We present new field and U-Pb analytical data from the Sonora Gulch Project that demonstrate a protracted history of polymetallic mineralization (Au-Ag-Cu-Zn ± Mo) associated with several pulses of Cretaceous magmatism. Recent exploration on the Sonora Gulch Project has highlighted the presence of two important mineralized zones: the Nightmusic zone, a mesothermal Au-enriched base metal skarn, and the Amadeus zone, an epithermal Au-Ag system. Four U-Pb age dates determined from each of two feldspar porphyry dykes (ca. 74 Ma), a weakly mineralized quartz porphyry stock (ca. 75 Ma) within the Nightmusic zone and the Au-Ag mineralized Amadeus stock (ca. 75 Ma), demonstrate the widespread occurrence of Late Cretaceous magmatism. The age determinations indicate that mineralization occurring within the Sonora Gulch project area are temporally equivalent to the Casino Cu-Au-Mo deposit, located roughly 40 km to the west-northwest. These new data extend the currently known eastern limit of Late Cretaceous magmatism and associated mineralization.

This data release presents the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) from trenches, channel cuts, test pits, and surface exposures of the Dotson and I and L Zone rare earth element deposits at Bokan Mountain, located in the southern part of Prince of Wales Island, southeastern Alaska. Bokan Mountain was formed by an Early Jurassic peralkaline igneous complex that intruded into lower Paleozoic rocks of the Alexander terrane of southeast Alaska. The pluton and surrounding country rocks host numerous mineral deposits and occurrences, including heavy rare earth element (HREE)-rich pegmatites and felsic dikes, as well as mineral deposits rich in uranium, thorium, HREE, and fluorine. Recent exploration by Ucore Rare Metals Inc. (http://ucore.com/) at Bokan Mountain has focused on the Dotson and I and L Zones, which together form a 2.5-km-long, 50 m-wide zone of thin felsic dikes and pegmatites (each rarely more than 2-m-wide individually) that are enriched in rare earth elements (REE). Ucore Rare Metals has reported an indicated resource of 4.788 million metric tons of ore at 0.602 percent total REE oxides and an inferred resource of 1.050 million metric tons of ore at 0.603 percent total REE oxides, using a cutoff of 0.4 percent total REE oxides; about 40 percent of the total REE oxides in these dikes and pegmatites are the HREE (Ucore Rare Metals, 2020). There is also potential for the production of by-product Nb, Zr, and Ti. This data release provides the analytical results of 42 rock samples collected by the author during a site visit to Bokan Mountain in August 2014. The samples represent a complete transect along the entire length of the combined I and L and Dotson Zones from the margin of the pluton to tidewater in Kendrick Bay. They provide a measure of the REE abundances and their variation throughout the deposit as well as material for detailed isotopic and mineral chemistry studies (Taylor and others, 2016, 2017). The samples were analyzed for 57 major and trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS and ICP-MSREE), and inductively coupled plasma-optical emission spectrometry for zirconium (ICPOES). The samples were also analyzed for major elements using wavelength dispersive x-ray fluorescence spectrometry (WDXRF). This data set is provided for future use in geologic, exploration, and environmental background studies of the Dotson and I and L Zone deposits. References listed here provide geologic context and additional descriptions on the geologic features represented by the rock samples: Barker, J.C., and Van Gosen, B.S., 2012, Alaska's rare earth deposits and resource potential: Mining Engineering, v. 64, no. 1, p. 20-32. Dostal, J., Karl, S.M., Keppie, J.D., Kontak, D.J., Shellnutt, J.G., 2013, Bokan Mountain peralkaline granitic complex, Alexander terrane (southeastern Alaska)-Evidence for Early Jurassic rifting prior to accretion with North America: Canadian Journal of Earth Sciences, v. 50, 678-691. Dostal, Jaroslav, Kontak, D.J., and Karl, S.M., 2014, The Early Jurassic Bokan Mountain peralkaline granitic complex (southeastern Alaska)-Geochemistry, petrogenesis and rare-metal mineralization: Lithos, v. 202-203, p. 395-412. Dostal, Jaroslav, and Shellnutt, J.G., 2016, Origin of peralkaline granites of the Jurassic Bokan Mountain complex (southeastern Alaska) hosting rare metal mineralization: International Geology Review, v. 58, no. 1, p. 1-13. Long, K.R., Van Gosen, B.S., Foley, N.K., and Cordier, David, 2010, The principal rare earth elements deposits of the United States-A summary of domestic deposits and a global perspective: U.S. Geological Survey Scientific Investigations Report 2010-5220, p. 28-34. Available at http://pubs.usgs.gov/sir/2010/5220/. MacKevett, E.M., Jr., 1963, Geology and ore deposits of the Bokan Mountain uranium-thorium area, southeastern

This data release presents the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) from trenches, channel cuts, test pits, and surface exposures of the Dotson and I and L Zone rare earth element deposits at Bokan Mountain, located in the southern part of Prince of Wales Island, southeastern Alaska. Bokan Mountain was formed by an Early Jurassic peralkaline igneous complex that intruded into lower Paleozoic rocks of the Alexander terrane of southeast Alaska. The pluton and surrounding country rocks host numerous mineral deposits and occurrences, including heavy rare earth element (HREE)-rich pegmatites and felsic dikes, as well as mineral deposits rich in uranium, thorium, HREE, and fluorine. Recent exploration by Ucore Rare Metals Inc. (http://ucore.com/) at Bokan Mountain has focused on the Dotson and I and L Zones, which together form a 2.5-km-long, 50 m-wide zone of thin felsic dikes and pegmatites (each rarely more than 2-m-wide individually) that are enriched in rare earth elements (REE). Ucore Rare Metals has reported an indicated resource of 4.788 million metric tons of ore at 0.602 percent total REE oxides and an inferred resource of 1.050 million metric tons of ore at 0.603 percent total REE oxides, using a cutoff of 0.4 percent total REE oxides; about 40 percent of the total REE oxides in these dikes and pegmatites are the HREE (Ucore Rare Metals, 2020). There is also potential for the production of by-product Nb, Zr, and Ti. This data release provides the analytical results of 42 rock samples collected by the author during a site visit to Bokan Mountain in August 2014. The samples represent a complete transect along the entire length of the combined I and L and Dotson Zones from the margin of the pluton to tidewater in Kendrick Bay. They provide a measure of the REE abundances and their variation throughout the deposit as well as material for detailed isotopic and mineral chemistry studies (Taylor and others, 2016, 2017). The samples were analyzed for 57 major and trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS and ICP-MSREE), and inductively coupled plasma-optical emission spectrometry for zirconium (ICPOES). The samples were also analyzed for major elements using wavelength dispersive x-ray fluorescence spectrometry (WDXRF). This data set is provided for future use in geologic, exploration, and environmental background studies of the Dotson and I and L Zone deposits. References listed here provide geologic context and additional descriptions on the geologic features represented by the rock samples: Barker, J.C., and Van Gosen, B.S., 2012, Alaska's rare earth deposits and resource potential: Mining Engineering, v. 64, no. 1, p. 20-32. Dostal, J., Karl, S.M., Keppie, J.D., Kontak, D.J., Shellnutt, J.G., 2013, Bokan Mountain peralkaline granitic complex, Alexander terrane (southeastern Alaska)-Evidence for Early Jurassic rifting prior to accretion with North America: Canadian Journal of Earth Sciences, v. 50, 678-691. Dostal, Jaroslav, Kontak, D.J., and Karl, S.M., 2014, The Early Jurassic Bokan Mountain peralkaline granitic complex (southeastern Alaska)-Geochemistry, petrogenesis and rare-metal mineralization: Lithos, v. 202-203, p. 395-412. Dostal, Jaroslav, and Shellnutt, J.G., 2016, Origin of peralkaline granites of the Jurassic Bokan Mountain complex (southeastern Alaska) hosting rare metal mineralization: International Geology Review, v. 58, no. 1, p. 1-13. Long, K.R., Van Gosen, B.S., Foley, N.K., and Cordier, David, 2010, The principal rare earth elements deposits of the United States-A summary of domestic deposits and a global perspective: U.S. Geological Survey Scientific Investigations Report 2010-5220, p. 28-34. Available at http://pubs.usgs.gov/sir/2010/5220/. MacKevett, E.M., Jr., 1963, Geology and ore deposits of the Bokan Mountain uranium-thorium area, southeastern

This data set compiles the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) at Bokan Mountain, located in the southern part of Prince of Wales Island, southeastern Alaska. Bokan Mountain was formed by an Early Jurassic peralkaline igneous complex that intruded into lower Paleozoic rocks of the Alexander terrane of southeast Alaska. The pluton and surrounding country rocks host numerous mineral deposits and occurrences, including heavy rare earth element (HREE)-rich pegmatites and felsic dikes, as well as mineral deposits rich in uranium, thorium, HREE, and fluorine. The Ross-Adams mine on Bokan Mountain exploited a uranium-thorium deposit intermittently from the late 1950s to 1971, and remains the only uranium producer in Alaska. Recent exploration by Ucore Rare Metals Inc. (http://ucore.com/) at Bokan Mountain has focused on the Dotson and I and L Zones, which together form a 2.5-km-long, 50 m-wide zone of thin felsic dikes and pegmatites (each rarely more than 2-m-wide) that are enriched in rare earth elements (REE). Ucore Rare Metals has reported an inferred resource for the combined zones as 5.275 million metric tons of ore at 0.654 percent total REE oxides, using a cutoff of 0.4 percent total REE oxides; about 40 percent of the total REE oxides in these dikes and pegmatites are the HREE (http://ucore.com/Ucore_43-101.pdf). This data release provides the analytical results of 153 rock hand samples collected by USGS geologists during site visits to Bokan Mountain in 2010, 2011, and field studies during 2014. The samples represent a variety of rock types associated with the Bokan Mountain igneous complex, including mineral deposits, prospects and occurrences, along with examples of unaltered intrusions of the pluton. The samples were analyzed for 55 major and trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS) and also analyzed for major elements using wavelength dispersive x-ray fluorescence spectrometry (WDXRF). This data set is provided for future use in geologic, exploration, and environmental background studies of Bokan Mountain and its mineral deposits.

This data set compiles the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) at Bokan Mountain, located in the southern part of Prince of Wales Island, southeastern Alaska. Bokan Mountain was formed by an Early Jurassic peralkaline igneous complex that intruded into lower Paleozoic rocks of the Alexander terrane of southeast Alaska. The pluton and surrounding country rocks host numerous mineral deposits and occurrences, including heavy rare earth element (HREE)-rich pegmatites and felsic dikes, as well as mineral deposits rich in uranium, thorium, HREE, and fluorine. The Ross-Adams mine on Bokan Mountain exploited a uranium-thorium deposit intermittently from the late 1950s to 1971, and remains the only uranium producer in Alaska. Recent exploration by Ucore Rare Metals Inc. (http://ucore.com/) at Bokan Mountain has focused on the Dotson and I and L Zones, which together form a 2.5-km-long, 50 m-wide zone of thin felsic dikes and pegmatites (each rarely more than 2-m-wide) that are enriched in rare earth elements (REE). Ucore Rare Metals has reported an inferred resource for the combined zones as 5.275 million metric tons of ore at 0.654 percent total REE oxides, using a cutoff of 0.4 percent total REE oxides; about 40 percent of the total REE oxides in these dikes and pegmatites are the HREE (http://ucore.com/Ucore_43-101.pdf). This data release provides the analytical results of 153 rock hand samples collected by USGS geologists during site visits to Bokan Mountain in 2010, 2011, and field studies during 2014. The samples represent a variety of rock types associated with the Bokan Mountain igneous complex, including mineral deposits, prospects and occurrences, along with examples of unaltered intrusions of the pluton. The samples were analyzed for 55 major and trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS) and also analyzed for major elements using wavelength dispersive x-ray fluorescence spectrometry (WDXRF). This data set is provided for future use in geologic, exploration, and environmental background studies of Bokan Mountain and its mineral deposits.

Recent mapping in the ‘Windy McKinley’ terrane of Stevenson Ridge area of western Yukon defined two subdivisions of the terrane, an imbricated ophiolite and a succession of predominantly fine-grained, variably carbonaceous and calcareous clastic rocks extensively intruded by Middle Triassic gabbro. Further work in 2007 has revealed a third subdivision of felsic metavolcanic and carbonaceous clastic rocks, also spatially associated with voluminous gabbro. The two subdivisions of the terrane containing gabbro are reminiscent of the two subdivisions of the Delta district of Alaska, and gabbroic rocks from the two areas are coeval and geochemically similar. If the Stevenson Ridge successions correlate with those of the Alaska Range, the mineral potential of the Stevenson Ridge area would be appropriately increased.