Harold R. Lang

Mapping from ASTER stereo image data: DEM validation and accuracy assessment

Abstract The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on-board the National Aeronautics and Space Administrations (NASAs) Terra spacecraft provides along-track digital stereo image data at 15-m resolution. As part of ASTER digital elevation model (DEM) accuracy evaluation efforts by the US/Japan ASTER Science Team, stereo image data for four study sites around the world have been employed to validate prelaunch estimates of heighting accuracy. Automated stereocorrelation procedures were implemented using the Desktop Mapping System (DMS) software on a personal computer to derive DEMs with 30- to 150-m postings. Results indicate that a root-mean-square error (RMSE) in elevation between ±7 and ±15 m can be achieved with ASTER stereo image data of good quality. An evaluation of an ASTER DEM data product produced at the US Geological Survey (USGS) EROS Data Center (EDC) yielded an RMSE of ±8.6 m. Overall, the ability to extract elevations from ASTER stereopairs using stereocorrelation techniques meets expectations.

ASTER as a source for topographic data in the late 1990s

Topography is a fundamental Earth characteristic that can be measured for studies of the land surface. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the EOS-AM1 platform will acquire along-track stereo data for topographic mapping. ASTER is capable of recording 771 digital stereo pairs per day, each covering 60/spl times/60 km on the ground, at 15-m resolution, with a base-to-height ratio of 0.6. According to present plans, approximately 30 digital elevation models (DEMs), accurate to within /spl plusmn/7 to /spl plusmn/50 m (RMSE/sub z/) will be produced daily by processing facilities in Japan and the United States. The Land Processes Distributed Active Archive Center (LP-DAAC) at the United States Geological Surveys (USGSs) EROS Data Center (EDC) will emphasize the use of automated stereocorrelation procedures to produce absolute DEMs tied to ground control. During the six-year mission, ASTER has the potential to provide a coherent, digital stereo data set covering all of the Earths land surface. At minimum, ASTER DEMs will augment topographic data from other sources. Results of simulations of ASTER stereo data using existing satellite and aircraft data over validation sites in Huntsville, AL, and Iguala, Mexico, illustrate the value of high-resolution ASTER DEMs and how actual ASTER DEMs will be validated.

ASTER preflight and inflight calibration and the validation of Level 2 products

Describes the preflight and inflight calibration approaches used for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). The system is a multispectral, high-spatial resolution sensor on the Earth Observing Systems EOS-AM1 platform. Preflight calibration of ASTER uses well-characterized sources to provide calibration and preflight round-robin exercises to understand biases between the calibration sources of ASTER and other EOS sensors. These round-robins rely on well-characterized, ultra-stable radiometers. An experiment field in Yokohama, Japan, showed that the output from the source used for the visible and near-infrared (VNIR) subsystem of ASTER may be underestimated by 1.5%, but this is still within the 4% specification for the absolute, radiometric calibration of these bands. Inflight calibration will rely on vicarious techniques and onboard blackbodies and lamps. Vicarious techniques include ground-reference methods using desert and water sites. A recent joint field campaign gives confidence that these methods currently provide absolute calibration to better than 5%, and indications are that uncertainties less than the required 4% should be achievable at launch. The EOS-AM1 platform will also provide a spacecraft maneuver that will allow ASTER to see the Moon, allowing further characterization of the sensor. A method for combining the results of these independent calibration results is presented. The paper also describes the plans for validating the Level 2 data products from ASTER. These plans rely heavily upon field campaigns using methods similar to those used for the ground-reference, vicarious calibration methods.

Multispectral Remote Sensing as Stratigraphic and Structural Tool, Wind River Basin and Big Horn Basin Areas, Wyoming

Stratigraphic and structural analyses of the Wind River basin and Big Horn basin areas of central Wyoming are in progress. One result has been the development of an approach to stratigraphic and structural analysis that uses photogeologic and spectral interpretation of multispectral image data to characterize the attitude, thickness, and lithology of strata. New multispectral systems that have only been available since 1982 are used with topographic data to map upper Paleozoic and Mesozoic strata exposed on the southern margin of the Bighorn Mountains. Landsat-acquired thematic mapper (TM) data together with topographic data are used to map lithologic contacts, measure dip and strike, and develop a stratigraphic column that is correlated with conventional surface and subsurface sections. Aircraft-acquired airborne imaging spectrometer (AIS) and thermal infrared multispectral scanner (TIMS) data add mineralogic information to the TM column, including the stratigraphic distribution of quartz, calcite, dolomite, smectite, and gypsum. Results illustrate an approach that has general applicability in other geologic investigations that could benefit from remotely acquired information about areal variations in attitude, sequence, thickness, and lithology of strata exposed at the earths surface. Application of our methods elsewhere is limited primarily by availability of multispectral and topographic data, and quality of bedrock exposures.

Constraining the Late Mesozoic and Early Tertiary Tectonic Evolution of Southern Mexico: Structure and Deformation History of the Tierra Caliente Region

We analyze the structure and assess the deformation history of the Tierra Caliente Metamorphic Complex (TCMC) of southern Mexico, where Laramide accretion of exotic terranes is in debate. The TCMC consists of a south‐plunging antiform fault that is bounded on both its eastern and western flanks. Tierra Caliente Metamorphic Complex rocks show at least two phases of compressional deformation. The first and most prominent records a mean tectonic transport direction of 068°. This phase is responsible for east‐verging asymmetrical folding and thrusting of both metamorphic and superjacent sedimentary rocks. The second phase has an average transport direction of 232° and is restricted to the western portion of the TCMC. A third phase is responsible for normal faulting. Lack of discernible deformation before Late Cretaceous time indicates that the main deformation phase is coincident with Laramide orogenesis elsewhere in the North American Cordillera. The stratigraphy, structure, and deformational history of the TCMC do not require accretion of exotic terranes. We explain the Mesozoic tectonostratigraphic evolution of the TCMC in terms of deposition and deformation of Mesozoic volcanic and sedimentary strata over the attenuated continental crust of the North American plate.

Spectral reflectance characterization (0.4 to 2.5 and 8.0 to 12.0 mu m) of Phanerozoic strata, Wind River basin and southern Bighorn Basin areas, Wyoming

ABSTRACT Reflectance spectroscopy, a useful analytical tool available to geologists for over 100 years, has not been widely used in petrologic or stratigraphic studies of sedimentary rocks. We are routinely using laboratory spectral reflectance data covering the 0.4 to 12.0 µm wavelength interval in an investigation of the stratigraphic and structural evolution of the Wind River and Bighorn basin areas, Wyoming. Two types of laboratory spectral reflectance measurements were made on 192 weathered outcrop, bedrock, and core samples: 1) hemispherical reflectance, from 0.4 to 2.5 µm (229 spectra) and 2) biconical reflectance, from 8.0 to 12.0 µm (84 spectra). Results show stratigraphic variations in the spectral properties of sedimentary rocks as encountered in the field. Sample mineralogy was determined using X-ray diffraction and interpretation of spectra. The mineralogy, lithology and stratigraphic distribution of samples are diverse and representative of Phanerozoic siliciclastic and carbonate strata encountered in foreland sedimentary basins. Spectra were sorted into 36 distinct groups, according to the presence or absence of 68 visible and infrared reflectance features. Many spectral features can be assigned to specific molecular phenomena and allow rapid determination of specific minerals. Minerals detectable spectrally include: gypsum, kaolinite, smectite, analcime, goethite, jarosite, calcite, dolomite, and feldspar. Results are contributing to our understanding of the depositional history of the Wind River and Bighorn basin areas; more importantly, results suggest that laboratory, field and remote reflectance spectroscopy have more general geologic applicability in studies of sedimentary rocks. Reflectance spectroscopy can augment conventional laboratory and field methods for petrologic analysis, correlation, interpretation of depositional environments, and construction of facies models.

THE ARCELIA GRABEN: NEW EVIDENCE FOR OLIGOCENE BASIN AND RANGE EXTENSION IN SOUTHERN MEXICO

Basin and Range extension, which began in the Tertiary and continues today, is well documented in Mexico north of the Trans-Mexican volcanic belt. In contrast, evidence for Basin and Range extension in southern Mexico is largely limited to the Oaxaca basin, a north-northwest–trending Miocene graben. We discovered another north-northwest–trending Tertiary basin, the Arcelia graben, approximately 200 km west of the Oaxaca basin and 50 km south of the Trans-Mexican volcanic belt. Arcelia graben subsidence began in the early Tertiary and mostly ended prior to accumulation of upper Oligocene volcanic rocks, indicating Basin and Range extension in this area was limited to a <32 m.y. interval in the Tertiary. Extension near Arcelia is among the oldest Basin and Range style deformation documented in Mexico. Most subsidence in the Arcelia graben preceded onset of Oaxaca basin subsidence by at least 8 m.y. This suggests the intriguing possibility of eastward migration of Basin and Range extension in southern Mexico during the middle Tertiary.

New Planktic Foraminiferal Data Documenting Coniacian Age For Laramide Orogeny Onset and Paleooceanography in Southern Mexico

A Late Cretaceous flysch comprising the 2600‐m‐thick Mexcala Formation records the initial local pulse of the Laramide Orogeny on the southern arm of the Mexican fold‐thrust belt in northeastern Guerrero State. We identified 15 planktic foraminiferal species from 35 productive shale samples that demonstrate that the Mexcala is assignable to the Dicarinella concavata biozone. Thus, in agreement with evidence from northern Mexico, the Laramide onset in southern Mexico occurred during Coniacian time. Paleozoogeographic interpretation of our faunas shows an oceanic connection with the Caribbean, and that the southern margin of the North American Plate in northern Guerrero must have been isolated from the Coniacian–early Santonian Pacific Ocean.

Preliminary Spectral and Geologic Analysis of Landsat-4 Thematic Mapper Data, Wind River Basin Area, Wyoming

A Landsat-4 Thematic Mapper (TM) image covering the Wind River Basin area, Wyoming, is under evaluation for stratigraphicand structural mapping, and for assessment of spectral and spatialcharacteristics using the six visible, near-infrared, and short-wavelengthinfrared bands.The image (path 36, row 30, ID # 40128-17232) was acquired on November 21, 1982. The data were obtained from the NASA Goddard Space Flight Center in radiometrically and geometrically correctedfullscene magnetic-tape format.To estimate equivalent Lambertian surface spectral reflectance, TMradiance data must first be calibrated to remove atmospheric andinstrumental effects. Reflectance measurements for homogeneousnatural and cultural targets in the scene were acquired during the period October 27-November 3, 1983, about one year after satellite dataacquisition. Scatterplots were prepared of image DN versus reflectancefor these sites. The scatterplots show the TM sensor system response islinear for the conditions of image acquisition and for the mix of terraincover types encountered.Low TM offset and gain settings result in encoded spectral data thatdo not occupy the full dynamic range (256 gray levels) of the TM.Calibration data acquired during the study were used to calculate new gainsand offsets that would improve scanner response for Earth scienceapplications.Analysis demonstrates that principal component images provideuseful structural and stratigraphic information. Principal componentscalculated from the correlation matix result from linear transformationsof ground reflectance. In images prepared from this transform, theseparation of spectral classes is largely independent of systematicatmospheric and instrumental factors.

Spectral stratigraphy: Remote sensing lithostratigraphic procedures for basin analysis, central wyoming examples

Stratigraphic and structural analysis of the Wind River and Bighorn basins of central Wyoming are in progress. One result has been the development of spectral stratigraphy, an approach to stratigraphic analysis that uses photogeologic and spectral interpretation of multispectral image data combined with topographic information to remotely characterize thickness and lithology of strata exposed in sedimentary basins. Thus, spectral stratigraphy is a new tool for use in integrated investigations of the evolution of sedimentary basins.Multispectral sensor systems that have been available since 1982 are used to analyze upper Paleozoic and Mesozoic strata on the southern margin of the Bighorn Mountains and the southern edge of the Bighorn Basin. Thematic Mapper (TM) data are used to develop stratigraphic columns and structural cross sections that are correlated with conventional surface and subsurface sections. Experimental thermal infrared aircraft data facilitate lithofacies/biofacies analysis of the monotonous Cretaceous Cody Shale sequence. Recently developed satellite and aircraft systems provide sufficient spectral resolution to allow for remote determination of the stratigraphic distribution of quartz, calcite, dolomite, gypsum, specific clay species, and other minerals diagnostic of depositional environments. Development of a desktop, computer-based, geologic analysis system that provides for automated stratigraphic interpretation and analysis of combined multispectral image and digital topographic data portends major advances in the application of spectral stratigraphy.Results demonstrate an approach with general applicability in other geologic investigations that could benefit from remotely acquired information about areal variations in sequence, attitude, thickness, and lithology of strata exposed at the Earths surface.