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US Department of the Interior Bureau of Land Management Gold Bar BLM U.S. Department of the Interior Bureau of Land Management Battle Mountain District Office Gold Bar Exploration Project Resource Report 3 Geology and Minerals DOI-BLM-NV-B010-2018-0038-EA Preparing Office Battle Mountain District Office 50 Bastian Road Battle Mountain, NV 89820 March 2019 Resource Report 3 - Geology and Minerals Table of Contents 3.1 AFFECTED ENVIRONMENT ................................................................................................................ 1 3.1.1 AREA OF ANALYSIS OF DIRECT AND INDIRECT EFFECTS ............................................ 1 3.1.2 DATA SOURCES AND METHODOLOGY ............................................................................ 1 3.1.3 REGULATORY FRAMEWORK ............................................................................................. 1 3.1.4 EXISTING CONDITIONS ....................................................................................................... 2 3.2 ENVIRONMENTAL CONSEQUENCES ................................................................................................. 7 3.2.1 PROPOSED ACTION ............................................................................................................. 8 3.2.1.1 Environmental Consequences ................................................................................ 9 3.2.2 NO ACTION ............................................................................................................................ 9 3.2.3 CUMULATIVE EFFECTS ....................................................................................................... 9 3.3 REFERENCES ...................................................................................................................................... 11 List of Figures Figure 3.1-1 Regional Geologic Map ............................................................................................................ 4 List of Acronyms & Abbreviations ARMPA Approved Resource Management Plan Amendment BLM Bureau of Land Management BMP Best Management Practices BMRR Bureau of Mining Regulation and Reclamation BP Before Present CAA Clean Air Act CEQ Council on Environmental Quality CESA Cumulative Effects Study Area CWA Clean Water Act DOI Department of the Interior EA Environmental Assessment EIS Environmental Impact Statement EPA Environmental Protection Agency EPO Exploration Plan of Operations ER Environmental Report ESA Endangered Species Act FLPMA Federal land Policy Management Act of 1976 FONSI Finding of No Significant Impact MBTA Migratory Bird Treaty Act MLFO Mount Lewis Field Office MMI McEwen Mining Inc. MMPA Mining and Mineral Policy Act of 1970 MSHA Mine Safety and Health Administration NDEP Nevada Department of Environmental Protection NDOW Nevada Department of Wildlife NEPA National Environmental Policy Act of 1969 NOI Notice of Intent NRHP National Register of Historic Places QAP Quality Assurance Plan RC Reverse Circulation RDPC Reclaimed Desired Plant Communities RFFA Reasonably Foreseeable Future Actions RMP Resource Management Plan ROD Record of Decision SHPO State Historic Preservation Officer SPP Stormwater Pollution Prevention TD Total Depth USFWS United States Fish and Wildlife Service UUD Unnecessary or undue degradation RESOURCE REPORT 3 - GEOLOGY AND MINERALS 3.1 AFFECTED ENVIRONMENT 3.1.1 Area of Analysis of Direct and Indirect Effects The direct and indirect effects area of analysis for the Proposed Action is the EPO Area. 3.1.2 Data Sources and Methodology The data sources used to describe the existing environment for geology and minerals for the Proposed Action include the following published reports, maps, and other information: • Geology and Gold Mineralization of the Gold Bar Deposit, Eureka County, Nevada (Broili et al., 1988); • Classification of Carbonate Rocks According to Depositional Texture (Dunham, 1962); • Paleontological Characterization of the Falcon to Gonder 345kV Transmission Project, Nevada (Firby, 1999); • Geology and Mineralization of the Gold Bar District, Southern Roberts Mountains (French et al., 1996); • NI 43-101 Technical Report, Gold Bar Project Feasibility Study (SRK, 2015); • Prefeasibility Geotechnical Pit Slope Evaluation, Gold Bar Project, Eureka County, Nevada (SRK, 2012a); • NI 43-101 Technical Report on Resources and Reserves, Gold Bar Project, Eureka County, Nevada (SRK, 2012b); • NI 43-101 Preliminary Assessment of U.S. Gold Corporation’s Gold Bar Project (Telesto Nevada, Inc., 2010); and • Preliminary Geologic Map of the Roberts Creek Mountain Quadrangle (Murphy et al., 1978). These data sources were reviewed and referenced to describe the existing environment, and the geologic and mineral characteristics of the analysis area. 3.1.3 Regulatory Framework The rights to access, acquire and develop mineral resources on lands administered by the Federal Government are provided under the General Mining Law passed by Congress in 1872. This body of law has been amended numerous times, and its latitude impacted by various subsequent environmental laws, including but not limited to NHPA, Clean Water Act (CWA), CAA, and ESA. Congress additionally directed the BLM to manage minerals development with authorization through 43 CFR 3800 et seq., in particular the impacts, under 43 CFR 3809. Congress affirmed the federal policies for development of mineral resources with passage of the 1970 Mining and Materials Policy Act and the 1980 Materials and Minerals Policy Research and Development Act. Gold Bar Exploration Project 1 Resource Report 3 - Geology 3.1.4 Existing Conditions The Proposed Action is within the Battle Mountain-Eureka Mineral Belt, a 120-mile long northwest trending high angle fault bounded structural setting, containing a number of sediment hosted disseminated gold deposits (Telesto Nevada, Inc., 2010). The EPO Area is located between the Central Nevada Seismic Belt and the Diamond Valley Fault Zone. The nearest earthquake epicenter greater than five on the Richter scale in historic times is located approximately 35 miles southeast of the EPO Area on the east side of the Diamond Range. The EPO Area is situated in a zone of reasonably low seismicity, with a 50-year, 10 percent probability exceedance peak horizontal ground acceleration (g) of approximately 0.09 g (SRK, 2012a). Physiographic and Topographic Setting The EPO Area is in the southern portion of the Roberts Mountains, which trend generally northeast-to- southwest as a triangular to rhomboidal shape, and are approximately 20 miles long and 14 miles wide. The Roberts Mountains are flanked by the Monitor Valley and Simpson Park Mountains to the west, the Kobeh Valley on the south, the Garden Valley and Sulphur Spring Range to the east, and the Denay Valley to the north. The Denay and Garden Valleys drain to the northeast to Pine Valley. The Monitor and Kobeh valleys drain into the Diamond Valley, a closed basin on the east side of the Sulphur Spring Range. Regional Geologic Setting and Regional Structural Development The EPO Area is located within the Great Basin region of the Basin and Range physiographic province and is characterized by a series of generally north-trending mountain ranges separated by broad basins. The Basin and Range physiography has developed from normal faulting that began approximately 17 million years ago and continues to the present (Stewart, 1980). The extensional block faulting uplifted the mountains, which consist of Precambrian- to-Tertiary-age bedrock unit. The basins are filled with thick accumulations of unconsolidated to consolidated sediments derived from erosion of the adjacent mountain ranges. These sediments form alluvial fans that surround the Roberts Mountains and form gradual slopes down to the valley bottoms. The centers of the valleys are dominated by alluvium along the ephemeral drainages. The thickness of these deposits ranges from a thin veneer on pediment slopes to one thousand feet or more near the central portions of the basins. The major geologic units in the Roberts Mountains include Cambrian through Devonian siliciclastic and carbonate sedimentary formations representing two depositional regimes. During the early Paleozoic era, northern Nevada was covered by seas, with deep water siliciclastic deposits towards the western part of the State and shallow water shelf and reef carbonates in the eastern part. Paleozoic sedimentary rocks form the regional basement throughout the area of analysis and have undergone a complex history of sedimentation and deformation. During the Late Devonian and Early Mississippian periods, sedimentary deposition was interrupted, and the Paleozoic sediments were uplifted, folded, and thrusted eastward during the Antler Orogeny (Roberts et al., 1967). The Roberts Mountains thrust is the term generally applied to the thrust that emplaced siliciclastic and volcanic rocks of Cambrian to Ordovician age (Western assemblage) over coeval carbonate rocks (Eastern assemblage). The Roberts Mountain thrust fault moved the Ordovician Vinini Formation of the Western Assemblage eastward over Eastern Assemblage carbonate rocks (Stewart, 1980). In areas of folding and uplift, erosion has opened windows through the Vinini Formation into the underlying Eastern Assemblage rocks. The Eastern assemblage units exposed in the windows are, from oldest to youngest, the upper Cambrian Hamburg Dolomite, Ordovician Eureka Quartzite and Hanson Creek Formation, Silurian Roberts Mountain Formation, Lone Mountain Dolomite, Devonian Nevada Formation, and Devil’s Gate Limestone.
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