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Challenge theme 7: Information support for management of border security and environmental protection: Chapter 9 in United States-Mexican Borderlands: Facing tomorrow's challenges through USGS science

Historically, international borders were located far from the major political and economic capitals of their countries and rarely received adequate planning or infrastructure development. Today, as a result of global economics and increased movement of goods between nations, border regions play a much greater role in commerce, tourism, and transportation. For example, Mexico is the second largest destination for United States exports (Woodrow Wilson Center Mexico Institute, 2009). The rapid population and economic growth along the United States–Mexican border, undocumented human border crossings, and the unique natural diversity of resources in the Borderlands present challenges for border security and environmental protection. Assessing risks and implementing sustainable growth policies to protect the environment and quality of life greatly increase in complexity when the issues cross an international border, where social services, environmental regulations, lifestyles, and cultural beliefs are unique for each country. Shared airsheds, water and biological resources, national security issues, and disaster management needs require an integrated binational approach to assess risks and develop binational management strategies.

United States-Mexico Borderlands↗

Flood information for flood-plain planning

Floods are natural and normal phenomena. They are catastrophic simply because man occupies the flood plain, the highwater channel of a river. Man occupies flood plains because it is convenient and profitable to do so, but he must purchase his occupancy at a price-either sustain flood damage, or provide flood-control facilities. Although large sums of money have been, and are being, spent for flood control, flood damage continues to mount. However, neither complete flood control nor abandonment of the flood plain is practicable. Flood plains are a valuable resource and will continue to be occupied, but the nature and degree of occupancy should be compatible with the risk involved and with the degree of protection that is practicable to provide. It is primarily to meet the needs for defining the risk that the flood-inundation maps of the U.S. Geological Survey are prepared.

Circular↗

The Alaska Mineral Resource Assessment Program: Guide to information contained in folio of geologic and mineral resource maps of the Philip Smith Mountains quadrangle, Alaska

The geology and mineral resources of the Philip Smith Mountains quadrangle were virtually unexplored until the investigations for oil began in northern Alaska. Construction of the Trans-Alaskan Pipeline System has now made the quadrangle accessible by road. In 1975 and 1976 a team of geologists, geochemists, and geophysicists investigated the quadrangle in order to assess its mineral resource potential. This report is a guide to the resulting folio of twelve maps that describe the geology, stream sediment geochemistry, aeromagnetic features, Landsat imagery, and mineral resources of the area. The bedrock geology and aeromagnetic surveys show that mineral deposits associated with intrusive rocks are probably absent. However, the geology and geochemical anomalies do indicate the possibility of vein and strata-bound deposits of copper, lead, and zinc in the Paleozoic shale and carbonate rocks in the southern part of the quadrangle and of stratabound deposits of zinc and copper in the Permian and Mesozoic shales along the mountain front. The northwestern part of the quadrangle has a low to moderate potential for oil or gas; Mississippian carbonate rocks are the most likely reservoir. The only minerals produced to date have been construction materials.

Alaska↗

Background information to accompany folio of geologic, mineral resource, geochemical, aeromagnetic, and gravity maps of the Hillsboro and San Lorenzo quadrangles, Sierra and Grant Counties, New Mexico, with sections on geochemistry and geophysics

The Hillsboro and San Lorenzo 15-minute quadrangles of southwestern New Mexico have been mapped at a 1:48,000 scale and selected mineralized areas within these quadrangles have been mapped in greater detail. This area of about 550 mi2 (1,424 km2) is within the southern part of the Black Range and includes much of the Mimbres Mountains and parts of the adjoining Black Range Primitive area. The region is highly mineralized with Laramide (75.1 ? 2.5 m.y.) and middle Tertiary (about 32 to 35 m.y.) intrusions providing the source for much of the base- and precious-metal mineralization. The porphyry copper deposit at Copper Flat is a subvolcanic Laramide quartz monzonite stock that was intruded into a thick section (>2,700 ft or >823 m) of Upper Cretaceous andesite. Numerous gold-bearing veins radiate from the central quartz monzonite stock, and locally offset a radial system of quartz latite dikes. Gold-bearing veins, chiefly along the south and east periphery of the stock, have provided the source for both gold lode and placer deposits. The middle Tertiary rhyolitic plugs, stocks, and dikes have intruded a dominantly carbonate section of Paleozoic sediments and bedding replacement deposits of zinc, lead, and copper are closely associated with tactite in the Carpenter (Swartz) mining district. The rich oxidized silver deposits of the Kingston district are largely fault controlled and a metallizing pluton is not present at the surface outcrop. Some of the silver-bearing base-metal veins in the Kingston district contain rhodochrosite, rhodonite, and alabandite and the highly oxidized parts of these veins have been mined for manganese ore. Very minor amounts of tungsten, as scheelite, occur in thin tactite zones along Tank Canyon, at the Silver Queen claims near Kingston, and at the Silver Tail group of mines along Pierce Canyon.

New Mexico↗

The Alaska Mineral Resource Assessment Program: Background information to accompany folio of geologic and mineral resource maps of the Circle quadrangle, Alaska

The geology, geochemistry, geophysics, and Landsat imagery of the Circle quadrangle were investigated by an interdisciplinary research team for the purpose of assessing the mineral potential of the area. The quadrangle covers approximately 15,765 km 2 in east-central Alaska; most of it is included in the mountainous Yukon-Tanana Upland physiographic division, but the northernmost part is in the low-lying Yukon Flats section. The Circle mining district, in the east-central part of the quadrangle, has been a major producing area of placer gold since its discovery in 1893. For descriptive purposes, the Circle quadrangle is divided into three areas: the northwest Circle quadrangle, the area north of the Tintina fault zone, and the area south of the Tintina fault zone. The Tintina fault zone extends northwesterly through the northern part of the quadrangle. The northwest Circle quadrangle contains mostly folded and faulted, slightly metamorphosed sedimentary rocks that are intruded by Tertiary granitic plutons. In the northern part of the area north of the Tintina fault zone (Little Crazy Mountains and northern east Crazy Mountains), the rocks consist primarily of the gabbro and basalt of the Circle Volcanics and minor associated chert, graywacke, and limestone. Elsewhere in this area (south of the Circle Volcanics and in the western Crazy Mountains), the rocks are mostly slightly metamorphosed Paleozoic sedimentary rocks that have been folded and faulted. Rocks in the largest part of the quadrangle, the area south of the Tintina fault zone, consist largely of pelitic rocks that are regionally metamorphosed to greenschist and amphibolite facies. Felsic plutons, mostly Tertiary in age, occur throughout the area. The metamorphic rocks are separated from sedimentary rocks on the northwest by thrust faulting. The aeromagnetic and gravity data show clear differences between the areas north and south of the Tintina fault zone. The metamorphic terrane to the south has low overall gravity and local gravity lows over exposed granitic plutons. It is hypothesized that magnetic chlorite schist infolded with nonmagnetic quartzite and schist account for east-northeast-trending magnetic highs that approximately parallel the regional strike of the most prominent foliation in the metamorphic rocks. North of the Tintina fault zone, the Circle Volcanics are characterized by high gravity and east-west-trending magnetic highs. The Tintina fault zone has an intense magnetic high near the western margin of the Circle quadrangle overlying the magnetic granodiorite of the Victoria Mountain pluton. A magnetic high near Circle Hot Springs is less intense, but broader, and could reflect a buried magnetic pluton similar to that of the Victoria Mountain pluton. Computer-enhanced Landsat images of the Circle quadrangle show trends and patterns of concentrations of linear features. Features trending northeast-southwest predominate throughout the quadrangle; northwest-southeast-trending linear features are found mostly south of the Tintina fault zone. High concentrations of linear features were not found to correspond to areas of known mineralization in any consistent or significant way that could presently be used in locating areas of mineralization. Geochemical and mineralogical studies of stream sediment and heavy-mineral concentrates from the Circle quadrangle identify areas of anomalous concentrations of metallic elements, including gold, silver, tin, tungsten, lead, antimony, zinc, thorium, uranium, and beryllium. The data delineate areas of known mineral occurrences and areas that may contain undiscovered mineral resources. To date, placer gold has been the only significant metallic mineral resource from the Circle quadrangle, but the general geologic setting, especially the presence of post-orogenic plutons, is similar to that of regions that contain tin greisen deposits, tungsten skarn deposits, lode gold deposits in metasedimentary rocks, and uranium vein deposits. Six areas or tracts were identified in which such deposits might occur, and two more tracts were delineated as possible for the occurrence of shale-hosted Lead-zinc deposits. The discovery of two diamonds in the gravels of Cooked Creek point to the slight possibility of finding placer or lode diamond deposits. Although most of the past and present gold mining has taken place in four areas in the quadrangle, a sedimentary basin near the town of Central was identified as possibly containing buried placer gold deposits or sedimentary uranium deposits.

Alaska↗