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Vincent J. Flanigan

Publications and source records attributed to Vincent J. Flanigan.

At least 19 recordsLinked to original sources
USGS1984

An evaluation of the applicability of the telluric-electric and audio-magnetotelluric methods to mineral assessment on the Arabian Shield, Kingdom of Saudi Arabia

Feasibility studies of two electromagnetic methods were made in selected areas of the Jabal Hibshi (1:250,000) quadrangle, 26F, in the Kingdom of Saudi Arabia in March of 1983. The methods tested were the natural source-field telluricelectric and audio-magnetotelluric methods developed and extensively used in recent years by the U.S. Geological Survey in some of its domestic programs related to geothermal and mineral resource assessment. Results from limited studies in the Meshaheed district, the Jabal as Silsilah ring complex, and across a portion of the Raha fault zone clearly demonstrate the appropriateness of these sub-regional scale, reconnaissance-type studies to mineral resource assessment. The favorable results obtained are largely attributed to distinctive and large contrasts in the electrical resistivity of the major rock types encountered. It appears that the predominant controlling factor governing the rock resistivities is the amount of contained clay minerals. Accordingly, unaltered (specifically, non-argillic) igneous and metamorphic rocks have very high resistivities; metasedimentary rocks of the Murdama group that contain several percent clay minerals have intermediate values of resistivity; and highly altered rocks, containing abundant clay minerals, have very low values of resistivity. Water-filled fracture porosity may be a secondary, but important, factor in some settings. However, influences from variations in interstitial or intercrystalline, water-filled porosity are probably small because these types of porosity are generally low. It is reasonable to expect similar results in other areas within the Arabian Shield.

Open-File Report↗
USGS1983

Ground-followup studies of the 1977 airborne electromagnetic survey in the Assifar and Mulhal areas, Wadi Bidah district, Kingdom of Saudi Arabia

Parts of four airborne electromagnetic (AEM) anomalies were selected for study in order to determine the cause of high conductivity of Precambrian rocks underlying extensive areas in the southern Wadi Bidah district, Kingdom of Saudi Arabia. In the Assifar area, which contains an ancient mine or prospect having the same name, geophysical data suggest that a mineralized body may lie beneath and immediately south of the ancient workings. Many other conductive zones detected during the course of the geophysical survey are thought to be related to metavolcanic rocks containing carbonaceous materials. Detailed geologic mapping, and possibly diamond core drilling, will be necessary to fully evaluate the area. In the Mulhal No. 2 area, located about 2 km south of the Mulhal ancient mine, geophysical studies suggest that mineralized rocks extend about 500 m along strike beneath outcrops of gossanous material. A brief review of the AEM ground-followup studies in the Wadi Bidah district suggests that most, if not all, of the AEM conductors are carbonaceous rocks. Secondary causes of conductivity are intense faulting and shearing.

Open-File Report↗
USGS1983

Time-domain electromagnetic tests in the Wadi Bidah District, Kingdom of Saudi Arabia

A time-domain electromagnetic (TDEM) method was tested in two areas of mineralization in Precambrian rocks in the Wadi Bidah district, Kingdom of Saudi Arabia. Transient-decay voltages in profile mode were measured across the Sha'ab at Tare and Rabathan prospects by use of three transmitterreceiver loop configurations. At the Sha'ab at Tare prospect all of the loop configurations indicated the mineralized zone. Analysis of the coincident loop data at Sha'ab at Tare reveals that gossanous and altered rock of i0 ohm-m resistivity extends to a depth of 35 m, where there is an unweathered, dry mineralized zone of about 1 ohm-m resistivity. The model further suggests that the rocks at a depth of 55 m and below the water table are even less resistive (0. 1 ohm-m). The TDEM method successfully discriminated conductors within from those below the weathered zone at the Rabathan prospect. Conductors below the weathered zone are identified by a lack of transient response in the early part of the transient decay curve, followed by an increasing response in the middle to late parts of the transient decay curve. Results of these limited tests suggest the potential value of integrating TDEM with other geophysical tools in the Kingdom. Recommendations are made to expand these tests into a more comprehensive program that will evaluate the TDEM potential in various geologic environments that are host to mineral deposits of diverse origin.

Open-File Report↗
USGS1979

A slingram survey on the Nevada Test Site: part of an integrated geologic geophysical study of site evaluation for nuclear waste disposal

A slingram geophysical survey was made in early 1978 as part of the integrated geologlcal-geophysical study aimed at evaluating the Eleana Formation as a possible repository for nuclear waste. The slingram data were taken over an alluvial fan and pediments along the eastern flank of Syncline Ridge about 45 km north of Mercury, Nevada, on the Nevada Test Site. The data show that the more conductive argillaceous Eleana Formation varies in depth from 40 to 85 m from west to east along traverse lines. Northeast-trending linear anomalies suggest rather abrupt changes in subsurface geology that may be associated with faults and fractures. The results of the slingram survey will, when interpreted in the light of other geologic and geophysical evidence, assist in understanding the shallow parts of the geologic setting of the Eleana Formation.

Open-File Report↗
USGS1979

Airborne gamma-ray spectrometry survey of the Jabal Sayid area, Kingdom of Saudi Arabia

An airborne gamma-ray spectrometer survey covering 2750 km 2 in the Jabal Sayid area, Kingdom of Saudi Arabia, was flown to measure anomalous concentrations of potassium in a known mineral belt. No anomalies were detected over the Jabal Sayid copper prospect, although part of the prospect is within a radioactive, high-dispersion halo associated with the Jabal Sayid granitic pluton. Anomalous potassium concentrations were detected in several areas north of the mine at Mand adh Dhahab and over the rhyolitic rocks of the mine itself. Count-rate ratios of the potassium (K 40 ), uranium (Bi 214) and thorium (Tl 208 ), reached a high of 24:1 for K:Th, and 11.6:1 for K:U. Count-rate ratios over granitic rocks are generally much lower. Areas of anomalous potassium correlate with rhyolitic rocks in some places. Other potassium anomalies have no known explanation, but may reflect unmapped potassium-rich rocks and(or) zones of hydrothermal alteration. These anomalies are considered as potential targets for further exploration, but ground follow-up investigations will be necessary to ascertain the exact cause of the anomalies.

Jabal Sayid area↗
USGS1977

Mapping the lateral boundaries of a cooling basaltic lava lake, Kilauea Iki, Hawaii

Two types of electromagnetic (EM) profiling techniques were used to delineate the surface projection of the edges of the still-molten basaltic lava lens that exists in Kilauea Iki Crater, Hawaii. These studies were made as part of an intensive geophysical program aimed at defining the overall configuration of the liquid core and the attendant hydrothermal fluids. The results of the profiling studies were presented orally at the Annual Fall Meeting of the American Geophysical Union held in San Francisco, Calif., December 6, 1976. This report summarizes in more detail the techniques, results, and some conclusions related to the EM profiling studies. The complete results of an intensive VLF study made by L. A. Anderson (U.S. Geol. Survey, oral communication, 1976) will be presented in a separate report. Only a few of these results are discussed here.

Hawaii↗
USGS1976

Ground magnetic and VLF studies at Midnite uranium mine, Stevens County, Washington

Ground magnetic and E-mode VLF measurements were made at more than 200 stations at the Midnite uranium Mine, Stevens County, Washington. The equipment was found to be light and foolproof, and each set of data was collected in one day, exclusive of surveying and marking the station points. The maps of contoured magnetic and VLF data resembled geologic maps of the area, showing many common features, as well as a few unique features on each map. Each showed some evidence of a small normal fault cutting the region; taken together, the evidence for this fault was judged to be much stronger, so that further structural details were inferred. Because of soil cover and inadequate outcrops, the presence of this fault had hitherto been unsuspected. A target area for further uranium mineralization north of the fault was indicated by this quick, inexpensive geophysical survey. The drilling program which Midnite Mine management had underway at that time had already outlined a mineralized zone in the indicated area.

Washington↗
USGS1976

Evaluation of the Umm Al Khabath copper prospect, Jabal Ibrahim quadrangle, sheet 20/41C, Kingdom of Saudi Arabia

The Umm Al Khabath copper prospect (lat 20°10'N.; long 41°23'E.) was tested by 815 m of diamond drilling in three holes. Meager metallization of copper, zinc, gold, and silver is related to a distinct phase of quartz-pyrite veinlet stockworks and associated silicification, sericitization, and pyritization. Alteration and metallization are within a major north-trending shear zone, 10-50 m wide. Lithologies cut by the shear zone are pyroclastic agglomerate and tuff with intercalated ferruginous chert, wacke, and basalt flows, all belonging to the Precambrian Baish Group. The outcrop of the shear zone for a length of 1400 m contains scattered gossan, local zones of abundant malachite and chrysocolla veinlets, patches of malachite-rich calcrete cap, and several shallow ancient workings. Composite chip samples taken from the surface across the sheared and altered zone contain anomalous concentrations of copper and zinc in amounts greater than can be expected from the weathering of the slightly metallized rock of the sheared and altered zone.

Jabal Ibrahim quadrangle↗
USGS1975

Geology of the Jabel Ishmas Quadrangle, Kingdom of Saudi Arabia

The Jabal Ishmas quadrangle (20/43A) is about 100 km northeast of Qal'at Bishah in the southern part of the Arabian Shield. Most of the terrane in the quadrangle slopes gently westward across broad expanses of pediment, from prominent mountainous north-south ridges in the east to the alluvial and eolian sand-covered plains of Wadi Bishah. Other than the widespread surficial deposits, the quadrangle is underlain by Precambrian metasedimentary, metavolcanic, and intrusive granitic to gabbroic rocks. Paraschist, paragneiss, and amphibolite of the Hali Group, the oldest rocks of the quadrangle, were derived from pelitic sediments, quartzite, limestone, and mafic to felsic volcanic rocks. The rocks were intensely deformed and regionally metamorphosed to the almandine-amphibolite facies during a long and complex period of Precambrian geological events prior to deposition of the rocks of the Halaban Group. Granodiorite gneiss, the most abundant rock in the quadrangle, is intrusive into and tectonically deformed with the Hall rocks. Relatively late during Precambrian time sedimentary and volcanic rocks of the Halaban Group were unconformably deposited on the Hali and granodiorite gneiss. The Halaban Group consists of a lower metaclastic unit of conglomerate, graywacke, shale, limestone, and chert, and an upper metavolcanic unit that is predominantly andesitic flow rocks, pyroclastic deposits, tuff, and subordinate basaltic rocks.

Open-File Report↗