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J.J. Norton

Publications and source records attributed to J.J. Norton.

At least 19 recordsLinked to original sources
USGS1994

Structure and bulk composition of the Tin Mountain pegmatite, Black Hills, South Dakota

Construction of structure contour and isopach maps has yielded a rather simple and orderly interpretation of the structure and has led to calculations of the tonnage of each of the internal units and of the bulk composition of the pegmatite. The outcropping part of the pegmatite trends S 75° E for 90 m and then connects with an arm of the pegmatite that plunges gently N-NW for approximately another 90 m. An albite-quartz-muscovite wall zone completely surrounds four inner units. Though these four inner units are termed zones, in accordance with standard practice, differentiation is more in a vertical direction than in a concentric arrangement. The upper two of these units are perthite rich.

North Dakota↗
USGS1990

Relations of zoned pegmatites to other pegmatites, granite, and metamorphic rocks in the southern Black Hills, South Dakota

The pegmatite field and the Harney Peak Granite of the southern Black Hills, South Dakota, form an igneous system that progresses from slightly biotitic muscovite granite through layered pegmatitic granite, with alternating sodic and potassic rocks, to simple plagioclase-quartz-perthite pegmatites, and on to zoned pegmatites. Most of the country rocks are Lower Proterozoic mica schists. At 1700 Ga, intrusion of the Harney Peak Granite created a large dome in these rocks, a thermal aureole with a staurolite, a first sillimanite isograd, and a small area of metamorphism above the second sillimanite isograd. The zoned pegmatites have a strong tendency to occur in clusters, and the types of pegmatites are different in different clusters. A less obvious tendency is a regional zonation in which rare-mineral pegmatites become more abundant and muscovite pegmatites less abundant toward the outskirts of the region. The composition of the granite indicates that its magma originated by partial melting of metasedimentary mica schists similar to those at the present surface. The pegmatitic nature of most of the granite probably reflects exsolution of an aqueous phase. -from Authors

American Mineralogist↗
USGS1983

Sequence of mineral assemblages in differentiated granitic pegmatites

Revised sequence is (1) plagioclase, quartz, muscovite, (2) plagioclase, quartz, (3) quartz, perthite, plagioclase, (4) perthite, quartz, (5) quartz, plagioclase, perthite, spodumene (or petalite), amblygonite, (6) quartz, spodumene (or petalite), (7) quartz, microcline or perthite, (8) quartz, and (9) lepidolite or lithian mica, plagioclase, quartz, microcline.

Economic Geology↗
USGS1983

Early Tertiary age of pitchstone in the northern Black Hills, South Dakota

A block of pitchstone in the northern Black Hills, South Dakota, is Paleocene in age, according to potassium-argon dating of biotite and fission-track dating of zircon in the sample. These data invalidate published suggestions that the age is much younger. The pitchstone is not extrusive in its present position but instead is in a volcanic pipe with other fragments that came downward from as much as 1100 meters above the modern surface.

South Dakota↗
USGS1964

Ancient granite gneiss in the Black Hills, South Dakota

Granite gneiss, with an age of approximately 2.5 billion years, in the Black Hills, South Dakota , provides a link betweeen ancient rocks in western Wyoming and Montana and in eastern North and South Dakota and Minnesota. The discovery suggests that early Precambrian rocks covered an extensive area in northcentral United States and were not restricted to several small nuclei.

South Dakota↗
USGS1960

Structure associated with rock creep in the Black Hills, South Dakota

Many areas of schist in the southern Black Hills, South Dakota, have a thin zone of disintegrated rock that is 4-10 feet below the ground surface and parallel to it. Fresh, undeformed schist overlying this zone has moved downhill in a mass-wasting process since the present surface was formed.

South Dakota↗