Geologic map of the Tanana A-1 and A-2 quadrangles, central Alaska

This report provides detailed (1:63,360-scale) mapping of the Tanana A-1 and A-2 quadrangles (500 square miles; equivalent to eight 7.5-minute quadrangles). The area is part of the Manley Hot Springs-Tofty mining districts and adjacent to the Rampart mining district to the south of the Tanana B-1 Quadrangle. This report includes detailed bedrock, surficial, structural, and stratigraphic data. Based on the resulting geologic maps, field investigations, and laboratory materials analyses, the report also includes derivative maps of geologic construction materials and geologic hazards. The Tanana A-1 and A-2 Quadrangles and surrounding area comprise several isolated mountainous ridges in the western Yukon-Tanana Upland...

Tags: 40Ar/39Ar, Aerial Photography, Aeromagnetic Map, Aeromagnetic Survey, Age Dates, All tags... Bibliography, Biostratigraphy, CIPW Norms, Carbonates, Cerium, Clastics, Conductivity Survey, Core Logs, Cultural Resources, Depositional Environment, Diagenesis, Disseminated, Economic Geology, Economic Study, Electromagnetic Survey, Epithermal, Erosion, Faulting, Folding, Fossils, Geologic Map, Geomorphology, Geophysical Map, Glacial, Glacial Processes, Gold, Greenschist, Greisen, Historic Resources, Hot Springs, K-Ar, Lab Methods, Lode, Magnetic Susceptibility, Magnetometer Survey, Major Oxides, Manley Basin, Marine, Measured Stratigraphic Section, Metamorphic Grade, Metamorphism, Mineralogy, Mining, Modal Analysis, Niobium, Ores, Orogeny, Paleobotany, Paleocurrent, Paleoenvironment, Paleontology, Palynology, Petrogenesis, Petrography, Petrology, Placer, Plutonic, Plutonic Hosted, Precious Metals, Production Data, Provenance, Rare Earth Elements, Reconstructions, Regional, Regional Metamorphism, Remote Sensing, Resistivity Survey, Resource Assessment, Sandstone, Sedimentary, Sedimentation, Shale, Silver, Structure, Structure Map, Surficial, Tectonic Map, Tectonics, Terranes, Topographic Map, Turbidites, Type Section, Uplift, Volcanic, Volcanic Hosted, Yukon River, geoscientificInformation, Fewer tags

Contemporaneous Trachyandesitic and Calc-alkaline Volcanism of the Huerto Andesite, San Juan Volcanic Field, Colorado, USA

Locally, voluminous andesitic volcanism both preceded and followed large eruptions of silicic ash-flow tuff from many calderas in the San Juan volcanic field. The most voluminous post-collapse lava suite of the central San Juan caldera cluster is the 28 Ma Huerto Andesite, a diverse assemblage erupted from at least 5-6 volcanic centres that were active around the southern margins of the La Garita caldera shortly after eruption of the Fish Canyon Tuff. These andesitic centres are inferred, in part, to represent eruptions of magma that ponded and differentiated within the crust below the La Garita caldera, thereby providing the thermal energy necessary for rejuvenation and remobilization of the Fish Canyon magma body....

Categories: Publication; Types: Citation, Journal Citation; Tags: Fish Canyon system, Journal of Petrology, alkaline, calc-alkaline, episodic magmatism, All tags... petrogenesis, Fewer tags