Engineering topics

Ryder, Graham

Publications and source records attributed to Ryder, Graham.

At least 37 records · Page 2

NASA NTRS1992

Apollo 15 impact melts, the age of Imbrium, and the Earth-Moon impact cataclysm

The early impact history of the lunar surface is of critical importance in understanding the evolution of both the primitive Moon and the Earth, as well as the corresponding populations of planetesimals in Earth-crossing orbits. Two endmember hypotheses call for greatly dissimilar impact dynamics. One is a heavy continuous (declining) bombardment from about 4.5 Ga to 3.85 Ga. The other is that an intense but brief bombardment at about 3.85 +/- Ga was responsible for producing the visible lunar landforms and for the common 3.8-3.9 Ga ages of highland rocks. The Apennine Front, the main topographic ring of the Imbrium Basin, was sampled on the Apollo 15 mission. The Apollo 15 impact melts show a diversity of chemical compositions, indicating their origin in at least several different impact events. The few attempts at dating them have generally not produced convincing ages, despite their importance. Thus, we chose to investigate the ages of melt rock samples from the Apennine Front, because of their stratigraphic importance yet lack of previous age definition.

Ryder, Graham↗

NASA NTRS1991

Lunar ferroan anorthosites and mare basalt sources - The mixed connection

Global overturn of a hot, gravitationally unstable lunar mantle immediately following the solidification of a magma ocean explains several characteristics of lunar petrology. Lunar mare basalt sources are inferred to be depleted in europium and alumina. These depletions are consensually attributed to complementary plagioclase floating from a magma ocean. However, in contrast to the mare basalt source parent magma, the ferroan anorthosite parent magma was more evolved by virtue of its lower Mg/Fe ratio and Ni abundances, although less evolved in its poverty of clinopyroxene constituents, flat rare earth pattern, and lower incompatible element abundances. The europium anomaly in mare sources is inferred to be present at 400 km depth, too deep to have been directly influenced by plagioclase crystallization. Massive overturning of the post-magma ocean mantle would have carried down clinopyroxene, ilmenite, and phases containing fractionated rare earths, europium anomalies, and some heat-producing radionuclides.

Ryder, Graham↗

NASA NTRS1991

Ar-40/Ar-39 ages of six Apollo 15 impact melt rocks by laser step heating

Fifteen high resolution (21-51 step) Ar-40/Ar-39 age spectra are obtained for six Apollo 15 impact melt rocks of different compositions, using a continuous laser system on submilligram subsamples and on single crystal plagioclase clasts. Four of the six samples gave reproducible age spectra with well-defined intermediate temperature plateaus over 48 percent or more of the Ar-39 released; the plateaus are interpreted as crystallization ages. Samples 15304,7,69, 15294,6,21 and 15314,26,156 gave virtually identical plateau ages whose weighted mean is 3870 + or - 6 Ma. These three melt rocks differ in composition and likely formed in three separate impact events.

Dalrymple, G. B.↗

NASA NTRS1991

Lunar and Planetary Science Conference, 21st, Houston, TX, Mar. 12-16, 1990, Proceedings

The present conference on lunar and planetary science discusses the geology and geophysics of Venus; the lunar highlands and regolith; magmatic processes of the moon and meteorites; remote sensing of the moon and Mars; chondrites, cosmic dust, and comets; ammonia-water mixtures; and the evolution of volcanism, tectonics, and volatiles on Mars. Attention is given to volcanism on Venus, pristine moon rocks, the search for Crisium Basin ejecta, Apollo 14 glasses, lunar anorthosites, the sources of mineral fragments in impact melts 15445 and 15455, and argon adsorption in the lunar atmosphere. Also discussed are high-pressure experiments on magnesian eucrite compositions, the early results of thermal diffusion in metal-sulfide liquids, preliminary results of imaging spectroscopy of the Humorum Basin region of the moon, high-resolution UV-visible spectroscopy of lunar red spots, and a radar-echo model for Mars. Other topics addressed include nitrogen isotopic signatures in the Acapulco Meteorite, tridymite and maghemite formation in an Fe-SiO smoke, and the enigma of mottled terrain on Mars.

Ryder, Graham↗

NASA NTRS1990

A distinct variant of high-titanium mare basalt from the Van Serg core, Apollo 17 landing site

A fragment of basalt picked from the drive tube collected at Van Serg crater at the Apollo 17 landing site has a bulk chemistry more primitive than that of other high-titanium mare basalt groups collected at the site. The sample has a fine-grained olivine phyric, subophitic texture that is distinct from that of other high-titanium basalt samples. The grain size and texture suggest that the sample has a composition close to that of a magma. The crystallization sequence, with appearance of oxide minerals later than in other groups, and other petrographic features such as more-calcic plagioclase and early pigeonite rather than augite, are consistent with this sample representing a distinct variant of Apollo 17 high-titanium basalts. It is not related through closed-system igneous processes to any of the other mare basalt groups identified among Apollo 17 samples. Its characters emphasize the complexity of contemporaneous magma processes on the moon and the heterogeneity of that part of the mantle that was melted.

Ryder, Graham↗

NASA NTRS1990

Lunar samples, lunar accretion and the early bombardment of the moon

The cratering history of the moon is reexamined taking data acquired over the last decade into account along with a newly accepted concept concerning the moon's origin. It is found that predictions of a heavy bombardment are not fulfilled by lunar characteristics as understood from sample and remote sensing studies, nor by lunar accretion history. There is strong evidence for the reality for a short, intense, cataclysmic bombardment at about 3.85 Ga.

Ryder, Graham↗

NASA NTRS1989

The Apollo 15 coarse fines (4-10 mm)

A new catalog of the Apollo 15 coarse fines particles is presented. Powell's macroscopic descriptions, resulting from his 1972 particle by particle binocular examination of all of the Apollo 15 4 to 10 mm fines samples, are retained. His groupings are also retained, but petrographic, chemical, and other data from later analyses are incorporated into this catalog to better characterize individual particles and describe the groups. A large number of particles have no characterization beyond that done by Powell. Complete descriptions of the particles and all known references are provided. The catalog is intended for anyone interested in the rock types collected by Dave Scott and Jim Irwin in the Hadley-Appenine region, and particularly for researchers requiring sample allocations.

Ryder, Graham↗

NASA NTRS1989

Lunar and Planetary Science Conference, 19th, Houston, TX, Mar. 14-18, 1988, Proceedings

Papers are presented on lunar highlands and lunar geology, igneous processes on the moon, and achondrites. Also considered are the geology, geochemistry, and atmosphere of Venus and Mars. Other topics include comets, cosmic dust, and primitive nebular materials. Experimental and theoretical studies on impact cratering are discussed, along with geological and geochemical studies of impact products.

Ryder, Graham↗

NASA NTRS1989

Mare basalts on the Apennine Front and the mare stratigraphy of the Apollo 15 landing site

Olivine-normative mare basalts are present on the Apennine Front as crystalline particles and shocked or shock-melted fragments. Picritic basalts, which may be related to the olivine-normative basalts by olivine accumulation, not only occur on the Front but such samples so far recognized are confined to it. Mare volcanic and impact glasses also occur on the Front; all are olivine-normative, though none are quite the equivalent of the typical olivine-normative mare group. The quartz-normative mare basalts are not present (or are extremely rare) on the Front either as crystalline basalts or shocked or glass equivalents. These observations are consistent with the olivine-normative mare basalts being both local and the youngest flows at the site, and the fragments being emplaced on the Front by impacts. The picritic basalts raise the distinct possibility that the olivine-normative basalts also ponded on the Front. An influx of olivine-normative basalts from exotic sources (e.g., a ray from Aristillus) is inconsistent with their abundance, their dominance in the mare soil chemistry, and their age, isotopic, and trace element similarities with the quartz-normative basalts. However, the thermal histories of the olivine-normative basalts require elucidation.

Ryder, Graham↗

NASA NTRS1988

Quenching and disruption of lunar KREEP lava flows by impacts

The results of a reexamination of petrography of the Apollo 15 KREEP basalts are reported. Several of the basalts contain yellow residual glasses which cross-cut the crystallized phases; some show more extreme disruption. The features of the glasses appear to be compatible only with impact disruption, ejection, and quenching from actively crystallizing flows, indicating a high impact flux immediately after the impact that formed the Imbrium basin. No other example of impacts into active lava flows is known in the solar system.

Ryder, Graham↗

NASA NTRS1988

The complexity, depth, and rapidity of processes that formed the lunar crust

From its birth the moon had a large-scale, complex magma system. The evidence is the massive differentiation of the moon that was partially preserved. The system might be a magma ocean or a magmasphere; even in the former case it was superposed by smaller but also very complex magma systems. The main episode produced a plagioclase-rich crust including genuine anorthosites; it was over by about 4.35 b.y. ago, although magmatism continues. The processes of crust-building remain in serious dispute. Lunar crusts; massive differentiation; crustal material composition; processes which produced crustal materials; and differences from earth are briefly discussed.

Ryder, Graham↗

NASA NTRS1988

Lunar and Planetary Science Conference, 18th, Houston, TX, Mar. 16-20, 1987, Proceedings

Papers on lunar and planetary science are presented, including petrogenesis and chemistry of lunar samples, geology and petrogenesis of the Apollo 15 landing site, lunar geology and applications, cratering records and cratering effects, differentiated meteorites, chondritic meteorites and asteroids, extraterrestrial grains, Venus, Mars, and icy satellites. The importance of lunar granite and KREEP in very high potassium basalt petrogenesis, indentifying parent plutonic rocks from lunar breccia and soil fragments, glasses in ancient and young Apollo 16 regolith breccias, the formation of the Imbrium basin, the chemistry and petrology of the Apennine Front, lunar mare ridges, studies of Rima Mozart, electromagnetic energy applications in lunar resource mining and construction, detecting a periodic signal in the terrestrial cratering record, and a search for water on the moon, are among the topics discussed. Other topics include the bidirectional reflectance properties of Fe-Ni meteorites, the nature and origin of C-rich ordinary chondrites and chondritic clasts, the dehydration kinetics of shocked serpentine, characteristics of Greenland Fe/Ni cosmic grains, electron microscopy of a hydrated interplanetary dust particle, trapping Ne, Ar, Kr, and Xe in Si2O3 smokes, gossans on Mars, and a model of the porous structure of icy satellites.

Ryder, Graham↗

NASA NTRS1988

The reliability of macroscopic identification of lunar coarse fines particles and the petrogenesis of 2-4 mm particles in Apennine Front sample 15243

Particles from the 15243 Apennine Front sample (Station 6) were studied using macroscopic, neutron activation, and petrographic methods. It was found that macroscopic identifications allow for good identification of the particles. It was shown that the Station 6 regolith must consist of a fine-grained, comparatively KREEP-poor material and a coarser component consisting of Apollo 15 KREEP basalts and KREEP-like impact melt fragments.

Ryder, Graham↗

NASA NTRS1988

Chemical dispersion among Apollo 15 olivine-normative mare basalts

Analysis of Apollo 15 olivine-normative mare basalts for major and minor elements suggests that the hypothesis that the coarser-grained varieties (olivine microgabbros) consist of two chemical groups is incorrect. Instead, it is found that there is a single group including vesicular, coarse-grained, and fine-grained basalts. For the entire suite, the dispersion of compositions along the olivine trend is too great to be explained by short-range unmixing of an unfractionated flow. It is suggested that the general trend for the suite is olivine separation, probably through crystal settling. The textures, mineralogical characteristics, and chemical variation of the olivine-normative basalts are shown to be consistent with a sequence of thin fractionating flows, all from a common parent.

Ryder, Graham↗

NASA NTRS1987

Lunar and Planetary Science Conference, 17th, Houston, TX, Mar. 17-21, 1986, Proceedings. Part 2

The topics discussed in this volume include lunar endogenic rocks and processes; lunar regoliths and breccias; the terrestrial planets; shergottites; primitive materials, exposure, and atmospheres; and impacts and crater tectonics. Papers are presented on the petrology and geochemistry of alkali gabbronorites from lunar breccia 67975; the formation of Apollo 17 orange and black glass beads; mixing levels, the Apennine Front soil component, and compositional trends in the Apollo 15 soils; the meteorite component of Apollo 16 noritic impact melt breccias; and constraints on the lithospheric structure of Venus from mechanical models and tectonic surface features. Consideration is also given to a fractal interpretation of topography and geoid spectra on the earth, moon, Venus, and Mars; rare earth patterns in shergottite phosphates and residues; nuclide production by primary cosmic-ray protons; gas chromatographic instrumentation for the analysis of aerosols and gases in Titan's atmosphere; and finite-element models of non-Newtonian crater relaxation.

Ryder, Graham↗

NASA NTRS1987

Petrographic evidence for nonlinear cooling rates and a volcanic origin for Apollo 15 KREEP basalts

The results of petrographic studies of Apollo 15 KREEP basalt fragments are discussed. The Apollo 15 KREEP basalts display a wide range of grain size and texture, with some samples showing evidence for a two-stage (slow early, fast late) cooling in the form of phenocrysts, glomerocrysts, and large proportions of residual quenched glass. Two-stage cooling is common in volcanic, dynamic environments. The inference that these and other Apollo 15 KREEP basalts are volcanic requires a reexamination of the chemical and isotopic constraints on the genesis and regenesis of KREEP and early lunar evolution.

Ryder, Graham↗

NASA NTRS1987

Chemical composition and origin of Apollo 15 impact melts

Fourteen Apollo 15 impact melt rocks were analyzed for major (fused bead microprobe) and trace element (INAA) abundances, and the compositions of these Apennine Front rocks were compared with samples from other landing sites. The rocks show a wide range in trace element abundances, although all but one have a typical KREEP incompatible element pattern and have low-K Fra Mauro basaltic or medium-K Fra Mauro basaltic compositions. The melt chemistries appear to form five groups (labeled A to E in order of decreasing incompatible elements), with the compositions unlike nearly all other impact melts and regoliths from highland sites. All groups except Group A may represent single impact events (either Imbrian or post-Imbrian). One unique sample has a non-KREEP incompatible element pattern, with low abundances and a positive Eu anomaly. Its target is believed to be either a pre-Imbrian melt or exotic.

Ryder, Graham↗

NASA NTRS1987

The moon

Analyses of lunar samples and lunar meteorites and theoretical models of lunar morphology and evolution are discussed, reviewing results published during the period 1983-1986. Topics examined include the collisional ejection hypothesis for the origin of the moon, lunar meteorites from Antarctica, mare basalts, igneous and polymict rocks of the lunar-highlands crust, seismic structure and the lunar interior, and lunar regolith. Proposals for a manned base on the moon and a lunar polar orbiter (the Lunar Geoscience Observer) are briefly considered.

Ryder, Graham↗