USGS Science⌕ Search

Geology topics

Jocelyn A. Peterson

Publications and source records attributed to Jocelyn A. Peterson.

16 recordsLinked to original sources
USGS1985

Map showing geochemical summary for the Bald Rock and Middle Fork Feather River Roadless Areas, Butte and Plumas counties, California

The Bald Rock Roadless Area consists of 3,850 acres in Butte County, Calif. The Middle Rock Feather River Roadless Area consists of 29,300 acres ub Butte and Plumas Counties, Calif. Both roadless areas are in the Plumas National Forest and are on the west slope of the northern Sierra Nevada southwest of Quincy, Calif. (fig. 1). The two roadless areas are alined along the Middle Fork of the Feather River where they include the narrow canyon bottoms and precipitous sidewalls of the Middle Fork and several tributary drainages. Altitudes range from 800 ft in the canyon of the Middle Fork to approximately 6,600 ft at the northwest corner of the map area. The geology of the roadless areas has been briefly summarized by Sorenson and Pietropaoll (1982). This paper summarizes and interprets the semiquantitative emission spectrographic analyses of 106 rock sample and 165 samples of nonmagnetics heavy-mineral stream-sediment concentrates from the Blad Rock and Middle Fork Feather River Roadless Area (Sorenson and others, 1982).

California↗
USGS1983

Map showing characteristics of lode gold in the Medford 1 degree by 2 degrees Quadrangle, Oregon-California

About 500 lode gold occurrences, prospects, and mines have been reported from the Medford 1 o x 2 o quadrangle, Oregon-California. Summary descriptions of individual lode gold deposits and districts which include those occurrences in the Medford 1 o x 2 o quadrangle have been published by Brooks and Ramp (1968) and Hotz (1971) and by others cited in the reference lists in these two publications. As part of the Medford CUSMAP project between 1974 and 1980, some of these deposits were examined in the field during geologic mapping and geochemical sampling and most of the available information on individual deposits was compiled into a CRIB computer file (Computerized Resource Information Bank). This report is a summary of the more pertinent geologic and economic characteristics of the lode gold deposits for use in the resource evaluation part of the Medford CUSMAP project. The significant features described include the distribution of deposits and their relation to gross geologic and lithologic features, production information, mineralogy of the ore and gangue, gold-silver ratios, and speculations on possible genetic models for some types of deposits.

California, Oregon↗
USGS1983

Mineral resource potential map of the Mount Eddy and Castle Crags Roadless Areas, Shasta, Siskiyou, and Trinity counties, California

Although ultramafic terranes such as that underlying the Mount Eddy and Castle Crags Roadless Areas may contain chromite, nickel, platinum-group metals, cobalt, and asbestos, there are no significant identified concentrations of these resources within the roadless areas. Platinum-group metals were sought but not detected in stream-sediment concentrates, although this does not rule out their possible occurrence. Nickel and cobalt did not occur in anomalous amounts although slightly higher nickel values in the northern part of the Mount Eddy Roadless Area may indicate low-grade mineralization within small dunite bodies, if the nickel occurs in sulfide phases rather than in olivine. The region has been examined on the surface for chromite and asbestos. Although both minerals are ubiquitous there is probably only a low potential for asbestos on the basis of the small size of veins at the surface. Only a few small areas of chromite were noted in the Mount Eddy Roadless Area; without subsurface data, however, any dunite body must be considered to have potential for chromite. The geochemical data for boron, barium, and mercury plus abundant quartz veining in gabbro and hornblende diorite suggest pervasive hydrothermal alteration, which could have formed mercury or vein gold deposits. Sand and gravel deposits occur in the Castle Crags Roadless Area but they cannot compete with superior deposits closer to markets. At a borrow pit northwest of the Mount Eddy Roadless Area, sheared serpentinite is quarried for road metal; similar rock occurs in the roadless area; however, better material is more readily available elsewhere.

California↗