Benjamin P. Magnin Eric D. Anderson 20240305 Version 1.0 tabular digital data https://www.sciencebase.gov U.S. Geological Survey Additional Information about Originators: Magnin, B.P., http://orcid.org/0000-0001-9951-4404; Anderson, E.D., http://orcid.org/0000-0002-0138-6166 Suggested Citation: Magnin, B.P., and Anderson, E.D., 2023, Magnetic susceptibility and density measurements in the Wet Mountains, Colorado, 2022 to 2023: U.S. Geological Survey data release, https://doi.org/10.5066/P9D3FQWZ https://doi.org/10.5066/P9D3FQWZ Warren C. Day 201909 1.2 publication n/a U.S. Geological Survey Suggested citation Day, W.C., 2019, The Earth Mapping Resources Initiative (Earth MRI)—Mapping the Nation’s critical mineral resources (ver. 1.2, September 2019): U.S. Geological Survey Fact Sheet 2019–3007, 2 p., https://doi.org/10.3133/fs20193007. https://doi.org/10.3133/fs20193007 The U.S. Geological Survey (USGS) collected rock magnetic susceptibility and density measurements to understand the causative sources of airborne magnetic and ground gravity survey anomalies in the Wet Mountains, Colorado. A total of 609 magnetic susceptibility and 86 density measurements were collected from outcrops and hand samples, respectively, from July 2022 to June 2023. These measurements aid the interpretation of newly collected geophysical data to identify concealed Ediacaran-Ordovician alkaline igneous features and potential rare earth element deposits. On average, 16 magnetic susceptibility and 4 density measurements were taken from each outcrop/hand sample to best represent the lithology. Outcrop/sample lithology was derived from field observations and previously published maps noted in the supplemental information section of the metadata file. Measurement locations were recorded using a handheld Global Position System. The data were collected to support the interpretation of airborne magnetic and ground gravity anomaly sources in the Wet Mountains, CO. The data may also be used for scientific studies of magnetic susceptibility. References used to determine geologic map units: Armbrustmacher, T.J., 1984, Alkaline rock complexes in the Wet Mountains area, Custer and Fremont counties, Colorado:U.S. Geological Survey Professional Paper 1269, p.4-5. https://doi.org/10.3133/pp1269 Armbrustmacher, T.J., 1988, Geology and resources of thorium and associated elements in the Wet Mountains area, Fremont and Custer counties, Colorado: U.S. Geological Survey Professional Paper 1049-F, plate 1, scale 1:48,000. https://doi.org/10.3133/pp1049F Brock, M.R., and Singewald, Q.D., 1968, Geologic map of the Mount Tyndall quadrangle, Custer County, Colorado: U.S. Geological Survey Geologic Quadrangle Map GQ-596, scale 1:24,000. https://doi.org/10.3133/gq596 Cullers, R.L., Griffin, T., Bickford, M.E., and Anderson, J.L., 1992, Origin and chemical evolution of the 1360 Ma San Isabel batholith, Wet Mountains, Colorado: A mid-crustal granite of anorogenic affinities: Geological Society of America Bulletin, v. 104, p. 316-328. https://doi.org/10.1130/0016-7606(1992)104%3C0316:OACEOT%3E2.3.CO;2 Dahlem, D.H., 1965, Geologic map and sections of the Lookout Mountain area, Fremont County, Colorado [Ph.D. thesis]: Ann Arbor, University of Michigan, 1:31,250. https://dx.doi.org/10.7302/10090 Scott, G.R., Taylor, R.B., Epis, R.C., and Wobus, R.A., 1978, Geologic map of the Pueblo 1 degree x 2 degrees quadrangle, south-central Colorado: U.S. Geological Survey Miscellaneous Investigations Series Map I-1022, scale 1:250,000. https://doi.org/10.3133/i1022 Sharp, W.N., 1978, Geologic map of the Silver Cliff and Rosita volcanic centers, Custer County, Colorado, U.S. Geological Survey Miscellaneous Investigations Series Map I-1081, scale 1:24,000. https://doi.org/10.3133/i1081 Shawe, D.R. and Parker, R.L., 1967, Mafic-ultramafic layered intrusion at Iron Mountain, Fremont County, Colorado: Contributions to General Geology, Geological Survey Bulletin 1251-A, plate 1, scale 1:62,500. https://doi.org/10.3133/b1251A Siddoway, C.S., Givot, R.M., Bodle, C.D., and Heizler, M.T., 2000, Dynamic versus anorogenic setting for Mesoproterozoic plutonism in the Wet Mountains, Colorado: Does the interpretation depend on level of exposure:? Rocky Mountain Geology, v. 35, no. 1, p. 910-111. https://doi.org/10.2113/35.1.91 Taylor, R.B., 1974, Reconnaissance geologic map of the Deer Peak quadrangle and southern part of the Hardscrabble Mountain quadrangle, Custer and Huerfano Counties, Colorado: U.S. Geological Survey Miscellaneous Investigations Series Map I-870, scale 1:24,000. https://doi.org/10.3133/i870 Taylor, R. B., Scott, G. R., Wobus, R. A., and Epis, R. C., 1975a, Reconnaissance geologic map of the Royal Gorge quadrangle, Fremont and Custer Counties, Colorado: U.S. Geological Survey Miscellaneous Investigations Series Map I-869, scale 1:62,500. https://doi.org/10.3133/i869 Taylor, R.B., Scott, G.R., Wobus, R.A., and Epis, R.C., 1975b, Reconnaissance geologic map of the Cotopaxi 15-minute Quadrangle, Fremont and Custer counties, Colorado: U.S. Geological Survey Miscellaneous Investigations Series Map I-900, scale 1:62,500. https://doi.org/10.3133/i900 20220722 20230609 ground condition Complete None planned -105.5393 -105.1680 38.3743 38.0625 ISO 19115 Topic Category geoscientificInformation None U.S. Geological Survey USGS Earth Mapping Resources Initiative Earth MRI Mineral Resources Program MRP Geology, Geophysics, and Geochemistry Science Center GGGSC USGS Thesaurus magnetic susceptibility magnetic susceptibility analysis bulk density USGS Metadata Identifier USGS:654526d0d34ee4b6e05bfd77 Common geographic areas Colorado USGS Geographic Names Information System (GNIS), https://geonames.usgs.gov Custer County Fremont County None. Please see 'Distribution Info' for details. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Benjamin P. Magnin U.S. Geological Survey, ROCKY MOUNTAIN REGION Student Trainee (Geology) mailing address

Denver Federal Center, Box 25046, Mail Stop 973

Denver CO 80225 US 8122405026 bmagnin@usgs.gov This dataset was funded by the U.S. Geological Survey Mineral Resources Program (MRP) and Earth Mapping Resources Initiative (Earth MRI). Data were collected by the authors. Environment as of Metadata Creation: Microsoft Windows 10 Enterprise Version 22H2 (Build 19045.3570); Microsoft Excel Version 2302 (Build 16130.20846); Metadata Wizard 2.0.7 Benjamin P. Magnin Eric D. Anderson 20230106 dataset https://www.sciencebase.gov U.S. Geological Survey Suggested citation: Magnin, B.P., and Anderson, E.D., 2023, Magnetic susceptibility measurements in the Wet Mountains, Colorado, 2021 to 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P96YTJ5F. https://doi.org/10.5066/p96ytj5f Benjamin P. Magnin Eric D. Anderson 20230106 dataset https://www.sciencebase.gov U.S. Geological Survey Suggested citation: Magnin, B.P. and Anderson, E.D., 2023, Gravity data in the Wet Mountains area, southcentral Colorado, 2021 to 2022: U.S. Geological Survey data release, https://doi.org/10.5066/P9XJ7FMM. https://doi.org/10.5066/p9xj7fmm Benjamin P. Magnin Eric D. Anderson 20240104 dataset https://www.sciencebase.gov U.S. Geological Survey Suggested citation: Magnin, B.P., and Anderson, E.D., 2024, Gravity data in the Wet Mountains area, southcentral Colorado, 2023: U.S. Geological Survey data release, https://doi.org/10.5066/P9KNDYU3. https://doi.org/10.5066/p9kndyu3 Benjamin P. Magnin Yvette D. Kuiper Eric D. Anderson 20230411 publication Tectonics vol. 42, issue 4 n/a American Geophysical Union (AGU) Suggested citation: Magnin, B.P., Kuiper, Y.D., and Anderson, E.D., 2023, Ediacaran‐Ordovician Magmatism and REE Mineralization in the Wet Mountains, Colorado, USA: Implications for Failed Continental Rifting: Tectonics, v. 42, no. 4. https://doi.org/10.1029/2022TC007674. https://doi.org/10.1029/2022TC007674 V. J. S. Grauch Eric D. Anderson Philip J. Brown II April D. Allen Langhans 20230228 dataset https://www.sciencebase.gov U.S. Geological Survey Suggested citation: Grauch, V.J.S., Anderson, E.D., Brown, P.J., and Allen Langhans, A.D., 2023, Airborne magnetic and radiometric survey of the Wet Mountains and surrounding region, Custer and Fremont Counties, south-central Colorado, 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P9PISI0X. https://doi.org/10.5066/p9pisi0x Equipment was monitored for proper function and data have been peer reviewed. Data were reviewed for validity and spatial consistency. Data set is considered complete for the sites measured. Users are advised to read the rest of the metadata record carefully for additional details. Spatial locations were determined using a Garmin Oregon 550 Global Position System (GPS). In general, the GPS unit used recorded sample locations to within 10 feet (3 meters) of the true location. The field locations were verified using a portable geographic information system (GIS). No formal positional accuracy tests were conducted. Magnetic susceptibility: Magnetic susceptibility measurements were collected using a SM-30 magnetic susceptibility meter. At each outcrop, the position and lithology were recorded and a series of 16 magnetic susceptibility measurements that best represented the particular lithology were made and recorded. Magnetic susceptibility measurements, lithology, and geographic coordinates were entered into a spreadsheet (MagSusc_data.csv). Density: Representative samples of lithologic units were collected from rock outcrops. Rock density was determined by the buoyancy method using an electronic scale. The mass of the rock sample was recorded. The rock volume was determined by comparing the mass of a beaker of water with the mass of the beaker of water with sample suspended and fully submerged. The density was then determined by dividing the mass of the rock with the volume of the rock. A series of three to four measurements were made for each location. Resulting measurements, lithology, and location information were entered into a spreadsheet (Density_data.csv). 20230610 Benjamin P. Magnin U.S. Geological Survey, ROCKY MOUNTAIN REGION Student Trainee (Geology) mailing address

Denver Federal Center, Box 25046, Mail Stop 973

Denver CO 80225 US 8122405026 bmagnin@usgs.gov No additional steps. 20230610 Point Entity point 695 0.00001 0.00001 Decimal degrees World Geodetic System 1984 (WGS 84) WGS_1984 6378137 298.257223563 MagSusc_data.csv Comma Separated Value (CSV) file containing data. USGS rock_type Type of rock on which the measurement was made. Producer Defined orthogneiss Metavolcanic gneiss Producer defined paragneiss Metasedimentary gneiss Producer defined carbonatite dike Carbonatite dike Producer defined fine grained gabbro Fine-grained gabbro Producer defined quartz syenite Quartz syenite Producer defined rhyolite Rhyolite Producer defined gneiss Gneiss Producer defined granitic gneiss Granitic gneiss Producer defined mixed metasedimentary and metavolcanic gneiss Interlayered metasedimentary and metavolcanic gneiss. Producer defined unit_name Name of unit on previously published geologic maps. Producer Defined Primary magmatic carbonatite Medium-grained dikes with greater than 50% carbonate minerals and variable amounts of alkali amphiboles, phlogopite, barite, fluorite, apatite, magnetite, and monazite. Producer defined Mafic-ultramafic layered intrusion at Iron Mountain Dark-gray to black, fine- to medium-grained, gabbro, pyroxenite, dunite, and anorthosite. Producer defined Complex at Democrat Creek Light- to medium-gray, fine- to medium-grained syenite stock with small amounts of associated mafic syenite and gabbro. Producer defined Rhyolite of Rosita Volcano White, gray, and red, flow-banded rhyolitic vitrophyres in flows and domes and subordinate ash-flow tuffs. Producer defined Migmatitic gneiss Layered gneisses composed mainly of feldspathic biotite-quartz-plagioclase gneiss with minor amounts of hornblende gneiss, calc-silicate gneiss, and garnetiferous and sillimanitic varieties. Variably migmatitic. Unit interpreted as formed from a metamorphosed sedimentary and volcanic sequence. Producer defined Alaskitic granite gneiss? Outcrop looks similar to the Alaskitic granite gneiss lithology described by Brock and Singewald (1968): Pink to white, fine- to medium-grained, weakly to strongly foliated equigranular granite. Producer defined Hornblende gneiss Non-layered amphibole and amphibole-plagioclase gneiss and some layered hornblende gneiss. Producer defined Not previously mapped or defined Geologic unit has not been previously mapped or defined. Producer defined age Geologic age of rock unit. Producer Defined Paleoproterozoic Paleoproterozoic Producer defined Cambrian-Ordovician Cambrian-Ordovician Producer defined Cambrian Cambrian Producer defined Oligocene Oligocene Producer defined Unknown Not previously dated Producer defined map_reference Geologic map spatially associated with the collected data and used to determine unit name. Full reference contained in the supplemental information section of this metadata file. Producer Defined Geologic map spatially associated with the collected data and used to determine unit name. Full reference contained in the supplemental information section of this metadata file. field_site Field site identifier. Producer Defined Field site identifier. latitude_WGS84 Latitude, in decimal degrees, referenced to the World Geodetic System (WGS84). Producer Defined 38.06251 38.35139 Decimal degree 0.00001 longitude_WGS84 Longitude, in decimal degrees, referenced to the World Geodetic System (WGS84). Producer Defined -105.53933 -105.16798 Decimal degree 0.00001 susceptibility_times_1000_SI Magnetic susceptibility with units of 10^-3 SI. Measurements recorded to three significant figures or to a resolution of 0.001 if low in value. Producer Defined 0.011 271.0 10^-3 SI sample_type Type of sample measured. Producer Defined outcrop Rock outcrop Producer defined Density_data.csv Comma Separated Value (CSV) file containing data. USGS Sample ID Unique identifier for each sample. Producer Defined Unique identifier for each sample. rock_type Type of rock on which the measurement was made. Producer Defined Pyroxenite Pyroxenite Producer defined Gabbro Gabbro Producer defined Anorthosite Anorthosite Producer defined Quartz syenite Quartz syenite Producer defined Foliated granite Foliated granite Producer defined Coarse-grained granite Coarse-grained granite Producer defined Biotite gneiss Biotite gneiss Producer defined Oxidized medium-grained granite Oxidized medium-grained granite Producer defined Biotite, garnet gneiss Biotite, garnet gneiss Producer defined Weakly foliated granite Weakly foliated granite Producer defined unit_name Name of unit on previously published geologic maps. Producer Defined Gabbro Black or greenish-black pyroxene gabbro; diabasic texture; locally grades to pyroxene-rich ultrabasic rock. Producer defined Complex at Democrat Creek Light- to medium-gray, fine- to medium-grained syenite stock with small amounts of associated mafic syenite and gabbro. Producer defined Migmatitic gneiss Layered gneisses composed mainly of feldspathic biotite-quartz-plagioclase gneiss with minor amounts of hornblende gneiss, calc-silicate gneiss, and garnetiferous and sillimanitic varieties. Variably migmatitic. Unit interpreted as formed from a metamorphosed sedimentary and volcanic sequence. Producer defined San Isabel batholith Gray to tan, coarse-grained, porphyritic biotite granite. Locally medium-grained and equigranular. Producer defined Migmatite Interlayered and intergrading biotite-quartz-plagioclase gneiss, sillimanite-biotite-quartz-plagioclase gneiss, granodiorite gneiss, and quartz monzonite gneiss. Producer defined Locke Park intrusion Pink to tan, medium- to coarse-grained, equigranular to slightly porphyritic, massive to moderately foliated biotite-muscovite granite. Producer defined Biotite gneiss Biotite-quartz-plagioclase paragneiss. Typically medium to light gray, medium grained, and strongly foliated; averages 5-10 percent biotite. Producer defined Biotite-hornblende gneiss, migmatitic Metasedimentary units with a geochemical signature indicative of immature sediments (e.g., metapelite, greywacke, arkose, and minor quartzose sediments) and interlayered calc-alkaline basalts. Producer defined age Geologic age of rock. Producer Defined Unknown Not previously dated Producer defined Cambrian Cambrian Producer defined Paleoproterozoic Paleoproterozoic Producer defined Mesoproterozoic Mesoproterozoic Producer defined map_reference Geologic map spatially associated with the collected data and used to determine unit name. Full reference contained in the supplemental information section of this metadata file. Producer Defined Geologic map spatially associated with the collected data and used to determine unit name. Full reference contained in the supplemental information section of this metadata file. latitude_WGS84 Longitude, in decimal degrees, referenced to the World Geodetic System (WGS84). Producer Defined 38.08140 38.37431 Decimal degree 0.00001 longitude_WGS84 Latitude, in decimal degrees, referenced to the World Geodetic System (WGS84). Producer Defined -105.51053 -105.17473 Decimal degree 0.00001 density_g_cc Rock density. Producer Defined 2.41 3.22 grams per cubic centimeter 0.01 sample_type Type of sample measured. Producer Defined hand sample Hand sample collected from an outcrop. Producer defined ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P9D3FQWZ None 20240305 Benjamin P. Magnin U.S. Geological Survey, ROCKY MOUNTAIN REGION Student Trainee (Geology) mailing address

Denver Federal Center, Box 25046, Mail Stop 973

Denver CO 80225 US 8122405026 bmagnin@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998