Geology topics

Goro Komatsu

Publications and source records attributed to Goro Komatsu.

4 recordsLinked to original sources

USGS2011

Utah's geologic and geomorphic analogs to Mars—An overview for planetary exploration

Utah offers spectacular geologic features and valuable analog environments and processes for Mars studies. Horizontal strata of the Colorado Plateau are analogous to Mars because the overprint of plate tectonics is minimal, yet the effects of strong ground motion from earthquakes or impacts are preserved in the sedimentary record. The close proximity of analog environments and lack of vegetative cover are advantages for field and remote-sensing studies. Dry, desert climate and modern wind processes of Utah are comparable to Mars and its current surface. Analogs in Utah include eolian, sabkha and saline bodies, glacial, lacustrine, spring, alluvial, fluvial, delta, and outflow channel depositional environments, as well as volcanic landforms and impact craters. Analogous secondary processes producing modification features include: diagenetic concretions, weathering and soils, sinkholes, sapping, knobs and pinnacles, crusts and varnish, and patterned grounds. Utah's physical and chemical environments are analogous to conditions on Mars where water existed and could support microorganisms. The development of Mars includes: ancient and modern depositional records, burial and diagenesis, uplift and tectonic alteration, and modern sculpting or weathering of the surface exposures. Recent satellite images are providing unprecedented details that rival the outcrop scale. Analogs in Utah are prime field localities that can be utilized in planning future robotic and human missions to Mars, and for teaching the next generation of planetary explorers.

Utah↗

USGS2010

Geomorphic knobs of Candor Chasma, Mars: New Mars Reconnaissance Orbiter data and comparisons to terrestrial analogs

High Resolution Imaging Science Experiment (HiRISE) imagery and digital elevation models of the Candor Chasma region of Valles Marineris, Mars, reveal prominent and distinctive positive-relief knobs amidst light-toned layers. Three classifications of knobs, Types 1, 2, and 3, are distinguished from a combination of HiRISE and Thermal Emission Imaging System (THEMIS) images based on physical expressions (geometries, spatial relationships), and spectral data from Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Type 1 knobs are abundant, concentrated, topographically resistant features with their highest frequency in West Candor, which have consistent stratigraphic correlations of the peak altitude (height). These Type 1 knobs could be erosional remnants of a simple dissected terrain, possibly derived from a more continuous, resistant, capping layer of pre-existing material diagenetically altered through recrystallization or cementation. Types 2 and 3 knobs are not linked to a single stratigraphic layer and are generally solitary to isolated, with variable heights. Type 3 are the largest knobs at nearly an order of magnitude larger than Type 1 knobs. The variable sizes and occasional pits on the tops of Type 2 and 3 knobs suggest a different origin, possibly related to more developed erosion, preferential cementation, or textural differences from sediment/water injection or intrusion, or from a buried impact crater. Enhanced color HiRISE images show a brown coloration of the knob peak crests that is attributable to processing and photometric effects; CRISM data do not show any detectable spectral differences between the knobs and the host rock layers, other than albedo. These intriguing knobs hold important clues to deducing relative rock properties, timing of events, and weathering conditions of Mars history.

Icarus↗

USGS2009

Deformation band clusters on Mars and implications for subsurface fluid flow

High-resolution imagery reveals unprecedented lines of evidence for the presence of deformation band clusters in layered sedimentary deposits in the equatorial region of Mars. Deformation bands are a class of geologic structural discontinuity that is a precursor to faults in clastic rocks and soils. Clusters of deformation bands, consisting of many hundreds of individual subparallel bands, can act as important structural controls on subsurface fluid flow in terrestrial reservoirs, and evidence of diagenetic processes is often preserved along them. Deformation band clusters are identified on Mars based on characteristic meter-scale architectures and geologic context as observed in data from the High-Resolution Imaging Science Experiment (HiRISE) camera. The identification of deformation band clusters on Mars is a key to investigating the migration of fluids between surface and subsurface reservoirs in the planet's vast sedimentary deposits. Similar to terrestrial examples, evidence of diagenesis in the form of light- and dark-toned discoloration and wall-rock induration is recorded along many of the deformation band clusters on Mars. Therefore, these structures are important sites for future exploration and investigations into the geologic history of water and water-related processes on Mars.

Geological Society of America Bulletin↗

USGS1999

Geologic map of the Barrymore Quadrangle (V-59), Venus

The Barrymore quadrangle (V–59) is a predominantly ridged plains region south of Imdr Regio, incorporating portions of Helen, Nuptadi, and Nsomeka Planitiae. The map area extends from lat 50°–75° S. and long 180°–240°, with nearly 70% coverage by cycle 1 synthetic aperture radar (SAR) images (left-look, incidence angles 16°–23°) and complete coverage by cycle 2 images (right-look, incidence angles 20°–25°) (fig. 1). The majority of the map area is covered by regional plains material that may either be smooth or deformed by wrinkle ridges or ridge belts of variable spacing. The difference in elevation between highest and lowest points in the map area is about 2.3 km. A north-south-oriented, 1,375-km linear ridge belt named “Saule Dorsa” is in the center of the region. The southern tip of this belt is intersected by a stratigraphically complicated, east-west-trending intermittent series of disrupted material, arcuate depressions and rises, regional plains, and volcanic centers. This region (hereafter referred to as the “east-west disrupted zone”) lies within a belt between 63°–67° S. extending from Kadlu Dorsa to Moombi Corona. A high concentration of canali-type channels (long sinuous lava channels that may contain subsidiary channels that branch off from the main channel [Baker and others, 1992; Komatsu and others, 1992]) occurs in Nsomeka Planitia. This includes Xulab Vallis and Citlalpul Valles, which form the eastern extent of a 3,000-km-long canali system (Komatsu and others, 1993). Three instances of canali bifurcation from north-south to east-west orientations occur in this region (fig. 2). Several large impact craters with fluidized ejecta blanket (FEB) outflows occur in the map area, along with some impact crater extended deposits (parabolas). The latter are mapped as surficial material using stipple patterns over the plains materials. These surficial deposits show variations in radar backscatter properties between cycle 1 and cycle 2 images related to orientation of aeolian dune or ripple faces (for example, Weitz and others, 1994; table 1). This region provides an interesting geologic setting for interpreting the history of regional and local plains formation and evolution, mainly due to development and subsequent deformation of the areally extensive plains units and accompanying canali (Komatsu and Baker, 1994).

IMAP↗