USGS Science⌕ Search

Geology topics

G. Donald Eberlein

Publications and source records attributed to G. Donald Eberlein.

15 recordsLinked to original sources
USGS1977

Spherulitic rhyolite dike from Goat Island, southeastern Alaska

Spherulites, as much as 4 mm in diameter, locally constitute almost 50 percent by volume of a dark-red rhyolite dike that intrudes porphyritic pyroxene gabbro along the northeast coast of Goat Island, 3.2 km northwest of Hydaburg, southeastern Alaska. The largest spherulites are composed mainly of o-quartz, whereas the smallest consist of a microcrystalline intergrowth of tridymite and alkali feldspar. Textural relations indicate that the radial and concentrically zoned structures are the products.of devitrification of glassy lava. The mineralogy of the dike is similar to that of other spherulitic rhyolites except that quartz occurs to the exclusion of cristobalite. The posteruptive formation of the spherulites has also resulted in alkali transfer, the groundmass of the dike being enriched in both sodium and potassium relative to the spherulites.

Alaska↗
USGS1974

Optical and X-ray crystallographic investigations of strontioginorites

Compositional, optical, and unit-cell data are presented for a suite of strontioginorites. These crystals show that Sr:Ca ≈ 1 is preferred. Lack of variation in the Sr:Ca resulted in no meaningful correlation between composition and physical properties.

Journal of Research of the U.S. Geological Survey↗
USGS1970

Lower Devonian graptolites from southeastern Alaska

The youngest zones of Monograptus occur in Devonian black shale and slate along the western shore of Prince of Wales Island and on Noyes Island, southeastern Alaska. The following five species of Monograptus , in close association with vascular plants and marine shelly faunas, indicate a Praguian, (Siegenian to Early Emsian), late Lower Devonian and possibly early Middle Devonian age: M. yukonensis Jackson & Lenz, M. n. sp. aff. yukonensis ? Jaeger & Stein, M. aeqimbilis notoaequakilis Jaeger & Stein, M. pacificus Jaeger n. sp. and M. craigensis Jaeger n. sp. The yukonensis zone containing M. craigensis in its upper part is followed stratigraphically higher by the M. pacificus zone – the youngest occurrence of Monograptus. The new species belong to the M. uncinatus group and, like most Praguian monograptids, have long dorsal tongues on their siculae. M. craigensis and M. pacificus increase to seven the number of species of Monograptus known from the Praguian. On the basis of the Alaskan material, the geographical distribution of M. aequabilis notoaequabilis now includes North America in addition to previously recorded occurrences in Australia, Southeast Asia, and Europe. This broad geographic distribution suggests that the last survivors of Monograptus had worldwide distribution and a rather uniform assemblage of species.

Alaska↗
USGS1970

Lead-, zinc-, and barite-bearing samples from the western Brooks Range, Alaska, with a section on petrography and mineralogy

Concentrations of base metal and barite of potential economic significance may be present in the western De Long Mountains, northwestern Alaska. Greater than 2 percent lead and 1 percent zinc were detected semiquantitatively in sulfide-bearing hand samples from one locality, and more than 10 percent lead was analyzed in a related stream sediment sample. The base metals as sulfides, along with barite, have been concentrated in Paleozoic and(or) Mesozoic sedimentary chert. Several other localities at which sulfides appear to be weathering are present within a 100-square-mlle area. Systematic prospecting should determine if the mineralization has regional significance and has resulted in deposits' of possible economic importance.

Alaska↗
USGS1950

Stratigraphy and structure of the Aupuk anticline

In addition to conducting an examination of the surface geology in the Southern Foothills province between the Killik River and east fork of the Etivluk River, Navy Oil Unit Party No. 5 was requested to map the Aupuk anticline during the 1950 field season, for the purpose of evaluating the petroleum possibilities thereof from the standpoints of favorable statigraphy and possible structural closure. Field mapping of the Aupuk anticline began on August 1, and about 1 month was devoted to the study. Party personnel consisted of G. Donald Eberlein and Charles D. Reynolds, geologists, W. L. D'Olier and W. D. Carter, field assistants, Richard Olson, camp cook, and Max H. Davis, weasel mechanic. Robort M. Chapman, geologist, visited the party for 1 week early in August to help start the work and shared, with Eberlein, the responsibilities associated with the final compilation of this report. Three weasels were used for daily transportation to the field and for moving camp. A 10-foot Link boat equipped with 5 hp. outboard motor was used to cross the Colville River. As field work progressed from west to east it became apparent that the camp equipment and weasels would have to be gotten across the Colville River if field work was to be completed by early September. This crossing was effected without incident at a point approximately 10 miles below the confluence of the Kurupa and Colville Rivers on August 26. The party reached Umiat on September 5.

Alaska↗