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M. H. Podwysocki

Publications and source records attributed to M. H. Podwysocki.

15 recordsLinked to original sources
USGS1990

Mineralized and unmineralized calderas in Spain; Part II, evolution of the Rodalquilar caldera complex and associated gold-alunite deposits

The Rodalquilar caldera complex is located in the western part of the Cabo de Gata volcanic field in southeastern Spain and is the first documented example of epithermal gold-alunite mineralization within a caldera in Europe. The Rodalquilar caldera is an oval collapse structure having a maximum diameter of 8 km and formed at 11 Ma from eruption of the Cinto ash-flow tuff. The oval Lomilla caldera, with a diameter of 2 km, is nested within the central resurgent dome of the older Rodalquilar caldera. The Lomilla caldera resulted from the eruption of the Lazaras ash-flow tuff which was ponded within the moat of the Rodalquilar caldera. The last phase of volcanic activity in the caldera complex was the emplacement of hornblende andesite flows and intrusions. This magmatic event resulted in structural doming of the caldera, opening of fractures and faults, and provided the heat source for the large hydrothermal systems which deposited quartz-alunite type gold deposits and base metal vein systems. The gold-alunite deposits are enclosed in areas of intense acid sulfate alteration and localized in ring and radial faults and fractures present in the east wall of the Lomilla caldera. Like other acid-sulfate type deposits, the Rodalquilar gold-alunite deposits are closely related in time and space to porphyritic, intermediate composition magma emplaced along caldera structures but unrelated to the caldera forming magmatic system. ?? 1990 Springer-Verlag.

Mineralium Deposita↗
USGS1987

Application of combined Landsat thematic mapper and airborne thermal infrared multispectral scanner data to lithologic mapping in Nevada

Future Landsat satellites are to include the Thematic Mapper (TM) and also may incorporate additional multispectral scanners. One such scanner being considered for geologic and other applications is a four-channel thermal-infrared multispectral scanner having 60-m spatial resolution. This paper discusses the results of studies using combined Landsat TM and airborne Thermal Infrared Multispectral Scanner (TIMS) digital data for lithologic discrimination, identification, and geologic mapping in two areas within the Basin and Range province of Nevada. Field and laboratory reflectance spectra in the visible and reflective-infrared and laboratory spectra in the thermal-infrared parts of the spectrum were used to verify distinctions made between rock types in the image data sets.

Nevada↗
USGS1983

Mapping of hydrothermally altered rocks using airborne multispectral scanner data, Marysvale, Utah, mining district

Multispectral data covering an area near Marysvale, Utah, collected with the airborne National Aeronautics and Space Administration (NASA) 24-channel Bendix multispectral scanner, were analyzed to detect areas of hydrothermally altered, potentially mineralized rocks. Spectral bands were selected for analysis that approximate those of the Landsat 4 Thematic Mapper and which are diagnostic of the presence of hydrothermally derived products. Hydrothermally altered rocks, particularly volcanic rocks affected by solutions rich in sulfuric acid, are commonly characterized by concentrations of argillic minerals such as alunite and kaolinite. These minerals are important for identifying hydrothermally altered rocks in multispectral images because they have intense absorption bands centered near a wavelength of 2.2 ??m. Unaltered volcanic rocks commonly do not contain these minerals and hence do not have the absorption bands. A color-composite image was constructed using the following spectral band ratios: 1.6??m/2.2??m, 1.6??m/0.48??m, and 0.67??m/1.0??m. The particular bands were chosen to emphasize the spectral contrasts that exist for argillic versus non-argillic rocks, limonitic versus nonlimonitic rocks, and rocks versus vegetation, respectively. The color-ratio composite successfully distinguished most types of altered rocks from unaltered rocks. Some previously unrecognized areas of hydrothermal alteration were mapped. The altered rocks included those having high alunite and/or kaolinite content, siliceous rocks containing some kaolinite, and ash-fall tuffs containing zeolitic minerals. The color-ratio-composite image allowed further division of these rocks into limonitic and nonlimonitic phases. The image did not allow separation of highly siliceous or hematitically altered rocks containing no clays or alunite from unaltered rocks. A color-coded density slice image of the 1.6??m/2.2??m band ratio allowed further discrimination among the altered units. Areas containing zeolites and some ash-fall tuffs containing montmorillonite were readily recognized on the color-coded density slice as having less intense 2.2-??m absorption than areas of highly altered rocks. The areas of most intense absorption, as depicted in the color-coded density slice, are dominated by highly altered rocks containing large amounts of alunite and kaolinite. These areas form an annulus, approximately 10 km in diameter, which surrounds a quartz monzonite intrusive body of Miocene age. The patterns of most intense alteration are interpreted as the remnants of paleohydrothermal convective cells set into motion during the emplacement of the central intrusive body. ?? 1983.

Advances in Space Research↗
USGS1983

Lithologic mapping using Landsat thematic mapper data

The Landsat-4 Thematic Mapper (TM), with its new near infrared bands centered at 1.65 μm and 2.20 μm and spatial resolution of 30 m has been used to distinguish rocks containing minerals having ferric-iron absorption bands in the visible and near-infrared and Al-O- and CO 3 absorption bands in the 2.1-2.4 μm regions. On the basis of characteristic absorption bands, digitally processed TM data were used to differentiate vegetated from non-vegetated areas, limonitic from nonlimonitic rocks, rocks containing minerals having absorption bands in the near-infrared region from rocks lacking infrared absorption bands. Specific minerals were detected in both the humid eastern and semi-arid western United States. The absorption bands in the near-infrared region were used to detect kaolinite in open-pit exposures of a kaolin mining district near Macon, Georgia; calcium carbonate in the back sands along the east coast of Floridia; and kaolinite, alunite, jarosite, sericite and gypsum in natural exposures near Boulder City, Nevada. These results show that the additional spectral bands in the near-infrared region and increased spatial resolution of the Thematic Mapper provide a valuable tool for distinguishing several significant geologic materials not distinguishable from space using previous imaging systems. They also show that TM data can be successfully used in a variety of geologic environments.

Pecora VIII Symposium↗
USGS1982

Evaulation of remote sensing, geological and geophysical data for south-central New York and northern Pennsylvania

A study was made of the relationship between lineaments observed on Landsat satellite images and the geologic framework of a portion of the Allegheny Plateau of south-central New York and northern Pennsylvania. The area is underlain by a relatively thick sequence of salt and other evaporites in the Silurian Salina Group and is a potential site for deep-storage of solid nuclear waste. A combination of remote sensing techniques, detailed geologic mapping and geophysical investigations were applied to the problem. Because of the premature termination of the Department of Energy contract, only a portion of the total work was completed. The completed portion of the project included 1) digital contrast enhancement of several Landsat multispectral scanner (MSS) images, 2) analysis of lineament patterns from a Landsat MSS-7 mosaic, 3) field mapping of bedrock joint patterns, 4) compilation and analysis of surface and subsurface structure and isopach maps, 5) collection and digital analysis of aeromagnetic data for southern New York, 6) compilation and analysis of aeromagnetic and gravity data for much of New York and Pennsylvania, and 7) analysis of seismic reflection survey lines for selected portions of New York and Pennsylvania. We identified eight major lineaments or lineament zones and studied them in detail. They typically represent linear alignments of the most conspicuous or prominent physiographic features observable on Landsat images. The Cortland-Ithaca, Watkins Glen-Tanghannock, Seneca Lake-Elmira, Painted Post-Blossburg and Endicott-Syracuse conspicuous lineaments include the Corning-Bath, Van Etten-Towanda, Van Etten-Candor and Van Etten-Odessa lineaments. In addition, a major fault system--the West Danby fault zone--was further defined by geologic and geophysical investigations during our study; the fault zone was not recognizable on satellite images. The lineaments and lineament zones were categorized by their azimuthal trends. Those with a northerly orientation (e.g. Van Etten-Towanda, Seneca Lake-Elmira, Painted Post-Blossburg and Endicott-Syracuse) are most common. Northeasterly lineaments (e.g. Cortland-Ithaca and Watkins Glen-Taughannock) also are common. The Corning-Bath and Van Etten-Odessa lineaments have a northwesterly orientation and the Van Etten-Candor lineament is the sole representative of the east-west direction. The West Danby fault system also trends east-west. All the lineaments or lineament zones studied appear to be related, in one fashion or another, to structural disturbances, because changes in the structural attitude of beds or thickness of rocks commonly occur along their extent. The changes in many instances occur on multiple stratigraphic horizons and in a manner suggestive of several different styles of tectonism, leading to the conclusion that the lineaments and lineament zones have been periodically reactivated during the Paleozoic and Mesozoic Eras. Aeromagnetic data commonly show a parallel alignment of contours juxtaposed or on line with lineaments and lineament zones, suggesting that these physiographic alignments owe their origin to features within the crystalline basement. Pre-Alleghanian faulting and depositional patterns show that the study area was affected by basement-controlled adjustments along and in the same direction as most of the lineaments and lineament zones. Actual displacements cannot be proven for all of the lineaments or lineament zones, but changes in dip of the rocks across these features suggest either basement hingelines or small displacement faulting which cannot be resolved by the present data. These displacements occurred in at least Middle-Late Ordovician, Middle-Late Silurian and the Early-Middle Devonian times. The major northeast trending lineament zones (Cortland-Ithaca and Watkins Glen-Taughannock) correspond in orientation and lie along the northeastward projection of the Rome Trough, a postulated Paleozoic aulacogen. Results of

Open-File Report↗