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NASA NTRS1974

Mauna Kea

Mauna Kea, the highest of Hawaii's five volcanoes, is the only high landmass in the central Pacific Ocean basin to bear unmistakable signs of Pleistocene glaciation. The stratigraphic record indicates that a summit ice cap formed and disappeared at least four times in the last 250,000 years, and that volcanic eruptions characterized not only the interglacial intervals, but also two of the glacial periods as well. Exposed rock units on the upper slopes of Mauna Kea have been divided into two major groups based on gross lithologic character. The Hamakua Group comprises the bulk of the subaerial shield of the volcano and consists largely of thin-bedded pahoehoe flows of olivine basalt. The overlying Laupahoehoe Group consists of a thin cap of alkalic lavas and pyroclastic layers confined largely to the upper slopes of the mountain. Interstratified with the volcanic units are sedimentary formations that provide evidence of four episodes of ice cap glaciation.

Porter, S. C.↗

NASA NTRS1973

Photogeology of the dark material in the Taurus-Littrow region of the moon

Regional relations and characteristics of the dark material as observed on photographs of the Taurus-Littrow region of the moon are reviewed to provide a background for interpretations of its nature and origin. The dark material seems to be a surficial deposit that covers mare and highland areas near the southeastern edge of the Serenitatis Basin. The age of the dark material, as deduced from photogeologic analysis, is ambiguous: contact relations near its western edge suggest that it is older than the central light basalts of Mare Serenitatis; evidence elsewhere indicates that it may be younger. The origin of the dark material is also uncertain, and the following alternate hypotheses are briefly considered: (1) thick regolith, (2) dark impact ejecta, (3) pyroclastic blanket, or (4) a material of different origin in different places.

Lucchitta, B. K.↗

NASA NTRS1974

Cinder cone growth modeled after Northeast crater, Mount Etna, Sicily

The structure, physical properties of ejecta, ballistics, and growth of Northeast crater, a young pyroclastic cone that originated in 1911 near the summit of Mount Etna, Sicily, were studied in order to form a model of volcano cinder cone growth. Four stages of growth were discerned: (1) a simple cone; (2) a cone with an outward-dipping talus slope; (3) destruction of rounded rim by the inward migration of the upper edge of the talus pile; and (4) extension of limits of talus pile beyond the ballistic limit of ejecta trajectories. The model is used to predict the features of lunar and Martian cones, assuming that they erupted under conditions qualitatively similar to Etna's Northeast crater.

Mcgetchin, T. R.↗

NASA NTRS1974

A proposed origin of the Olympus Mons escarpment

Olympus Mons (Nix Olympica) on Mars is delimited by a unique steep, nearly circular scarp. A pyroclastic model is proposed for the construct's origin. It is postulated that the Olympus Mons plateau is constructed predominantly of numerous ash-flow tuffs which were erupted from central sources over an extended period of time. Lava flows may be intercalated with the tuffs. A schematic radial profile incorporating the inferred compaction zones for an ash sheet is proposed. Following emplacement, eolian (and possibly fluvial) erosion and abrasion during dust storms would act on the ash sheets. Interior portions of the sheets would spall and slump following eolian erosion, generating steep, relatively smooth boundary scarps. The scarp would be circular due to symmetrical distribution of compaction zones. The model implies further that the Olympus Mons plateau rests on a more resistant rock substrate.

King, J. S.↗

NASA NTRS1974

Orange material in the Sulpicius Gallus formation at the southwestern edge of Mare Serenitatis

Orange and red materials were observed and photographed in the dark mantle of the Sulpicius Gallus Formation on the southwestern rim of the Serenitatis basin. These materials occur only within the dark mantle that overlies old rilled mare and highland units and are absent on the younger mare unit in this area. Orange and red materials occur predominantly as halos, patches, or rays around fresh impact craters ranging in diameter from less than 50 to 250 m and in layers exposed at the base of the dark mantle deposit in the steep walls of a depression and a graben. Red material is present in the highland subsurface, possibly as dikes. We conclude that orange material, locally underlain by red material, occurs in the dark mantle to a depth of about 50 m as locally stratified but discontinuous pyroclastic deposits and that it may have been produced by multiple 'fire foundation' eruptions during the later stages of accumulation of the older mare basalt units.

Lucchitta, B. K.↗

NASA NTRS1974

Petrography of Apollo 17 soils

An analysis of soils collected on the valley floor at Taurus-Littrow (dark mantle) reveals that these soils are formed by comminution of mare basalt flows and a clastic deposit consisting of black and orange glass spheres. There is no evidence for the pyroclastic origin of the dark mantle. It is found that the North Massif soils contain a large amount of mare-derived fragments being transported horizontally from the basaltic valley floor. A light mantle deposit of uniform composition including comminuted noritic and anorthositic breccia is observed. It is suggested that the light mantle is an avalanche deposit from regolith developed high on the South Massif.

Heiken, G.↗

NASA NTRS1974

A general model for the textural evolution of lunar soil

The investigation reported is concerned with the qualitative expansion of an earlier model developed by Lindsay (1971, 1972, 1973). Questions regarding the maturity of lunar soils are examined. A multivariate model related to textural maturity is considered, taking into account mean and standard deviations, the asymmetry of the grain size curve, the kurtosis anomaly, and pyroclastic materials. It is concluded that the mean grain size and the standard deviation of the lunar soil can be used as general indicators of the textural maturity of the soil anywhere on the lunar surface.

Lindsay, J. F.↗

NASA NTRS1977

Introduction to the Apollo collections. Part 1: Lunar igneous rocks

The basic petrographic, chemical, and age data is presented for a representative suite of igneous rocks gathered during the six Apollo missions. Tables are given for 69 samples: 32 igneous rocks and 37 impactites (breccias). A description is given of 26 basalts, four plutonic rocks, and two pyroclastic samples. The textural-mineralogic name assigned each sample is included.

Mcgee, P. E.↗

NASA NTRS1977

The Aristarchus-Harbinger region of the moon - Surface geology and history from recent remote-sensing observations

Photographic and remote sensing observations made from earth and Apollo orbiting spacecraft were used to study the Aristarchus Plateau-Montes Harbinger region. The appearance of the area is described, and a delineation of geologic map units and their stratigraphic relationships is presented. Physical and chemical properties of certain of the geologic units are deduced, and the interrelationships between materials of volcanic and impact origin, including the effects of excavation, redistribution, and mixing of previously deposited materials by younger impact craters, are discussed. A detailed geologic history of the region is developed. Attention is directed to the anomalous red dark mantle on the plateau; it is thought that this layer consists of fine-grained block-free material containing a relatively large fraction of orange glass, and that this layer is probably of pyroclastic origin, laid down at some time during the Imbrian period of mare flooding.

Zisk, S. H.↗

NASA NTRS1977

The Procellarum volcanic complexes - Contrasting styles of volcanism

Three major volcanic complexes have long been recognized in the Oceanus Procellarum region. Detailed study shows that the complexes share some characteristics and also display major differences which provide clues to eruption style. The Rumker Hills occupy 5000 sq km in northern Procellarum and are apparently Imbrian-Eratosthenian in age; they are dominated by domes, suggesting relatively low effusion rates. The Aristarchus Plateau-Prinz/Harbinger region occupies 40,000 sq km in central Procellarum and is predominantly Imbrian in age; it is dominated by large sinuous rilles and associated dark mantling deposits of probable pyroclastic origin, suggesting relatively high eruption rates. The Marius Hills occupy 35,000 sq km in south-central Procellarum and appear to be predominantly Eratosthenian in age; they are dominated by low domes, steep domes, cones, and sinuous rilles, suggesting variable eruption rates and possible different volatile contents associated with eruption conditions that produced each type of feature. The volcanic complexes, particularly Aristarchus and Marius, appear to be the sources for much of the central Procellarum mare fill.

Whitford-Stark, J. L.↗

NASA NTRS1975

Geology of the Taurus-Littrow valley floor

The paper surveys the geology of the Taurus-Littrow valley which is located in a graben that is radial to Mare Serenitatis. The basalt fill is characterized; basalt extrusion in the valley continued until about 3.7 b.y. ago and was quickly followed by deposition of glass beads that formed a mantling unit of probable pyroclastic origin. The glass-bead unit in combination with the overlying regolith forms an unconsolidated surficial deposit with an average thickness of about 14 m. The components of the regolith are described. It is thought that most of the craters are part of a secondary cluster formed by projectiles from Tycho. Age estimates for the central cluster and the light mantle are presented.

Wolfe, E. W.↗

NASA NTRS1978

On the origin of Luna 24 basalts and soils

Analyses of fine-grained very low titanium (VLT) basalt from the Luna 24 drill core suggest that a single homogeneous magma is represented by the sample. In particular, the small variation in MgO contents of the fine-grained basalt, together with the tight clustering of the compositions of brown glasses (which may be pyroclastic equivalents of the VLT basalt), provides evidence for the single-magma hypothesis. The high-Mg component in the soil samples, though not obviously explainable in petrographic terms, may be derived from material similar to olivine vitrophyre and its degraded products, or from some other high-Mg VLT basalt.

Ryder, G.↗

NASA NTRS1978

Modeling lunar volcanic eruptions

Simple physical arguments are used to show that basaltic volcanos on different planetary bodies would fountain to the same height if the mole fraction of gas in the magma scaled with the acceleration of gravity. It is suggested that the actual eruption velocities and fountain heights are controlled by the velocities of sound in the two phase gas/liquid flows. These velocities are in turn determined by the gas contents in the magma. Predicted characteristics of Hawaiian volcanos are in excellent accord with observations. Assuming that the only gas in lunar volcano is the CO which would be produced if the observed Fe metal in lunar basalts resulted from graphite reduction, lunar volcanos would fountain vigorously, but not as spectacularly as their terrestrial counterparts. The volatile trace metals, halogens, and sulfur released would be transported over the entire moon by the transient atmosphere. Orange and black glass type pyroclastic materials would be transported in sufficient amounts to produce the observed dark mantle deposits.

Housley, R. M.↗

NASA NTRS1978

Core 74001/2 - Grain size and petrology as a key to the rate of in-situ reworking and lateral transport on the lunar surface

A suite of samples from the double drive tube 74001/2 has been studied. Material from this core mainly consists of orange and black droplets interpreted to be volcanic pyroclastic ejecta. Grain size analysis indicates that this material is very homogeneous in its grain size properties. It is also the finest and best sorted suite of soil samples in the lunar collection having a mean grain size of 40 microns and a mean standard deviation of 1.75 phi. The upper 5.5 cm of this core has apparently undergone in situ reworking by meteorites over a period of about 10 million years. This reworked zone contains 'exotic' grains including basalt, mineral fragments, vitric breccias, and agglutinates. One type of agglutinate is unique and has been made primarily from orange and black glass droplets melted and welded together by micrometeorite impacts. Other agglutinates are made mainly from basaltic fragments and minerals. The amount of 'exotic' material added to the core combined with an estimate of the location of the source areas for the 'exotic' material allows us to estimate that a maximum of about 0.36 gm per sq cm of regolith surface is added from a radius of about 1 meter in 10 million years. Furthermore, no more than about 0.01 gm per sq cm of regolith surface is added from a radius of about 100 meters in 10 million years.

Mckay, D. S.↗

NASA NTRS1978

Depositional and surface exposure history of the Shorty Crater core 74001/2 - FMR and magnetic studies

Surface exposure (maturity) indices and concentrations of FeO and metallic iron were determined at 0.5-cm intervals of the Apollo 17 core section, which sampled a pyroclastic deposit on the rim of Shorty Crater. The determinations showed that all of the soil in the core is extremely immature. An exposure history of the core is proposed: accumulation (about 3.6 billion years ago), shallow burial (during the first 20 million years), deep burial (till about 10-15 million years ago), followed by excavation (10-15 million years ago), and in situ reworking (till the present).

Morris, R. V.↗

NASA NTRS1978

Mare volcanism in the Herigonius region of the moon

The paper considers the area in the vicinity of the crater Herigonius. This area contains numerous sinuous rilles, craters with irregular planimetric form, possible pyroclastic cones, and other features of probable volcanic origin, and appears to be the vent region that supplied lavas both northward to Oceanus Procellarum and southward to the Humorum basin. The approach used involves photogeologic interpretation of surface features and mapping of mare units to derive a regional stratigraphic sequence. The sequence of mare volcanism provides insight into the complex emplacement of lunar lavas and the general volcanic history of the moon.

Greeley, R.↗

NASA NTRS1978

Volcanism in the Noachis-Hellas region of Mars, 2

Mariner 9 and Viking Orbiter imagery has been examined to investigate volcanism in the Noachis-Hellas region of Mars. A wide variety of probable and possible volcanic features, including cinder cones, flood lavas, wrinkel ridges, cratered domes on the floors of impact craters, shield volcanoes, and possible stratovolcanoes has been observed. The flood lavas of ridged plains and broad, low shield volcanoes are indicative of very fluid lavas of ultrabasic or very basic basaltic composition. Evidence for relatively recent pyroclastic volcanism is present in numerous probable cinder cones and some isolated cratered mountains tentatively identified as stratovolcanoes. The volcanic complex and ridged plains at 68 deg S, 323 deg W appear to be relatively young. The occurrence of the five major volcanic centers of the Noachis-Hellas region at the intersections of ancient Hellas impact basin rings with a postulated northeast-trending fracture system suggests that large-scale volcanic activity may have begun soon after formation of the basin.

Peterson, J. E.↗

NASA NTRS1979

Scanning Auger Microprobe and atomic absorption studies of lunar volcanic volatiles

Results on lunar volatile transport processes have been obtained by studying green and brown glass droplets, orange and black core tube samples and the surface sample 74241 with the Scanning Auger Microprobe (SAM) and by Flameless Atomic Absorption Analysis (FLAA). SAM analyses show that the most dominant volatiles in the top few atomic layers of droplets are Zn and S, confirming that the surface Zn and S are good indicators of pyroclastic origin, and they are not entirely present as ZnS. In addition, FLAA thermal release profiles show that almost all the Zn and Cd are on grain surfaces, indicating that Zn and Cd were completely outgassed from lava fountain products during the volcanic eruption, were recondensed during or after the eruptions, and are thus present as surface coating.

Cirlin, E. H.↗