Research about southeastern Alaska

USGS1996

Metamorphic facies map of southeastern Alaska: Distribution, facies, and ages of regionally metamorphosed rocks

Nearly all of the bedrock in Southeastern Alaska has been metamorphosed, much of it under medium-grade conditions during metamorphic episodes that were associated with widespread plutonism. The oldest metamorphisms affected probable arc rocks near southern Prince of Wales Island and occurred during early and middle Paleozoic orogenies. The predominant period of metamorphism and associated plutonism occurred during Early Cretaceous to early Tertiary time and resulted in the development of the Coast plutonic-metamorphic complex that extends along the inboard half of Southeastern Alaska. Middle Tertiary regional thermal metamorphism affected a large part of Baranof Island.

Alaska↗

USGS1959

Field observations on effects of Alaska earthquake of 10 July 1958

The Alaska earthquake of 10 July 1958 was caused by movement on the Fairweather fault amounting to at least 21 1/2 feet horizontally and 3 1/2 feet vertically. Effects of strong shaking were evident over a large area in southeastern Alaska. In Lituya Bay an enormous wave, possibly resulting from a rockslide, reached a maximum height of more than 1700 feet.

Alaska↗

USGS1955

Geology of two areas of pegmatite deposits in southeastern Alaska

A pegmatite deposit about 600 feet in diameter crops on a high bluff less than one-half mile east of a small unnamed cove between Redfish and Byron Bays, on the west coast of Baranof Island, southeastern Alaska. The deposit which comprises several pegmatite bodies consists of quartz, albite-oligoclase, microcline and mica, listed in the order of their relative abundance. Feldspar and quartz crystals locally attain a length of more than 1 foot. Some muscovite mica up to 2 inches in diameter occurs, but the major part of the mica is contained in concentrations, containing mica flakes one-half inch across, that often are as large as 10 feet across. Ruby mica of strategic grade has been obtained from float from this deposit. None of the rarer minerals such as beryl, columbite-tantalite or cassiterite that often occur in pegmatites were observed in the preliminary examination; and small-size concentrate samples obtained by panning stream sands from the area did not contain recognizable amounts of these rarer minerals. One sample contained a few grains identified as cassiterite. No radioactive anomalies were detected in the pegmatites, or in the stream concentrates. The large tonnage of material available arid the favorable location by a good anchorage on an ocean route are favorable factors that should contribute to the development of the deposits. Other deposits of comparable size probably occur in the area.

Alaska↗