Geology topics
John J. Matzko
Publications and source records attributed to John J. Matzko.
Composition of coarse-grained magnetite from pegmatite dikes related to plutons of quartz monzonite in the Jabal Lababa area, Kingdom of Saudi Arabia
Crystals of magnetite as large as 30 mm long and 7 mm thick are locally present in quartz-rich zones of interior and exterior pegmatite dikes related to plutons of quartz monzonite in the Jabal Lababa area. Niobium, tin, and yttrium are strongly enriched in six specimens of magnetite from interior pegmatite dikes in a small pluton where these elements form geochemical anomalies in nonmagnetic heavy-mineral concentrates from wadi sediment. Less abundant anomalous elements in the magnetite are molybdenum, lead, and zirconium, which also tend to be present in anomalous amounts in the nonmagnetic concentrates from the niobium-bearing pluton. The most anomalous trace element in the magnetite is zinc, which is at least 10 times as abundant as it is in the quartz monzonite plutons or in the nonmagnetic concentrates. The capacity of magnetite to scavenge molybdenum, zinc, niobium, lead, tin, yttrium, and zirconium suggests the possible utility of magnetite as a geochemical sample medium.
Microscopic determination of the nonopaque minerals
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Radioactive anomaly and mineralogy of the lower part of the Tabuk Formation, Al Qassim area, Kingdom of Saudi Arabia
A radioactive anomaly about 10 km long was detected by an airborne survey of the Tabuk Formation, about 75 km west-northwest of Buraydah in northeastern Saudi Arabia. The gamma-spectrometer anomaly is 6 to 10 times higher than background over the adjacent Precambrian shield area and indicates anomalous concentrations of thorium-bearing minerals. Radioactive detrital minerals identified are zircon, monazite, xenotime, huttonite, and sphene. These minerals account for the anomaly; uranium and potassium-bearing minerals contribute only slightly to the overall spectrometer response. Several varieties of zircon have different morphologies, inclusions, and degree of freshness. Colorless, possibly relatively young grains showing a bright orange fluorescence, and radiation-damaged probably relatively older zircons without any fluorescence, suggest recycling during more than one erosion cycle and at least two different sources for the sediments of the Tabuk Formation. The antipathetic association of allanite and monazite further supports the thesis of more than one source for the sediments of the Tabuk Formation.
A summary of niobium and rare earth localities from Ha'il and other areas in western Saudi Arabia: a preliminary study
Investigations in 1965 located veins containing radioactive material in the Halaban Group on the east side of a granite pluton at Jabal Aja near Ha'il. Later study extended the known area of radioactivity to a total length of about 30 km. Mineralogic studies indicated that the samples were low in uranium and that the radioactivity was due principally to thorium in niobium-bearing minerals. Two samples were reexamined to identify the sources of radioactivity, but X-ray and alpha plate studies did not reveal the radioactive minerals, even though uranium mineralization was indicated by the alpha plates. Further sampling is suggested to isolate the sources of radioactivity. This study indicates that niobium occurrences are related to alkaline intrusives in many areas of western Saudi Arabia. These areas should be investigated for their possible niobium and rare earth contents; their uranium content is apparently too low to be of economic interest.
Black monazite from Taiwan
Two forms of detrital monazite are known in offshore bars in southwestern Taiwan: a yellow-green to colorless form and an unusual but abundant pelletlike form, generally black but also colored gray or brown. These black pellets, which are about 160 by 200 microns in size, are composed of fine-grained monazite crystals from 2 to 20 microns in size. The pellets are associated with highly variable amounts of discrete grains of detrital quartz, rutile, amphibole, tourmaline, and other minerals. Intergrown with the monazite are quartz, a cerium oxide mineral, chlorite, sulfides, and other minerals. Opaqueness of the pelletlike monazite is due principally to the cryptocrystalline nature of part of the monazite; only a small part of the opaqueness can be attributed to opaque inclusions. The black pelletlike monazite lacks thorium and has a high content of europium. In this respect, as in color, shape, size, and inclusions, the pelletlike monazite differs from the yellow-green detrital monazite. Despite the fact that they occur together in the littoral placers, they appear to have had different origins. The yellow-green monazite originated as an accessory mineral in plutonic rocks and has accumulated at the coast through erosion and transport. The origin of the pelletlike monazite is as yet unknown, but it is here inferred that it originated in unconsolidated coastal plain sediments through migration of cerium from the detrital monazite during weathering, and of the intermediate-weight mobile rare earths from clay minerals during diagenesis. Possibly these pelletlike grains are detrital particles formed through erosion and transport from originally larger aggregates cemented by diagenetic monazite.
Antimony deposits of Quetta-Pishin District, Quetta Division, Pakistan
Vein-type deposits of antimony ore, consisting of stibnite and quartz, are found in the hanging wall of faults cutting slate of probable Miocene age 15 miles northeast of Qila Abdullah in the Quetta-Pishin District. The ore is associated with zones of oxidized slate. Although the known deposits are small, the oxidized zones are found over several square miles, and the prospects for additional ore are encouraging. Deposits of stibnite and oxidized rock are also found in the Qila Viala area, about 25 miles east of the Qila Abdullah deposits. Geologic relationships in the two areas are similar and suggest that deposition of stibnite and quartz, accompanied by alteration of the host rocks, has taken place on a regional scale. This greatly increases the area to be investigated as well as the possibility that deposits of economic value can be found. A program for further geological investigations is recommended.
Mineralogy of ironstones from the Chichali and Makarwal areas, Mianwali and Kohat Districts, Pakistan
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Stratigraphy and mineralogy of laterite beds near Ziarat, Quetta Division, Pakistan
Ferruginous aluminous laterite beds crop out in the Ziarat-Loralai area east of Quetta for a strike length of about 60 miles. The beds are steeply dipping, sometimes overturned and faulted, and have an average thickness of 8 feet. Detailed mineralogical and chemical analyses were made on chip-channel samples from four sections of the laterite in the vicinity of the village of Ziarat. One of the sections, 9 1/2 miles southeast of Ziarat, is 21 feet thick and has an average content of 42 percent available alumina, 3.6 percent silica, and 31 percent Fe 2 0 3 . The other sections have an average available alumina content of less than 32 percent. The alumina minerals present are mostly boehmite and diaspore, with minor amounts of kaolinite. The laterite beds, which are between the Dunghan Formation of Paleocene age and the Parh Limestone of Cretaceous age, appear to mark the Cretaceous-Tertiary boundary; if this relationship is confirmed by further work, it would be of considerable assistance in prospecting for aluminous rocks in this and other parts of Pakistan.
Examination of selected radioactive samples from Pakistan
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Reconnaissance for uranium and thorium in Alaska, 1954
During 1954 reconnaissance investigations to locate minable deposits of uranium and thorium in Alaska were unsuccessful. Areas examined, from which prospectors had submitted radioactive samples, include Cap Yakataga, Kodiak Island, and Shirley Lake. Unconcentrated gravels from the beach at Cape Yakataga average about 0.001 percent equivalent uranium. Uranothorianite has been identified by X-ray diffraction data and is the principal source of radioactivity in the Cape Yakataga beach sands studied; but the zircon, monazite, and uranothorite are also radioactive. The black, opaque uranothorianite generally occurs as minute euhedral cubs, the majority of which will pass through a 100-mesh screen. The bedrock source of the radioactive samples from Kodiak Island was not found; the maximum radioactivity of samples from the Shirley Lake area was equivalent to about 0.02 percent uranium. Radiometric traverses of the 460-foot level of the Garnet shaft of the Nixon Fork mine in the Nixon Fork mining district indicated a maximum of 0.15 mr/hr. In the Hot Springs district, drill hole concentrates of gravels examined contained a maximum of 0.03 percent equivalent uranium. A radioactivity anomaly noted during the Survey's airborne reconnaissance of portions of the Territory during 1954 is located in the Fairhaven district. A ground check disclosed that the radioactivity was due to accessory minerals in the granitic rock.
Summary of reconnaissance for uranium in Alaska, 1955
Reconnaissance for uranium in Alaska during 1955 included airborne radiometric traverses, examination of radioactivity anomalies found during the airborne traverses, examination of prospector leads, and examination of areas that seems geologically favorable for the occurrence of uranium. The airborne radiometric traverses in central Alaska revealed 33 anomalies considered worth examining. The ground examinations of a few of these anomalies indicated that they were due to radiation of from accessory minerals in intrusive granitic rocks. The examination of prospector leads revealed several radioactivity anomalies of interest and one, near Bokan Mountain on prince of Wales Island, of possible commercial importance.
Lead-alpha age determinations of granitic rocks from Alaska
Lead-alpha activity age determinations were made on zircon from seven granitic rocks of central and southeastern Alaska. The results of the age determinations indicate two periods of igneous intrusion, one about 95 million years ago, during the Cretaceous period, and another about 53 million years ago, during the early part of the Tertiary. The individual ages determined on zircon from 2 rocks from southeastern Alaska and 1 from east-central Alaska gave results of 90, 100, and 96 million years; those determined on 4 rocks from central Alaska gave results of 47, 56, 58, and 51 million years.
Phosphate deposits in northern Alaska
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Radiometric investigations along the Taylor Highway and part of the Tanana River, Alaska
No abstract available.
Radiometric traverse along the Yukon River from Fort Yukon to Ruby, Alaska, 1949
In 1949, a radiometric traverse was made of rocks exposed along the banks of and near the Yukon River about Fort Yukon to Ruby, Alaska. Granitic rocks of Tertiary age and of Devonian or Carboniferous age and sandstone beds of Cretaceous age gave the highest readings obtained in the field. Other rock types examined were greenstone of Devonian or Carboniferous age and metamorphic rocks of Devonian and pre-Devonian age, sedimentary rocks, and liginite of Tertiary age, and alluvial deposits of Quaternary age. The most radioactive sample, from Melozitna River canyon, contained only 0.017 percent equivalent uranium.
Reconnaissance for radioactive deposits in Alaska, 1953
During the summer of 1953 the areas investigated for radioactive deposits in Alaska were on Nikolai Creek near Tyonek and on Likes Creek near Seward in south-central Alaska where carnotite-type minerals had been reported; in the headwaters of the Peace River in the eastern part of the Seward Peninsula and at Gold Bench on the South Fork of the Koyukuk River in east-central Alaska, where uranothorianite occurs in places associated with base metal sulfides and hematite; in the vicinity of Port Malmesbury in southeastern Alaska to check a reported occurrence of pitchblende; and, in the Miller House-Circle Hot Springs area of east-central Alaska where geochemical studies were made. No significant lode deposits of radioactive materials were found. However, the placer uranothorianite in the headwaters of the Peace River yet remains as an important lead to bedrock radioactive source materials in Alaska. Tundra cover prevents satisfactory radiometric reconnaissance of the area, and methods of geochemical prospecting such as soil and vegetation sampling may ultimately prove more fruitful in the search for the uranothorianite-sulfide lode source than geophysical methods.
Reconnaissance for radioactive deposits in eastern Alaska, 1952
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