John C. Mars

Lithologic mapping in the Mountain Pass, California area using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data

Abstract Evaluation of an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image of the Mountain Pass, California area indicates that several important lithologic groups can be mapped in areas with good exposure by using spectral-matching techniques. The three visible and six near-infrared bands, which have 15-m and 30-m resolution, respectively, were calibrated by using in situ measurements of spectral reflectance. Calcitic rocks were distinguished from dolomitic rocks by using matched-filter processing in which image spectra were used as references for selected spectral categories. Skarn deposits and associated bright coarse marble were mapped in contact metamorphic zones related to intrusion of Mesozoic and Tertiary granodioritic rocks. Fe-muscovite, which is common in these intrusive rocks, was distinguished from Al-muscovite present in granitic gneisses and Mesozoic granite. Quartzose rocks were readily discriminated, and carbonate rocks were mapped as a single broad unit through analysis of the 90-m resolution, five-band surface emissivity data, which is produced as a standard product at the EROS Data Center. Three additional classes resulting from spectral-angle mapper processing ranged from (1) a broad granitic rock class (2) to predominately granodioritic rocks and (3) a more mafic class consisting mainly of mafic gneiss, amphibolite and variable mixtures of carbonate rocks and silicate rocks.

Regional mapping of phyllic- and argillic-altered rocks in the Zagros magmatic arc, Iran, using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and logical operator algorithms

A method for regional mapping of phyllic and argillic hydrothermally altered rocks using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data was developed and tested at the Cuprite, Nevada, calibration and validation site, and then extensively used in the Zagros magmatic arc in Iran, which consists of the High Zagros and Jebal Barez Mountains, and the Bazman volcanic area. Logical operator algorithms were developed to perform multiple band ratio and threshold value calculations, which can be applied to a scene using a single algorithm, thus eliminating separate production and application of vegetation and dark pixel masks. Argillic and phyllic band-ratio logical operators use band ratios that define the 2.17 µm and 2.20 µm absorption features to map kaolinite and alunite, which are typical in argillic-altered rocks, and muscovite, which is a common mineral in phyllic-altered rocks. Regional mapping of the Zagros magmatic arc using the logical operators illustrates distinctive patterns of argillic and phyllic rocks that can be associated with regional structural features and tectonic processes, and that can be used in regional mineral assessments. Semicircular patterns, 1–5 km in diameter, of mapped phyllic- and argillic-altered rocks are typically associated with Eocene to Miocene intrusive igneous rocks, some of which host known porphyry copper deposits, such as at Meiduk and Sar Cheshmeh. Linear phyllic-altered rock patterns associated with extensive faults and fractures indicate potential epithermal or polymetallic vein deposits. On the basis of argillic and phyllic alteration patterns, ∼50 potential porphyry copper deposits were mapped northwest of the Zagros-Makran transform zone in an eroded, exhumed, and dormant part of the magmatic arc, whereas only 11 potential porphyry copper deposits were mapped to the southeast of the transform, in the volcanically active part of the magmatic arc. The Zagros-Makran transform zone, which separates the volcanically dormant and active parts of the Zagros magmatic arc, exhibits extensive linear patterns of phyllic-altered rocks that indicate the potential for polymetallic-epithermal vein deposits.

Mapping mine wastes and analyzing areas affected by selenium-rich water runoff in southeast Idaho using AVIRIS imagery and digital elevation data

Abstract Remotely sensed hyperspectral and digital elevation data from southeastern Idaho are combined in a new method to assess mine waste contamination. Waste rock from phosphorite mining in the area contains selenium, cadmium, vanadium, and other metals. Toxic concentrations of selenium have been found in plants and soils near some mine waste dumps. Eighteen mine waste dumps and five vegetation cover types in the southeast Idaho phosphate district were mapped by using Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) imagery and field data. The interaction of surface water runoff with mine waste was assessed by registering the AVIRIS results to digital elevation data, enabling determinations of (1) mine dump morphologies, (2) catchment watershed areas above each mine dump, (3) flow directions from the dumps, (4) stream gradients, and (5) the extent of downstream wetlands available for selenium absorption. Watersheds with the most severe selenium contamination, such as the South Maybe Canyon watershed, are associated with mine dumps that have large catchment watershed areas, high stream gradients, a paucity of downstream wetlands, and dump forms that tend to obstruct stream flow. Watersheds associated with low concentrations of dissolved selenium, such as Angus Creek, have mine dumps with small catchment watershed areas, low stream gradients, abundant wetlands vegetation, and less obstructing dump morphologies.

ASTER spectral analysis and lithologic mapping of the Khanneshin carbonatite volcano, Afghanistan

Advanced Spaceborne Thermal and Reflection Radiometer (ASTER) data of the early Quaternary Khanneshin carbonatite volcano located in southern Afghanistan were used to identify carbonate rocks within the volcano and to distinguish them from Neogene ferruginous polymict sandstone and argillite. The carbonatitic rocks are characterized by diagnostic CO3 absorption near 11.2 μm and 2.31–2.33 μm, whereas the sandstone, argillite, and adjacent alluvial deposits exhibit intense Si-O absorption near 8.7 μm caused mainly by quartz and Al-OH absorption near 2.20 μm due to muscovite and illite. Calcitic carbonatite was distinguished from ankeritic carbonatite in the short wave infrared (SWIR) region of the ASTER data due to a slight shift of the CO3 absorption feature toward 2.26 μm (ASTER band 7) in the ankeritic carbonatite spectra. Spectral assessment using ASTER SWIR data suggests that the area is covered by extensive carbonatite flows that contain calcite, ankerite, and muscovite, though some areas mapped as ankeritic carbonatite on a preexisting geologic map were not identified in the ASTER data. A contact aureole shown on the geologic map was defined using an ASTER false color composite image (R = 6, G = 3, B = 1) and a logical operator byte image. The contact aureole rocks exhibit Fe2+, Al-OH, and Fe, Mg-OH spectral absorption features at 1.65, 2.2, and 2.33 μm, respectively, which suggest that the contact aureole rocks contain muscovite, epidote, and chlorite. The contact aureole rocks were mapped using an Interactive Data Language (IDL) logical operator. A visible through short wave infrared (VNIR-SWIR) mineral and rock-type map based on matched filter, band ratio, and logical operator analysis illustrates: (1) laterally extensive calcitic carbonatite that covers most of the crater and areas northeast of the crater; (2) ankeritic carbonatite located southeast and north of the crater and some small deposits located within the crater; (3) agglomerate that primarily covers the inside rim of the crater and a small area west of the crater; (4) a crater rim that consists mostly of epidote-chlorite-muscovite–rich metamorphosed argillite and sandstone; and (5) iron (Fe3+) and muscovite-illite–rich rocks and iron-rich eolian sands surrounding the western part of the volcano. The thermal infrared (TIR) rock-type map illustrates laterally extensive carbonatitic and mafic rocks surrounded by quartz-rich eolian and fluvial reworked sediments. In addition, the combination of VNIR, SWIR, and TIR data complement one another in that the TIR data illustrate more laterally extensive rock types and the VNIR-SWIR data distinguish more specific varieties of rocks and mineral mixtures.

Mapping hydrothermally altered rocks by analyzing hyperspectral image (AVIRIS) data of forested areas in the Southeastern United States

Abstract Analysis of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data of the Carolina slate belt, a region in the Southeastern United States, has shown that certain types of hydrothermally altered rocks can be delineated based on the spectral reflectance characteristics of forest vegetation growing on them. These altered rocks are typically highly silicified and commonly associated with gold, silver, and pyrophyllite ores. Field evaluation of the resulting forest classification identified several previously unmapped areas of altered rocks, and no areas that were mapped erroneously. Distinction of the altered rocks from unaltered siliceous volcanic bedrock areas, also silica-rich, is especially significant as chestnut oak forests are characteristic of both. We conclude that the dominant chestnut oak canopy and the lack of other species that are usually present here on the unaltered rocks, result in lower apparent canopy density at the altered sites, which is expressed in the AVIRIS data by lower O–H absorption intensity. These differences in species composition and canopy architecture may be caused by one or several factors, including soil depth and physical properties, direction and steepness of slope, moisture availability, and the amount of nutrients present and their availability to the trees.

Upper Devonian–Mississippian stratigraphic framework of the Arkoma Basin and distribution of potential source-rock facies in the Woodford–Chattanooga and Fayetteville–Caney shale-gas systems

Wireline logs were used to document the stratigraphic framework of Upper Devonian–Mississippian strata in the Arkoma Basin, and maps of high-gamma ray (HGR) log response were used to analyze the spatial distribution of potential source rocks in the Woodford–Chattanooga and Fayetteville–Caney shale-gas systems. The Woodford–Chattanooga shale is a transgressive deposit that accumulated on an arid continental margin influenced by marine upwelling and minimal sediment influx. A broad HGR depocenter along the southwestern margin of the basin includes two areas of higher accommodation containing the thickest HGR concentrations. Basin-wide patterns of HGR likely reflect broad tectonic influence on accommodation. The proportion of chert in the formation increases eastward and southward, likely reflecting latitudinal and bathymetric influence on the accumulation of siliceous ooze. The Lower Mississippian Burlington sequence, which lies between the two shale-gas systems, comprises carbonate ramp and distal shale deposits. Proximal ramp facies form an apron around the southern flank of the Ozark uplift and grade radially basinward into distal facies. An Upper Mississippian succession in the east includes lowstand deposits of the Batesville delta, which onlap the relict Burlington ramp. Basinwide, the succession includes the transgressive Fayetteville–Caney shale overlain by regressive deposits of the proximal Pitkin Limestone and distal upper Fayetteville (Arkansas) and “false” Caney (Oklahoma) shale. The HGR shale is concentrated in an area of intermediate accommodation on the western margin of the Mississippi Embayment and just basinward of the Pitkin Limestone pinchout in Arkansas, and in an area of relatively high accommodation in Oklahoma.

Stratigraphy and Holocene Evolution of Mobile Bay in Southwestern Alabama

ABSTRACT Mobile Bay is a large (1058 km2) estuarine system in southwestern Alabama. On the basis of borings, vibracores, radiocarbon dating, and high resolution seismic lines, Holocene inundation of the bay has been reconstructed. A paleotopographic map delineates an entrenched river valley that occupied the present-day bay area during the last Pleistocene lowstand. Vertical stacking of Holocene facies seen in vibracores and boring logs records the evolution of the bay during postglacial sea-level rise and the resumption of deposition above the Late Pleistocene exposure surface. Two types of vertical sequences are present in Mobile Bay sediments. The first type is a fining-upward sequence that formed as beach, marsh, and near-shore sediments were covered by open-bay muds. Local progradation of the bay-head delta and the Dauphin Island-Morgan Peninsula barrier complex has produced the second type, a fining then coarsening-upward sequence. A disconformable contact with the pre-Holocene sediments is recognizable on seismic lines by erosional truncation and in cores by coloration, root mottling, and radiocarbon ages greater than 17,500 years before present (Y. B. P.). Bay inundation commenced approximately 7,500 Y. B. P. and proceeded in two phases. The first phase, from 7,500 to 6,000 Y. B. P., was a time of rapid relative sea level rise in which 70% of the bay was inundated. Rapid submergence below normal wave base produced a low energy, open-bay setting in the central part of the bay. In this area, vertical sequences are characterized by thin near-shore and beach deposits ( 5 m). By 6,000 Y. B. P., the bay extended farther to the north and was slightly deeper than the present-day bay. The second phase, from 6,000 Y. B. P. to present, was a time of slow relative sea-level rise. Slow inundation resulted in more time for sediments to be reworked and to accumulate above normal wave base. Thus, vertical sequences from the slowly inundated bay margins contain thick sections of near-shore and beach facies (> 5 m) overlain by thin sections of open-bay mud (< 1 m). Both length and depth of the bay decreased as the bay-head delta prograded and the bay filled. Decreasing length and shallowing of the bay over this time resulted in increasing riverine dominance and a diminishing of the northward intrusion of high salinity Gulf of Mexico waters.

New method to integrate remotely sensed hydrothermal alteration mapping into quantitative mineral resource assessments

Hydrothermal alteration data mapped using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) were compiled into hydrothermal alteration polygons for use in an assessment of porphyry copper mineral resource potential in the southwestern United States. Hydrothermal alteration polygons along with geochemistry, gravity and magnetic, lithologic, and deposit and prospects data were compiled in a GIS to produce a quantitative set of physical properties for each polygon that were effectively used in making estimates of undiscovered deposits for each permissive tract. Results show a higher estimate of potential undiscovered deposits (17 vs 14) for permissive tracts when ASTER alteration data were used in the assessment.

Alteration, slope-classified alteration, and potential lahar inundation maps of volcanoes for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Volcano Archive

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Littoral assessment of mine burial signatures (LAMBS): buried landmine/background spectral-signature analyses

The objective of the Office of Naval Research (ONR) Rapid Overt Reconnaissance (ROR) program and the Airborne Littoral Reconnaissance Technologies (ALRT) projects LAMBS effort is to determine if electro-optical spectral discriminants exist that are useful for the detection of land mines in littoral regions. Statistically significant buried mine overburden and background signature data were collected over a wide spectral range (0.35 to 14 µm) to identify robust spectral features that might serve as discriminants for new airborne sensor concepts. LAMBS has expanded previously collected databases to littoral areas - primarily dry and wet sandy soils - where tidal, surf, and wind conditions can severely modify spectral signatures. At AeroSense 2003, we reported completion of three buried mine collections at an inland bay, Atlantic and Gulf of Mexico beach sites. We now report LAMBS spectral database analyses results using metrics which characterize the detection performance of general types of spectral detection algorithms. These metrics include mean contrast, spectral signal-to-clutter, covariance, information content, and spectral matched filter analyses. Detection performance of the buried land mines was analyzed with regard to burial age, background type, and environmental conditions. These analyses considered features observed due to particle size differences, surface roughness, surface moisture, and compositional differences.