Infrasonic resonance has previously been measured in terrestrial caves by other researchers, wher... more Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs) on Tharsis, suggested as candidate cave entrance locations. The results show that, for several possible cave air movement periods, we are able to infer the approximate cave volumes. The utility of inferring cave volumes for planetary cave exploration is discussed. caves, resonance, Mars, wind, cave volume
North-polar temporal monitoring by the High Resolution Imaging Science Experiment (HiRISE) orbiti... more North-polar temporal monitoring by the High Resolution Imaging Science Experiment (HiRISE) orbiting Mars has discovered new, dramatic examples that Mars' CO 2-dominated seasonal volatile cycle is not limited to quiet deposition and sublimation of frost. In early northern martian spring, 2008, HiRISE captured several cases of CO 2 frost and dust cascading down a steep, polar scarp in discrete clouds. Analysis of morphology and process reveals these events to be similar to terrestrial powder avalanches, sluffs, and falls of loose, dry snow. Potential material sources and initiating mechanisms are discussed in the context of the Martian polar spring environment and of additional, active, aeolian processes observed on the plateau above the scarp. The scarp events are identified as a trigger for mass wasting of bright, fractured layers within the basal unit, and may indirectly influence the retreat rate of steep polar scarps in competing ways.
Water has supposedly marked the surface of Mars and produced characteristic landforms. To underst... more Water has supposedly marked the surface of Mars and produced characteristic landforms. To understand the history of water on Mars, we take a close look at key locations with the High-Resolution Imaging Science Experiment on board the Mars Reconnaissance Orbiter, reaching fine spatial scales of 25 to 32 centimeters per pixel. Boulders ranging up to ∼2 meters in diameter are ubiquitous in the middle to high latitudes, which include deposits previously interpreted as finegrained ocean sediments or dusty snow. Bright gully deposits identify six locations with very recent activity, but these lie on steep (20° to 35°) slopes where dry mass wasting could occur. Thus, we cannot confirm the reality of ancient oceans or water in active gullies but do see evidence of fluvial modification of geologically recent mid-latitude gullies and equatorial impact craters.
Introduction: This abstract summarizes current results and planned activities from an ongoing ini... more Introduction: This abstract summarizes current results and planned activities from an ongoing initiative to construct a series of high-resolution structural and geologic maps in the east Candor Chasma region of Valles Marineris, Mars. The goal of this work is to advance current understanding of the coupled structural evolution of eastern Candor Chasma and the sedimentary deposits within it through a campaign of geologic unit and structural mapping at spatial resolutions that are at least an order of magnitude finer than has been achieved by previous studies in this part of Valles Marineris. This will be accomplished by characterizing the structure of the sedimentary deposits using digital elevation models (DEMs) derived from publicly released, stereo image pairs acquired by the High Resolution Imaging Science Experiment (HiRISE) camera. Work is progressing in two map areas on and adjacent to Nia Mensa (Fig. 1). Mapping is most mature in the northern Nia Mensa map area, and an initia...
Introduction: Clastic sedimentary deposits are well– known source regions for terrestrial undergr... more Introduction: Clastic sedimentary deposits are well– known source regions for terrestrial underground reservoirs of volatiles because of the high porosities and permeabilities of these rocks [1,2]. Faults and their surrounding damage zones play an important role in controlling the pathways along which volatiles tend to migrate within these reservoirs. This is because faults and attendant damage zones can act as either barriers [3–6] or conduits [7–9] to the movement of volatiles within the reservoir. Where exposed through erosion, fault–controlled reservoirs offer excellent opportunities to examine past tectonic, geochemical, hydrologic and biologic processes that originally occurred in the subsurface. The light-toned layered deposits on Mars show abundant evidence of diagenetic alteration that is attributed to subsurface fluid flow. These deposits are in places highly fractured. Therefore understanding the implications of brittle fracturing on fluid flow potential through these dep...
published in: Lunar and Planetary Science XXXVI, CDROM, Lunar and Planetary Institute, Houston (2... more published in: Lunar and Planetary Science XXXVI, CDROM, Lunar and Planetary Institute, Houston (2005). Lunar and Planetary Science XXXVI (2005) 1008.pdf
Introduction: High-resolution geologic and structural mapping of four key sites in west Candor Ch... more Introduction: High-resolution geologic and structural mapping of four key sites in west Candor Chasma is nearing completion, and new mapping is commencing at three sites in east Candor Chasma (Fig. 1). These high-resolution maps are constructed using digital elevation models (DEMs) and orthorectified imagery constructed from stereo HiRISE observations. The maps have been, or will be, formally published through the US Geological Survey’s Scientific Investigations Map series at 1:18,000 scale. This paper presents a synthesis of results from west Candor and introduces the three new sites in east Candor. West Candor Chasma: Mapping in west Candor Chasma focused on the separate regions of central Candor Colles, southeast and west Ceti Mensa and east Candor Sulci. The central Candor Colles map has been published [1] and the remaining three maps are currently under review. These maps focus on the stratified sedimentary deposits within the chasma – the canonical Late Hesperian to Early Amaz...
published in: Lunar and Planetary Science XXXIV, CD-ROM, Lunar and Planetary Institute, Houston (... more published in: Lunar and Planetary Science XXXIV, CD-ROM, Lunar and Planetary Institute, Houston (2003). Lunar and Planetary Science XXXIV (2003) 1283.pdf
INTRODUCTION: Tharsis-radial graben and pit crater chains (catenae) have been interpreted as the ... more INTRODUCTION: Tharsis-radial graben and pit crater chains (catenae) have been interpreted as the result of igneous dike intrusions [1,2,3], which attain lengths in excess of 2000 km from the center of the Tharsis volcano–tectonic province. Based on the assumption that these Tharsis–radial graben and pit crater chains are underlain by dikes, geodynamic models of lithospheric uplift have been proposed to account for the stress state required for Tharsis–radial dike propagation [4] and the attendant magma fluxes have been estimated [2]. In this abstract, we test the fundamental assumption that Tharsis–radial pit crater chains are underlain by igneous dikes by examining Phlegethon, Acheron and Tractus Catenae on the southeast flank of Alba Patera. Following [5] we compare MOLA–based topography against standard numerical model predictions of surface deformation above buried and surface– breaking dikes and normal faults. We find that these pit crater chains have local cross–strike topogra...
Introduction: Magnitudes of shear displacement along normal and thrust faults on Mercury and Mars... more Introduction: Magnitudes of shear displacement along normal and thrust faults on Mercury and Mars are characteristically smaller relative to their length, compared to the displacement to length ratios of faults on Earth (Fig. 1) [1]. Displacement to length ratios are typically 6 x 10 or 6.7 x 10 for faults on Mars [2,3] and 6.5 x 10 for faults on Mercury [Watters et al., 2000]. On Earth, this ratio is typically 2–5 x 10 over a range of tectonic settings and rock types [4–8]. Faults on Mercury and Mars thus have less displacement relative to their length than faults on Earth. Under–displacement of fractures (faults and joints) on Mercury and Mars is attributed to these planets’ smaller gravitational accelerations relative to Earth [1]. Fracture displacements may be either shear for faults or dilation for joints. The ratio of a fracture’s displacement to its length is a function of the deformation modulus of the surrounding rock mass, the yield strength of the rock near the fracture t...
Current studies of wrinkle ridge development suggest that wrinkle ridges are the surface expressi... more Current studies of wrinkle ridge development suggest that wrinkle ridges are the surface expressions of thrust folds. Specifically, wrinkle ridges may develop in a manner similar to terrestrial blind thrust anticlines [1]. The mechanical models presented here show that the width of the blind thrust anticline is dependent on fault dip and height, and that anticline height is sensitive to the slip magnitude and fault depth. These models can be used to extract subjacent fault and lithologic information from wrinkle ridge topography.
Résumé/Abstract Direct satellite data reception at high temporal frequencies and automated proces... more Résumé/Abstract Direct satellite data reception at high temporal frequencies and automated processing enable near-real-time, near-continuous thermal monitoring of volcanoes. We review what has been achieved in terms of turning this capability into real-time tools of use ...
HiRISE DTMs are produced at 1 m/px and 2 m/px, depending on source image mode. The procedure used... more HiRISE DTMs are produced at 1 m/px and 2 m/px, depending on source image mode. The procedure used to create the DTMs and their associated orthoimages is described here, as well as the products being made available via the PDS starting in 2010.
The strength and deformability of light-toned layered deposits are estimated based on measurement... more The strength and deformability of light-toned layered deposits are estimated based on measurements of porosity from Microscopic Imager data acquired by MER Opportunity during its traverse from Eagle Crater to Erebus Crater.
We present an inventory of geomorphic analogues for Lake Bonneville and Mars, with focus on poten... more We present an inventory of geomorphic analogues for Lake Bonneville and Mars, with focus on potential standing-water features. The goal is to understand water as a geomorphic agent at a variety of temporal and spatial scales.
High-resolution imagery reveals unprecedented lines of evidence for the presence of deformation b... more 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 fl uid fl ow in terrestrial reservoirs, and evidence of diagenetic processes is often preserved along them. Deformation band clusters are identifi ed 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 identifi cation of deformation band clusters on Mars is a key to investigating the migration of fl uids between surface and subsurface reservoirs in the planet's vast sedimentary deposits. Similar to terrestrial examples, evidence of diagenesis in the form of lightand 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 waterrelated processes on Mars.
The Jurassic Navajo Sandstone contains multiple features similar to the sedimentary record on Mar... more The Jurassic Navajo Sandstone contains multiple features similar to the sedimentary record on Mars. Terrestrial analogs provide key constraints and a comparative framework for remotely interpreting martian properties, processes, and history.
Faults on smaller planets and satellites than Earth have less offset D per unit length L, resulti... more Faults on smaller planets and satellites than Earth have less offset D per unit length L, resulting in smaller D/L ratios. This systematic reduction is real and results from gravity scaling of the faulting process. Quantitative scaling predictions closely match the observations.
HiRISE images reveal numerous positive relief knobs amidst layered deposits in West Candor Chasma... more HiRISE images reveal numerous positive relief knobs amidst layered deposits in West Candor Chasma. We document knob characteristics and present possible origins utilizing Earth analogs. The knobs may hold records of Mars past global water cycle.
Infrasonic resonance has previously been measured in terrestrial caves by other researchers, wher... more Infrasonic resonance has previously been measured in terrestrial caves by other researchers, where Helmholtz resonance has been suggested as the plausible mechanism resulting in periodic wind reversals within cave entrances. We extend this reasoning to possible Martian caves, where we examine the characteristics of four atypical pit craters (APCs) on Tharsis, suggested as candidate cave entrance locations. The results show that, for several possible cave air movement periods, we are able to infer the approximate cave volumes. The utility of inferring cave volumes for planetary cave exploration is discussed. caves, resonance, Mars, wind, cave volume
North-polar temporal monitoring by the High Resolution Imaging Science Experiment (HiRISE) orbiti... more North-polar temporal monitoring by the High Resolution Imaging Science Experiment (HiRISE) orbiting Mars has discovered new, dramatic examples that Mars' CO 2-dominated seasonal volatile cycle is not limited to quiet deposition and sublimation of frost. In early northern martian spring, 2008, HiRISE captured several cases of CO 2 frost and dust cascading down a steep, polar scarp in discrete clouds. Analysis of morphology and process reveals these events to be similar to terrestrial powder avalanches, sluffs, and falls of loose, dry snow. Potential material sources and initiating mechanisms are discussed in the context of the Martian polar spring environment and of additional, active, aeolian processes observed on the plateau above the scarp. The scarp events are identified as a trigger for mass wasting of bright, fractured layers within the basal unit, and may indirectly influence the retreat rate of steep polar scarps in competing ways.
Water has supposedly marked the surface of Mars and produced characteristic landforms. To underst... more Water has supposedly marked the surface of Mars and produced characteristic landforms. To understand the history of water on Mars, we take a close look at key locations with the High-Resolution Imaging Science Experiment on board the Mars Reconnaissance Orbiter, reaching fine spatial scales of 25 to 32 centimeters per pixel. Boulders ranging up to ∼2 meters in diameter are ubiquitous in the middle to high latitudes, which include deposits previously interpreted as finegrained ocean sediments or dusty snow. Bright gully deposits identify six locations with very recent activity, but these lie on steep (20° to 35°) slopes where dry mass wasting could occur. Thus, we cannot confirm the reality of ancient oceans or water in active gullies but do see evidence of fluvial modification of geologically recent mid-latitude gullies and equatorial impact craters.
Introduction: This abstract summarizes current results and planned activities from an ongoing ini... more Introduction: This abstract summarizes current results and planned activities from an ongoing initiative to construct a series of high-resolution structural and geologic maps in the east Candor Chasma region of Valles Marineris, Mars. The goal of this work is to advance current understanding of the coupled structural evolution of eastern Candor Chasma and the sedimentary deposits within it through a campaign of geologic unit and structural mapping at spatial resolutions that are at least an order of magnitude finer than has been achieved by previous studies in this part of Valles Marineris. This will be accomplished by characterizing the structure of the sedimentary deposits using digital elevation models (DEMs) derived from publicly released, stereo image pairs acquired by the High Resolution Imaging Science Experiment (HiRISE) camera. Work is progressing in two map areas on and adjacent to Nia Mensa (Fig. 1). Mapping is most mature in the northern Nia Mensa map area, and an initia...
Introduction: Clastic sedimentary deposits are well– known source regions for terrestrial undergr... more Introduction: Clastic sedimentary deposits are well– known source regions for terrestrial underground reservoirs of volatiles because of the high porosities and permeabilities of these rocks [1,2]. Faults and their surrounding damage zones play an important role in controlling the pathways along which volatiles tend to migrate within these reservoirs. This is because faults and attendant damage zones can act as either barriers [3–6] or conduits [7–9] to the movement of volatiles within the reservoir. Where exposed through erosion, fault–controlled reservoirs offer excellent opportunities to examine past tectonic, geochemical, hydrologic and biologic processes that originally occurred in the subsurface. The light-toned layered deposits on Mars show abundant evidence of diagenetic alteration that is attributed to subsurface fluid flow. These deposits are in places highly fractured. Therefore understanding the implications of brittle fracturing on fluid flow potential through these dep...
published in: Lunar and Planetary Science XXXVI, CDROM, Lunar and Planetary Institute, Houston (2... more published in: Lunar and Planetary Science XXXVI, CDROM, Lunar and Planetary Institute, Houston (2005). Lunar and Planetary Science XXXVI (2005) 1008.pdf
Introduction: High-resolution geologic and structural mapping of four key sites in west Candor Ch... more Introduction: High-resolution geologic and structural mapping of four key sites in west Candor Chasma is nearing completion, and new mapping is commencing at three sites in east Candor Chasma (Fig. 1). These high-resolution maps are constructed using digital elevation models (DEMs) and orthorectified imagery constructed from stereo HiRISE observations. The maps have been, or will be, formally published through the US Geological Survey’s Scientific Investigations Map series at 1:18,000 scale. This paper presents a synthesis of results from west Candor and introduces the three new sites in east Candor. West Candor Chasma: Mapping in west Candor Chasma focused on the separate regions of central Candor Colles, southeast and west Ceti Mensa and east Candor Sulci. The central Candor Colles map has been published [1] and the remaining three maps are currently under review. These maps focus on the stratified sedimentary deposits within the chasma – the canonical Late Hesperian to Early Amaz...
published in: Lunar and Planetary Science XXXIV, CD-ROM, Lunar and Planetary Institute, Houston (... more published in: Lunar and Planetary Science XXXIV, CD-ROM, Lunar and Planetary Institute, Houston (2003). Lunar and Planetary Science XXXIV (2003) 1283.pdf
INTRODUCTION: Tharsis-radial graben and pit crater chains (catenae) have been interpreted as the ... more INTRODUCTION: Tharsis-radial graben and pit crater chains (catenae) have been interpreted as the result of igneous dike intrusions [1,2,3], which attain lengths in excess of 2000 km from the center of the Tharsis volcano–tectonic province. Based on the assumption that these Tharsis–radial graben and pit crater chains are underlain by dikes, geodynamic models of lithospheric uplift have been proposed to account for the stress state required for Tharsis–radial dike propagation [4] and the attendant magma fluxes have been estimated [2]. In this abstract, we test the fundamental assumption that Tharsis–radial pit crater chains are underlain by igneous dikes by examining Phlegethon, Acheron and Tractus Catenae on the southeast flank of Alba Patera. Following [5] we compare MOLA–based topography against standard numerical model predictions of surface deformation above buried and surface– breaking dikes and normal faults. We find that these pit crater chains have local cross–strike topogra...
Introduction: Magnitudes of shear displacement along normal and thrust faults on Mercury and Mars... more Introduction: Magnitudes of shear displacement along normal and thrust faults on Mercury and Mars are characteristically smaller relative to their length, compared to the displacement to length ratios of faults on Earth (Fig. 1) [1]. Displacement to length ratios are typically 6 x 10 or 6.7 x 10 for faults on Mars [2,3] and 6.5 x 10 for faults on Mercury [Watters et al., 2000]. On Earth, this ratio is typically 2–5 x 10 over a range of tectonic settings and rock types [4–8]. Faults on Mercury and Mars thus have less displacement relative to their length than faults on Earth. Under–displacement of fractures (faults and joints) on Mercury and Mars is attributed to these planets’ smaller gravitational accelerations relative to Earth [1]. Fracture displacements may be either shear for faults or dilation for joints. The ratio of a fracture’s displacement to its length is a function of the deformation modulus of the surrounding rock mass, the yield strength of the rock near the fracture t...
Current studies of wrinkle ridge development suggest that wrinkle ridges are the surface expressi... more Current studies of wrinkle ridge development suggest that wrinkle ridges are the surface expressions of thrust folds. Specifically, wrinkle ridges may develop in a manner similar to terrestrial blind thrust anticlines [1]. The mechanical models presented here show that the width of the blind thrust anticline is dependent on fault dip and height, and that anticline height is sensitive to the slip magnitude and fault depth. These models can be used to extract subjacent fault and lithologic information from wrinkle ridge topography.
Résumé/Abstract Direct satellite data reception at high temporal frequencies and automated proces... more Résumé/Abstract Direct satellite data reception at high temporal frequencies and automated processing enable near-real-time, near-continuous thermal monitoring of volcanoes. We review what has been achieved in terms of turning this capability into real-time tools of use ...
HiRISE DTMs are produced at 1 m/px and 2 m/px, depending on source image mode. The procedure used... more HiRISE DTMs are produced at 1 m/px and 2 m/px, depending on source image mode. The procedure used to create the DTMs and their associated orthoimages is described here, as well as the products being made available via the PDS starting in 2010.
The strength and deformability of light-toned layered deposits are estimated based on measurement... more The strength and deformability of light-toned layered deposits are estimated based on measurements of porosity from Microscopic Imager data acquired by MER Opportunity during its traverse from Eagle Crater to Erebus Crater.
We present an inventory of geomorphic analogues for Lake Bonneville and Mars, with focus on poten... more We present an inventory of geomorphic analogues for Lake Bonneville and Mars, with focus on potential standing-water features. The goal is to understand water as a geomorphic agent at a variety of temporal and spatial scales.
High-resolution imagery reveals unprecedented lines of evidence for the presence of deformation b... more 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 fl uid fl ow in terrestrial reservoirs, and evidence of diagenetic processes is often preserved along them. Deformation band clusters are identifi ed 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 identifi cation of deformation band clusters on Mars is a key to investigating the migration of fl uids between surface and subsurface reservoirs in the planet's vast sedimentary deposits. Similar to terrestrial examples, evidence of diagenesis in the form of lightand 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 waterrelated processes on Mars.
The Jurassic Navajo Sandstone contains multiple features similar to the sedimentary record on Mar... more The Jurassic Navajo Sandstone contains multiple features similar to the sedimentary record on Mars. Terrestrial analogs provide key constraints and a comparative framework for remotely interpreting martian properties, processes, and history.
Faults on smaller planets and satellites than Earth have less offset D per unit length L, resulti... more Faults on smaller planets and satellites than Earth have less offset D per unit length L, resulting in smaller D/L ratios. This systematic reduction is real and results from gravity scaling of the faulting process. Quantitative scaling predictions closely match the observations.
HiRISE images reveal numerous positive relief knobs amidst layered deposits in West Candor Chasma... more HiRISE images reveal numerous positive relief knobs amidst layered deposits in West Candor Chasma. We document knob characteristics and present possible origins utilizing Earth analogs. The knobs may hold records of Mars past global water cycle.
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