Geology topics

Charles Anderson

Publications and source records attributed to Charles Anderson.

3 recordsLinked to original sources

USGS2017

Influence of precipitation and crop germination on resource selection by mule deer (Odocoileus hemionus) in southwest Colorado

Mule deer ( Odocoileus hemionus ) populations in the western United States provide many benefits to local economies but can also cause considerable damage to agriculture, particularly damage to lucrative crops. Limited information exists to understand resource selection of mule deer in response to annual variation in crop rotation and climatic conditions. We tested the hypothesis that mule deer select certain crops, and in particular sunflower, based on annual climatic variability. Our objective was to use movements, estimates of home range, and resource selection analysis to identify resources selected by mule deer. We used annually-derived crop-specific datasets along with Global Positioning System collars to monitor 14 mule deer in an agricultural area near public lands in southwestern Colorado, USA. We estimated home ranges for two winter seasons that ranged between 7.68 and 9.88 km 2 , and for two summer seasons that ranged between 5.51 and 6.24 km 2 . Mule deer selected areas closer to forest and alfalfa for most periods during 2012, but selected areas closer to sunflower in a majority of periods during 2013. Considerable annual variation in climate patterns and precipitation levels appeared to influence selection by mule deer because of variability in crop rotation and success of germination of specific crops.

Colorado, Utah↗

USGS2015

Conflict minerals from the Democratic Republic of the Congo—Tin processing plants, a critical part of the tin supply chain

Summary The U.S. Geological Survey (USGS) analyzes mineral and metal supply chains to identify and describe major components of material flows from ore extraction, through intermediate forms, to a final product. Supply chain analyses may be used (1) to identify risks to the United States associated with the supply of critical and strategic minerals and metals and (2) to provide greater supply chain transparency so that policymakers have the fact-based information needed to formulate public policy. This fact sheet focuses on the post-mining/pre-consumer-product part of the tin supply chain. The USGS National Minerals Information Center (NMIC) has been asked by governmental and non-governmental organizations to provide information about tantalum, tin, tungsten, and gold (collectively known as “3TG minerals”) processing facilities worldwide in response to U.S. legislation aimed at identifying and removing the supply chain links between the trade in these minerals and civil unrest in the Democratic Republic of the Congo (DRC) and adjacent countries. Post-beneficiation processing plants (generally called smelters and refineries) for 3TG mineral ores and concentrates were identified by company and industry association representatives as being a link in the 3TG mineral supply chain through which these minerals can be traced to their source of origin (mine). The determination of the source of origin is critical to the development of a complete and transparent conflict-free mineral supply chain. Tungsten processing plants were the subject of the first fact sheet in this series published by the USGS NMIC in August 2014. Background information about historical conditions and multinational stakeholders’ voluntary due diligence guidance for minerals from conflict-affected and high-risk areas was presented in the tungsten fact sheet. Tantalum processing plants were the subject of the second fact sheet in this series published by the USGS NMIC in December 2014. This fact sheet, the third in the series about 3TG minerals, focuses on the tin supply chain by listing selected processors that produced tin materials commercially worldwide during 2013–14. It does not provide any information regarding the sources of the material processed in these facilities.

Fact Sheet↗

USGS1950

Alteration and metallization in the Bagdad porphyry copper deposit, Arizona

The porphyritic to seriate-textured quartz monzonite host-rock at Bagdad was changed by hypogene alteration to a granular rock in which the plagioclase became albitic, orthoclase and quartz increased in amount, and hornblende and book-biotite were recrystallized to pale brown leafy biotite. Hypogene sulfides, pyrite and chalcopyrite, were added during the process of alteration, accompanied in part by sericite. Molybdenite is younger than the chalcopyrite. Locally, the host rock was altered to a quartz-orthoclase-sericite facies containing more quartz and orthoclase than is found in the main alteration facies. Chemical analyses indicate that alteration and mineralization of the host rock resulted in loss of iron, lime, and soda, and addition of sulfur, copper, and potash.Supergene changes include the formation of a chalcocite blanket in late Pliocene or early Pleistocene time. Chalcocite replaced chalcopyrite in preference to pyrite. The chalcocite blanket is truncated by the present erosion surface and its distribution can be recognized from the character of the iron oxide left in the leached cavities. Along some of the fractures and faults, supergene clay is present, consisting of kaolinite and a member of the saponite-montmorillonite group.

Arizona↗