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Jakes, P.

Publications and source records attributed to Jakes, P..

15 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Geochemical zoning and early differentiation in the moon

The volatile elements (e.g., Rb, Pb, Tl, Bi, Cs) seem to have been depleted at the time of lunar accretion. Accordingly, it may be assumed that the moon initially accreted from refractory material. The good correlation between volatile/involatile element ratios (e.g., Cs/U, K/La, K/Zr) in both highland and maria samples means that element distribution in lunar crustal rocks is not governed by volatility differences. This and other evidence encourages the view that the moon was accreted homogeneously. A consequence of homogeneous accretion theories is that very efficient large-scale element fractionation is required to account both for the high near-surface concentrations of refractory elements (e.g., Th, U, REE, Zr, Ba, etc.) and for the Ca-Al-rich crust.

Taylor, S. R.↗
NASA NTRS1974

Excess europium content in Precambrian sedimentary rocks and continental evolution

It is proposed that the europium excess in Precambrian sedimentary rocks, relative to those of younger age, is derived from volcanic rocks of ancient island arcs, which were the source materials for the sediments. Precambrian sedimentary rocks and present-day volcanic rocks of island arcs have similar REE patterns, total REE abundances, and excess Eu, relative to the North American shale composite. The present upper crustal REE pattern, as exemplified by that of sediments, is depleted in Eu, relative to chondrites. This depletion is considered to be a consequence of development of a granodioritic upper crust by partial melting in the lower crust, which selectively retains europium.

Jakes, P.↗
NASA NTRS1974

Phase chemistry of Apollo 14 soil sample 14259

Optical, X-ray-diffraction and electron-microprobe techniques were used to investigate 0.26 gm of Apollo 14 soil sample 14259. Major element microprobe analyses were made of 470 mineral grains and 388 glass grains. The mineral abundances in the soil are 45% plagioclase, 41% pyroxene, 7% olivine, 3% oxides, 2% K-feldspar; 1% nickel-iron, and less than 1% troilite. The glasses have a wide range of compositions but preferred values are evident and are interpreted as representative of rock types contributing to the soil at the Fra Mauro site. Eleven per cent of the glasses have compositions like those of mare basalts or mare soils and are believed to be mare-derived. Eighty-six per cent of the glasses are equivalent in composition to basalts that have higher Al, and lower Ca/Al and Fe/Mg ratios than mare basalts. The most abundant compositional type is named Fra Mauro basaltic glass and is subdivided into three related types. The other major glass type in the soil corresponds in composition to anorthositic gabbro.

Aitken, F. K.↗
NASA NTRS1974

Feldspar basalts in lunar soil and the nature of the lunar continents

It is found that 25% on the Apollo-14 glasses have the same composition as the glasses in two samples taken from the Luna-16 column. The compositions are equivalent to feldspar basalt and anorthosite gabbro, and are similar to the feldspar basalts identified from Surveyor-7 analysis for lunar continents.

Reid, A. M.↗
NASA NTRS1974

The geochemical evolution of the moon

Evidence for and implications of homogeneous accretion of the moon are considered. Interelement ratios are used to calculate the composition of the highland crust. The rare-earth data for the highlands show a positive Eu anomaly, allowing the deduction that the interior has a negative anomaly. The Cr/Ni ratios in the highlands are considered in regard to the overall lunar abundance of the siderophile elements. These abundance data and the constraints from the heat flow measurements are next used to set limits on the bulk composition for the moon. The geochemical constraints are integrated with the petrological and geophysical data in an attempt to provide a consistent model for the geochemical evolution of the moon.

Taylor, S. R.↗
NASA NTRS1973

Major element chemistry of glasses in Apollo 14 soil 14156.

Glasses in a soil sample (14156) from the middle layer of the trench at the Fra Mauro landing site show a wide range of compositions clustered around certain preferred compositions. Ninety per cent of the glasses are of two major types - Fra Mauro basalt (63%) with high K and 17 wt % Al2O3 and Highland basalt or anorthositic gabbro (27%) with low K and 25 to 26 wt % Al2O3. The glass population is almost identical with that of the comprehensive soil 14259.

Reid, A. M.↗
NASA NTRS1972

Major and trace element abundances in volcanic rocks of orogenic areas.

The composition of recent island-arc volcanic rocks in relation to their geographic and stratigraphic relations is discussed. The differences in composition between volcanic rocks and those in continental margins are pointed out. Trace elements and major elements are shown to suggest a continuous gradational sequence from tholeiites through calc-alkaline rocks to shoshonites.

Jakes, P.↗
NASA NTRS1972

Petrology of a portion of the Mare Fecunditatis regolith.

Extensive microprobe analyses have been made of pyroxenes, plagioclases, olivines, opaque minerals, and glasses in two 0.025 g lunar samples returned from the Luna 16 mission, with the aim to characterize the Mare Fecunditatis regolith. No major differences were found between the near surface soil horizon A and horizon D at approximately 30 cm depth. Resulting characteristics of the mineral examined are presented and discussed.

Jakes, P.↗
NASA NTRS1971

Microprobe analyses of glasses and minerals from Luna-16 soil

Electron microprobe analyses are presented for nine elements in 250 glasses and 434 pyroxenes, eight elements in 113 olivines, and six elements in 354 feldspars, 35 spinels, and 159 ilmenites. All grains are from the 125-425 micron fraction of horizon A and horizon D soil from the Luna 16 sample. A norm is presented for each glass analysis and the structural formula is calculated for each mineral analysis.

Brown, R. W.↗
NASA NTRS1971

Composition of island arcs and continental growth.

Island arc volcanism has contributed and is still contributing to continental growth, but the composition of island arcs differs from that of the upper continental crust in its lower abundance of Si, K, Rb, Ba, Sr and light rare earth elements. In their advanced stage of evolution, island arcs contain more than 80% of tholeiitic and 15% of ?island arc' calc-alkaline rocks with varied SiO2 contents. The larger proportion of tholeiitic rocks is in the lower crustal levels. The high stratigraphical levels of the island arcs are composed of tholeiitic plus calc-alkaline and/or high potash (shoshonitic) associations with higher abundances of K, Rb, Sr, and Ba. Stratification of the island arc crust is accentuated by another type of calc-alkaline volcanism (Andean type) originating at a late stage of arc evolution, probably by partial melting at the base of the crust. This causes enrichment of the upper crust in K, Rb, Ba and REE and accounts for upper crustal abundances of these elements as well as of SiO2.

Jakes, P.↗
NASA NTRS1971

Apollo 14 - Nature and origin of rock types in soil from the Fra Mauro formation.

Compositions of glasses in the Apollo 14 soil correspond to four types of Fra Mauro basalts, to mare basalts and soils, and, in minor amounts, to gabbroic anorthosite and potash granite. The Fra Mauro basalts can be related by simple low pressure crystal-liquid fractionation that implies a parent composition like that of Apollo 14 sample 14310.

Aitken, F. K.↗