Download or read book Silicic Volcanism and Granulite Xenoliths from the Aleutian Islands Alaska written by Jay David Romick and published by . This book was released on 1990 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geologic Reconnaissance of Kiska Island Aleutian Islands Alaska written by Robert Roy Coats and published by . This book was released on 1961 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reconnaissance Geology of Some Western Aleutian Islands Alaska written by Robert Roy Coats and published by . This book was released on 1956 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1990 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geology of the Delarof and Westernmost Andreanof Islands Aleutian Islands Alaska written by George Dewitt Fraser and published by . This book was released on 1959 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Petrology of Three Volcanic Suites Umnak and Bogoslof Islands Aleutian Islands Alaska written by Frank M. Byers and published by . This book was released on 1961 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geologic Reconnaissance of Gareloi Island Aleutian Islands Alaska written by Robert Roy Coats and published by . This book was released on 1959 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bibliography and Index of Geology written by and published by . This book was released on 1990 with total page 1660 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geology of Segula Davidof and Khvostof Islands Alaska written by Willis Howard Nelson and published by . This book was released on 1959 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geology and Geochemistry of Early Tertiary Submarine Volcanic Rocks of the Aleutian Islands and Their Bearing on the Development of the Aleutian Island Arc written by James L. Rubenstone and published by . This book was released on 1984 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geology of Kasatochi Volcano Aleutian Islands Alaska written by Christopher Nye and published by . This book was released on 2017 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Kasatochi volcano is located at the intersection of the flat, shallow Aleutian platform and the Bering slope rise, an area of high biologic productivity. As a result, the island hosts a large sea lion colony and nesting sites for hundreds of thousands of seabirds. A large eruption in 2008 blanketed the island in pyroclastic deposits, covering nesting sites and almost all existing vegetation. A multidisciplinary effort to document recovery of the ecosystem was initiated, and this study of the geology of the island was undertaken as part of that effort." -- Introduction.

Download or read book The Aleutian Islands Their People and Natural History written by Henry Bascom Collins and published by . This book was released on 1945 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contains 3 papers about Aleutian Islands, Alaska. Topics include description and geology of islands, discovery and early history, ethnic relationships of the Aleuts, Aleutian land-bridge theory, ethnology, wildlife, and vegetation.

Download or read book The Petrology of Ultramafic and Mafic Xenoliths from Kanaga Island the Central Aleutians written by Rebecca Ruth Pope and published by . This book was released on 1983 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Petrological Constraints on the Origin of Enclaves from Kasatochi Volcano Aleutian Islands Alaska written by Adrienne Kentner and published by . This book was released on 2013 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Products of the 2008 eruption of Kasatochi volcano in the Aleutian Islands, Alaska, include mafic and ultramafic crystalline intrusive rocks. I analyzed 42 such samples that were collected from Kasatochi in 2012. The mafic enclaves are hornblende gabbros that are texturally and compositionally layered and are composed of plagioclase (An91−93), pargasitic hornblende, clinopyroxene, and accessory magnetite. The ultramafic samples include variable amounts of clinopyroxene and olivine with interstitial pargasitic hornblende and accessory spinel. Modal mineral abundances in the ultramafic enclaves were used to classify the samples as wehrlite, olivine-clinopyroxenite, and clinopyroxenite. Compositions of interstitial hornblende in the pyroxenite samples are the same as those for the gabbro, implying that the ultramafic enclaves resided within the same magma as the cumulate gabbro long enough to begin re-equilibration. The results of both whole-rock X-ray fluorescence and mineral electron microprobe analyses of the pyroxenite and peridotite samples indicate a non-mantle source: clinopyroxene Cr# is less than 25, Ni-in-olivine is less than 1600 ppm, and spinel is Cr# is less than 50. The presence of disequilibriurn textures, such as resorption in clinopyroxene, intimate a prolonged residence time in the host magma. Bulk and mineral compositions for representative mafic and ultramafic samples show that the two sample suites are chemically unrelated and therefore have different igneous origins. The mafic samples display textures and compositions that reflect a cumulate origin related to magma stored below Kasatochi, both of which were brought to the surface during the 2008 eruption. I also interpret the ultramafic enclaves as cumulates, but from a separate, unrelated magmatic source. The ultramafic and mafic enclaves from Kasatochi share mineralogical and compositional similarities with inclusions from neighboring Adak Island, suggesting that similar igneous processes occur at both volcanic centers.

Download or read book Geology of Buldir Island Aleutian Islands Alaska written by Robert Roy Coats and published by . This book was released on 1951 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geology of Buldir Island Aleutian Islands Alaska the geography and geologic history of the island with its flora and the petrographic and chemical character of its volcanic rocks written by Robert Roy Coats and published by . This book was released on 1953 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book LA ICP MS Zircon Geochronology of Granulite Xenoliths from the Geronimo Volcanic Field SE Arizona written by Mikaela Alaine Rader and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lower crustal granulite xenoliths entrained in alkaline basalts from the Geronimo Volcanic Field (GVF), SE Arizona, provide constraints on composition, structure, and age of the lower crust in the southern Basin and Range. The GVF is located in the Mazatzal Province, accreted to the southern margin of Laurentia at ~1.69-1.65 Ga. Previous work conducted in this area provided information on the petrology, geochemistry and geothermometry for the xenolith suite, but age constraints of the xenoliths were limited to Nd model ages, making it difficult to place the evolution of the lower crust in the broader context of the geologic history of the region. This project uses zircon U-Pb geochronology and Hf-isotope analysis to determine the age of formation of GVF lower crust, as well as provide evidence for subsequent tectonic events that impacted its composition. Samples for this suite range in composition from mafic meta-cumulates (plg + cpx ± opx ± ol ± sp) to metadiorites and quartzofeldspathic lithologies (plg + kspar + cpx + ox ± qtz ± opx). GVF xenoliths analyzed for U-Pb geochronology present three distinct zircon age populations at ~1.63-1.65 Ga, ~1.48-1.42 Ga, and ~76-2 Ma, with the majority of young ages concentrated between 35-25 Ma. Zircon U-Pb ages for quartzofeldspathic lithologies present evidence of an event at ~1.65 Ga, suggesting an age of formation consistent with the age of the Mazatzal terrane. However, one quartzofeldspathic zircon core was dated at 2.38 Ga, suggesting the presence of an older component during formation of the Mazatzal crust, possibly originating as cratonic Laurentian sediment. Two quartzofeldspathic xenoliths (MR-GN21-39 and MR-GN21-53) contain zircon cores with discordant U-Pb ages that trend toward ~1.48-1.42 Ga, suggesting modification of the Mazatzal terrane beginning at ~1.48 Ga, the onset of the Picuris Orogeny and widespread 1.48-1.35 Ga plutonism in the southwestern US. These same quartzofeldspathic samples present young ages ranging from ~50-15 Ma, suggesting later alteration of the Proterozoic terrane by Tertiary magmatism associated with Farallon slab subduction. Metadiorites, which were previously inferred to be ~ 1.4 Ga on the basis of whole rock Nd model ages, yielded zircon U-Pb ages ranging from ~76 to 2 Ma, suggesting an origin through thermal resetting of zircons in older Paleoproterozoic crust or addition of new juvenile melts that assimilated Paleoproterozoic crust during magmatic underplating in the Cenozoic. Zircon Hf isotope data from both quartzofeldspathic and metadiorite lithologies are consistent with mantle separation at 2.4 Ga, following an intermediate (176Lu/177Hf = 0.018) crustal isotope evolution path. The existence of positive [epsilon]Hf(t) values in Mesoproterozoic zircon cores of some quartzofeldspathic xenoliths suggest reworking of this older Paleoproterozoic crust sometime between the time of Mazatzal formation and the 1.4 Ga Picuris orogeny and/or the widespread A-type granite event that also occurred across Laurentia at about this time. Eocene to Oligocene age zircons have [epsilon]Hf(t) values that range from -17 to 0, suggesting significant lower crustal modification during Farallon slab subduction.