Report of Investigation 2017-10, Geologic map of Mount Chiginagak volcano, Alaska, provides 1:25,000 geologic mapping of the Chiginagak volcano. Mount Chiginagak is a hydrothermally active volcano on the Alaska Peninsula, approximately 170 km south-southwest of King Salmon, Alaska. This small stratovolcano, approximately 8 km in diameter, has erupted through Tertiary to Permian sedimentary and igneous rocks. The eruptive products of Chiginagak volcano record a history of chiefly andesite lava flows and associated block-and-ash flows. The oldest lavas exposed are Pleistocene in age and are found everywhere around the edifice except in the northeast sector, where Holocene lava flows dominate the landscape. Holocene activity has covered the northeast flank with rubbly-topped andesite lava flows that extend as far as 4.6 km from their source vent at the summit crater. The farthest-reaching volcanic deposits are on the southeast flank, where block-and-ash-flow, pyroclastic-flow, and lahar deposits extend down valley as far as 9 km from the summit. Limited exposure of deposits of a presumed plinian eruption of middle Pleistocene age indicate at least one episode of explosive activity in Chiginagak's past. This 1:25,000 scale geologic map and accompanying report document the age, geochemical, and spatial distribution of eruptive products of the Mount Chiginagak volcano. Map units are interpreted from field observations, satellite imagery interpretation, geochemical and geochronological analysis. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/29769.

This map is the result of field investigations by DGGS in 1997 and 1998. This geologic map and report supersede the previously released Public Data File 99-24B, Preliminary interpretive bedrock geologic map of the Healy A-6 Quadrangle, southcentral Alaska. The current map has been updated to include mapping of areas adjacent to the Healy A-6 Quadrangle, newly interpreted bedrock units based on newly acquired analytical, paleontologic, and Ar40/Ar39 data. Ages for the rock units were modified. Field investigations were part of a two-year mapping program to provide geologic ground truth for airborne geophysical surveys flown by DGGS in the Chulitna region of southcentral Alaska during 1996.

A database of the geologic map of the Katmai Volcanic Cluster as described in the original abstract: This digital publication contains all the geologic map information used to publish U.S. Geological Survey Geologic Investigations Map Series I-2778 (Hildreth and Fierstein, 2003). This is a geologic map of the Katmai volcanic cluster on the Alaska Peninsula (including Mount Katmai, Trident Volcano, Mount Mageik, Mount Martin, Mount Griggs, Snowy Mountain, Alagogshak volcano, and Novarupta volcano), and shows the distribution of ejecta from the great eruption of June, 1912 at Novarupta. Widely scattered erosional remnants of volcanic rocks, unrelated to but in the vicinity of the Katmai cluster, are also mapped. Distribution of glacial deposits, large landslides, debris avalanches, and surficial deposits are a snapshot of an ever-changing landscape.

A database of the geologic map of the Katmai Volcanic Cluster as described in the original abstract: This digital publication contains all the geologic map information used to publish U.S. Geological Survey Geologic Investigations Map Series I-2778 (Hildreth and Fierstein, 2003). This is a geologic map of the Katmai volcanic cluster on the Alaska Peninsula (including Mount Katmai, Trident Volcano, Mount Mageik, Mount Martin, Mount Griggs, Snowy Mountain, Alagogshak volcano, and Novarupta volcano), and shows the distribution of ejecta from the great eruption of June, 1912 at Novarupta. Widely scattered erosional remnants of volcanic rocks, unrelated to but in the vicinity of the Katmai cluster, are also mapped. Distribution of glacial deposits, large landslides, debris avalanches, and surficial deposits are a snapshot of an ever-changing landscape.

This dataset comprises the locations of volcanoes and volcanic centers in Alaska.

Alamagan Volcano is a Quaternary stratovolcano along the Mariana Arc, an active subduction zone in the western Pacific Ocean. Although primarily submerged, its peak reaches above sea level, with subaerially-exposed volcanic deposits dating back through the Holocene to the late Pleistocene. These feature data represent such deposits and other geologic features of Alamagan Volcano, describing its interpreted eruptive history.

Alamagan Volcano is a Quaternary stratovolcano along the Mariana Arc, an active subduction zone in the western Pacific Ocean. Although primarily submerged, its peak reaches above sea level, with subaerially-exposed volcanic deposits dating back through the Holocene to the late Pleistocene. These feature data represent such deposits and other geologic features of Alamagan Volcano, describing its interpreted eruptive history.

This publication provides digital point data for the locations of 127 volcanic centers in Alaska younger than 2 million years. Information about whether a volcano has been historically active is also provided. Detailed information about each center can be found on the Alaska Volcano Observatory website at http://www.avo.alaska.edu

This dataset contains 40Ar/39Ar isotopic data and ages for rocks from the Yukon-Tanana upland of eastern Alaska and the northern Aleutian Range of south-central Alaska. The entire sample suite was collected as part of geological mapping and supporting geochemical and geochronological analysis were conducted from 2013 to 2019 by the Mineral Resources Program of the U.S. Geological Survey (USGS). Legacy bedrock samples archived from earlier USGS field investigations were also analyzed in some cases. Hornblende, muscovite, and (or) biotite were extracted from bedrock samples of igneous and metamorphic rocks and analyzed at the University of Alaska Fairbanks Geochronology Laboratory in order to determine the 40Ar/39Ar age of each mineral phase. The data tables accompanying this data release report the resulting 40Ar/39Ar analytical data and interpreted ages for each mineral separated from a bulk rock sample.

This data set contains 40Ar/39Ar isotopic data and ages for rocks from the Yukon-Tanana upland of eastern Alaska and the northern Aleutian Range of south-central Alaska. The entire sample suite was collected as part of geological mapping and supporting geochemical and geochronological analysis were conducted from 2013 to 2019 by the Mineral Resources Program of the U.S. Geological Survey (USGS). Legacy bedrock samples archived from earlier USGS field investigations were also analyzed in some cases. Hornblende, muscovite, and (or) biotite were extracted from bedrock samples of igneous and metamorphic rocks and analyzed at the University of Alaska Fairbanks Geochronology Laboratory in order to determine the 40Ar/39Ar age of each mineral phase. The data tables accompanying this data release report the resulting 40Ar/39Ar analytical data and interpreted ages for each mineral separated from a bulk rock sample.