An overview is presented on the efforts being made to estimate the time that the magnetic field(s... more An overview is presented on the efforts being made to estimate the time that the magnetic field(s) existed and acted on meteorite parent bodies. The basic premise is that if a sample exhibits a low K-Ar age, it is the requisite amount of Ar-40. This assumption is applied to a preliminary analysis of the Farmington chondrite.
... We have rather arbitrarily selected a Ba value of 2 ppm to be used for Pena Blanca Spring. ..... more ... We have rather arbitrarily selected a Ba value of 2 ppm to be used for Pena Blanca Spring. ... 4A. GW Cameron, in The Origin and Evolution of Atmospheres and Oceans, edited by PJ Brancazio and AGW Cameron (John Wiley & Sons, Inc., New York, 1964), Chap. 10. 5P. ...
ABSTRACT The error involved in the determination of the Al26 concentration by the method of Rowe ... more ABSTRACT The error involved in the determination of the Al26 concentration by the method of Rowe and his co-workers was measured and the values they reported should be increased by a factor of 1.36 ± 0.05. The potassium contents of the meteorites measured by Roweet al., are not affected by this error and can be used with confidence.
Abstract Uranium-helium “ages” have been determined for a suite of 25 whole-rock basalts from Mad... more Abstract Uranium-helium “ages” have been determined for a suite of 25 whole-rock basalts from Madeira and Porto Santo islands in the Madeira Archipelago. We include petrographic descriptions of these samples. Uranium measurements were by delayed-neutron activation analysis. Helium measurements were by isotopic dilution in an all-metal system characterized by very low argon and helium blanks. For 19 of the samples “preferred” K Ar ages were also obtained. None of the rocks are concordant in these two ages; all have lost helium. The uranium-helium “ages” are best described, on the average, as equal to 74% of the K Ar ages minus 0.2 m.y. Nevertheless in our suite of young, chemically similar lavas the correlation between the K Ar age and the helium content is good enough to make the helium measurement worthwhile as a check on a possibly anomalous argon age, especially in a system where the additional labor required to make the helium is minimal. The Columbia River basalt from which standard samples BCR-1 and BCR-2 were prepared was also dated. Its uranium-thorium-helium “age”, 4.45 ± 0.24 m.y. shows that this rock has retained even less of its radiogenic helium (30%) than the island basalts.
We have confirmed reports by Rowe et al. indicating that a strong (4.6 kOe) magnetic field influe... more We have confirmed reports by Rowe et al. indicating that a strong (4.6 kOe) magnetic field influences the rate of reduction of some cobalt and iron oxides. In addition to our earlier gravimetric methods, we simultaneously carried out an evolved gas analysis such as that described by Gallagher et al. The discrepant results may arise from differences in experimental conditions used by the two groups. We used isothermal reduction, whereas Gallagher et al. used constantly increasing temperatures. Perhaps the latter are not sensitive to small changes in rate. (AIP)
Recent advances in plasma chemistry (1-3) have yielded impressive results and hold great promise ... more Recent advances in plasma chemistry (1-3) have yielded impressive results and hold great promise for meteoritic studies. Our initial experiments (4, unpublished data) indicate that low temperature oxygen plasmas may be effective in extracting noble gases from cosmological samples. One notable advantage is that the noble gases are extracted at temperatures ≤ 250 °C. This reduces background problems associated with the high temperatures necessary for complete gas extraction in ultra-high vacuum heating. Additionally, problems of high temperature diffusive mixing of the component gases are alleviated. Furthermore, the oxygen plasma releases the noble gases from the carbonaceous car rier(s), via oxidation of the carrier to CO(g), C02(g) and H20(g), before significant gas release begins from the other components of the sample. This allows the separation and measurement of the noble gases from the carbonaceous carrier as well as the rest of the meteorite in a single sample. Presented at the 54th Annual Meeting of the Meteoritical Society
Journal of Environmental Science and Health . Part A: Environmental Science and Engineering and Toxicology, 1990
The chemical environment of barium in Portland cement which is doped with barium nitrate was inve... more The chemical environment of barium in Portland cement which is doped with barium nitrate was investigated using x‐ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR). The barium doped cement showed tremendous increases in carbonate content over the undoped cement. An XPS sulfate signal was observed in the cement doped with 20% w/w Ba(NO3)2 but not in the 0
ABSTRACT An overview of this subject is presented. The paper includes a glossary of magnetism ter... more ABSTRACT An overview of this subject is presented. The paper includes a glossary of magnetism terminology and a discussion of magnetic techniques used in meteorite research. These techniques comprise thermomagnetic analysis, alternating field demagnetization, thermal demagnetization, magnetic anisotropy, low-temperature cycling, and coercive forces, with emphasis on the first method. Limitations on the validity of paleointensity determinations are also discussed.
Many of the unusual magnetite morphologies previously observed only in the CI chondrites have bee... more Many of the unusual magnetite morphologies previously observed only in the CI chondrites have been seen in the CM chondrites, Essebi and Haripura. These include: heavily textured spheroids, which are possibly spherulites, found both singly and in groups of up to a dozen and ranging in size from ~4 to 10 Pm in diameter; collections of microcrystals varying from ~0.3 to 6 ym in diameter; spheres of ~1 to 6 ym in diameter; layered, nearly circular plates, forming a spheroidal plaquette ~7.5 pm in diameter; clusters of variable sized nodules, ~1.5 to 6 ym, with concave features; framboidal magnetite; and finally collections of less distinctive globules.
... The General Electric group, along with Lea-key (11) conducted FT measurements on volcanic gla... more ... The General Electric group, along with Lea-key (11) conducted FT measurements on volcanic glass at the Olduvai Gorge site from the same deposit previously dated by 40K-40Ar. ... encountered when a heavy nucleus recoils from an a parhe emission (12). ...
An overview is presented on the efforts being made to estimate the time that the magnetic field(s... more An overview is presented on the efforts being made to estimate the time that the magnetic field(s) existed and acted on meteorite parent bodies. The basic premise is that if a sample exhibits a low K-Ar age, it is the requisite amount of Ar-40. This assumption is applied to a preliminary analysis of the Farmington chondrite.
... We have rather arbitrarily selected a Ba value of 2 ppm to be used for Pena Blanca Spring. ..... more ... We have rather arbitrarily selected a Ba value of 2 ppm to be used for Pena Blanca Spring. ... 4A. GW Cameron, in The Origin and Evolution of Atmospheres and Oceans, edited by PJ Brancazio and AGW Cameron (John Wiley & Sons, Inc., New York, 1964), Chap. 10. 5P. ...
ABSTRACT The error involved in the determination of the Al26 concentration by the method of Rowe ... more ABSTRACT The error involved in the determination of the Al26 concentration by the method of Rowe and his co-workers was measured and the values they reported should be increased by a factor of 1.36 ± 0.05. The potassium contents of the meteorites measured by Roweet al., are not affected by this error and can be used with confidence.
Abstract Uranium-helium “ages” have been determined for a suite of 25 whole-rock basalts from Mad... more Abstract Uranium-helium “ages” have been determined for a suite of 25 whole-rock basalts from Madeira and Porto Santo islands in the Madeira Archipelago. We include petrographic descriptions of these samples. Uranium measurements were by delayed-neutron activation analysis. Helium measurements were by isotopic dilution in an all-metal system characterized by very low argon and helium blanks. For 19 of the samples “preferred” K Ar ages were also obtained. None of the rocks are concordant in these two ages; all have lost helium. The uranium-helium “ages” are best described, on the average, as equal to 74% of the K Ar ages minus 0.2 m.y. Nevertheless in our suite of young, chemically similar lavas the correlation between the K Ar age and the helium content is good enough to make the helium measurement worthwhile as a check on a possibly anomalous argon age, especially in a system where the additional labor required to make the helium is minimal. The Columbia River basalt from which standard samples BCR-1 and BCR-2 were prepared was also dated. Its uranium-thorium-helium “age”, 4.45 ± 0.24 m.y. shows that this rock has retained even less of its radiogenic helium (30%) than the island basalts.
We have confirmed reports by Rowe et al. indicating that a strong (4.6 kOe) magnetic field influe... more We have confirmed reports by Rowe et al. indicating that a strong (4.6 kOe) magnetic field influences the rate of reduction of some cobalt and iron oxides. In addition to our earlier gravimetric methods, we simultaneously carried out an evolved gas analysis such as that described by Gallagher et al. The discrepant results may arise from differences in experimental conditions used by the two groups. We used isothermal reduction, whereas Gallagher et al. used constantly increasing temperatures. Perhaps the latter are not sensitive to small changes in rate. (AIP)
Recent advances in plasma chemistry (1-3) have yielded impressive results and hold great promise ... more Recent advances in plasma chemistry (1-3) have yielded impressive results and hold great promise for meteoritic studies. Our initial experiments (4, unpublished data) indicate that low temperature oxygen plasmas may be effective in extracting noble gases from cosmological samples. One notable advantage is that the noble gases are extracted at temperatures ≤ 250 °C. This reduces background problems associated with the high temperatures necessary for complete gas extraction in ultra-high vacuum heating. Additionally, problems of high temperature diffusive mixing of the component gases are alleviated. Furthermore, the oxygen plasma releases the noble gases from the carbonaceous car rier(s), via oxidation of the carrier to CO(g), C02(g) and H20(g), before significant gas release begins from the other components of the sample. This allows the separation and measurement of the noble gases from the carbonaceous carrier as well as the rest of the meteorite in a single sample. Presented at the 54th Annual Meeting of the Meteoritical Society
Journal of Environmental Science and Health . Part A: Environmental Science and Engineering and Toxicology, 1990
The chemical environment of barium in Portland cement which is doped with barium nitrate was inve... more The chemical environment of barium in Portland cement which is doped with barium nitrate was investigated using x‐ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR). The barium doped cement showed tremendous increases in carbonate content over the undoped cement. An XPS sulfate signal was observed in the cement doped with 20% w/w Ba(NO3)2 but not in the 0
ABSTRACT An overview of this subject is presented. The paper includes a glossary of magnetism ter... more ABSTRACT An overview of this subject is presented. The paper includes a glossary of magnetism terminology and a discussion of magnetic techniques used in meteorite research. These techniques comprise thermomagnetic analysis, alternating field demagnetization, thermal demagnetization, magnetic anisotropy, low-temperature cycling, and coercive forces, with emphasis on the first method. Limitations on the validity of paleointensity determinations are also discussed.
Many of the unusual magnetite morphologies previously observed only in the CI chondrites have bee... more Many of the unusual magnetite morphologies previously observed only in the CI chondrites have been seen in the CM chondrites, Essebi and Haripura. These include: heavily textured spheroids, which are possibly spherulites, found both singly and in groups of up to a dozen and ranging in size from ~4 to 10 Pm in diameter; collections of microcrystals varying from ~0.3 to 6 ym in diameter; spheres of ~1 to 6 ym in diameter; layered, nearly circular plates, forming a spheroidal plaquette ~7.5 pm in diameter; clusters of variable sized nodules, ~1.5 to 6 ym, with concave features; framboidal magnetite; and finally collections of less distinctive globules.
... The General Electric group, along with Lea-key (11) conducted FT measurements on volcanic gla... more ... The General Electric group, along with Lea-key (11) conducted FT measurements on volcanic glass at the Olduvai Gorge site from the same deposit previously dated by 40K-40Ar. ... encountered when a heavy nucleus recoils from an a parhe emission (12). ...
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Papers by Marvin W Rowe