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Andrew Griscom

Publications and source records attributed to Andrew Griscom.

At least 55 records · Page 3Linked to original sources
USGS1983

An aeromagnetic interpretation of eleven map sheets, scale 1:250,000, in the southern Najd and part of the southern Tuwayq quadrangles, Kingdom of Saudi Arabia

Eleven magnetic interpretation maps (scale 1:250,000) have been prepared for the area .of. exposed crystalline rocks in the Southern Najd and part of the Southern Tuwayq quadrangles (scale 1:500,000) from available published data. Boundaries of a variety of rock units that produce distinctive magnetic anomalies .or anomaly patterns are delineated. In some cases these magnetic boundaries correspond with previously mapped geologic contacts, and in other cases they indicate the possibility of additional, as yet unmapped, geologic contacts. The magnetic boundaries also allow the extrapolation of geologic contacts across areas covered by Quaternary deposits. Many boundaries are identified as part of the Najd fault system, and offset magnetic anomalies may be correlated across certain fault zones. Approximate dips were calculated for a few boundaries that represent igneous contacts, faults, or unconformities. Some characteristic anomalies appear to be associated in a general way with areas of gold mineralization and thus provide a guide for further prospecting.

Open-File Report↗
USGS1982

Mineral resource potential map of the Whitewater Wilderness Study Area, Riverside and San Bernardino counties, California

Geological, geochemical, and geophysical evidence, together with a 'review of historical mining and prospecting activities, suggests that most of the Whitewater Wilderness Study Area has low potential for all types of mineral and energy resources- including precious and base metals, building stone and aggregate, fossil fuels, radioactive-mineral resources, and geothermal resources. One small area in the southern part of the study area shows evidence of gold and silver mineralization, and this locality has a low to moderate potential for the discovery of low-grade gold and silver resources.

California↗
USGS1982

Mineral resource potential map of the Bighorn Mountains Wilderness Study Area (CDCA-217), San Bernardino County, California

Geological, geochemical, and geophysical evidence, together with a review of historical mining and prospecting activities, suggests that most of the Bighorn Mountains Wilderness Study Area has low potential for the discovery of all types of mineral and energy resources-including precious and base metals, building stone and aggregate, fossil fuels, radioactive-mineral resources, and geothermal resources. Low-grade mineralization has been documented in one small area near Rattlesnake Canyon, and this area has low to moderate potential for future small-scale exploration and development of precious and base metals. Thorium and uranium enrichment have been documented in two small areas in the eastern part of the wilderness study area; these two areas have low to moderate potential for future small-scale exploration and development of radioactive-mineral resources.

California↗
USGS1981

Map showing aeromagnetic interpretation of the Baker-Cypress BLM Instant Study Area and Timbered Crater Forest Service Further Planning Areas, Modoc, Shasta, and Siskiyou counties, California

The data for the aeromagnetic map of the Baker-Cypress and Timbered crater areas were collected in 1978 and compiled at a scale of 1 :62,500 (U,S, Geological Survey, 1979). East-west traverses were spaced at 0.8-km intervals at a constant altitude of 1370 m (4500 ft) above sea level, Contour interval is 20 and 100 gammas, depending upon the steepness of local gradients in the Earth's magnetic field. A regional magnetic field (the International Geomagnetic Reference Field - 1975, updated to the month flown) of approximately 5-6 gammas/km was removed from the data be fore con touring.

California↗
USGS1980

Aeromagnetic and interpretation map of the King Range and Chemise Mountain Instant Study Areas, Northern California

The data for the aeromagnetic map (sheet 1) of the King Range and Chemise Mountain areas wre collected in 1978 and compiled at a scale of 1:62,500. Northeast-southwest traverses were spaced at 0.8-km intervals at an altitude for 300 m above the ground surface and 600 m above the ocean because of cliffs along the shore. The contour interval is 10 of or 50γ, depending on the steepness of local gradients in the Earth's magnetic field. A regional field of approximately 5.6 γ/km was removed from the data before contouring.

California↗
USGS1980

Maps showing aeromagnetic survey and interpretation of the Virgin Mountains Instant Study Area Clark County, Nevada

Data for the aeromagnetic map (fig. 1) of the Virgin Mountains Instant Study Area wre collected in 1978 and compiled at a scale of 1:62,500. North-south traverses were spaced at 0.8-km intervals at an altitude of about 300m above the surface of the ground. The contour interval is 20 and 100 gammas, depending on the steepness of local magnetic gradients in the Earth's magnetic field. A regional field (the International Geomagnetic Reference Field - 1975) of approximately 5-6 gammas/km was removed from the data before contouring by computer.

Nevada↗
USGS1979

The Alaskan Mineral Resource Assessment Program: Background information to accompany folio of geologic and mineral resource maps of the Talkeetna quadrangle, Alaska

The Talkeetna 1° by 3° quadrangle, which consists of about 17,155 km 2 in south-central Alaska, was investigated by integrated field and laboratory studies in the disciplines of geology, geochemistry, geophysics, and Landsat data interpretation for the purpose of assessing its mineral resource potential. Past mineral production has been limited to gold from the Yentna district, but the quadrangle contains potentially significant resources of tin and silver and possibly a few other commodities including chromite and copper. The results of the mineral resource assessment are given in a folio of maps which are accompanied by descriptive texts, diagrams, tables, and pertinent references. This Circular provides background information on these investigations and integrates the component maps. A bibliography cites both specific and general references to the geology and mineral deposits of the quadrangle.

Alaska↗
USGS1979

The Alaskan Mineral Resource Assessment Program: Background information to accompany folio of geologic and mineral resource maps of the Big Delta quadrangle, Alaska

The geology, geochemistry, geophysics, and Landsat imagery of the Big Delta quadrangle, 16,335 km 2 in the Yukon-Tanana Upland of east-central Alaska, were investigated, and maps and reports were prepared by an interdisciplinary research team for the purpose of assessing the mineral potential. The quadrangle is dominantly a complex terrane of greenschist- to amphibolitefacies metamorphic rocks that have been intruded by Mesozoic and Tertiary dioritic to granitic rocks and are overlain by Tertiary sedimentary and volcanic rocks. Serpentinized peridotite and associated greenstone, graywacke, and chert crop out in some places. The quadrangle is bisected by the northeastward-trending Shaw Creek fault, which, on the basis of aeromagnetic interpretation and geologic data, is postulated to have left-lateral offset of as much as 48 km. On the northwest side of the Shaw Creek fault, metamorphic rock units have a northwesterly regional trend, and the oldest rocks could be Precambrian in age. Gneiss and schist in the southwestern part of the quadrangle are derived from both igneous and sedimentary protoliths, some of which may be as old as Precambrian. Other rock units, which include calcareous schist and thin-layered marble, black quartzite, semischist, and cataclastic rocks, are considered to be of probable Paleozoic age, although no fossils have yet been found in these rocks. Radiolarians and conodonts in chert associated with greenstone and ultramafic rocks indicate that the chert is of Permian age. Potassium-argon ages on igneous rocks of the Big Delta quadrangle fall into two groups: those with biotite, muscovite, hornblende, and sanidine ages between 50 to 69 m.y.; and those with biotite, hornblende, and sanidine ages between 88 to 105 m.y. The younger of these two groups appears to indicate the time of a plutonic event marked by intrusion of mostly small, isolated plutons, including hypabyssal stocks, and the eruption of silicic volcanic rocks. Most of the plutons are quartz monzonite to granite. The older group of ages (88 to 105 m.y.) on igneous rocks includes ages on the largest plutons of the Yukono-Tanana Upland. The rocks range from diorite to quartz monzonite in composition. The potassium-argon ages on the metamorphic rocks of the Big Delta quadrangle, like those obtained elsewhere in the Yukon-Tanana Upland, appear to have been partly or completely reset by subsequent thermal events. Vein and placer gold deposits have been mined in the Big Delta quadrangle, and although indications of mineralization are widespread, no other mineral deposits have yet been identified. The geologic, geochemical, and geophysical data are compatible with several types of deposits, including porphyry copper, massive sulfide, and skarn deposits. In certain aspects, the geology of the quadrangle is similar to areas in the eastern part of the Yukon-Tanana Upland and Canada where mineral deposits are known.

Alaska↗