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Taylor, G. J.

Publications and source records attributed to Taylor, G. J..

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Foraging westward for pristine nonmare rocks - Complications for petrogenetic models

New advances are reported concerning an investigation which is being conducted to find and characterize more 'pristine' (compositionally endogenous) lunar rocks. Eleven nonmare samples are characterized petrographically and (except for two clasts that were prohibitively small) by chemical composition. The samples are assessed whether they are pristine on the basis of diagnostic features discussed by Warren and Wasson (1977). Five samples are found to be almost certainly pristine. They include the alkali-rich anorthosite 12073c, the troctolite 14179c, the anorthositic troctolite 14321c1, the troctolitic anorthosite 14321c2, and the anorthositic norite 15565c. Correlations between petrochemistry and longitude are also investigated, taking into account Eu fractionations, Sc-Ti-Sm fractionations, and Ca/Na-Mg/Fe fractionations.

Warren, P. H.↗
NASA NTRS1981

Petrochemical constraints on lateral transport during lunar basin formation

Lunar ANT petrochemistry correlates with longitude, allowing the sampled region of the moon to be divided into three geochemical provinces: western (Apollo 12 and 14), near-eastern (Apollo 11, 15, 16 and 17) and far-eastern (Luna 16, 20 and 24). A western ANT rock has a far greater Eu anomaly for a given Sm content than does a near-eastern ANT rock, which is in turn has a somewhat greater Eu anomaly than does a far-eastern ANT rock. Distinct differences are also observed in Sc/Sm and Ti/Sm ratios (western ANT rocks have lower ratios) and in the abundances of alkali-rich anorthosites (five of the six known anorthosites from the west are approximately four times richer in Na and K than are ferroan anorthosites, whereas none of the 40 known anorthosites from the near east is alkali-rich). The existence of this distinct correlation of ANT geochemical properties with longitude implies that even during the first few hundred m.y. of lunar history basin-forming impacts were not capable of efficiently redistributing material laterally across the lunar surface.

Warren, P. H.↗
NASA NTRS1980

The nature and origin of ureilites

A theory of the origin of ureilites is presented based on mineralogical and petrological investigation of eight species including Kenna, Novo Urei, and Goalpara. The theory suggests that ureilites are primarily olivine-pigeonite cumulates crystallized from a silicate liquid which also contained suspended solid carbon phases. The carbon induced reduction of the melt and affected the ureilite mineral compositions. Petrofabric analyses show that mafic silicates are oriented in lineated and foliated patterns similar to cumulate rocks; strain rate of silicates suggests that ureilites were deformed after lithification by a mild tectonic stress and a moderate to severe shock.

Berkley, J. L.↗
NASA NTRS1980

Metamorphism of the H-group chondrites - Implications from compositional and textural trends in chondrules

The paper discusses element bulk compositions of 373 chondrules from 18 H3 to H6 chondrites determined by broad-beam electron probe analysis. Bulk chondrule FeO and Al2O3 amounts increase and TiO2 and Cr2O3 decrease with increasing petrologic type; normative faylite, albite, and plagioclase amounts increase through the petrologic sequence. Chondrule diameters correlate with phenocryst sizes in porphyritic chondrules of type 3 chondrites, but this correlation is diminished in the higher petrologic types. The compositional trends in chondrules through the petrologic sequence are attributed to diffusion and equilibration among chondrules, and between chondrules and matrix in response to increasing degrees of thermal metamorphism. It is suggested that H-group chondrites are formed by accretion of high-temperature (chondrules) and low-temperature (matrix) materials. Internal reheating of the parent materials to different temperatures caused compositional equilibration, grain coarsening, and reduction of FeO to Fe(0) by carbon.

Lux, G.↗
NASA NTRS1980

Petrology of 60035 - Evolution of a polymict ANT breccia

Extensive analysis of the lunar rock sample 60035 with optical microscopy and electron microprobe methods show it to be a polymict ANT breccia partly coated with glass, containing abundant clasts which have troctolitic/noritic anorthosite compositions. At least two episodes of crushing and mixing were involved in the petrogenesis of 60035, and annealing and mineral equilibration have not been extensive since the formation of the breccia.

Warner, R. D.↗
NASA NTRS1980

Aluminous mare basalts - New data from Apollo 14 coarse fines

Four aluminous mare basalt fragments selected from the Apollo 14 coarse fines collection are described: 14004,34 has an intergranular texture; 14160,103 and 14168,38 are granular; and 14256,10 is a fine-grained metabasalt. Pyroxene compositional trends vary among the fragments: in 14004,34 the trend is from ferroaugite to pyroxferrite; 14160,103 exhibits well-defined iron enrichment trends involving both pigeonite and augite; 14168,38 contains mostly pigeonite with minor augite; and pyroxene compositions in 14256,10 cluster in two distinct populations, high- and low-Ca. The igneous textures (except for 14256,10), the absence of discernible clasts, and low Ni compositions of metal grains lead to the conclusion that the fragments are pieces of pristine aluminous mare basalts. The marked differences in the REE patterns rule out a close genetic relation between any of the four basalts.

Warner, R. D.↗
NASA NTRS1979

Petrogenesis of Luna 16 aluminous mare basalts

Bulk compositions, petrology and mineralogy of Luna 16 aluminous mare basalt particles of less than 0.5 mm are described. The data rule out any close genetic relationships between Luna 16 and other major types of lunar mare basalts. Compared to high-Ti mare basalts, the Luna 16 basalts contain lower TiO2 and Ta and higher Al2O3 and REE abundances, suggesting that the Luna 16 source rocks crystallized later than (i.e. stratigraphically above) the ilmenite-bearing high-Ti basalt cumulate source rocks. The REE pattern for the Luna 16 basalts requires that the source material from which they were derived crystallized from a light REE enriched magma.

Ma, M.-S.↗
NASA NTRS1979

Pyroxenes in Serra de Mage - Cooling history in comparison with Moama and Moore County

Thin sections and single grains of pyroxenes from the Serra de Mage feldspar cumulate eucrites were studied by X-ray crystallography, electron microprobe and optical techniques. It was concluded that the pyroxene crystallized as pigeonite. On cooling augite was exsolved along (001) and inverted to hypersthene, with exsolution of (100) augite from hypersthene during continued slow cooling. The estimated original bulk composition of the pigeonite pyroxene is Wo10En51Fs39. The compositional data, textural relations, and existence of P2 sub 1 ca hypersthene suggest very low cooling (about 0.0004 deg C/year) below 800 deg. The Serra de Mage augite lamellae were found to be as thick or thicker than those of Moore County and Moama meteorites.

Harlow, G. E.↗
NASA NTRS1979

The Shaw meteorite - History of a chondrite consisting of impact-melted and metamorphic lithologies

Three intermingled lithologies are identified in the Shaw L-group chondrite: a light-colored lithology with a poikilitic texture, consisting of olivine and augite crystals surrounded by larger orthopyroxene grains; a dark-colored lithology containing remnant chondrules and exhibiting a microgranular texture; and a gray lithology which appears to be intermediate between the other two. Contrary to published opinions, the Shaw meteorite contains normal L-group chondrite abundances of metal and troilite, though these phases are irregularly distributed. The lithological analyses suggest that 4.52 Byr ago an impact took place on the L-group chondrite parent object of Shaw.

Taylor, G. J.↗
NASA NTRS1979

The unique nature of Apollo 17 VLT mare basalts

Three very low-Ti (VLT) basalt fragments (two with granular texture and one with granular to subophitic texture) were found during a study of light-colored lithic fragments hand-picked from the Apollo-17 deep drill core. In the present paper, some unique features of these fragments are revealed.

Wentworth, S.↗
NASA NTRS1979

Apollo 17 high-Ti mare basalts - New bulk compositional data, magma types, and petrogenesis

Bulk compositional and mineral chemical data for 28 previously unanalyzed samples support the classification of Apollo-17 high-Ti mare basalts into three-types (A, B, and C), defined on the basis of analyses of fine-grained basalts. The most MgO- and TiO2-rich fine-grained basalts of these types appear to be the best choices for representing the compositions of the parent magmas.

Warner, R. D.↗
NASA NTRS1979

Stratigraphy and depositional history of the Apollo 17 drill core

Lithologic abundances obtained from modal analyses of a continuous string of polished thin sections indicate that the Apollo 17 deep drill core can be divided into three main zones: An upper zone (0-19 cm depth) characterized by high abundances of agglutinates (30%) and a high ratio of mare to non-mare lithic fragments (less than 0.8); a coarse-grained layer (24-56 cm) rich in fragments of high-Ti mare basalts and mineral fragments derived from them, and poor in agglutinates (6%); and a lower zone (56-285 cm) characterized by variable but generally high agglutinate abundances (25%) and a low ratio of mare to nonmare lithic fragments (0.6). Using observations of the geology of the landing site, the principles of cratering dynamics, and the vast amount of data collected on the core, the following depositional history for the section of regolith sampled by the Apollo 17 drill core: was devised.

Taylor, G. J.↗
NASA NTRS1978

Fluorescent accessory phases in the carbonaceous matrix of ureilites

The carbonaceous matrix of ureilite meteorites (C-bearing olivine-pigeonite achondrites) contain abundant minute phases that emit a multicolored fluorescence under electron bombardment. These include NaCl and KCl, found in all seven ureilites studied, high-Si glass with pyroxene and chlorapatite quench crystals in North Haig, an unidentified high-Ca-Al-Cl phase in Novo Urei, and possibly free SiO2 in Novo Urei and Dingo Pup Donga. The origin of these phases is uncertain but some, especially chlorides and glass, may represent residual postcumulus materials precipitated from a late-stage interstitial liquid during the igneous phase of ureilite history.

Berkley, J. L.↗
NASA NTRS1978

VLT mare basalts - Impact mixing, parent magma types, and petrogenesis

Available major-element compositions of very low-Ti (VLT) mare basalt lithic fragments and glasses are examined. Many of the lithic fragments contain relic mineral and sometimes lithic clasts, which suggests that many samples of VLT mare basalt glasses and lithic fragments were formed by impact melting. Therefore, some may have compositions that represent mixtures of VLT mare basalts and other types of rocks, not authentic igneous rock compositions. In spite of this problem, a number of possible parent magma compositions are identified. These hypothetical magmas vary in CaO/Al2O3(0.9-1.1), FeO (17 to 24 wt. %), Fe/(Fe + Mg) (0.34-0.46), and K2O (0-0.2 wt. %). Each may have differentiated to produce a wide variety of derivative magmas. Calculations involving olivine fractionation from the proposed parent magmas indicate the Luna 24 ferrobasalts might have formed from a magma whose composition is similar to that of a group of high-MgO (about 13-14 wt. %) Apollo 17 VLT mare basalt glasses.

Taylor, G. J.↗
NASA NTRS1978

Chemistry and petrology of Luna 24 lithic fragments and less than 250-micron soils - Constraints on the origin of VLT mare basalts

Results are reported on a combined INAA-petrologic study of 17 small (0.2-1.5 mg) Luna 24 lithic and mineral fragments and INAA study of 5 bulk soils and mineral separates from gabbro 24170. Lithic and mineral fragments are classified into VLT mare basalts (ferrobasalt and metabasalts), low-Ti, variolitic mare basalt, gabbros, melt rock and soil breccia. Data indicate 5 possible magma types, represented by: (1) VLT ferrobasalt and gabbro fragments, with low-TiO2 (about 1%), slightly bow-shaped REE pattern, and low REE concentrations (5-10X chondritic); (2) a ferrobasalt (Laul et al., 1978) and metabasalt fragments with major and trace element contents similar to (1), but positive Eu anomalies; (3) one gabbro fragment with distinctive pyroxene compositional trend (increasing Ti with nearly constant Fe/Fe + Mg) and highest REE contents of any Luna 24 mare basaltic sample, (4) a gabbro fragment with considerably less V and Cr2O3 than ferrobasalt and metabasalt fragments; and (5) variolitic basalt fragment with higher Ti2(2.3%) than other Luna 24 basalts and pyroxene that has increasing then decreasing Ti with increasing Fe/Fe + Mg. Trace element data place constraints on the nature of the source region and possible parent magmas for the Luna 24 VLT ferrobasalt.

Ma, M.-S.↗