Publications

VNIR-SWIR (400–2500 nm) reflectance measurements were made on the surfaces of various cores, cuttings and sample splits of sedimentary rocks from the Tertiary Jackson Group, and Catahoula, Oakville and Goliad Formations. These rocks vary in composition and texture from mudstone and claystone to sandstone and are known host rocks for roll front uranium occurrences in Karnes and Live Oak...

The Great Lakes Tectonic Zone (GLTZ) forms the boundary between the Wawa-Abitibi subprovince (north side) and Minnesota River Valley subprovince (south side) within the Archean Superior Province. The GLTZ is concealed for all of its 1100 km length, except south of Marquette in the central Upper Peninsula of Michigan (Sims, 1991; Sims and Day, 1993). Near KI Sawyer, it is exposed as a NW...

The ca. 2737 Ma (Souders, 2023) Mentor anorthosite intrusive complex (MAIC) lies near the northern margin of the Wawa subprovince of the Archean Superior Province, in an area of northwestern Minnesota where the Wawa, Quetico, and Wabigoon subprovinces are juxtaposed in close proximity (Fig. 1). The rocks of interest are entirely concealed by 10s to >100 m of unconsolidated Quaternary...

The type locality for the upper Oligocene Nuwok Member of the Sagavanirktok Formation (Carter Creek, North Slope, Alaska, USA) contains abundant occurrence of glendonite, a pseudomorph after the calcium carbonate mineral ikaite, which typically forms in the shallow subsurface of cold marine sediments. The region during the time of Nuwok Member deposition was located at a high latitude...

High-temperature quartz veins were identified in drill core at ~600 m below the Sunnyside epithermal base and pre-cious metal deposit in southwestern Colorado. The veins consist of early anhedral quartz that shows a bluish ca-thodoluminescence emission and hosts heterogenous silicate melt inclusions. The early quartz is overgrown by a later generation of quartz that exhibits euhedral...

Recent field and geochronological studies in eight 7.5-minute quadrangles near Mount Rogers in Virginia, North Carolina and Tennessee recognize (1) important stratigraphic and structural relationships for the Neoproterozoic Mount Rogers and Konnarock Formations, and the northeast end of the Mountain City window; (2) the separation of Mesoproterozoic rocks of the Blue Ridge into three age...

The Red Mountain district in southwestern Colorado produced base and precious metals hosted in breccia pipes and vein structures related to an extensive lithocap that overlies pervasive quartz-sericite-pyrite alteration. A helicopter-borne time-domain electromagnetic survey flown over the district yielded resistivity values that range from tens to thousand or more ohm-m, with lesser...

The Pogo Au deposit is the largest of a number of gold occurrences in eastern interior Alaska, that occur along a broad trend from west of Pogo to Black Mountain. Some of these occurrences are hosted in amphibolite facies gneisses and others in mid-Cretaceous igneous rocks that intruded the older metamorphic rocks. All occurrences contain arsenopyrite and pyrite. Whole rock geochemical...

Increasing demand for Ge and Co has led to a renewed interest and focus on advancing our understanding of the occurrence, distribution, and sequestration of these critical elements in known ore deposits. A workflow using a variety of analytical techniques and co-registered datasets has been developed and was applied to the carbonate hosted Bornite Cu-Co (Zn,-Ge) deposit in Alaska, where...

The U.S. Geological Survey (USGS) has established robust collaborations with domestic state and international geological surveys to provide geophysical and other types of earth science data that act to underpin critical mineral research efforts across the United States, Canada, and Australia. The Earth Mapping Resource Initiative (EMRI) is a national-scale collaborative effort with state

Carbonatite-hosted rare earth element (REE) deposits are the primary source of the world’s light REEs and have the potential to be a source of heavy REEs. The Mount Weld REE deposit in Western Australia is hosted in a lateritic sequence that reflects supergene enrichment of the underlying carbonatite complex. Similar to other carbonatite-related ore deposits, ore from Mount Weld displays...

Today’s global economy is challenged to meet the growing demand for commodities used in existing and emerging advanced technologies. Critical minerals are commodities found in a wide variety of ore deposits that are vital to the economic or national security of individual nations that are vulnerable to supply disruption. The U.S. Geological Survey is striving to advance understanding of...