl et al 2004;Werner and Białek 2004).…”

Section: The Next Stage Of Palaeomagnetic Laboratory In a Newmentioning

confidence: 99%

Fifty Years of Palaeomagnetic Studies in the Institute of Geophysics, Polish Academy of Sciences

Kądziałko-Hofmokl

Werner

Kruczyk

2014

Achievements, History and Challenges in Geophysics

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Palaeo-and archaeomagnetic investigations in the Institute of Geophysics were initiated at the beginning of 1960s. The archaeomagnetic study was performed in the Geomagnetic Observatory in Hel till the mid-1980s and was resumed lately in the Warsaw laboratory. Palaeomagnetic study begun in 1963 but the palaeomagnetic group obtained necessary place for the laboratory in the Central Geophysical Observatory in the newly finished building in Belsk later in 1966. Formally, the Paleomagnetic Laboratory was established in 1972. From the very beginning, palaeomagnetic studies were accompanied by studies of magnetic properties of rocks and minerals-carriers of natural remanence and by measurements of magnetic susceptibility and its anisotropy. Therefore, the laboratory became successively equipped with the apparatus for strictly palaeomagnetic study (astatic and spinner magnetometers and demagnetizing devices) as well as with devices for rock-magnetic investigations (apparatus for thermoanalysis, system for measuring of hysteresis parameters and for study of magnetic remanence at low temperatures, torsion balance, device for study of magnetic properties under mechanical stress and temperature, device for study of alterations of magnetic minerals based on thermally stimulated emission of exo-electrons (TSEE). The last three devices have not been in use for several years. At the end of 1980s, the Institute moved to a new building and the whole laboratory was moved to Warsaw. Moving palaeomagnetic measurements to town was possible due to the replacement of spinner magnetometer by the cryogenic magnetometer SQUID, which is much more sensitive and less affected by the urban disturbances. Computer software packages that are written in the Institute or obtained from their inventors became a great help in the interpretation of experimental results. Palaeomagnetic investigations have been performed in our laboratory on rocks of various origins and age, coming from various regions of Poland and other countries often in cooperation with scientists from foreign laboratories. Numerous palaeomagnetic results that are obtained in our laboratory are in

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Homogeneous magnetic susceptibilities of tektites: Implications for extreme homogenization of source material

Cited by 11 publications

References 27 publications

Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

Magnetic measurements of glass from Tikal, Guatemala: Possible tektites

Fifty Years of Palaeomagnetic Studies in the Institute of Geophysics, Polish Academy of Sciences

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