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Kaplan, I. R.

Publications and source records attributed to Kaplan, I. R..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

The stereoisomeric composition of phytanyl chains in lipids of Dead Sea sediments

Lipid extracts from five recent Dead Sea sediments were analyzed for isoprenoid compounds and the following were isolated: free and phospholipid-bound di-O-phytanylglycerol, free phytanol and free and esterified phytanic acid. The phytanyl groups of the diether and the free phytanol were oxidized to the corresponding phytanic acid; the stereoisomeric composition of the derived phytanic acids as well as of the ester-bound phytanic acid was determined by open-tubular gas-liquid chromatography of the corresponding methyl esters on butanediolsuccinate polyester. Only the 3R, 7R, 11R-isomer of phytanic acid was detected in each of the phytanate samples, indicating that these phytanyl chains in the Dead Sea sediments are most likely derived from extremely halophilic bacteria rather than from phytol of chlorophyll origin. These findings also provide further evidence that the mixtures of RRR and SRR-phytanic acids previously isolated from organic-rich shales were most likely derived from the phytyl chain in chlorophyll.

Anderson, R.↗
NASA NTRS1977

Thermal alteration experiments on organic matter from recent marine sediments in relation to petroleum genesis

Three fractions of organic matter: lipid (benzene:methanol-extractable), humic acid (alkali-extractable) and kerogen (residue) were extracted from a young marine sediment (Tanner Basin, offshore southern California) and heated for different times (5-116 hr) and temperatures (150-410 C). The volatile (gases) and liquid products, as well as residual material, were then analyzed. On a weight basis, the lipid fraction produced 58% of the total identified n-alkanes, the kerogen fraction 41%, and the humic acid less than 1%. The volatiles produced by heating the lipid and humic acid fractions were largely CO2 and water, whereas those produced from heated kerogen also included methane, hydrogen gas and small amounts of C2-C4 hydrocarbons. A mechanism for hydrocarbon production due to the thermal alteration of organic constituents of marine sediment is discussed.

Ishiwatari, R.↗
NASA NTRS1977

Color of kerogen as index of organic maturity

Kerogen from the Tanner basin off southern California was heated under nitrogen at different temperatures and times and subsequently was studied under the transmitted light microscope. Samples darken in color from yellow through shades of brown to black with increasing thermal maturation. The transition from dark brown to very dark brown marks the range of maximum n-alkane generation where the residue attains an atomic H/C of about 0.80 plus or minus 0.05. The apparent activation energy for this transition was about 45 plus or minus 5 kcal per mole.

Peters, K. E.↗
NASA NTRS1977

Thermal alteration experiments on organic matter in recent marine sediments as a model for petroleum genesis

The fate of naturally occurring lipids and pigments in a marine sediment exposed to elevated temperatures was studied. Samples of a young marine sediment from Tanner Basin, California, were heated to a series of temperatures (65-200 C) for varying periods of time (7-64 days). The sediment was analyzed prior to and after heating for pigments, isoprenoid compounds, alcohols, fatty acids, and hydrocarbons. Structural changes caused by heating unextractable organic material (kerogen) were also studied, and the significance of the results for understanding petroleum genesis is considered. Among other results, fatty acids and hydrocarbons increased in abundance although there appeared to be no obvious precursor-to-product relationship via simple decarboxylation reactions. Chlorins were partially converted into porphyrins. The phytyl side chain of pheophytin was initially preserved intact by reduction of the phytyl double bond, but later converted to a variety of isoprenoid compounds including alkanes. Thermal grafting of components onto kerogen occurred as well as structural changes caused by heat.

Baedecker, M. J.↗
NASA NTRS1977

Solar wind nitrogen - Mechanisms for isotopic evolution

Isotope systematics of nitrogen implanted in the lunar regolith indicate that the N-15/N-14 ratio at the source of the nitrogen has increased substantially with time. This source is most plausibly identified as the solar wind reservoir. However, rigorous testing of possible mechanisms for isotopic evolution of the solar convective zone shows that they all fail, by large factors, to explain the observed effect. Evolutionary processes on the lunar surface may be similarly eliminated, leaving the lunar nitrogen isotope anomaly currently unexplained.

Kerridge, J. F.↗
NASA NTRS1976

Thermal alteration of young kerogen in relation to petroleum genesis

Kerogen, humic acid, and lipid material were separated from a young marine sediment and heated in sealed tubes in a nitrogen atmosphere at 150 and 410 C. Gaseous and liquid products generated during heating, and also the residual organic material, were characterized by gas-liquid chromatography, elemental analysis, infrared and electron spin resonance spectroscopy, and X-ray diffraction.

Ishiwatari, R.↗
NASA NTRS1976

Light element geochemistry of the Apollo 15 site

Abundances of C, N, S, and He and contents of CH4 and metallic Fe at Hadley-Apennine are typical of a mixed mare and highland environment. Isotopic compositions of C, N, and S similarly conform in most cases to patterns observed elsewhere on the moon. Systematic relationships between S abundance and total Fe content are apparent for crystalline rocks from most landing sites but their full significance is not yet understood.

Kaplan, I. R.↗
NASA NTRS1975

Light element geochemistry of the Apollo 16 site

The abundance and isotopic composition of carbon, sulfur, and nitrogen, the abundance of helium and hydrogen, and the content of metallic iron are reported for lunar surface samples from the Apollo 16 landing site at Cayley-Descartes. The light elements show marked interstation variability at the site. The abundances in soils of C, N, He, and H are apparently controlled mainly by exposure to the solar wind, through implantation or stripping processes. Carbon abundances (but not observed isotopic distributions) are compatible with a model in which equilibrium is established after 10,000-100,000 yr between solar wind input and loss by proton stripping. Sulfur abundances in soils are apparently controlled by abundances in local country rocks, but the lunar S cycle is quite complex. A metallic iron component may have originated by solar wind reduction of lunar Fe(2+).

Kerridge, J. F.↗
NASA NTRS1975

Evidence for meteoritic sulfur in the lunar regolith

Abundance and isotopic data are presented for a suite of 19 soils from the Apollo 16 mission. It is concluded that the S systematics of the lunar regolith support a model in which S from a number of indigenous rock types is mixed with a time-dependent, extralunar component of probably meteoritic origin. This mixture is processed on the lunar surface by a time-dependent mechanism which removes S-32 enriched S from the moon, enriching the residue in S-34. The loss of S by this mechanism approximately equals the meteoritic input, producing the apparent coincidence between rock abundances and abundances in soils which has led to adoption of simplified mixing models. In reality, at least for the Apollo 16 site, addition of meteoritic S slightly outweighs loss from the moon, resulting in a positive trend.

Kerridge, J. F.↗
NASA NTRS1974

Carbon, nitrogen and sulfur in lunar fines 15012 and 15013 - Abundances, distributions and isotopic compositions

Lunar fines 15012,16 and 15013,3 were analyzed by stepwise pyrolysis and acid hydrolysis as well as complete combustion in oxygen to determine carbon, nitrogen and sulfur. In addition, hydrogen was analysed during pyrolysis as well as during hydrolysis. By comparison of the distribution frequencies of C, N, S, H2 and Fe with He-4, considered to have arisen from solar wind contribution, it is concluded that nitrogen and hydrogen have largely a solar origin. Carbon has a significant solar contribution, and metallic iron may have resulted from solar wind interaction with ferrous minerals on the lunar surface. Sulfur probably has a predominantly lunar origin. There is no direct evidence for meteorotic contribution to these samples. Solar wind interaction also has a marked effect on the stable isotope distribution of C-13/C-12, N-15/N-14, and S-34/S-32. In all cases, the heavy isotope was most enriched in the smallest grain-size fraction.

Chang, S.↗
NASA NTRS1974

Thermal alteration of organic matter in recent marine sediments. 1: Pigments

Sediment from Tanner Basin, the outer continental shelf off Southern California, was analyzed for photosynthetic pigments and their derivatives, namely carotenes and chlorins. Samples of the sediment were also exposed to raised temperatures (65, 100, 150 C) for various periods of time (1 week, 1 month, 2 months). Analysis of the heat-treated sediment revealed the presence of alpha-ionene and 2,6-dimethylnapthalene, thermal degradation products of Betacarotente. Chlorins were converted to nickel porphyrins of both DPEP and etio series. Possible mechanisms of these transformations are presented.

Ikan, R.↗
NASA NTRS1974

Thermal alteration of organic matter in recent marine sediments. 2: Isoprenoids

A series of isoprenoid compounds were isolated from a heat treated marine sediment (from Tanner Basin) which were not present in the original sediment. Among the compounds identified were: phytol, dihydrophytol, c-18-isoprenoid ketone, phytanic and pristanic acids, c-19 and c-20-monoolefines, and the alkanes pristane and phytane. The significance and possible routes leading to these compounds is discussed.

Ikan, R.↗
NASA NTRS1974

Accumulation and isotopic evolution of carbon on the lunar surface

The processes of hydrogen stripping, agglutination and impact comminution, acting upon a regolith containing both indigenous and solar wind-implanted carbon, provide a quantitative explanation for the relationship between carbon abundance and isotopic composition observed for Apollo 16 soils.

Kerridge, J. F.↗
NASA NTRS1974

Light element geochemistry of the Apollo 17 site

Abundances of C, N, S, He, H, and metallic iron at Taurus-Littrow are typical of a mixed mare and highland environment. Isotopic compositions of C, N, and S also generally conform to patterns observed elsewhere on the moon. Further evidence is presented for a complex lunar S cycle.

Petrowski, C.↗
NASA NTRS1973

Nature and changes in organic matter in organic sediments

A series of isoprenoid compounds were isolated from a heat treated marine sediment (from Tanner Basin) which were not present in the original sediment. Among the compounds identified were: phytol, dihydrophytol, C-18-isoprenoid ketone, phytanic and pristanic acids, C-19- and C-10-monoolefines, and the alkanes pristane and phytane. The significance and possible routes leading to these compounds is discussed.

Kaplan, I. R.↗