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Gilbertson L.H.,Natural History Museum of Los Angeles County | Fritz R.S.,East Resources Inc.
American Malacological Bulletin | Year: 2012

In the northern Santa Rita Mountains, Pima County, Arizona, there are three named species of the helminthoglyptid landsnail Sonorella Pilsbry, 1900: Sonorella magdalenensis (Stearns, 1890), S. walkeri walkeri Pilsbry and Ferris, 1915, and S. rosemontensis Pilsbry, 1939. Of these taxa, Pilsbry (1939) originally named S. rosemontensis based on shell characters alone. Later, he dissected and described the reproductive organs from a specimen preserved in alcohol that was collected at a location different from the type locality. Subsequently, Walter B. Miller collected two snails, calling them S. rosemontensis, because they were collected at Pilsbry's S. rosemontensis locality. He noted that their male genitalia did not resemble those described by Pilsbry; rather, they closely resembled those of S. w. walkeri. Our examination of shell and reproductive anatomies of snails from the S. rosemontensis type locality near the north end of the Santa Rita Mountains, as well as specimens in the Santa Barbara Museum of Natural History collection lead us to conclude that snails previously referred to as S. rosemontensis are synonymous with S. w. walkeri, and that in his original description of the reproductive anatomy of S. rosemontensis, Pilsbry mistakenly dissected a specimen of S. magdalenensis. . Source


Ballenger J.A.M.,Speedway | Holliday V.T.,University of Arizona | Kowler A.L.,University of Arizona | Reitze W.T.,University of Arizona | And 3 more authors.
Quaternary International | Year: 2011

Whether or not abrupt Younger Dryas climate change affected regional paleoenvironments and late Pleistocene hunter-gatherer populations is an important topic in the archaeology of the American Southwest. This paper reviews multiple, age-resolved proxy evidence to gauge the magnitude and direction of Younger Dryas Chronozone (YDC) environmental changes in different settings and systems. There is no record of YDC pluvial lake highstands in Arizona or New Mexico, but there are impressive records of vegetation, faunal, stable isotope, and geomorphological change coincident with the YDC. These correlate with important adaptive changes in human hunting and land use, as revealed in the analysis of the spatiotemporal distribution of late Pleistocene hunting technologies. Clovis and Folsom projectile point distributions do not support extant models of paleoenvironmental conditions in these interpretations. Significant cultural changes that coincide with the YDC include the Clovis-to-Folsom transition, the demise of mammoth hunting and the development of a highly successful emphasis on bison, increased regionalization, and the abandonment of the northwestern Chihuahuan and the Sonoran deserts by mobile, big-game hunters. © 2011 Elsevier Ltd and INQUA. Source


Ertekin T.,Pennsylvania State University | Harris R.,National Fuel Gas Supply Corporation | Dudenas P.J.,East Resources Inc.
Proceedings - SPE Annual Technical Conference and Exhibition | Year: 2010

The capstone design courses in Petroleum and Natural Gas Engineering program at Penn StateUniversity are structured to provide students with a three- semester capstone experience. This sequence of three courses was started as a new course learning model within the context of ABET 2000 Criteria and was reformatted again during the 2007-08 Academic Year. The design sequence starts with the beginning of the spring semester of the junior year and continues during the subsequent fall and spring semesters of the senior year. These three courses provide students with the opportunity to put all the course material they have taken (and they are taking concurrently) into practice. Students typically work in three to four person teams on the same project during the last three semesters of their college education and team compositions are retained throughout the duration of the design project. The results of each phase of the design project are presented in front of a panel whose members are comprised of faculty members and industry representatives at the conclusion of each of the three semesters. During the capstone design experience students utilize and implement their analytical and numerical skills and their decision making competencies in petroleum engineering applications. Further emphasis is also placed on improving their soft skills such as written and verbal communication proficiency development during the creative process of engineering design. Copyright 2010, Society of Petroleum Engineers. Source


McKechnie C.L.,University of Saskatchewan | Annesley I.R.,University of Saskatchewan | Annesley I.R.,East Resources Inc. | Ansdell K.M.,University of Saskatchewan
Canadian Mineralogist | Year: 2012

The Fraser Lakes area in the Wollaston Domain, in northern Saskatchewan, Canada, is located 25 km from the southeastern edge of the uranium-rich Athabasca Basin; it hosts a number of U- and Th-REE-bearing granitic pegmatites and leucogranites. At Fraser Lakes Zone B, the pegmatites and leucogranites intrude the deformed contact between Paleoproterozoic metasedimentary gneisses of the Wollaston Group and Archean orthogneisses, and have characteristics typical of the Abyssal pegmatite subclass. For two examples of Group-A U- and Th-enriched pegmatite and leucogranite, and two examples of Group-B Th- and LREE-enriched pegmatite and leucogranite samples that have minimal petrographic evidence of later alteration, we analyzed selected minerals by electron microprobe to provide constraints on the age and temperature of intrusion. The Group-A pegmatites contain uraninite with variable CaO and SiO2, indicative of later recrystallization, uranoan thorite spatially associated with complexly zoned zircon (with some intermediate solid-solution between the two minerals), rare coffinite, and titaniferous magnetite and ilmenite where they intrude the Archean orthogneisses. CHIME dating of the most pristine uraninite yielded ages between 1.85 and 1.80 Ga, consistent with crystallization from the pegmatite-forming melt. The Group-B pegmatites contain monazite-(Ce) with significant Th substitution, uranoan thorite, zircon (also showing extensive solid-solution toward thorite), and rare xenotime and pyrochlore. CHIME dating of monazite from the Group-B pegmatites gave older ages of ca. 2.1 to 2.2 Ga, suggesting that they are xenocrysts from the source region of the melt. Biotite dehydration reactions have led to significant development of leucosome in the host pelitic gneisses, and likely resulted in the formation of granitic melt at depth. Source


McKechnie C.L.,University of Saskatchewan | Annesley I.R.,University of Saskatchewan | Annesley I.R.,East Resources Inc. | Ansdell K.M.,University of Saskatchewan
Canadian Mineralogist | Year: 2012

The Fraser Lakes Zone B is a U-Th-REE deposit hosted by granitic pegmatite and leucogranite located in the Wollaston Domain of northern Saskatchewan, Canada, in close proximity to the uranium-rich Athabasca Basin. Here, these magmatic rocks are hosted within Paleoproterozoic metasedimentary gneisses of the Wollaston Group and the underlying Archean orthogneisses. The intrusive bodies at Fraser Lakes Zone B are interpreted to have formed from crustal melts generated by upper-amphibolite- to granulite-facies metamorphism during the ca. 1.8 Ga Trans-Hudson orogeny. Three pelitic gneiss host-rock samples with the least petrographic evidence of later alteration and suitable assemblages for P-T-t constraints were analyzed with an electron microprobe. Mineral assemblages in the pelitic gneisses, combined with chemical zoning in garnet, garnet-biotite and Ti-in-biotite geothermometry, and GBPQ geobarometry, suggest a peak T of about 750 to 780°C and a P of about 6 to 8 kbar, followed by isothermal decompression to a pressure of about 3 kbar. The low-P (retrograde) part of the P-T path is partially constrained by the presence of spinel in some pelitic gneiss samples. These constraints on temperature and pressure are consistent with partial melting, which would have generated significant amounts of melt via biotite-dehydration reactions. Evidence for this is in the form of abundant leucosome in the pelitic gneisses; however, these are generally not connected to the mineralized pegmatites. Instead, melt generated from similar rocks at slightly deeper crustal levels is believed to have crystallized within a structural trap at Fraser Lakes Zone B to form the U-Th-REE-mineralized granitic pegmatites and leucogranites. Source

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