Four maps showing lithologic distributions of selected parts of the Jurassic San Rafael Group and related units, Utah, Colorado, Arizona, and New Mexico
No abstract available.
Arizona, Colorado, New Mexico, Utah↗
Geology topics
James C. Wright
Publications and source records attributed to James C. Wright.
An annotated bibliography of fauna and flora described from the Dockum Group of Triassic age in eastern New Mexico and West Texas
This annotated bibliography was prepared by Warren I. Finch from a rough copy compiled by the late James C. Wright in either late 1967 or early 1968 as an aid to his understanding of the stratigraphic distribution of uranium deposits in Triassic rocks of the Southern high Plains. He did not finish it, inasmuch as several references listed are not annotated. Nevertheless, it is fairly complete for North American literature for years prior to 1967, but it does not contain any papers published in Europe, several of which are pertinent. A few papers oil localities in Wyoming, the Colorado Plateau region, and Mexico are annotated for the purposes of generic and stratigraphic comparison. Wright collated many of the data; cross references are abundant. The bibliography is presented as prepared by Wright; editing was held to a minimum. No additional check was made of the source materials for accuracy of the data--for example, spellings of fossil names. The stratigraphic nomenclature is that: used in the reports cited and may or may not conform to that currently accepted by the U.S. Geological Survey. A list of non-annotated references cited in the annotations was added.
New Mexico, Texas↗
The White Pine copper deposit, Ontonagon County, Michigan
Copper, largely in the mineral chalcocite, is found in the lowermost beds of the Nonesuch shale over many square miles near White Pine, Ontonagon County, Mich. The Nonesuch shale, of late Keweenawan age, is about 600 feet thick and is composed largely of gray siltstone. It overlies 2,300 to 5,500 feet of red sandstones and conglomerates, the Copper Harbor conglomerate. This formation, in turn, overlies the middle Keweenawan Portage Lake lava series, in which occur the famous native-copper deposits of the south shore of Lake Superior. The White Pine mine is 45 to 70 miles west-southwest of the principal native copper mines.The copper-bearing beds at White Pine are primarily in the lower 20to 25 feet of the Nonesuch shale. This cupriferous zone is divided in local usage into four stratigraphic units, which are, in ascending order, the lower sandstone (the uppermost bed of the Copper Harbor conglomerate), the parting shale, the upper sandstone, and the upper shale. The sequence of beds is almost identical in the upper and parting shales, suggesting cyclic sedimentation. This sequence and the distribution of sedimentary facies are attributed to two submergences, separated by an emergence, of a deltaic area.Practically all the copper occurs in the upper and parting shales, except in a small area near the White Pine fault where it is abundant in the upper and lower sandstones. It is present in five different layers in amounts that average from 1 to 3 percent. The total amount of copper in each bed is generally higher where the bed is thick, and thickness, in turn, seems to be greatest in areas that were hollows away from the main channel or channels of the ancient delta. Copper content of the shale beds typically decreases as their sand content increases. The extent of individual copper-bearing beds 1 to 3 feet thick is measurable in square miles.The local occurrence of copper in the upper and lower sandstone beds can be reasonably explained as the result of hydrothermal transportation from the White Pine fault up the dip of the relatively permeable sandstone to the crest of an adjacent anticline. Distribution of copper in the parting and upper shales, on the other hand, seems to be completely independent of local structure, faults, and rock permeability. For the area as a whole the control is lithologic and stratigraphic. Probably the copper was dropped into or precipitated within the original mud; it may conceivably have replaced with exquisite detail something else that was so deposited.
Michigan↗
A magnetic anomaly near Bear Lake, Houghton County, Michigan
A large magnetic anomaly of unknown origin occurs about 1 1/2 miles east of Bear Lake, Houghton County, Michigan, in secs. 24 and 258 T. 56 N., R. 34 W. The occurrence is isolated in an area of very weakly magnetic rocks and has special geologic interest because it is adjacent to a non-magnetic rhyolite porphyry body that is stratigraphically higher than any other known igneous rock in the Keweenawan series. An aeromagnetic survey of the Michigan copper district by the Geophysics Branch of the U. S. Geological Survey in 1948 first revealed the anomaly (Fig. 1). The anomalous area has been more fully outlined by a dip-needle survey, and briefly discusses the geology of the area and possible significance of the anomaly.
Michigan↗