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G. Chase Tibbitts

Publications and source records attributed to G. Chase Tibbitts.

13 recordsLinked to original sources
USGS1981

A qualitative appraisal of the hydrology of the Yemen Arab Republic from Landsat images

Landsat-1 and Landsat-2 images were analyzed in June 1976 to describe the flow regimens of streams and the regional distribution of vegetation in the Yemen Arab Republic (YAR). The findings provide a factual basis for planning a surface-water data collection program, and for preparing maps of plant distribution and agricultural land use. They lay the foundation for modernized water development, and for effecting a program of country-wide water management in the YAR.

Open-File Report↗
USGS1980

Ground-water resources investigation in the Amran Valley, Yeman Arab Republic

A program of hydrologic studies and exploratory drilling was conducted intermittently between 1974 and 1978 to evaluate the water-bearing properties of the unconsolidated alluvial sediments and associated rocks in the semi-arid Amran Valley basin, an 800-square-kilometer area in north-central Yemen Arab Republic. Inventory data from 395 wells were compiled, observation well and rain-gage networks were established and 16 standard complete chemical analyses were made for samples from selected wells. The water resources of the area were overexploited. The chemical quality of the water is generally good. Four aquifer tests were run to determine transmissivity and storage characteristics. The pumping tests show that groundwater occurs under semi-confined leaky-aquifer conditions in the valley fill. Wells drilled in the alluvial fill of the south-central part of the valley have the highest yields. Wells penetrating the limestone and volcanic rocks generally have little or no yield except in fracture zones. Basalt flows occur interbedded with the wadi alluvium at several depths. Cropping out rocks in the Amran Valley range in age from late Jurassic to Holocene. (USGS)

Open-File Report↗
USGS1979

Petrographic and trace-element data on rocks from the Yemen Arab Republic

Petrographic descriptions are given for rocks in the Yemen Arab Republic (YAR), including mainly Precambrian igneous and metamorphic rocks from the southeastern part of the country, which previously was geologically undescribed. Also included are descriptions of Cretaceous and/or Tertiary lavas of the Yemen Volcanics, Miocene(?) alkali granite, Pliocene caprock of the Guma salt dome, and late Pleistocene and Holocene basalts of the Aden Volcanic Series (?). The petrographic studies permitted the selection of 11 samples of rock for future use in obtaining isotopic analyses for age determinations. Analyses of these rock specimens for trace amounts of gold, indium, mercury, selenium, and thallium completed the geochemical studies. Results of these analyses are interpreted to show that regional geochemical exploration should be undertaken for base and precious metals near Jibal Hufash, the Manakhah area, the region around Al Bayda, the Sa'dah-Majadh area, and the Wadi Jawf area. Additional studies of trace elements in commercial salt deposits of the YAR should be made to evaluate the amounts of mercury and selenium in this industrial raw material.

Open-File Report↗
USGS1977

Data from geologic investigations in the Yemen Arab Republic during 1976

The results of semiquantitative spectrographic analyses for 31 elements in 126 specimens of rocks from the Yemen Arab Republic, collected mainly during February 1976 from the Precambrian area in the southeastern part of the country, provide background data for use in geochemical evaluation of areas potentially favorable for mineral deposits. Gold and thorium were undetected; the lower limits of determination are 10 parts per million (ppm) and 20 ppm, respectively. For the other elements, the abundances follow geochemical norms for crustal distribution: (1) Fe, Nb, and Zr in Holocene weathering products; (2) Ca and Sr in Pliocene limestone; (3) Mo in Pliocene(?) or Miocene(?) dikes; (4) Be, La, and Sn in Miocene(?) alkalic granite; (5) As, Be, and La in Tertiary and/or Cretaceous felsic tuff; (6) V in Tertiary and/or Cretaceous carbonaceous sedimentary rocks interbedded with volcanic rocks; (7) Be, La, Sn, and Zr in Tertiary and/or Cretaceous undivided volcanics; (8) Sn and W in Precambrian felsite and pegmatite; (9) Co, Cr, Ni, and Ti in Precambrian mafic rocks; (10) Mg and Sr in Precambrian marble and calcsilicate rocks; (11) Y in Precambrilan schist; (12) B and Sc dispersed in rocks of many ages; and (13) Ag, Ba, Bi, Cd, Cu, Mn, Pb, Sb, Sn, and Zn in a hydrothermal replacement deposit in Precambrian sediment. None of the rocks contained as much as 205 ppm equivalent uranium. The highest values for Ag, Cu, Pb, Zn, and Cd were obtained on a sample of hydrothermally altered siltstone not personally collected by the writers. It was said to have come from the Ma'rib area in the eastern part of the Yemen Arab Republic. The source must be studied, because this single sample is high-grade base-metal ore. Among the samples collected by the writers, the economically most significant are altered tuffs, ignimbrites, and felsites exposed between Jibal Hufash and Manakhah on the road from Hudaydah to San'a'. They are strongly anomalous for As and weakly anomalous, variously, for Hg, Mo, and Pb, which elements may constitute an epigenetic dispersion pattern from hidden sulfide deposits. Inasmuch as chalcopyrite and native copper have been reported in the vicinity of Jabal Haraz in the Manakhah area, the rocks of the Yemen Volcanics in this region should be explored for base-metal sulfide deposits. The first results of paleontologic examinations of fossils collected during 1975 and 1976 are presented, as are a list of Landsat images covering the Yemen Arab Republic, and a selected bibliography of reports on geology and the allied sciences relating to the Yemen Arab Republic.

Open-File Report↗
USGS1976

Trace elements in some rocks and slag from the Yemen Arab Republic and their bearing on the iron ore near Sa'dah

Thirty-seven samples of rocks, saprolite, laterite, gossan, and slag were collected in the Yemen Arab Republic during June-July 1975 when field work was conducted to refine an interpretation of the regional geology made from LANDSAT-1 images by M. J. Grolier. These samples we reanalyzed in the laboratories of the U. S. Geological Survey, and the results were interpreted for use in programs of economic development as a guide for the evaluation of mineral resources in the Yemen Arab Republic. The work was undertaken as part of the program of the U. S. Agency for International Development with the cooperation of the Mineral and Petroleum Authority, Ministry of Economy, Yemen Arab Republic.

Open-File Report↗
USGS1969

Water levels and artesian pressures in the Chad Basin of northeastern Nigeria, 1963-68

This report presents records of water levels and artesian pressures collected during 1963-68 on an observational network of 116 dug wells and boreholes (drilled wells) in the Chad Basin of northeastern Nigeria. The Chad Basin is underlain by the Chad Formation, a series of fluvio-lacustrine sediments which attain a thickness of 1,500 feet or more in Nigeria. Three water-bearing zones, designated Upper, Middle and Lower, have been identified in the Chad Formation of Nigeria. The Upper Zone aquifer, which contains water under both unconfined and confined conditions, provides the principal source of water to dug wells for domestic and village water supply. The Middle Zone aquifer is tapped by numerous deep boreholes (drilled wells) which provide water by artesian flow in more than 13,000 square miles of Nigeria north and east of Maiduguri. The Lower Zone, which is also confined has only been identified thus far (1969) in the vicinity of Maiduguri.

Chad Basin↗
USGS1954

Summary of geology and ground-water resources of the Eastern Shore peninsula, Virginia: a preliminary report

The U.S. Geological Survey, in cooperation with the Virginia Division of Geology (Virginia Division of Mineral Resources), conducted an investigation of the geology and ground-water resources of the Coastal Plain of Virginia. This report summarizes preliminary findings from exploratory test drilling done to ascertain whether there are any satisfactory water-bearing zones deeper than those in general use.

Virginia↗