Geologic studies in Alaska by the U.S. Geological Survey, 1991
This collection of twenty-one papers continues the annual series of U.S. Geological Survey reports on the geology of Alaska. These contributions, which include full-length Articles and shorter Geologic Notes, are grouped under two broad headings: Mineral Resource Studies (ten papers) and Geologic Framework Studies (eleven papers). Reports on mineral resources discuss exploration geochemistry in the Howard Pass quadrangle, lditarod quadrangle, and Admiralty Island, a mineral resource appraisal of the Bethel quadrangle, a fluid-inclusion study in the Nome Gold District, geochemistry of lode-gold deposits in the Seldovia quadrangle, a new occurrence of placer gold in the Seldovia quadrangle, gold in coal in the Healy quadrangle, experimental abrasion of detrital gold, and a new occurrence of rareearth minerals in southeastern Alaska. Under the heading of Geologic Framework Studies are reports on sedimentology and (or) stratigraphy in the Seldovia, Lime Hills, and Medfra quadrangles, the Kandik region, and the Alexander terrane in southeastern Alaska. Other papers report on the isotope geochemistry of veins and thermal maturity of the Kandik region, metamorphism and deformation of the Yukon-Tanana and Taylor Mountain terranes in eastcentral Alaska, magnetic susceptibilities of plutonic rocks in southeastern Alaska, terrane nomenclature in northern Alaska, and uplift of Mt. McKinley. These studies span nearly the entire State from the North Slope and Brooks Range to interior, western, southwestern, southcentral, and southeastern Alaska (fig. 1 ). Two bibliographies on Alaskan geology at the end of the volume list ( 1) reports about Alaska in USGS publications released in 1991, and (2) reports about Alaska by USGS authors in publications outside the USGS in 1991.