Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have... more Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have the potential to provide not only compositional information about both the local and regional geology of the Moon but also information about the impact flux over time. We present in this paper the results of 73 new 40 Ar/ 39 Ar analyses of well-characterized, inclusion-free lunar impact glasses and demonstrate that size, shape, chemical composition, fraction of radiogenic 40 Ar retained, and cosmic ray exposure (CRE) ages are important for 40 Ar/ 39 Ar investigations of these samples. Specifically, analyses of lunar impact glasses from the Apollo 14, 16, and 17 landing sites indicate that retention of radiogenic 40 Ar is a strong function of post-formation thermal history in the lunar regolith, size, and chemical composition. This is because the Ar diffusion coefficient (at a constant temperature) is estimated to decrease by ~3-4 orders of magnitude with an increasing fraction of non-bridging oxygens, X(NBO), over the compositional range of most lunar impact glasses with compositions from feldspathic to basaltic. Based on these relationships, lunar impact glasses with compositions and sizes sufficient to have retained ~90% of their radiogenic Ar during 750 Ma of cosmic ray exposure at time-integrated temperatures of up to 290K have been identified and are likely to have yielded reliable 40 Ar/ 39 Ar ages of formation. Additionally, ~50% of the identified impact glass spheres have formation ages of 500 Ma, while ~75% of the identified lunar impact glass shards and spheres have ages of formation 2000 Ma. Higher thermal stresses in lunar impact glasses quenched from hyperliquidus temperatures are considered the likely cause of poor survival of impact glass spheres, as well as the decreasing frequency of lunar impact glasses in general with increasing age. The observed age-frequency distribution of lunar impact glasses may reflect two processes: (i) diminished preservation due to spontaneous shattering with age; and (ii) preservation of a remnant population of impact glasses from the tail end of the terminal lunar bombardment having 40 Ar/ 39 Ar ages up to 3800 Ma. A protocol is described for selecting and analysing lunar impact glasses.
1200 kilometers of boundaries surveyed in 1685-1910 and marked by stone walls were measured usi... more 1200 kilometers of boundaries surveyed in 1685-1910 and marked by stone walls were measured using LiDAR (Light Detection and Ranging) images With the exception of lower declinations (i.e., 1.5 degrees eastward) in 1775-1810, the results are in good agree with the gufm1 and IGRF12 geomagnetic field models When associated with accurate land surveys, durable, human-engineered structures on land (e.g., stone walls; roads) contain information about geomagnetic declination
Purpose This paper aims to describe a multifaceted campus-wide initiative to retain transfer stud... more Purpose This paper aims to describe a multifaceted campus-wide initiative to retain transfer students that was undertaken when it was recognized that their retention rates were lower than those of first-time, full-time students. Design/methodology/approach The Enhancing Student Experience (ESE) Working Group at the University at Albany (UAlbany) brought together key parties from Student Affairs and academic units, including the University Libraries, and provided an energizing arena in which existing student engagement and retention endeavors were discussed and coordinated, and new initiatives were inspired. Findings This paper reflects the work of a subcommittee of the ESE group that focused on developing strategies to increase the retention rate of students who transferred to UAlbany, and identifying characteristics of those first-time, full-time students who transferred from UAlbany. The efforts discussed in this paper, which were guided by professional experiences, institutional ...
Lunar and Planetary Science Conference, Mar 1, 1996
... [2] Shearer CK et a!. (1994) Geochim. Cosmochim. Acta, 58, p. 53495362. [3] Longhi J. (1987) ... more ... [2] Shearer CK et a!. (1994) Geochim. Cosmochim. Acta, 58, p. 53495362. [3] Longhi J. (1987) PLPSC 17, p. 349-360. [4] Delano JW and McGuire J. (1992) LPI Tech. Rpt. 92-09, p. 7-9. [5]Delano JW et al. (1994) LPS-XXV, p. 325-326. [6] Hanson B. et al. (1996) Amer. ...
Journal of the American Chemical Society, Oct 1, 2009
The montmorillonite clay-catalyzed reactions of nucleotides generate oligomers as long as 50mers.... more The montmorillonite clay-catalyzed reactions of nucleotides generate oligomers as long as 50mers. The extent of catalysis depends on the magnitude of the negative charge on the montmorillonite lattice and the number of cations associated with it. When cations in raw montmorillonites are replaced by sodium ions, the resulting Na +-montmorillonite does not catalyze oligomer formation because they saturate the interlayers between the platelets of montmorillonites, which blocks the binding of the activated monomers. Treating the montmorillonite with dilute hydrochloric acid replaces the cations on the raw montmorillonite with protons. The protonated montmorillonite, titrated to pH 6-7, serves as a catalyst for the formation of RNA oligomers. The titration does not add sufficient sodium ions to the interlayers of the montmorillonite platelets to prevent the activated monomer from entering. It was noted that noncatalytic montmorillonites have a higher negative charge on their platelets that is due mainly to the natural substitution of the tetravalent and trivalent elements in the montmorillonite lattice with trivalent and divalent metal ions, respectively. The larger negative charge on these montmorillonites was demonstrated by the almost 2-fold greater amounts of sodium hydroxide needed to titrate noncatalytic montmorillonites as compared to the catalytic montmorillonites. Adsorption isotherms established that the equilibrium binding is strongest for ImpA and weakest for ImpU. Of the 22 montmorillonites investigated, 12 were catalysts. This research provides insight into the mechanism of the catalytic process.
ABSTRACT The 40Ar/39Ar technique applied to impact glass has been used to date both terrestrial a... more ABSTRACT The 40Ar/39Ar technique applied to impact glass has been used to date both terrestrial and lunar impact events. The ability to utilize the 40Ar/39Ar technique rests on the assumption that impact glasses are closed to the loss of daughter product, 40Ar∗, after formation. Diffusion experiments were performed on three Apollo 16 lunar impact glasses and yielded activation energies for 39Ar of ∼17 to 20 kcal mol-1 and log10(D0/a2) values of -5.2 to -6.0 s-1. The resulting diffusion coefficients are interpreted as minimum values and the Apollo 16 glass is probably some of the least retentive of lunar glasses, as the degree of non-bridging oxygen is at one end of the range in lunar glasses. At temperatures below the glass transition temperature (i.e., ∼660°C), the data can be explained by volume diffusion from a single diffusion domain. Modeling shows that Apollo 16 composition glass could lose significant quantities of radiogenic argon (40Ar∗) (∼90-100% over 20-40 Myr assuming a diffusion domain size (a) of 75 μm) due to diurnal temperature variations on the lunar surface, although 40Ar∗ loss is highly sensitive to exposure duration and effective diffusion domain size. Modeling shows that loss from transient thermal events (e.g., heating to ∼200°C for 102 yr duration) can also cause partial resetting of apparent 40Ar/39Ar ages. In small (a=75 μm) glasses a maximum of 50-60% of 40Ar∗ is lost over 4 Ga when buried to depths corresponding to temperatures of -15°C. Results indicate that caution should be exercised in interpreting lunar impact glass 40Ar/39Ar ages, as the assumption of closed system behavior may have been violated, particularly in glasses with low fractions of non-bridging oxygen.
Chrome rich spinel is a detrital component in turbidites from the well-exposed, mid-late Cretaceo... more Chrome rich spinel is a detrital component in turbidites from the well-exposed, mid-late Cretaceous "Tianba Flysch" sequence in the Nieru Valley, southern Tibet. Microprobe results indicate that the spinels have a well-developed Fe-Ti trend, and have Cr/(Cr+Al) 0.4-0.65, Mg/(Mg+Fe2+) 0.3-0.9, and TiO2 >1 wt.%. The compositional range of these detrital spinels closely matches that of spinels from intra-plate basalts, and
Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have... more Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have the potential to provide not only compositional information about both the local and regional geology of the Moon but also information about the impact flux over time. We present in this paper the results of 73 new 40 Ar/ 39 Ar analyses of well-characterized, inclusion-free lunar impact glasses and demonstrate that size, shape, chemical composition, fraction of radiogenic 40 Ar retained, and cosmic ray exposure (CRE) ages are important for 40 Ar/ 39 Ar investigations of these samples. Specifically, analyses of lunar impact glasses from the Apollo 14, 16, and 17 landing sites indicate that retention of radiogenic 40 Ar is a strong function of post-formation thermal history in the lunar regolith, size, and chemical composition. This is because the Ar diffusion coefficient (at a constant temperature) is estimated to decrease by ~3-4 orders of magnitude with an increasing fraction of non-bridging oxygens, X(NBO), over the compositional range of most lunar impact glasses with compositions from feldspathic to basaltic. Based on these relationships, lunar impact glasses with compositions and sizes sufficient to have retained ~90% of their radiogenic Ar during 750 Ma of cosmic ray exposure at time-integrated temperatures of up to 290K have been identified and are likely to have yielded reliable 40 Ar/ 39 Ar ages of formation. Additionally, ~50% of the identified impact glass spheres have formation ages of 500 Ma, while ~75% of the identified lunar impact glass shards and spheres have ages of formation 2000 Ma. Higher thermal stresses in lunar impact glasses quenched from hyperliquidus temperatures are considered the likely cause of poor survival of impact glass spheres, as well as the decreasing frequency of lunar impact glasses in general with increasing age. The observed age-frequency distribution of lunar impact glasses may reflect two processes: (i) diminished preservation due to spontaneous shattering with age; and (ii) preservation of a remnant population of impact glasses from the tail end of the terminal lunar bombardment having 40 Ar/ 39 Ar ages up to 3800 Ma. A protocol is described for selecting and analysing lunar impact glasses.
1200 kilometers of boundaries surveyed in 1685-1910 and marked by stone walls were measured usi... more 1200 kilometers of boundaries surveyed in 1685-1910 and marked by stone walls were measured using LiDAR (Light Detection and Ranging) images With the exception of lower declinations (i.e., 1.5 degrees eastward) in 1775-1810, the results are in good agree with the gufm1 and IGRF12 geomagnetic field models When associated with accurate land surveys, durable, human-engineered structures on land (e.g., stone walls; roads) contain information about geomagnetic declination
Purpose This paper aims to describe a multifaceted campus-wide initiative to retain transfer stud... more Purpose This paper aims to describe a multifaceted campus-wide initiative to retain transfer students that was undertaken when it was recognized that their retention rates were lower than those of first-time, full-time students. Design/methodology/approach The Enhancing Student Experience (ESE) Working Group at the University at Albany (UAlbany) brought together key parties from Student Affairs and academic units, including the University Libraries, and provided an energizing arena in which existing student engagement and retention endeavors were discussed and coordinated, and new initiatives were inspired. Findings This paper reflects the work of a subcommittee of the ESE group that focused on developing strategies to increase the retention rate of students who transferred to UAlbany, and identifying characteristics of those first-time, full-time students who transferred from UAlbany. The efforts discussed in this paper, which were guided by professional experiences, institutional ...
Lunar and Planetary Science Conference, Mar 1, 1996
... [2] Shearer CK et a!. (1994) Geochim. Cosmochim. Acta, 58, p. 53495362. [3] Longhi J. (1987) ... more ... [2] Shearer CK et a!. (1994) Geochim. Cosmochim. Acta, 58, p. 53495362. [3] Longhi J. (1987) PLPSC 17, p. 349-360. [4] Delano JW and McGuire J. (1992) LPI Tech. Rpt. 92-09, p. 7-9. [5]Delano JW et al. (1994) LPS-XXV, p. 325-326. [6] Hanson B. et al. (1996) Amer. ...
Journal of the American Chemical Society, Oct 1, 2009
The montmorillonite clay-catalyzed reactions of nucleotides generate oligomers as long as 50mers.... more The montmorillonite clay-catalyzed reactions of nucleotides generate oligomers as long as 50mers. The extent of catalysis depends on the magnitude of the negative charge on the montmorillonite lattice and the number of cations associated with it. When cations in raw montmorillonites are replaced by sodium ions, the resulting Na +-montmorillonite does not catalyze oligomer formation because they saturate the interlayers between the platelets of montmorillonites, which blocks the binding of the activated monomers. Treating the montmorillonite with dilute hydrochloric acid replaces the cations on the raw montmorillonite with protons. The protonated montmorillonite, titrated to pH 6-7, serves as a catalyst for the formation of RNA oligomers. The titration does not add sufficient sodium ions to the interlayers of the montmorillonite platelets to prevent the activated monomer from entering. It was noted that noncatalytic montmorillonites have a higher negative charge on their platelets that is due mainly to the natural substitution of the tetravalent and trivalent elements in the montmorillonite lattice with trivalent and divalent metal ions, respectively. The larger negative charge on these montmorillonites was demonstrated by the almost 2-fold greater amounts of sodium hydroxide needed to titrate noncatalytic montmorillonites as compared to the catalytic montmorillonites. Adsorption isotherms established that the equilibrium binding is strongest for ImpA and weakest for ImpU. Of the 22 montmorillonites investigated, 12 were catalysts. This research provides insight into the mechanism of the catalytic process.
ABSTRACT The 40Ar/39Ar technique applied to impact glass has been used to date both terrestrial a... more ABSTRACT The 40Ar/39Ar technique applied to impact glass has been used to date both terrestrial and lunar impact events. The ability to utilize the 40Ar/39Ar technique rests on the assumption that impact glasses are closed to the loss of daughter product, 40Ar∗, after formation. Diffusion experiments were performed on three Apollo 16 lunar impact glasses and yielded activation energies for 39Ar of ∼17 to 20 kcal mol-1 and log10(D0/a2) values of -5.2 to -6.0 s-1. The resulting diffusion coefficients are interpreted as minimum values and the Apollo 16 glass is probably some of the least retentive of lunar glasses, as the degree of non-bridging oxygen is at one end of the range in lunar glasses. At temperatures below the glass transition temperature (i.e., ∼660°C), the data can be explained by volume diffusion from a single diffusion domain. Modeling shows that Apollo 16 composition glass could lose significant quantities of radiogenic argon (40Ar∗) (∼90-100% over 20-40 Myr assuming a diffusion domain size (a) of 75 μm) due to diurnal temperature variations on the lunar surface, although 40Ar∗ loss is highly sensitive to exposure duration and effective diffusion domain size. Modeling shows that loss from transient thermal events (e.g., heating to ∼200°C for 102 yr duration) can also cause partial resetting of apparent 40Ar/39Ar ages. In small (a=75 μm) glasses a maximum of 50-60% of 40Ar∗ is lost over 4 Ga when buried to depths corresponding to temperatures of -15°C. Results indicate that caution should be exercised in interpreting lunar impact glass 40Ar/39Ar ages, as the assumption of closed system behavior may have been violated, particularly in glasses with low fractions of non-bridging oxygen.
Chrome rich spinel is a detrital component in turbidites from the well-exposed, mid-late Cretaceo... more Chrome rich spinel is a detrital component in turbidites from the well-exposed, mid-late Cretaceous "Tianba Flysch" sequence in the Nieru Valley, southern Tibet. Microprobe results indicate that the spinels have a well-developed Fe-Ti trend, and have Cr/(Cr+Al) 0.4-0.65, Mg/(Mg+Fe2+) 0.3-0.9, and TiO2 >1 wt.%. The compositional range of these detrital spinels closely matches that of spinels from intra-plate basalts, and
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