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Geochemical analyses of rock samples collected from the Dora Bay peralkaline igneous complex, Prince of Wales Island, southeastern Alaska

July 14, 2021

This data release presents the major and trace element chemistry of rock samples collected by the U.S. Geological Survey (USGS) from surface exposures of the Dora Bay igneous complex (DBIC), located in the southern part of Prince of Wales Island, southeastern Alaska. The DBIC is Early Jurassic in age (Bala and others, 2014) and is U-Th-heavy rare earth element (HREE)-enriched like the Bokan Mountain intrusive complex 30 km to the south (Philpotts and others 1998; Dostal and others, 2011; Taylor and others, 2016; 2017). However, the DBIC is significantly less-well-mineralized and is under-explored due to complicated private land status issues. HREE-enriched eudialyte-bearing pegmatites and felsic dikes have been discovered in numerous places within and along the margins of the pluton and extending up to 1 km into the country rocks as well as molybdenite and iron oxide mineral occurrences at its margins (Barker and Mardock, 1990; Philpotts and others, 1993; Taylor and others, 2014). Uncertainty of global REE supply and the subsequent spike in prices in 2008 resulted in renewed exploration at the DBIC by Avalon in 2010 and Sealaska Native Corporation in 2014-2015 (Buckley and Taylor, 2014). The DBIC was included in recent studies by the USGS Mineral Resources Program as part of an effort to understand the distribution of REE resources in the United States. This data release provides the analytical results of 54 rock samples collected by the authors during a site visit to the DBIC in June-July 2015. The samples represent transects along the major exposed ridgelines and outcrops within the complex. They provide a measure of the REE abundances and their variation throughout the complex as well as material for detailed isotopic and mineral chemistry studies. The samples were analyzed for 60 major and trace elements by inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS)after a sodium fusion digestion and 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 DBIC. References listed here provide geologic context and additional descriptions on the geologic features represented by the rock samples: Bala, S.A., Holm-Denoma, C.S., Neymark, L.A., Taylor, C.D., Pietruszka, A.J., and Driscoll, R.L., 2014, U-Pb zircon ages and mineralogy of the Dora Bay intrusive complex and heavy REE-bearing pegmatite dikes: Geological Society of America Abstracts with Programs, v. 46, no. 6, p. 782, Abstract No. 324-11. Barker, J.C., and Mardock, Cheryl, 1990, Rare-earth element- and yttrium-bearing pegmatite dikes near Dora Bay, southern Prince of Wales Island: U.S. Bureau of Mines Open-File Report 19-90, 41 p. 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. Buckley, Steve, and Taylor, Cliff, 2014, Mineral potential on Sealaska Corporation Lands, southeast Alaska: Alaska Miner's Association Biennial Conference on Alaskan Mining, Anchorage, Nov. 3-7, Abstracts of Papers, p. x. Dostal, J., Kontak, D.J., Hanley, J., and Owen, V. 2011. Geological investigation of rare earth element and uranium deposits of the Bokan Mountain Complex, Prince of Wales Island, Southeastern Alaska. U.S. Geological Survey Mineral Resources External Research Report G09AP00039, p. 122. 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/. Philpotts, J., Taylor, C.D., Evans, J., and Emsbo, P., 1993, Newly discovered molybdenite occurrences at Dora Bay, Prince of Wales Island, southeast Alaska, and preliminary scanning electron microprobe studies, in Bradley, D., and Dusel-Bacon, C., eds., 1992 Geologic Studies in Alaska: U.S. Geological Survey Bulletin 2068, p. 187-196. Philpotts, J.A., Taylor, C.D., Tatsumoto, Mitsunobu, and Belkin, H.E., 1998, Petrogenesis of late-stage granites and Y-REE-Zr-Nb-enriched vein dikes of the Bokan Mountain stock, Prince of Wales Island, southeastern Alaska, U.S. Geological Survey Open File Report, OFR 98-0459, 71 p. Taylor, C.D., Philpotts, J.A., Hedderly-Smith, D.A., and Horton, J.D., 2014, Geology and geochemistry of the Dora Bay peralkaline intrusive complex and associated eudialyte-bearing HREE-enriched dikes, Prince of Wales Island, southeast Alaska: Geological Society of America Abstracts with Programs, v. 46, no. 6, p. 782 Abstract No. 324-10. Taylor, C.D., Aleinikoff, J.N., Holm-Denoma, C.S., Neymark, L.A., Bala, S.A., Pascarelli, S.E., Pillers, R.M., Karl, S.M., Van Gosen, B.S., Morgan, L.E., and Cosca, M.A., 2016, New geochronologic constraints on the formation and hydrothermal enrichment of the Bokan Mountain peralkaline igneous complex and associated HREE deposits, southeastern Alaska, USA: Geological Society of America Abstracts with Programs, v. 48, no. 7, Abstract no. 286288. Taylor, C.D., Lowers, H.A., Adams, D.T., and Robinson, R.J., 2017, Geochemistry and mineralogy of the Dotson Zone HREE deposit in the Bokan Mountain peralkaline igneous complex, southeastern Alaska, USA. Proceedings of the 14th SGA Biennial Meeting, 20-23 August 2017, Quebec City, Canada, p. 1329-1332.