Element mobility due to weathering in the L5 Bayard chondrite

Abstract— In order to assess weathering effects, sixteen elements were determined by neutron activation in the surficial layer and the interior of the extensively weathered Bayard L5 chondrite. Na, As, Sb, La and Sm show enrichment in the surface; for these elements soil concentrations are greater than in the meteorite. Elements showing no significant differences between surface and interior are Sc, Cr, Fe, Co, Ni, Zn, Se, Eu, Yb, Ir and Au; with the exception of Eu and Yb, soil concentrations were lower than those in the chondrite. Concentrations of Fe, Ni and Co, and to some extent Na, are lower than the mean of the L-chondrite values probably due to oxidation and leaching from the chondrite. The data support an L classification for the Bayard chondrite.     

The effect of mining and related activities on the sediment–trace element geochemistry of Lake Coeur d'Alene,Idaho, USA. Part III. Downstream effects: the Spokane River Basin

During 1998/1999, surface and subsurface sediment samples were collected along the entire length of the Spokane River from its outlet at the northern end of Lake Coeur d'Alene (CDA), Idaho, to Lake Roosevelt on the Columbia River, Washington. The study was conducted to determine if the trace element enrichments observed in Lake CDA and on the floodplain and in the CDA River extend through the Spokane River Basin (SRB). As in Lake CDA, surface sediments in the SRB are enriched in Pb, Zn, As, Cd, Sb and Hg relative to local background levels. Pb, Cd and Zn are the most elevated, with maximum enrichment occurring in the upper Spokane River in close proximity to Lake CDA. On average, enrichment decreases downstream, apparently reflecting both increased distance from the inferred source (the CDA River Basin), as well as increased dilution by locally derived but unenriched materials. Only Cd and Zn display marked enrichment throughout the SRB. Pb, Zn and Cd seem to be associated mainly with an operationally defined iron oxide phase, whereas the majority of the As and Sb seem to be matrix‐held. Subsurface sediments also are enriched in Pb, Zn, As, Cd, Sb and Hg relative to background levels. Based on ¹³⁷Cs and excess ²¹⁰Pb dating, trace element enrichment began in the middle part of the SRB (Long Lake) between 1900 and 1920. This is contemporaneous with similar enrichments observed in Lake CDA, as well as the completion of Long Lake Dam (1913). In the most downstream part of the basin (Spokane River Arm of Lake Roosevelt), enrichment began substantially later, between 1930 and 1940. The temporal difference in enrichment between Long Lake and the River Arm may reflect the latter's greater distance from the presumed source of the enrichment (the CDA River Basin); however, the difference is more likely the result of the completion of Grand Coulee Dam (1934–1941), which formed Lake Roosevelt, backed up the Spokane River, and increased water levels in the River Arm by about 30 m.     

Observations of the 4000 Å break strength in the spectra of elliptical and S0 galaxies

Spectrophotometric observations of the 4000 Å break strength in a large sample of nearby E and S0 galaxies are described. A tight relationship between luminosity and break strength is found, though it is too shallow at the bright end to serve as a useful distance indicator. Correlations are found between the break strength and various metal lines, Balmer lines, and the Greenwich gradient, which demonstrate the sensitivity of the break to both metallicity and composite temperature effects.     

The Travis County,Texas, meteorites

Abstract— Studies of 52 specimens recovered from the find site of the original Travis County meteorite reveal the presence of two distinct meteorites. Travis County (a), which includes the original Travis County meteorite, is the more abundant meteorite and is classified as an H5(S4) shock-blackened chondrite. Travis County (b) is classified as an H4(S2) chondrite with rare chondritic clasts of H group parentage, indicating that the meteorite is a breccia.     

Lunar crater depths from orbiter IV long-focus photographs

The paper presents method and results for the determination of the depths of more than 1900 small lunar craters from measures of shadows on the long-focus pictures obtained by Lunar Orbiter IV. The method for converting the measured shadow length into the true length in nature of the shadow hypotenuse is new and is applicable to other planetary bodies provided comparable spacecraft ephemerides are available. The measures were made with a simple surveyor's plotting scale on the standard Orbiter IV photographic enlargements. The results indicate that the smaller lunar (D < 30 km) craters are appreciably deeper than is indicated by earlier work using imagery obtained at terrestrial observatories.     

Possible effect of subsurface inhomogeneities on the lunar microwave spectrum

Inhomogeneities beneath the lunar surface could alter the average microwave emission spectrum of the Moon in a fashion generally consistent with observations, even in the absence of an average heat flux or density gradients with depth. The lunar subsurface was modeled as an inhomogeneous lossy dielectric with three-dimensional refractive index fluctuations characterized by independent horizontal and vertical correlation lengths. The model suggests that attempts to infer the physical properties of the Moon from the lunar microwave spectrum could be significantly inaccurate if subsurface scattering were neglected.