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C. L. Hummel

Publications and source records attributed to C. L. Hummel.

10 recordsLinked to original sources
USGS1972

Geology and mineral deposits of the Wadi an Nuqumi quadrangle, Kingdom of Saudi Arabia

The rocks, structures, and mineral deposits of the Wadi an Nuqumi quadrangle were formed during three periods of deformation, two of Precambrian age and one of Tertiary and Recent age. The older Precambrian Halaban cycle produced the thick eugeosynclinal suite of interlayered metasedimentary and metavolcanic rocks comprising the Halaban Formation, the numerous synorogenic granitic masses which intrude the layered rocks, and the northward-trending tectonic, plutonic, and metamorphic features of all these rocks which constitute the basic grain of the area. The older Halaban features are everywhere strongly transected, but only slightly deformed and offset, by many eastward-northeastward-, and northwestward-striking fractures and strike-slip faults. Silicic dikes are emplaced in these fractures, and several kinds of barren and metalliferous veins are closely associated with them. All these features are here thought to have formed during a period of deformation of late Precambrian age which produced the Najd Wrench Fault Zone; therefore, these features are named for it. Sporadic remnants of once far more extensive basaltic lava fields and the north-northwestward-striking vertical fractures which occur in them and contain volcanic vents from which they were extruded are the youngest rocks and structures in the Wadi an Nuqumi area. They are thought to have formed during the period of tectonic and volcanic activity which also produced the Red Sea graben. The principal mineral deposits of the Wadi an Nuqumi area are silicified-carbonate breccia veins which occur in structures of the Najd Wrench Fault deformation and metalliferous quartz veins which are closely associated with them. Only the latter possesses any economic potential, the most promising being the gold and silver-bearing quartz-base metal veins of the Al Numrahniyah and Muthaheel ancient mines.

Open-File Report↗
USGS1972

Geology and mineral deposits of the Jabal ash Shumta quadrangle, Kingdom of Saudi Arabia

Rocks, structures, and mineral deposits which are the result of both the older Halaban petro-tectonic cycle and the younker Najd Wrench Fault deformation are present in the Ash Shumta area. Northward-trending belts of granitic rocks and folded, layered metavolcanic and metasedimentary rocks of the Halaban Formation which they intrude represent the effects of the Halaban cycle. These older rocks are everywhere transected and deformed by northwestward- and northeastward-striking fractures and strike-slip faults and by eastward-striking fractures and fracture-controlled silicic dikes which belong to the Najd Wrench Fault deformation. Several kinds of epigenetic mineral deposits of hydrothermal origin are present throughout the Ash Shumta area. All occur in or ape closely associated with structures of the Najd Wrench Fault deformation. The mineralization which produced the deposits is thought to have taken place during the period of deformation which produced the Najd Wrench Fault structures. The hydrothermal deposits include many metalliferous quartz veins most of which occur in three mineralized areas: two major areas at Jabal Ash Shumta and Jabal El Khom in the northern half of the quadrangle and a minor area along Wadj al Boharah in the southeastern part of the quadrangle. The metalliferous lodes possess the only economic potential in the area of the Jabal Ash Shumta quadrangle. These lodes consist mainly of gold and base metal-bearing quartz veins, some of which were mined for gold in ancient times. The mineralized area at Jabal Ash Shumta has the best of these veins. Higher temperature veins with wolframite as a major constituent and beryl as a minor one occur in a granite cupola in the eastern part of the El Khom area. These veins have altered, gneissen-like wall rocks. Although the grade of the veins is low at the surface, the made could increase at depth. The tungsten-bearing veins and El Khom area possess the greatest economic promise in the Jabal Ash Shumta quadrangle. They deserve detailed surface investigation followed if needed by exploration at depth.

Open-File Report↗
USGS1972

Report of the field trip, February 24 to April 2, 1965 in part of the northeastern Hijaz quadrangle, Saudi Arabia

In 1963, in response to a request from the Ministry of Petroleum and Mineral Resources, the Saudi Arabian Government and the U. S. Geological Survey, U. S. Department of the Interior, with the approval of the U. S. Department of State undertook a joint and cooperative effort to map and evaluate the mineral potential of central and Saudi Arabia. The results of this program are being released in USGS open files in the United States and are also available in the Library of the Ministry of Petroleum and Mineral Resources. Also on open file in that office is a large amount of material, in the form of unpublished manuscripts, maps, field notes, drill logs, annotated aerial photographs, etc., that has resulted from other previous geologic work by Saudi Arabian government agencies. The Government of Saudi Arabia makes this information available to interested persons, and has set up a liberal mining coda which is included in "Mineral Resources of Saudi Arabia, a Guide for Investment and Development," published in 1965 as Bulletin 1 of the Ministry of Petroleum and Mineral Resources, Directorate General of Mineral Resources, Jiddah, Saudi Arabia.

Hijaz quadrangle↗