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Judith M. Back

Publications and source records attributed to Judith M. Back.

2 recordsLinked to original sources

Geology for a changing world 2010-2020-Implementing the U.S. Geological Survey science strategy

This report describes a science strategy for the geologic activities of the U.S. Geological Survey (USGS) for the years 2010-2020. It presents six goals with accompanying strategic actions and products that implement the science directions of USGS Circular 1309, 'Facing Tomorrow's Challenges-U.S. Geological Survey Science in the Decade 2007-2017.' These six goals focus on providing the geologic underpinning needed to wisely use our natural resources, understand and mitigate hazards and environmental change, and understand the relationship between humans and the environment. The goals emphasize the critical role of the USGS in providing long-term research, monitoring, and assessments for the Nation and the world. Further, they describe measures that must be undertaken to ensure geologic expertise and knowledge for the future. The natural science issues facing today's world are complex and cut across many scientific disciplines. The Earth is a system in which atmosphere, oceans, land, and life are all connected. Rocks and soils contain the answers to important questions about the origin of energy and mineral resources, the evolution of life, climate change, natural hazards, ecosystem structures and functions, and the movements of nutrients and toxicants. The science of geology has the power to help us understand the processes that link the physical and biological world so that we can model and forecast changes in the system. Ensuring the success of this strategy will require integration of geological knowledge with the other natural sciences and extensive collaboration across USGS science centers and with partners in Federal, State, and local agencies, academia, industry, nongovernmental organizations and, most importantly, the American public. The first four goals of this report describe the scientific issues facing society in the next 10 years and the actions and products needed to respond to these issues. The final two goals focus on the expertise and infrastructure needed to ensure the long-term sustainability of the geological sciences in the USGS. The ultimate goal of USGS science and of the strategy laid out in this document is to contribute to the development of a sustainable society that operates in harmony with the Earth systems that society depends upon. As we begin the second decade of the 21st century, our Nation faces growing challenges in resource availability, climate and environmental change, and natural hazards. Meeting these challenges will require strong collaboration across the natural and social sciences and extensive partnerships with both the public and private sectors. The six goals described in this document represent a mix of scientific focus areas and operational necessities that together provide a comprehensive roadmap for USGS geologic science to effectively contribute to the USGS mission, providing science for a changing world.

Circular↗

Geology of the Barite Hill gold-silver deposit in the southern Carolina slate belt

Barite Hill is a stratiform gold-silver deposit associated with base metal sulfides and barite in greenschist facies rocks. The deposit, southernmost of four recently mined gold deposits in the Carolina slate belt, is located in the Lincolnton-McCormick district of Georgia and South Carolina, which includes several known gold-silver and base metal deposits in a Kuroko-type geological setting along with deposits of kyanite and manganese. Approximately 1,835,000 g of gold was produced mainly from oxidized ores in the Main and Rainsford pits from 1990 until their closing in 1994. Ore is hosted by sericitically altered felsic metavolcanic and metasedimentary rocks of the Late Proterozoic Persimmon Fork Formation. The deposit is stratigraphically below an overturned contact between upper and lower pyroclastic units, which overlie the Lincolnton metarhyolite, an intrusive unit. Gold-silver-rich zones in the Main pit are partly coincident with lenses of siliceous barite rock, but not confined to them, and occur more commonly in pyrite-quartz-altered fragmental rock. The Main pit ore is stratigraphically overlain by a zone of base metal and barite enrichment, which is, in turn, overlain by a talc-tremolite alteration zone locally. Siliceous barite zones are absent in the Rainsford pit, and gold-silver minerals are associated with silicified rocks and chert. The Barite Hill deposit is interpreted to be the result of Kuroko-type, volcanogenic, base metal sulfide mineralization, followed by gold-silver mineralization under epithermal conditions with the following stages of evolution: (1) massive sulfides, barite, and fine-grained siliceous exhalites were deposited during Late Proterozoic to Cambrian submarine volcanism, which was related to plate convergence and subduction in a microcontinental or island-arc setting distant from the North American continental plate; (2) Au-Ag-Te and base and precious metal Te-Se-Bi minerals were deposited either during waning stages of hydrothermal activity in a failed massive sulfide system or in a separate event; (3) sulfides and silica-barite rock recrystallized during regional deformation and greenschist facies metamorphism related to the Middle to Late Ordovician collision of the Carolina terrane with the North American continental plate; (4) quartz, barite, and gold were remobilized and formed veins that cut across cleavage; (5) orebodies were offset along high-angle faults; and (6) during weathering, base metal sulfides and barite dissolved and reprecipitated as supergene euhedral barite crystals that line ferric iron oxide-hydroxide gossans.

Economic Geology↗