Observations of actively forming lava tubes and associated structures, Hawaii
Lava tube and channel development in basalt flow in upper east rift zone of Kilauea volcano, Hawaii
Greeley, R.↗
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Lava tubes of the cave basalt, Mount Saint Helens, Washington
Geomorphology of basaltic lava tubes from Mount St. Helens, Washington
Greeley, R.↗
Some chemical features of lavas from the Manu'a Islands, Samoa
Manua Islands /Samoa/ lavas chemical composition, geology and probable history
Hubbard, N. J.↗
Mare Imbrium lava flows and their relationship to color boundaries, part M
The Apollo 15 metric camera photography provided a number of spectacular views of most of the southern and central portions of the unique systems of major lava flows that stretch diagonally across Mare Imbrium from the general area of Euler Crater to a point east of Le Verrier Crater. A preliminary examination of the photographs indicates that the source of the material comprising the major flows is situated to the west of Euler Crater and south of the limits of the photographic coverage. The photographs also show clearly that most, if not all, the mare ridges included were formed after the solidification of the flows. Few color boundaries exist in the area of metric photography where the illumination angle is low enough to show the fronts of some of the very thin flows. However, patches of redder material lying northeast of Mt. Lahire are found to be enclosed by low flow fronts, confirming the theory that the redder material represents an earlier filling of the Imbrium basin.
Whitaker, E. A.↗
Lava filled craters and the thermal history of the lunar surface.
Discussion of a hypothesis according to which two separate phases of lunar crust heating could be responsible for the formation of Mare Smythii and Tsiolkovsky crater, two lava-filled relatively recent lunar features which cannot be easily explained by other hypotheses. A small-crater count in eight flat floored larger craters is conducted in an attempt to support the two-phase heating hypothesis, on a theory that the distribution of the smaller craters by size may indicate a recurrence of lunar crust heating. Further counts are suggested for a more substantiated conclusion.
Beals, C. S.↗
Volatile compounds released during lunar lava fountaining
A modified radiochemical neutron activation analysis was used to determine 24 elements in three sieve separates and in HCl leach, HF etch, and residue fractions of the 500-62 micron separate of orange glass fines 74220. Six elements - In, Cd, Zn, Ga, Ge, and Au - were strongly concentrated in the leach, indicating that they were present as a surface deposit, probably a sublimate resulting from condensation of lava-fountain volatiles which expelled the orange glass onto the lunar surface.
Wasson, J. T.↗
Silica activity in lunar lavas
Calculated values of log alpha SiO2 in lunar magmas range from approximately -0.8 to unity in the temperature range of 1100-1300 C. High-titanium mare basalts begin crystallizing at silica activities insufficient for orthopyroxene saturation; in contrast to terrestrial lavas, silica activities rise substantially with crystallization and cause silica saturation in the residuum. Igneous rocks of the highland regions have relatively higher initial silica activities than mare basalts. Thermodynamic calculations indicate that high-titanium mare basalts could be derived from a 90 to 240-km deep source region containing olivine and orthopyroxene in addition to other phases.
Nash, W. P.↗
A model for the evolution of opaques in mare lavas
The apparent 'reduced' state of the opaque mineral assemblages of mare basalts has led to various hypotheses on their origin through reduction by various media. A model is developed whereby the presence of trivalent titanium (Ti/3+/) and metallic iron in mare lavas at low oxygen fugacities automatically leads to the production of the observed assemblages by cooling near the mare basalt solidus. The 'reduced' assemblages may evolve isochemically at oxygen fugacities near the iron-ilmenite-ferropseudobrookite buffer by a reaction of the form Fe(2+)+2 Ti(3+) = metallic iron +2 Ti(4+).
Haselton, J. D.↗
Endogenic craters on basaltic lava flows - Size frequency distributions
Circular crater forms, termed collapse depressions, which occur on many basalt flows on the earth have also been detected on the moon and Mars and possibly on Mercury and Io. The admixture of collapse craters with impact craters would affect age determinations of planetary surface units based on impact crater statistics by making them appear anomalously old. In the work described in the present paper, the techniques conventionally used in planetary crater counting were applied to the determination of the size range and size frequency distribution of collapse craters on lava flows in Idaho, California, and New Mexico. Collapse depressions range in size from 3 to 80 m in diameter; their cumulative size distributions are similar to those of small impact craters on the moon.
Greeley, R.↗
Radar scatterometry of sand dunes and lava flows
Four frequency like polarized scatterometer data over a sand dune field and a volcanic field were analyzed to understand the scattering characteristics of these two terrain types as a function of frequency and incidence angle. For the frequency range studied (400 MHz to 13.3 GHz) unvegetated sand dunes are specular reflectors that return an echo to the radar antenna particularly when the geometry is such that the dune slope is nearly perpendicular to the antenna. Vegetation on the dunes can cause significant backscatter. Lava flows are strong diffuse scatterers which have backscatter values similar to coniferous forest at certain frequencies. Different observation frequencies are required for different situations. The scatterometer data correlate well with radar images.
Blom, R.↗
Classification of volcanoes of the Kane Patera Quadrangle of Io: Proportions of lava flows and pyroclastic flows
Voyager 1 images show 14 volcanic centers wholly or partly within the Kane Patera quadrangle of Io, which are divided into four major classes: (1) shield with parallel flows; (2) shield with early radial fan shapd flows; (3) shield with radial fan shaped flows, surfaces of flows textured with longitudinal ridges; and (4) depression surrounded by plateau-forming scarp-bounded, untextured deposits. The interpretation attempted here hinges largely on the ability to distinguish lava flows from pyroclastic flows by remote sensing.
Elston, W. E.↗
Geomorphic Classification of Lava Flows on Io
The lava flows on Io are classified into the following categories: broad, filamental, digitate, intercalated, sheet, and contained. Each classification is described according to flow distribution, geomorphology, color, thickness, and source.
Pieri, D. C.↗
Characteristics of Basaltic Lava Flows on Venus
Some ideas relating to the formation of lava flows on Venus are reviewed. The surface morphological features seen in the panoramic images made by the Venera 13 and 14 landers are examined in detail. The major element compositions measured by the Soviet probes indicate that the surface rocks at the Venera 13 site resemble a terrestrial tholeite composite whereas the Venera 14 rocks are similar to terrestrial alkali basalts. Few data exist on the rheological properties of such magma types on Earth; these properties are a strong function of magma volatile content, and there are important gaps in our knowledge of the typical volatiles to be associated with the magmas on Venus. However, the suggestion that Venusian magmas may be water poor together with consideration of the fact that the high Venusian surface temperatures may cause magmas to experience up to 50 K less cooling during their rise to the surface than corresponding terrestrial counterparts, leads to the finding that Venusian magmas may typically have plastic viscosities, E, up to a factor of three greater than terrestrial counterparts on eruption. A similar analysis of yield strength variations with temperature, magma composition and volatile content suggests that temperature will exert the main control and that Venusian magma yield strengths, Y, may be a factor of several times smaller than those of terrestrial equivalents.
Wilson, L.↗
Thermal Infrared Observations of Lava Flows During the 1984 Mauna Loa Eruption
Thermal infrared videotape images of the flowing lava streams and the vent areas at 10.6 microns were made, as well as some broadband images in the 8 to 12 micron range (for gas plume detection). These data were calibrated with on-site hand-held radiometer measurements, in-flow thermocouple measurements, and with later laboratory kiln measurements. Infrared video data are useful in quantitatively assessing the pattern and mode of flow thermal losses, particularly with regard to radiative losses from established/incipient floating crust. The general cooling of the flows downstream was readily apparent. Upper reaches of the active flow exhibited nearly crust-free main channels, radiating at about 700 to 800 degrees C. Below about the 7500 foot level (about 8 km from the vent) the flows formed nearly continuous crust and tended to spread, become less well-defined and founder due to a reduction in slope. Nevertheless, in thermal IR observations, the surface trace of the active subsurface channel was visible, radiating at about 500 to 700 degrees C. At the active flow front, most solid crust radiated at temperatures less than 500 to 600 degrees C, however bright high temperature interiors (approximately 900 to 1000 degrees C) were clearly visible though evolving fissures.
Pieri, D. C.↗
Hadley Rille, lava tubes and mare volcanism at the Apollo 15 site
Hadley Rille appears to be a collapsed lava tube/channel, whose formation history may be more intimately related to the mare units sampled at 15 than was previously thought. More work is needed relating samples and observations from Apollo 15 to the rille and its geologic evolution. As the only sinuous rille visited during the Apollo missions, Hadley Rille represents a data source that is directly applicable to the deciphering of processes involved in lunar mare volcanism.
Greeley, R.↗
The role of porosity in thermal inertia variations on basaltic lavas
Thermal inertia, defined as the square root of the product of thermal conductivity, density, and specific heat, has been noted to vary in inverse proportion to porosity in Hawaiian basalts. It is presently suggested that porosities of the order of more than 80 percent are required if the low thermal inertias observed in Martian shield volcanoes are the result of pristine lava flow surface properties. An aeolian origin is held to be most likely in view of thermal measurements on Mars; the volcanic surfaces in question are anticipated to have a short lifetime in their environment.
Zimbelman, James R.↗
Lava flows as kinematic waves
A recently proposed model for the emplacement of lava flows is reinterpreted as a kinematic wave theory for the depth of the flow. Explicit kinematic wave solutions and their properties are derived for three time-dependent boundary conditions of practical interest. These boundary conditions correspond to effusion rates that decrease, increase, and crest and broadly reflect types of eruption behavior documented in the geologic literature. Particular attention is given to the way source behavior propagates along the flow in relation to the advance of the flow itself.
Baloga, Stephen↗
Simulations of lava flows on Mars
One way to approach the understanding of the lava flows observed in the Viking images is to use well-documented terrestrial flows and to simulate comparable eruptions adjusted for Martian conditions. The detailed documentation available for several episodes of the 1983 to 1984 PuuOo eruption can be used in combination with an extension of the emplacement theory for solitary lobate flows to simulate comparable eruptions on the surface of Mars. For simplicity, the simulation is restricted to differences in the gravity between earth and Mars.
Baloga, S.↗