Publications

North-central and northeast Nevada contains numerous large plutons and smaller stocks but also contains many small, shallowly emplaced intrusive bodies, including dikes, sills, and intrusive lava dome complexes. Decades of geologic investigations in the study area demonstrate that many ore deposits, representing diverse ore deposit types, are spatially, and probably temporally and...

Geological sources of metals (especially arsenic and zinc) in aquifer bedrock were evaluated for their potential to contribute elevated values of metals to ground and surface waters in and around Rockingham County, New Hampshire. Ayotte and others (1999, 2003) had proposed that arsenic concentrations in ground water flowing through bedrock aquifers in eastern New England were elevated as...

Heavy oil and natural bitumen are oils set apart by their high viscosity (resistance to flow) and high density (low API gravity). These attributes reflect the invariable presence of up to 50 weight percent asphaltenes, very high molecular weight hydrocarbon molecules incorporating many heteroatoms in their lattices. Almost all heavy oil and natural bitumen are alteration products of...

This report presents reconnaissance geochemical data for a cooperative study in the Fortymile Mining District, east-central Alaska, initiated in 1997. This study has been funded by the U.S. Geological Survey (USGS) Mineral Resources Program. Cooperative funds were provided from various State of Alaska sources through the Alaska Department of Natural Resources. Results presented here...

Introduction: ASTER data and logical operators were successfully used to map phyllic and argillic-altered rocks in the southeastern part of Afghanistan. Hyperion data were used to correct ASTER band 5 and ASTER data were georegistered to orthorectified Landsat TM data. Logical operator algorithms produced argillic and phyllic byte ASTER images that were converted to vector data and...

This paper summarizes the results of field and laboratory investigations, including whole-rock geochemistry and radiogenic isotopes, of outcrop and drill core samples from volcanogenic massive sulfide (VMS) deposits and associated metaigneous rocks in the Wood River area of the Bonnifield mining district, northern Alaska Range (see fig. 1 of Editors’ Preface and Overview). U-Pb zircon...

On July 8, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor acquired satellite imagery of a 60-kilometer-wide swath covering a portion of the Bonnifield mining district within the southernmost part of the Tintina Gold Province, Alaska, under unusually favorable conditions of minimal cloud and snow cover. Although rocks from more than eight different

This report presents results on the occurrence and biogeochemistry of unusual plant species, and of their supporting sediment, in an undisturbed volcanogenic massive sulfide deposit in the Tintina Gold Province (see fig. 1 of Editors’ Preface and Overview). The extraordinary plant assemblage found growing in the acidic metal-rich waters that drain the area is composed predominantly of

The Red Mountain volcanogenic massive sulfide (VMS) deposit exhibits well-constrained examples of acid-generating, metal-leaching, metal-precipitation, and self-mitigation (via co-precipitation, dilution, and neutralization) processes that occur in an undisturbed natural setting, a rare occurrence in North America. The unmined pyrite-rich deposit displays a remarkable environmental...

The Black Mountain tectonic zone in the YukonTanana terrane of east-central Alaska is a belt of diverse northeast-trending geologic features that can been traced across Black Mountain in the southeast corner of the Big Delta 1°×3° degree quadrangle. Geologic mapping in the larger scale B1 quadrangle of the Big Delta quadrangle, in which Black Mountain is the principal physiographic...

Magnetic anomaly patterns on opposite sides of the mapped Tintina fault in eastern Alaska and western Canada show an apparent offset of about 490 kilometers (km), probably of Eocene age. This estimate is compared with previous geologically based estimates of 400 to 430 km and paleomagnetically based estimates of more than 1,100 km. The apparent geophysical alignments have geologic

The Pogo lode gold deposit was discovered in eastern Alaska in the early 1990s and provided the opportunity to study elemental distribution and mobility in the natural environment prior to mine development. Studying mineralized systems prior to mining allows us to compare the natural biogeochemical signature in mineralized versus nonmineralized areas. The resultant data and...