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W.F. Cannon

Publications and source records attributed to W.F. Cannon.

At least 55 records · Page 3Linked to original sources
USGS1991

Deep crustal structure of the Precambrian basement beneath northern Lake Michigan, midcontinent North America

A deep seismic-reflection profile in northern Lake Michigan, midcontinent North America, provides a cross section of the crust across the 1850 Ma Penokean orogen, in which an Early Proterozoic island-arc complex was deformed between two converging Archean continental masses. The island-arc crust is about 40 km thick and has a few kilometres of intensely reflective rocks near its base, above which it is variably reflective to transparent. The Archean terranes have thicker crust, as much as 50 km, the lower 20-25 km of which is strongly reflective. Abrupt offsets of Moho near terrane boundaries may have been preserved since accretion during the Penokean orogeny.

Geology↗
USGS1982

Mineral-resource assessment of the Iron River 1° x 2° quadrangle, Michigan and Wisconsin

The Iron River 1° x 2° quadrangle contains identified resources of copper and iron. Copper-rich shale beds in t1n north part of the quadrangle contain 12.2 billion pounds (5.5 billion kg) of copper in well-studied deposits including 9.2 billion pounds (4.2 billion kg) that are economically mineable by 1980 standards. At least several billion pounds of copper probably exist in other parts of the same shale beds but not enough data are available to measure the amount. A small amount, about 250 million pounds (113 million kg), of native copper is known to remain in one abandoned mine, and additional but unknown amounts remain in other abandoned mines. About 13.25 billion tons (12.02 billion t) of handed iron-formation averaging roughly 30 percent iron are known within 500 feet (152.4 m) of the surface in the Gogebic, Marquette, and Iron River-Crystal Falls districts. Some, probably small, percentage of that might someday be mineable as taconite, but none is now believed to be economic. Some higher grade iron concentrations exist in tin same iron-formations. Such material was the basis of former mining of iron in the region, but a poor market for such ore and depletion of many deposits has lead to the decline of iron mining in the quadrangle. No iron mines of the quadrangle were being worked in 1981. Many parts of the quadrangle contain belts of favorable host rocks for mineral deposits. Although no deposits are known in these belts, undiscovered deposits of copper, zinc, lead, silver, uranium, phosphate, nickel, chromium, platinum, gold, and diamonds could exist.

Michigan, Wisconsin↗
USGS1979

The Yellow Dog peridotite and a possible buried igneous complex of lower Keweenawan age in the northern peninsula of Michigan

Partly serpentinized peridotite of early Keweenawan age crops out in two places along a 20-kilometer-long zone of positive aeromagnetic anomalies in northern Marquette County, Michigan. Most of the area is mantled by Pleistocene drift with few bedrock exposures. Petrographic and electron microprobe studies show that the peridotite was originally a plagioclase lherzolite containing 40 to 50 percent olivine (Fo8 0 ) and approximately 10 to 15 percent each of enstatite (En 78 Wo 04 Fs 18 ) and diopsidic augite (En 47 Wo 42 Fs 11 ). The plagioclase varies from 5 to 10 percent, and according to Morris (1977) is labradorite with a composition of An 57-65 . Major oxide minerals (4 to 6 percent) are ilmenite and magnetite. Sulfides comprise 1 to 2 percent of the peridotite and are chiefly pyrrhotite, pentlandite, and chalcopyrite. Ground magnetic, gravity, and very low frequency electro-magnetic (VLF-EM) surveys have refined the location and magnitude of anomalies previously known only from aeromagnetic studies. These surveys together with soil geochemical studies suggest that peridotite, and possibly other mafic rocks forming a differentiated igneous complex, may occur throughout a belt 20 kilometers long (east-west) and 1 to 2 kilometers wide (north-south). Differentiated igneous complexes in many parts of the world are hosts for copper, nickel, chromium, or precious-metal deposits. The peridotite in the area of this study is anomalously rich in copper and sulfur compared to world-wide averages for peridotite. Positive electro-magnetic anomalies found near the peridotite outcrops may be caused by sulfide-rich zones in the igneous rocks and should be explored further for copper-nickel mineralization.

Michigan↗
USGS1977

The Yellow Dog peridotite and a possible buried igneous complex of Lower Keweenawan Age in the northern peninsula of Michigan

Partly serpentinized peridotite of early Keweenawan age crops out in two places along a 20-km-long zone of positive aeromagnetic anomalies in northern Marquette County, Michigan. Most of the area is mantled by Pleistocene drift and the bedrock is not exposed. Petrographic and electron microprobe studies show that the peridotite was originally a plagioclase lherzolite containing 40-50% olivine (Fo8 0 ) and approximately 10-15% each of enstatite (En 78 Wo 04 Fs 18 ) and diopsidic augite (En 47 Wo 42 Fs 11 ), with 5-10% calcic labradorite (~An 70 ). Major oxide minerals (4-6%) are ilmenite and magnetite. Sulfides comprise 1 to 2 percent of the peridotite and are chiefly pyrrhotite, pentlandite, and chalcopyrite. Ground magnetic, gravity, and very low frequency electro-magnetic surveys have refined the location and magnitude of anomalies previously known only from aeromagnetic studies. These surveys together with soil geochemical studies suggest that peridotite, and possibly other mafic rocks forming a differentiated igneous complex, may occur throughout a belt 20 km long (E-W) and 1-2 km wide (N-S). Differentiated igneous complexes in many parts of the world are hosts for Cu, Ni, Cr, or precious metal deposits. The peridotite in the area of this study is anomalously rich in Cu and S compared to world-wide averages for peridotite. Positive electro-magnetic anomalies found near the peridotite outcrops may be caused by sulfide-rich zones in the igneous rocks and should be explored further for Cu-Ni mineralization.

Michigan↗
USGS1974

Geologic interpretation of gravity profiles in the western Marquette district, northern Michigan

The presence of elongate troughs of Precambrian X (middle Precambrian) rocks in Precambrian W (lower Precambrian) rocks in the western Marquette district of northern Michigan has been known since the late 1800s. However, little data can be brought to bear on estimates of the depth and cross-sectional configuration of these features. For this reason, gravity models and geologic interpretations were made from gravity profiles measured over the Marquette Trough, Republic Trough, and Mitchigan River Trough. Gravity-model studies, combined with geologic studies, indicate that near Humboldt, Michigan, the Marquette Trough is ∼2,438 m deep and asymetrically shaped, the deepest section being near the southern edge; near the west end of Lake Michigamme, the Marquette Trough is about 1,097 m deep at its northern edge; the Republic Trough is about 1,524 m deep at a point ∼2.4 km northwest of its southeastern end; and the Mitchigan River Trough is probably a fault-bounded westward-dipping monocline ∼610 m deep.

Michigan↗
USGS1974

Stratigraphic relationships within the Baraga Group of Precambrian age, central Upper Peninsula, Michigan

Details of the stratigraphic section in parts of northern Michigan have been known for many years, but correlation of units between geographically separated areas has been partly speculative. Mapping in the Witch Lake quadrangle has filled the gap between well-studied areas of the Marquette trough and parts of Iron and Dickinson Counties and has helped to correlate units in the Baraga Group (Precambrian X). Iron-formations are important marker beds; because of their magnetic properties they can be traced with certainty through poorly exposed areas. The magnetic Fence River Formation is now known to be stratigraphically beneath the Bijiki Iron-formation Member of the Michigamme Formation but may be equivalent to the Greenwood Iron-formation Member which crops out in parts of the Marquette trough to the east The Hemlock Formation (volcanic) underlies the Fence River and has been traced from near its type locality in Iron County to the south flank of the Marquette trough. These relationships provide the key to understanding the lateral facies changes responsible for the stratigraphic complexities of the Baraga Group.

Michigan↗
USGS1973

Geology of part of the southern complex, Marquette district, Michigan

The southern complex, south of the Marquette synclinorium in the Marquette district of Michigan, is dominantly granitic. The granitic parts of the complex have Rb-Sr ages of about 2.5 b.y. and are classed as of Precambrian W age. The rocks are divided into two major units: (1.) Bell Creek Gneiss consisting mostly of coarse megacrystic granitic rocks and lesser amounts of mafic gneiss and metasedimentary rocks in layers concordant to the foliation of the granitic gneiss, and (2) Compeau Creek Gneiss, previously described to the east, which is mostly medium-grained granitic gneiss and lesser amounts of massive granitic rocks and locally abundant xenoliths of mafic and metasedimentary rocks. Compeau Creek Gneiss intrudes Bell Creek Gneiss throughout the area. Mafic and metasedimentary rocks in the Bell Creek Gneiss are interpreted as remnants of a greenstone belt. The granitic parts of the Bell Creek Gneiss are of problematic origin. Their composition suggests a magmatic origin, but they do not intrude any rocks with which they are in contact; they form concordant layers in all observed places. Granitic parts of the Compeau Creek Gneiss are suspected to be highly altered and partly melted sedimentary rocks. The mafic parts are probably xenoliths of mafic rocks from the Bell Creek Gneiss.

Michigan↗