Analyses of Apollo 11 and 12 rocks and soils by neutron activation

Neutron activation analysis of Apollo 11 and 12 rocks and soils, and X ray fluorescence and radiochemistry dat

The causes for geographical variations in OS187/OS186 at the Cretaceous-Tertiary boundary

Researchers at Yale has approached the problem of the osmium isotopic composition of marine deposits formed in contact with both oxidized and reduced bottom waters. The measured (187) Os/(186) Os ratios of modern bulk sediment can be explained using mixing equations involving continental detrital, volcaniclastic, cosmogenic and hydrogeneous components. These studies show that sediments deposited under reducing marine conditions contain a hydrogenous component which is enriched in Re and has a radiogenic (187) Os/(186) Os ratio. The presence of such a hydrogenous component in the marine fish clay at Stevns Klint can account for the elevation of its (187) Os/(186) Os ration above the expected meteoritic value. Mass balance considerations require the Re/Os ratio of the phase precipitated from the terminal Cretaceous sea at Stevns Klint to have been about one tenth the value observed in contemporary deposits in the Black Sea, assuming Re has not been lost (or Os gained) subsequent to precipitation. In continental sections, the elevation of the (187) Os/(186) Os ratio in boundary layers may be due to precipitation from continental waters of crustally-derived radiogenic osmium either contemporaneous with the meteoritic (or mantle) osmium deposition or later during diagenesis

The meteorite and tektite collections of Yale University

The last catalogue of the meteorite collections at Yale University was made by Kurt Servos (1956) and included the Peabody Museum Collection and the Bosch Collection which was provisionally deposited at Yale University in 1949…

George Veronis: An appreciation

George Veronis was born in New Brunswick, New Jersey on June 3, 1926, one of six accomplished children of a Greek immigrant couple. He grew up in Easton, Pennsylvania, where his talent for mathematics was recognized early on. World War II interrupted his education, however, and he enlisted in the U.S. Navy where he served aboard submarines in the Pacific Ocean. With the end of the global conflict, George entered college on the G.I. Bill and graduated with a B.S. in Mathematics from nearby Lafayette College in 1950..

Magnesium, strontium, and barium concentrations and calcite-aragonite ratios of some recent molluscan shells

Approximately 100 recent molluscan shells have been analyzed spectrographically for Mg, Sr and Ba; their calcite-aragonite ratios were determined by X-ray diffraction. The methods are described in detail. The most important parameter controlling the concentration of these trace elements in calcium carbonate shells appears to be generic association rather than water temperature or calcite-aragonite ratio of the shell. As a group, snails are higher in Mg and lower in Sr and Ba than clams...

Δ14C balance for the Gulf of Maine, Long Island Sound and the northern Middle Atlantic Bight: Evidence for the extent of the Antarctic Intermediate Water contribution

The radiocarbon signatures of the western Sargasso Sea and the atmosphere as a function of time over the past 200 years are known. These can be combined with seawater dissolved inorganic carbon (DIC) radiocarbon data from the Gulf of Maine and the northern Middle Atlantic Bight (MAB), including Long Island Sound (LIS), for 1983 and pre-1955 shell analyses for radiocarbon, to set the amount of Antarctic Intermediate Water (AAIW) required to balance the 14C budget in the northern MAB. Approximately 40% of the water entering the Middle Atlantic Bight from the north must be AAIW, the other 60% being Sargasso Sea water. Contemporary water from LIS, a part of northern MAB, can be explained as a mixture of Sargasso Sea water and Gulf of Maine water but at times in the past more low-14C water (AAIW) was added to this mixture as recorded in shells from LIS. This implies variations in upwelling rates over time in the region of the Middle Atlantic Bight

Climatic Implications of Barbados Coral Growth

Results from a coral growth band analysis utilizing samples of M. annularis from the Recent Barbados reef and from three fossil raised reefs (Barbados I, II, and III dated at 82,000, 105,000, and 125,000 yrs. B.P.) indicate that in the Barbados II collection both average band width and variability were lower than in the other samples. We suggest the climate during formation of the 105,000 yrs. B.P. reef was significantly different than that of the present

Lead Precipitation Fluxes at Tropical Oceanic Sites Determined From ^(210)Pb Measurements

Concentrations of lead, ^(210)Pb, and ^(210)Po were measured in rain selected for least influence by local sources of contamination at several tropical and subtropical islands (Enewetak; Pigeon Key, Florida; and American Samoa) and shipboard stations (near Bermuda and Tahiti). Ratios expressed as ng Pb/dpm ^(210)Pb in rain were 250–900 for Pigeon Key (assuming 12% adsorption for ^(210)Pb and no adsorption for lead), depending on whether the air masses containing the analyzed rain came from the Caribbean or from the continent, respectively; about 390 for the northern Sargasso Sea downwind from emissions of industrial lead in North America; 65 for Enewetak, remote from continental emissions of industrial lead in the northern hemisphere; and 14 near Tahiti, a remote location in the southern hemisphere where industrial lead emissions to the atmosphere are much less than in the northern hemisphere. (The American Samoa sample yielded a higher ratio than Tahiti; the reason for this is not clear but may be due to local Pb sources.) The corresponding fluxes of lead to the oceans, based on measured or modeled ^(210)Pb precipitation fluxes, are about 4 ng Pb/cm^2y for Tahiti, 10 for Enewetak, and 270 for the Sargasso Sea site, and between 110 to 390 at Pigeon Key

A 200 Year Record of Carbon-13 and Carbon-14 Variations in a Bermuda Coral

A 200 year old brain coral, captured in Bermuda in 1976 was slabbed and x-rayed. Using the annual growth bands sequential, dated samples were taken over the entire growth period of the coral and analyzed for Δ14C, δ13C and δ18O. During the past 80 years atmospheric variations in Δ14C and δ13C due to human effects, such as release of bomb C-14 and dilution of both C-14 and C-13 by fossil fuel burning, are closely tracked by the coral. Prior to 1900 divergences between the coral and tree Δ14C and δ13C can be related to world-wide changes in plant production and possibly oceanic upwelling rates

The effect of weathering regime on uranium decay series and osmium in two soil profiles

Two soil profiles from the United States with radically different emplacement and climatic histories were analyzed for U, Th and members of the 238U decay series (234U, 230Th, 226Ra, 210Pb), 137Cs and osmium isotopes. The arid New Mexico profile is developed on an approximately 250,000 years old colluvium while the temperate New Hampshire profile is formed on till after the last glaciation at about 10,000 years ago. Both the profiles show significant 234U/238U, 230Th/234U and 226Ra/230Th disequilibria, however, in the New Hampshire profile, the disequilibria are far more pronounced in mid-depths (20-50 cm). High Os concentration with highly radiogenic 187Os/188Os is another characteristic of the mid-depths of the New Hampshire profile. This layer, particularly at about 30-40 cm depth has the characteristics of a soil developed on black shale, as evidenced from both the high U and Os concentrations and the large excess of 230Th over 238U. This profile clearly shows that the regolith on which the contemporary soil is developing was not homogeneous. The presence of measurable excess 226Ra activity over 230Th activity in both profiles suggests the need for a source of 226Ra external to the regolith in both cases. Atmospheric deposition of 226Ra is a possible source for this 226Ra excess and brings to light the important role of atmospheric deposiion of nuclides and their transport in the soil profile in pedogenic processes. It also shows that regolith developed by glacial processes need not be homogeneous, thereby confounding the understanding of vertically modified soil profiles