Download or read book Geological and Geophysical Studies of Chromite Deposits in the Josephine Peridotite Northwestern California and Southwestern Oregon written by and published by . This book was released on 1984 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Peridotite of Elliott County Kentucky written by Joseph Silas Diller and published by . This book was released on 1887 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deformation of the Josephine Peridotite California and Oregon written by James George Evans and published by . This book was released on 1987 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Corundum and the Peridotites of Western North Carolina written by Joseph Hyde Pratt and published by . This book was released on 1905 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Occurrence and Distribution of Corundum in the United States written by Joseph Hyde Pratt and published by . This book was released on 1901 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reports of the North Carolina Geological and Economic Survey written by North Carolina Geological and Economic Survey and published by . This book was released on 1905 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bulletin Division of Mineral Resources written by North Carolina. Division of Mineral Resources and published by . This book was released on 1896 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book U S Geological Survey Professional Paper written by and published by . This book was released on 1984 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Minerals Yearbook written by and published by . This book was released on 1909 with total page 912 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Isotope Geochemistry of Abyssal Peridotites and Related Rocks written by Jonathan E. Snow and published by . This book was released on 1993 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation studies several aspects of the formation of the Earth's oceanic mantle and crust, using a variety of geologic techniques, principally major elements, radiogenic isotopes and trace elements, but including petrography, mineral chemistry, x-ray diffraction, seafloor geomorphology, and analysis of the tectonics of fracture zones. The first chapter is an introduction to the problems to be addressed in this work. The second chapter examines the composition of basalts erupted near the Atlantis II Fracture Zone on the Southwest Indian Ridge. Trends in major element compositions of those basalts can be related directly to the nearby presence of the fracture zone. The effects of mantle composition and crustal level lateral transport of magma in the rift system can be ruled out by the analysis of isotopes and the geomorphology of the fracture zone floor. This is the best demonstration to date of a transform fault effect on basalt compositions. In trying to quantify putative transform fault effects documented at other fracture zones, no systematic correlation of transform offset age with mantle temperature change can be found, suggesting that mantle composition and lateral transport phenomena play a larger than expected role in the evolution of those areas. The third chapter relates to oceanic mantle rocks as they are altered at or near the Earth's surface. The major elements which make up abyssal peridotites are extensively redistributed by the alteration they have undergone. Mg is shown to be extracted from the peridotites, and a variety of trace elements added. This elemental redistribution is taken as evidence for extensive Mg transport by circulating waters. Since the solubility of Mg-bearing minerals in hydrothermal solutions is quite limited, much lower temperatures and much higher water /rock ratios are required to explain the major element compositions of the peridotites than had previously been assumed. The behavior of the Nd, Sr and Os isotopic systems during seafloor alteration was also studied. The isotope systematics of these rocks strongly support the hypothesis of high water /rock ratios in the formation of serpentinized abyssal peridotites. Nonetheless, Nd and Sr reside in a phase which is resistant to alteration (clinopyroxene) and the concentration of Os is high relative to that of seawater, so that it too appears resistant to alteration. Primary mantle isotopic signatures may be obtained from abyssal peridotites by careful analysis, even of extremely weathered rocks. Radiogenic strontium in excess of what could be introduced by seawater contamination or in situ radiogenic growth in a reasonable period of time was also found. These observations confirm earlier work which had been discredited for many years. The only plausible mechanism for the formation of this "orphan" S7Sr is that it is introduced as part of a sedimentary component which infiltrates the rock during metamorphism and/ or weathering. The 87Sr may be contained by or sorbed onto extremely fine clay particulates, or colloidal suspensions, as opposed to the dissolved ionic Sr which is normally thought of as characterizing the Sr isotopic composition of seawater. The high water/rock ratios required by the bulk isotopic analysis, as well as the pervasive elemental redistribution arguing for extensive near-surface weathering at high water /rock ra.tios strongly support this hypothesis. Given pervasive percolation of water throughout the samples, sufficient radiogenic, sediment-derived strontium may be drawn deep into the crust in the course of its weathering to cause such high B7SrfB6Sr ratios. The fourth chapter deals exclusively with primary mantle isotopic information from abyssal peridotites. This is the first study which has attempted to relate the Os isotopic system in the oceanic mantle to other isotopic systems and to trace elements. It is possible, with some extreme assumptions, to model the range of Os isotopes in the oceanic mantle alone in a standard model of formation of the depleted mantle by extraction of the crust. The additional constraints provided by the study of Nd isotopes in depleted mantle rocks from the oceans show that partial melt extraction and the formation of a depleted reservoir alone are not sufficient to account for the range of both N d and Os isotopes in the Earth's mantle. Possible mechanisms for the decoupling of the Os and Nd isotopic systems include elemental fractionation via the porous flow of basalt through the mantle, mantle metasomatism, recycling of a subducted component in the mantle and core formation. The core extraction model is pursued in some detail. Such core extraction models can account for the distributions and isotopic compositions of compatible and incompatible trace elements in the Earth's mantle, but they are highly non-unique, and thus difficult to test
Download or read book Index to North American Geology Paleontology Petrology and Mineralogy for the Years 1892 1900 Inclusive written by Fred Boughton Weeks and published by . This book was released on 1902 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Encyclop dia Britannica written by Hugh Chisholm and published by . This book was released on 1911 with total page 1056 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geological Survey Professional Paper written by and published by . This book was released on 1966 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Gregory Rift Valley and Neogene recent Volcanoes of Northern Tanzania written by John Barry Dawson and published by Geological Society of London. This book was released on 2008 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure and volcanic activity of the northern Tanzania sector of the Gregory Rift Valley have hitherto been less well described than those in Ethiopia and Kenya. This book focuses on northern Tanzania where, although the volcanic area is smaller than those to the north, there are major features such as Kilimanjaro, the highest mountain on the African continent; Ngorongoro, one of the largest calderas on Earth; and Oldoinyo Lengai, the world's only active carbonatite volcano. Following an account of the discovery and early exploration of the rift valley, there are descriptions of the individual volcanoes. These are set within the context of the regional geology and geophysics of the rift valley, and in relation to the structural evolution of the rift and its associated sedimentary basins which include Olduvai, an important site in the history of human evolution The volume concludes with a discussion of the volcanism as related to the plume-related African Superswell.
Download or read book Report of Investigations written by and published by . This book was released on 1946 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Economic Geology of the Amity Quadrangle Eastern Washington County Pennsylvania written by Frederick Gardner Clapp and published by . This book was released on 1907 with total page 948 pages. Available in PDF, EPUB and Kindle. Book excerpt:
