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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Geology and tectonics of the Archean Superior Province, Canadian Shield

Superior Province consists mainly of Late Archean rocks with Middle Archean gneisses in the south, and possibly in the north. The Late Archean supracrustal sequences are of island arc and interarc affinity and are cut by abundant plutonic rocks, including early arc-related intrusions, late synorogenic intrusions, and post-orogenic plutons that are possibly the product of crustal melting caused by thermal blanketing of newly-thickened continental crust combined with high mantle heat flux. The contemporaneity of magmatic and deformational events along the lengths of the belts is consistent with a subduction-dominated tectonic regime for assembly of the Kenoran Orogen. Successive addition of volcanic arcs accompanied and followed by voluminous plutonism resulted in crustal thickening and stabilization of the Superior craton prior to uplift of Kapuskasing granulites, emplacement of the Matachewan diabase dykes, and Early Proterozoic marginal rifting.

Card, K. D.↗
NASA NTRS1992

Chemical variation and zoning of olivine in lunar dunite 72415 - Near-surface accumulation

Electron microprobe remeasurements have been used to reevaluate the range of olivine compositions, including CaO, in lunar dunite sample 72415 and compare that range with olivines in established plutonic rocks. Olivines from ferroan anorthosite 62237 and samples from the Stillwater intrusion were analyzed; literature data for other lunar and terrestrial plutonic samples were used for comparisons. The analyses show that the lunar dunite 72415 contains a range of olivine compositions, that the olivines are zoned, and that they have CaO abundances that are consistent with shallow hypabyssal rather than deep plutonic accumulation.

Ryder, Graham↗
NASA NTRS2002

Two New Evolved Gabbroic Samples from Apollo 16

We have found petrographic and geochemical data for two evolved monomict mafic rocks collected at the Apollo 16 site. While they somewhat resemble sodic ferrogabbro, they may be fragments of the Th-rich plutonic rocks thought to underlie the PKT. Additional information is contained in the original extended abstract.

Zeigler, R. A.↗
NASA NTRS1993

Melt rock components in KREEPy breccia 15205: Petrography and mineral chemistry of KREEP basalts and quartz-normative mare basalts

Many current models for the origin of lunar highland rocks feature as an essential component the assimilation of KREEPy material by primitive magmas parental to the Mg-rich suite and alkali suite plutonic rocks. Similar models have also been proposed for the origin of various mare basalt suites. However, any model which considers assimilation of KREEP an important petrologic process must sooner-or-later deal with the question: what is KREEP? Because pristine KREEP basalts are rare, and most known samples are small (e.g., 15382/15386), the geochemical variability of KREEP basalts is poorly known. Other KREEP compositions which are commonly used in these models include the hypothetical 'high-K KREEP' component of Warren and Wasson, which is derived from Apollo 14 soil data, and the 'superKREEP' quartz-monzodiorite 15405. Lunar breccia 15205 is a polymict regolith breccia that consists of approximately 20% KREEP basalt clasts and 20% quartz-normative basalt clasts in a KREEP-rich matrix. Bulk rock mixing calculations show that this sample comprises about 84% KREEP. The clasts range up to 1 cm in size, but most are considerably smaller. The primary aim is to characterize pristine KREEP basalts petrographically, to establish the range in chemical compositions of KREEP basalts, and to test models that were proposed for their origin. In addition, we may be able to extend the compositional range recognized in the quartz-normative basalt suite and cast some light on its origin as well. Preliminary whole rock geochemical data on the KREEP basalts are presented in a companion paper by M.M. Lindstrom and co-workers. Concentration is on petrography and mineral chemistry of these clasts, and the implications these data have for the origin of the different melt rock suites.

Shervais, John W.↗
NASA NTRS1974

Phase equilibria study of pseudobrookite type minerals

Pseudobrookite, is found in volcanic rocks, and the mineral armalcolite ((Fe,Mg)Ti2O5) found in the Apollo 11 and subsequent lunar samples seems to be unique to the moon. In plutonic rocks on the earth, ilmenite and rutile were found with what appears to be an equilibrium liquidus texture, while on the moon armalcolite often appears to be the primary liquidus phase among Ti-oxides. This suggests that total pressure may be a factor in the formation of these minerals, and a knowledge of the phase relations in this system yields information about the pressure under which a given magma crystallized.

Friel, J. J.↗
NASA NTRS1986

Geochemistry of granitoid rocks from the western Superior Province: Evidence for 2- and 3-stage crustal evolution models

The Superior Province is divisible into subprovinces that can be classified as greenstone-tonalite, paragneiss, or batholitic terranes and are distinguished by differences in lithologic proportions, metamorphic grade, and structural style. The origin and significance of contrasting geochemical characteristics of plutonic rocks from the Winnipeg River subprovince (a batholithic terrane) and the Wabigoon subprovince (a greenstone-tonalite terrane) are discussed.

Beakhouse, G. P.↗
NASA NTRS1983

Use of olivine and plagioclase saturation surfaces for the petrogenetic modeling of recrystallized basic plutonic systems

During petrogenetic studies of basic plutonic rocks, there are at least three major questions to be considered: (1) what were the relative proportions of cumulate crystals and intercumulus melt in a given sample? (2) what is the composition and variation in composition of the melts within the pluton? and (3) what is the original composition of the liquids, their source and evolution prior to the time of emplacement? Use of both saturation surfaces can place strong limits on the compositions of potential cumulate phases and intercumulus melts. Consideration of appropriate trace elements can indicate whether a sample is an orthocumulate, adcumulate or mesocumulate. Thus, when trace element and petrographic data are considered together with the saturation surfaces, it should be possible to begin to answer the three major questions given above, even for strongly recrystallized basic plutons.

Hanson, G. N.↗
NASA NTRS1988

Significance of elevated K/Rb ratios in lower crustal rocks

The granulite uncertainty principle, which states that it is difficult or impossible to determine with certainty the maximum geopressure and geotemperature that a granulite has experienced, is addressed. Also, geochemical fingerprinting cannot always be used reliably in the nebulous region that is transitional between metamorphic and igneous environments. Ion exchange thermometers are typically useful to approximately 800 C in slowly cooled plutonic rocks unless one uses a reintegration technique on unmixed minerals, or unless a metastable mineral assemblage can be observed. It is argued that in most granulites, fossil temperatures are typically obliterated by reequilibration and/or deformation during slow cooling. Granulite metamorphism may be further complicated by the common association with igneous activity. The previously-used geochemical indicators such as high K/Rb ratios and LIL depletion may not be strictly the result of granulite facies metamorphic depletion, but also may result from igneous processes, which depend on bulk and mineral compositions and on the mineralogy of the protolith. Detailed geologic mapping will be the ultimate arbitrator of whether a given geochemical signature is the result of igneous or metamorphic processes.

Frost, B. Ronald↗
NASA NTRS1980

Rocks of the early lunar crust

Data are summarized which suggest a model for the early evolution of the lunar crust. According to the model, during the final stages of accretion, the outer part of the moon melted to form a magma ocean approximately 300 km deep. This ocean fractionated to form mafic and ultramafic cumulates at depth and an overlying anorthositic crust made up of ferroan anorthosites. Subsequent partial melting in the primitive mantle underlying the crystallized magma ocean produced melts which segregated, moved upward, intruded the primordial crust, and crystallized to form layered plutons consisting of Mg-rich plutonic rocks. Intense impact bombardment at the lunar surface mixed and melted the rocks of the two suites to form a thick layer of granulated debris, granulitic breccias, and impact-melt rocks.

James, O. B.↗
NASA NTRS1993

Basaltic Volcanism and Ancient Planetary Crusts

The purpose of this project is to decipher the origin of rocks which form the ancient lunar crust. Our goal is to better understand how the moon evolved chemically and, more generally, the processes involved in the chemical fractionation of terrestrial planetoids. This research has implications for other planetary bodies besides the Moon, especially smaller planetoids which evolved early in the history of the solar system and are now thermally stable. The three main areas focused on in our work (lunar mare basalts, KREEP basalts, and plutonic rocks of the lunar highlands) provide complementary information on the lunar interior and the processes that formed it.

Shervais, John W.↗
NASA NTRS1980

Significance of major and minor element variations in plagioclase in sodic ferrogabbro and breccia matrix in lunar highlands sample 67915

Attention is given to the significance of the results of a study of Ca, K, Ti, Fe, Mn, and Mg variations in plagioclase in highlands sample 67915,84. This polymict breccia from Outhouse Rock station 11 at the Apollo 16 site has been selected for study because it contains a wide variety of clast types, including a differentiated type-sodic ferrogabbro. It is found that the data on Ca, K, Ti, Fe, Mn, and Mg in plagioclase show no evidence of reaction between sodic ferrogabbro and breccia matrix clasts. Two groups of plagioclase compositions have been recognized in the breccia matrix. The data suggest that the prebreccia characteristics of plagioclase compositions have been preserved in 67915. Data on Mg/(Mg+FE) ratios suggest that the sodic ferrogabbro and the intermediate-Ca plagioclase clasts could be related to the Mg-rich plutonic rock suite and the high-Ca plagioclase clasts to the ferroan anorthosites.

Weiblen, P. W.↗
NASA NTRS1976

Apollo 17, Station 6 boulder sample 76255 - Absolute petrology of breccia matrix and igneous clasts

The matrix of 76255 is the finest-grained, most clast-laden, impact-melt polymict breccia sampled from the Station 6 boulder. The paper speculates on how the matrix of 76255 fits into and enhances existing thermal models of breccia lithification. Emphasis is on the detailed petrology of five lithic clasts, two of which display mineralogical and textural affinities to mare basalts, while three, a gabbro, a norite, and a troctolite are considered primitive plutonic rocks.

Warner, J. L.↗
NASA NTRS1975

Magma genesis by in situ melting within the lunar crust

Blue-gray breccia 73217 represents a brecciated and partially melted assemblage of plutonic rock fragments. The textural and chemical evidence leads to the conclusion that the melt was generated within the lunar crust and that subsequent cooling and crystallization occurred prior to the transportation of this rock to the surface. The melt generated in this fashion, by in situ melting at depth, of moderately Mg-rich rocks, produced a liquid enriched in Fe, Ti, K, and P which could produce sodic ferrogabbro and granitic rocks similar to the light portion of 12013, but not KREEP.

Crawford, M. L.↗
NASA NTRS1980

A pristine eucrite-like gabbro from Descartes and its exotic kindred

A coarse-grained plagioclase-pyroxene gabbro (61224,6) with a cumulate texture suggestive of a slowly cooled plutonic rock was recovered from the 4-10 mm fraction of an Apollo 16 soil. The rock is uncommonly poor in feldspar and rich in Na for a lunar highlands lithology. Trace element analyses show extremely low siderophile element concentrations which confirm the pristine character indicated by the texture. The composition of 61224,6 is compared with those of 3 other pristine, exceptionally mafic, nonmare gabbros and of certain eucrites. 61224,6 and the three other gabbros have notable chemical differences but share relatively high ratios of Ti/Sm and Sc/Sm which suggest a possible genetic relationship. We conclude that 61224,6 represents a Na-rich cumulate from a layered intrusion within the highlands crust.

Marvin, U. B.↗
NASA NTRS1984

Petrology and chemistry of hyperferroan anorthosites and other clasts from lunar meteorite ALHA81005

The results of petrographic and chemical studies of 11 previously undescribed clasts from the lunar meteorite Allan Hills A81005 are reported. The majority of lithic clasts in this regolith breccia are granular to cataclastic polymict breccias that are mixtures of ferroan anorthosites and troctolitic Mg-suite plutonic rocks with mg' greater than 84, An 97, and REE abundances consistent with those of known Mg-suite rocks. Clasts of appropriate Mg-suite end members have not been found in 81005, although magnesian olivine fragments are present. Impact-melt clasts similar in composition to bulk 81005 also occur. AH81005 is low in KREEP.

Goodrich, C. A.↗
NASA NTRS1986

Tectonic setting and evolution of late Archaean greenstone belts of Superior Province, Canada

Late Archean (3.0-2.5 Ga) greenstone belts are a major component of the Superior Province of the Canadian Shield where alternating, metavolcanic - rich and metasedimentary - rich subprovinces form a prominent central striped region bordered in part by high-grade gneiss subprovinces, the Pikiwitonei and Minto in the north, and the Minnesota River Valley in the south. The high-grade gneiss subprovinces are characterized by granulite facies gneiss of plutonic and supracrustal origin, and by abundant plutonic rocks. Minnesota River Valley has rocks older than 3.5 Ga; absolute ages of Pikiwitonei and Minto rocks are unknown but Minto does have north-south structural trends distinctive from the dominant east-west structures of Superior Province. A discussion follows.

Card, K. D.↗
NASA NTRS1987

The composition and history of breccia 67015 from North Ray Crater

Feldspathic fragmental breccia (FFB) 67015 from the rim of North Ray Crater was examined and was found to be the most diverse and complex of the Apollo 16 FFBs. It contains a wider range of clast types than any of the others and is not dominated by any single lithology. Several crystalline lithologies, occurring in minor amounts, were identified that represent highland plutonic rocks. Plagioclase fragments are the most abundant breccia constituent, followed by clasts of impact melt rocks and granulites. The impact melts are of two main types: feldspathic fragment-laden melts and mafic, KREEPy melt rocks of VHA basalt composition. Textural evidence indicates that some of the VHA melts were hot and plastic when they accumulated into the breccia. Ar-40 - Ar-39 dates show that both types of melts solidified about 3.9 x 10 to the 9th years ago. Magnetic measurements on clasts show a scatter of NMR directions, making it impossible to read a consistent imprint of an ancient dipolar magnetic field. Previous studies of Apollo 16 stratigraphy suggested that KREEPy melt rocks were introduced to the site as Imbrium impact ejecta, about 3.8 million years ago. Present results indicate that the highlands crust contained KREEP components as early as 3.9 x 10 to the 9th years ago.

Marvin, Ursula B.↗
NASA NTRS1987

Heat production in an Archean crustal profile and implications for heat flow and mobilization of heat-producing elements

Concentrations of heat producing elements (Th, U, and K) in 58 samples representative of the main lithologies in a 100-km transect of the Superior Province of the Canadian Shield have been obtained. The relatively large variation in heat production found among the silicic plutonic rocks is shown to correlate with modal abundances of accessory minerals, and these variations are interpreted as premetamorphic. The present data suggest fundamental differences in crustal radioactivity distributions between granitic and more mafic terrains, and indicate that a previously determined apparently linear heat flow-heat production relationship for the Kapuskasing area does not relate to the distribution of heat production with depth.

Ashwal, L. D.↗