Stable isotopic studies of H,C,N,O and S in samples of Martian origin

The present day geochemical cycles of volatile elements through the various reservoirs on Earth are largely understood within the context of the planet's standing as a geologically and biologically evolved body. In terrestrial studies stable isotope measurements of light elements (H, C, N, O and S) can be utilized to obtain insight into the conditions prevailing during formation of rocks of various types. Perhaps the most important problem which could be addressed by light element studies of the sorts of specimen likely to be available from remote automatic sampling, would be the role of volatiles during evolution. Of fundamental importance here is the question of whether Mars was volatile rich or volatile poor. The only way to fully comprehend the effects of volatile cycling through the mantle crust and regolith atmosphere polar cap system of Mars, is by analyses of appropriate returned samples. In order to interpret the record of geological activity in Martian samples it will be necessary to understand how the past, or present, surface environment may have acted to disturb the primary characteristics of the rocks

Lunar nitrogen: Secular variation or mixing?

The two current models to explain the nearly 40% variation of the lunar nitrogen isotopic composition are: (1) secular variation of solar wind nitrogen; and (2) a two component mixing model having a constant, heavy solar wind admixed with varying amounts of indigenous light lunar N (LLN). Both models are needed to explain the step pyrolysis extraction profile. The secular variation model proposes that the low temperature release is modern day solar wind implanted into grain surfaces, the 900 C to 1100 C release is from grain surfaces which were once exposed to the ancient solar wind but which are now trapped inside agglutinates, and the >1100 C release as spallogenic N produced by cosmic rays. The mixing model ascribes the components to solar wind, indigenous lunar N and spallogenic N respectively. An extension of either interpretation is that the light N seen in lunar breccias or deep drill cores represent conditions when more N-14 was available to the lunar surface

The Distribution of Ar and Xe Inside Diamond Grains from Efremovka

Analysis of the release pattern of Ar and Xe from grain size fractions of Efremovka presolar diamonds at stepped combustion and pyrolysis indicates that in both cases the gases release as a result of destruction of the diamond lattice

The carbon and nitrogen stable isotope geochemistry of two lunar meteorites: ALHA-81005 and Y-86032

The carbon and nitrogen stable isotope geochemistry of two lunar meteorites, ALHA-81005 and Y-86032 has been compared with that of an Apollo 16 regolith breccia, 60016. Although much of the carbon present in all three samples is terrestrial organic contamination, the meteorites have higher carbon abundances and lighter isotopic compositions than 60016. The non-contaminant carbon in ALHA-81005 and Y-86032 occurs as two distinct components, combusting between 550-700℃ and 900-1100℃. Since these components are absent from the pristine lunar breccia, they must have been added (i) from the impactor which ejected the meteorites from the Moon; (ii) in the Antarctic or (iii) be representative of a lunar environment not sampled by Apollo missions. At temperatures over 1100℃, spallogenic carbon combusts, with elevated δ^C, greater than 0‰. Nitrogen systematics are less-well resolved than carbon, partly due to the lower amounts of nitrogen gas liberated by the meteorites. Nitrogen abundance of ALHA-81005 and Y-86032 fall in the range of values from lunar breccias and δ^N values follow the heavy-light-heavy pattern characteristic of such samples. Spallogenic carbon and nitrogen are more abundant in ALHA-81005 than Y-86032,in keeping with its longer exposure age. Nitrogen data are consistent with identification of ALHA-81005 and Y-86032 as lunar highland breccias compacted from immature regolithic material

The exposure history of the Apollo 16 site: An assessment based on methane and hydrolysable carbon

Nineteen soils from eight stations at the Apollo 16 landing site have been analyzed for methane and hydrolysable carbon. These results, in conjunction with published data from photogeology, bulk chemistry, rare gases, primordial and cosmogenic radionuclides, and agglutinate abundances have been interpreted in terms of differing contributions from three components-North and South Ray Crater ejecta and Cayley Plains material

The Holbrook Meteorite - 99 Years Out in the Weather

At 7:15pm on the evening of 19th July 1912, a bright fireball appeared in the sky above Navajo County, Arizona [1]. After several loud detonations, approximately 16,000 mostly pea-sized stones fell near the Arntz siding of the Santa Fe Railroad, 7 miles from the town of Holbrook. A search orchestrated by W.M.Foote resulted in nearly 220 kg of material being recovered; samples were exchanged with a great many of the World's Museums [2]. In 1931 Harvey Nininger revisited the site and was able to find another 23 kg that had originally been missed [3]. One of us (EKG) returned again in 1968 and found a further ca 1.5 kg specimen [4]. Meteorite hunters have been going back to Holbrook ever since in the hope of more finds. For example in 2001 a group of 45 searchers accumulated 440 g of previously overlooked L6 group meteorite fragments. In 2011, the 99th anniversary of the event, Rubin Garcia located 11 mini-meteorites [5]