Reconnaissance wadi-sediment geochemical survey of the Biʾr Jarbuah area, Kingdom of Saudi Arabia
No abstract available.
Open-File Report↗
Geology topics
Ralph P. Christian
Publications and source records attributed to Ralph P. Christian.
Reconnaissance wadi-sediment geochemical survey of the Bi'r Jarbuah area, Kingdom of Saudi Arabia
A reconnaissance wadi-sediment geochemical survey for gold was conducted in the Bi'r Jarbuah Area (lat 20° 45' 00"-21 ° 00' 00" N., long 43° 30' 00"- 43° 41' 00" K). The area is located in the northern part of a regional concentration of gold occurrences, the Jabal Ishmas-Wadi Tathlith gold belt. Panned concentrates and minus-80-mesh fractions were obtained from 300 samples collected from a 320 km 2 area and analysed by atomic-absorption spectroscopy. Analyses of the pannedconcentrate samples proved to be more definitive than sieved samples in delineating areas of mineralization. Most of the anomalous gold-and arsenic-bearing wadi-sediment samples are located along an irregular contact between gneissic and dioritic rocks in the center of an area characterized by the presence of subparallel dacitic dike swarms. Most of the ancient gold mines are also located along this contact. Gold is associated with arsenic but not with silver. Five areas containing gold-anomalies areas and 6 areas containing tellurium anomalies and the contact zone between the diorite and the paragneiss are recommended for further investigation of precious-metals resources.
Open-File Report↗
An evaluation and geochemical survey of the Farah Garan East Prospect, Southeast Asir, Kingdom of Saudi Arabia
The Farah Garan East prospect (MODS 4886) is located in the southeastern part of the Precambrian Arabian Shield of Saudi Arabia, about 15 km east-northeast of Zahran Al Janub and 1 km northeast of the ancient mines at Farah Garan. Ore minerals at the Farah Garan East prospect are pyrite, tennantite, galena, and sphalerite. These are sparsely and erratically distributed in west-dipping beds of dolomite, dolomite-talc breccia, and carbonate-sericite phyllite, and in associated breccias and zones of carbonate-altered mafic metavolcanic rocks, all of Precambrian age. Concordant beds of dolomite and carbonate-sericite phyllite are interlayered with metavolcanic rocks and are interpreted as volcanic-related submarine hydrothermal deposits of Precambrian age. Funnel-shaped bodies of dolomite-talc breccia that crop out near the north and south ends of the dolomite beds are interpreted as submarine hot-spring vent breccias. Aprons of exhalative dolomite thin laterally outward from these vents. Discordant and concordant zones of carbonate-altered metavolcanic rocks, east of and structurally below the hot-spring vents, probably represent pathways of hydrothermal circulation along networks of fractures in volcanic rocks, subjacent to these Precambrian submarine hot-spring vents. Ore minerals in outcrops, and geochemically anomalous concentrations of gold, silver, copper, lead, zinc, arsenic, antimony, and tellurium are present in carbonate-rich rocks of the hot-spring assemblage. This indicates that the ore minerals and elements were deposited originally as constituents of the hot-spring assemblage. However, exposed ore-mineral occurrences are small and sparse, and geochemical anomalies are small, irregularly distributed, and of subeconomic grade. Furthermore, weak electromagnetic anomalies do not indicate the presence of subsurface bodies of concentrated, conductive ore minerals. Therefore, no drilling is recommended.
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Optical and X-ray crystallographic investigations of strontioginorites
Compositional, optical, and unit-cell data are presented for a suite of strontioginorites. These crystals show that Sr:Ca ≈ 1 is preferred. Lack of variation in the Sr:Ca resulted in no meaningful correlation between composition and physical properties.
Journal of Research of the U.S. Geological Survey↗