Laurel G. Woodruff

The Midcontinent Rift System (MRS) of North America is one of the world’s largest continental rifts and has an age of 1.1 Ga (giga-annum). The MRS hosts a diverse suite of magmatic and hydrothermal mineral deposits in the Lake Superior region where rift rocks are exposed at or near the surface. As part of the construction of a database summarizing information on mineral deposits in the...

A goal of the USGS Earth Mapping Resources Initiative (Earth MRI) program, which partners the USGS with State Geological Surveys, Federal agencies, and the private sector, is to collect new geological, geophysical, geochemical, and topographic (lidar) data in key areas of the U.S., with the purpose of stimulating domestic mineral exploration and production of critical minerals. As a...

In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 36 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.) (https://pubs.usgs.gov/of/2018/1021/ofr20181021.pdf). Acquiring information on possible domestic sources...

In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 35 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.) (https://pubs.usgs.gov/of/2018/1021/ofr20181021.pdf). Acquiring information on possible domestic sources...

Samples for analysis were selected from 1) archived rotosonic cores drilled by the Minnesota Geological Survey and archived at the Lands and Minerals Drill Core Library, Minnesota Department of Natural Resources, Hibbing, Minnesota, USA; or b) freshly collected rotosonic cores, collected on-site at the time of coring. Cores in the sample archive are stored in wooden core-boxes in ambient...

The U.S. Geological Survey (USGS) collected rock physical property measurements to help understand causative sources of gravity and magnetic survey anomalies in the Iron Mountain-Menominee region, Michigan-Wisconsin. A total of 2,356 measurements of magnetic susceptibility and density from 152 locations have been conducted on Precambrian rocks. The measurements aid in interpretation of...

To document regional water quality in areas of potential base-metal mining, bedrock, soil, streambed sediment, and surface-water samples were collected and analyzed in three watersheds that cross the basal part of the Duluth Complex (northeastern Minnesota). The three watershed each had different mineral-deposit settings: (1) copper-nickel-platinum group element mineralization (Filson...

In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 35 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.). Acquiring information on possible domestic sources of these critical minerals is the basis of the USGS...

The table contains oxide and cation compositions of olivine grains from drill core of the Duluth Complex, Minnesota. The oxides were determined by electron probe microanalysis (EPMA) and are reported in weight percent (wt%). The cations were calculated based on the oxide compositions and are reported in mole percent (mol%). Olivine is a magnesium iron orthosilicate mineral with the...

The table contains oxide and cation compositions of feldspar grains from drill core of the Duluth Complex. The oxides were determined by electron probe microanalysis (EPMA) and are are reported in weight percent (wt%). The cations were then calculated and are reported in mole percent (mol%). Feldspar grains are a group of rock-forming tectosilicate minerals with potassium (K), sodium (Na...

The table contains oxide and cation compositions of pyroxene grains from drill core in the Duluth Complex. The oxides were determined by electron probe microanalysis (EPMA) and are reported in weight percent (we%). The cations were calculated from the oxide concentrations and are reported in mole percent (mol%). Pyroxene minerals are a group of rock-forming inosilicate minerals with...

This table reports major, minor, and trace element compositions of bulk drill core samples from the Duluth Complex, Minnesota. Major elements were measured using wavelength dispersive X-ray fluorescence (XRF) and inductively coupled plasma atomic emission spectrometry (ICP-AES); minor and trace elements were determined using ICP-AES, inductively coupled plasma mass spectrometry (ICP-MS)...