Glass Compositions And Pressures Of Partial Crystallization Of Magmas Erupted Along The Galapagos Spreading Center
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Glass Compositions And Pressures Of Partial Crystallization Of Magmas Erupted Along The Galapagos Spreading Center
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Author : Katherine A. Haines
language : en
Publisher:
Release Date : 2018
Glass Compositions And Pressures Of Partial Crystallization Of Magmas Erupted Along The Galapagos Spreading Center written by Katherine A. Haines and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Galapagos Islands categories.
As part of a larger project to understand mid ocean ridge systematics and the accretion of oceanic crust, this study will focus on the Galapagos Spreading Center (GSC) and the interaction of the Galapagos plume with mid-ocean ridge processes. Glasses data from along the GSC were used to calculate pressures of partial crystallization using the Kelley and Barton method (2008) that can then be related to depths within the Earth. Depending on the range of pressures of crystallization, models of crustal accretion can then be interpreted from the results. Pressure results can also be related to chemistry along the ridge to further understand how pressures can relate to the Galapagos plume, transform faulting and propagating tips. Chemistry shows the Galapagos plume to affect the GSC from 95.5°W and 86.5°W. Calculated pressures range from east to west along the GSC. The western GSC yields an average pressure of 160 MPa which correlates to 5.6 km into the crust. The central GSC, including plume affected ridge, yields an average pressure of 260 MPa. This correlates to a depth of 9.1 km in the crust. The western GSC yields an average pressure of 172 MPa which correlates to 6 km within the crust. Overall, these average pressures are within range of a 10 km thick crust. However, individual glass results yield a maximum pressure of ~820 MPa. This pressure would correspond to depths that extend into the mantle. Higher pressure results can be explained by crustal-magma processes such as assimilation or magmatic processes such as mixing. K2O vs. P2O5 (wt. %) diagrams suggest that there are mantle heterogeneities along the ridge. This paper will discuss and interpret the results of these high pressures and correlate high-pressure results to chemistry as well as geologic location.
An Integrated Petrological And Geochemical Approach To Understanding Magmatism Along The East Pacific Rise
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Author : Christina Louise Zerda
language : en
Publisher:
Release Date : 2016
An Integrated Petrological And Geochemical Approach To Understanding Magmatism Along The East Pacific Rise written by Christina Louise Zerda and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
The 65,000 km long Mid-Ocean Ridge system marks the site where oceanic crust is created by the intrusion and eruption of magma formed by decompression melting in the mantle. Newly formed oceanic lithosphere spreads at rates from ~ 10 to 200 mm yr-1, and there is a direct relationship between spreading rate and the pressure of partial crystallization of magma. The East Pacific Rise (EPR) is a fast-spreading ridge that extends from ~ 55°S into the Gulf of California with ~ 20 axial discontinuities. The segment from 5°N to 14°N contains the Siqueiros and Clipperton transforms as well as 5 overlapping spreading centers. These axial discontinuities have been associated with relatively high pressures of partial crystallization for erupted magmas by some workers, who also suggest that magma crystallization beneath the EPR began in the upper mantle. In order to test this proposal, new pressures of partial crystallization of magmas from the EPR from 5°N to 14°N have been calculated using the method of Kelley & Barton, (2008). Pressures were calculated for 5384 MORB glasses from two different datasets. One dataset is from the online Petrological Database (PetDB) and the other is from an internally-consistent compilation of glass analyses by Gale et al., (2013). No difference in calculated pressures was found for the two datasets, with both yielding an average pressure of ~ 218 MPa. After correcting for the water column and filtering to exclude results for samples that did not form by cotectic crystallization, the final average pressure of the ridge was calculated to be 198 ± 3.26 MPa, which is equivalent to a depth of 6.95 ± 0.115 km. This corresponds to a depth very close to the base of the crust. The average pressures of partial crystallization for the Siqueiros (232 ± 25.4 MPa) and Clipperton (199 ± 21.3 MPa) transforms are virtually identical to those calculated for normal ridge segments. This leads to the conclusion that high pressures do not necessarily correlate with axial discontinuities along this portion of the EPR. About 13% of the samples do yield high pressures (P = 300 MPa) of crystallization. Careful filtration of these results using regression methods to define the MgO contents of glasses lying along the liquid + ol + plag + cpx cotectic led to the removal of some, but not all, high-pressure results. Some of the high-pressure glasses have anomalous chemical compositions (elevated K2O and Al2O3, low CaO) that appears to reflect assimilation of crustal material, but it is important to note that magma-crust interaction does not explain all of the high pressure glasses present along the ridge. High-pressure glasses from 11°47’N, for example, have compositions that provide no evidence for magma-crust interaction. The results for these glasses support the suggestion that crystallization of magmas erupted along the EPR began at sub-crustal depths. It is concluded that detailed petrological and geochemical studies of glasses from selected localities are necessary to better constrain the origin of high pressure glasses.
Essentials Of Igneous And Metamorphic Petrology
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Author : B. Ronald Frost
language : en
Publisher: Cambridge University Press
Release Date : 2014
Essentials Of Igneous And Metamorphic Petrology written by B. Ronald Frost and has been published by Cambridge University Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Nature categories.
Concise introductory textbook on the petrology of igneous and metamorphic rocks for one-semester courses. Topics are organized around the types of rocks to expect in tectonic environments, rather than around rock classifications. Application boxes engage students by showing how petrology connects to wider aspects of geology. Includes end-of-chapter exercises.
Elements Of Physical Oceanography
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Author : John H. Steele
language : en
Publisher: Academic Press
Release Date : 2009-12-16
Elements Of Physical Oceanography written by John H. Steele and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-12-16 with Science categories.
Elements of Physical Oceanography is a derivative of the Encyclopedia of Ocean Sciences, 2nd Edition and serves as an important reference on current physical oceanography knowledge and expertise in one convenient and accessible source. Its selection of articles—all written by experts in their field—focuses on ocean physics, air-sea transfers, waves, mixing, ice, and the processes of transfer of properties such as heat, salinity, momentum and dissolved gases, within and into the ocean. Elements of Physical Oceanography serves as an ideal reference for topical research. References related articles in physical oceanography to facilitate further research Richly illustrated with figures and tables that aid in understanding key concepts Includes an introductory overview and then explores each topic in detail, making it useful to experts and graduate-level researchers Topical arrangement makes it the perfect desk reference
Encyclopedia Of Ocean Sciences
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Author :
language : en
Publisher: Academic Press
Release Date : 2019-04-12
Encyclopedia Of Ocean Sciences written by and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-04-12 with Science categories.
The oceans cover 70% of the Earth’s surface, and are critical components of Earth’s climate system. This new edition of Encyclopedia of Ocean Sciences, Six Volume Set summarizes the breadth of knowledge about them, providing revised, up to date entries as well coverage of new topics in the field. New and expanded sections include microbial ecology, high latitude systems and the cryosphere, climate and climate change, hydrothermal and cold seep systems. The structure of the work provides a modern presentation of the field, reflecting the input and different perspective of chemical, physical and biological oceanography, the specialized area of expertise of each of the three Editors-in-Chief. In this framework maximum attention has been devoted to making this an organic and unified reference. Represents a one-stop. organic information resource on the breadth of ocean science research Reflects the input and different perspective of chemical, physical and biological oceanography, the specialized area of expertise of each of the three Editors-in-Chief New and expanded sections include microbial ecology, high latitude systems and climate change Provides scientifically reliable information at a foundational level, making this work a resource for students as well as active researches
The Pressures Of Partial Crystallization Along The Galapagos Spreading Center
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Author : Katherine A. Haines
language : en
Publisher:
Release Date : 2016
The Pressures Of Partial Crystallization Along The Galapagos Spreading Center written by Katherine A. Haines and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Crystallization categories.
Modern Methods Of Igneous Petrology
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Author : James NICHOLLS
language : en
Publisher: Walter de Gruyter GmbH & Co KG
Release Date : 2018-12-17
Modern Methods Of Igneous Petrology written by James NICHOLLS and has been published by Walter de Gruyter GmbH & Co KG this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-12-17 with Science categories.
Volume 24 of Reviews in Mineralogy attempted to bring together the basic data and fundamental theoretical constraints on magmatic processes with applications to specific problems in igneous petrology. The Mineralogical Society of America (MSA) sponsored the short course on "Modern Methods of Igneous Petrolgy: Understanding Magmatic Processes" at the Cathedral Hill Hotel in San Francisco, California in December 1990. It was organized by the editors, Jim Nicholls and Kelly Russell, and presented by the authors of this volume to about 80 participants in conjunction with the Fall Meeting of the American Geophysical Union.
Petrological Constraints On Magma Plumbing Systems Along Mid Ocean Ridges
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Author : Jameson Lee Scott
language : en
Publisher:
Release Date : 2011
Petrological Constraints On Magma Plumbing Systems Along Mid Ocean Ridges written by Jameson Lee Scott and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Abstract: Plate spreading at the mid-ocean ridges is accompanied by intrusion of dikes and eruption of lava along the ridge axis. It has been suggested that the depth of magma chambers that feed the flows and dikes is related to the heat flux - the higher the heat flux the shallower the magma chamber. To examine this hypothesis, I determined the depths of magma chambers beneath the intermediate spreading Juan de Fuca Ridge (JdF) in the northeast Pacific and the slow spreading Reykjanes Ridge (RR) south of Iceland. Pressures of partial crystallization were determined by comparing the compositions of natural liquids (glasses) with those of experimental liquids in equilibrium with olivine, plagioclase, and clinopyroxene at different pressures and temperatures using the method described by Kelley and Barton (2008). Chemical analyses mid-ocean ridge basalts glasses sampled from along the RR and JdF were used as liquid compositions. Samples with anomalous chemical compositions and samples that yielded pressures associated with unrealistically large uncertainties were filtered out of the database. The calculated pressures for the remaining 519 for the RR and 479 samples for the JdF were used to calculate the depths of partial crystallization and to identify the likely location of magma chambers. The RR results indicate that the pressure of partial crystallization decreases from 102 ± 33 MPa at the Charlie Gibbs Fracture Zone to 21 ± 12 MPa at 56°N, then increases to 367 ± 68 MPa as Iceland is approached. Four magma lenses were identified at depths of 2.5±.8km, 5.2±.8km, 5.9±1km, and 6.7±1. The magma lens at 2.46±.83 km agrees very well with seismically imaged sill at 2.5 km (Peirce et al 2007). The JDF results indicate that the pressure of partial crystallization decreases from 200 to100±50 MPa from the Blanco fracture zone to the north along the Cleft segment of the ridge. Calculated pressures remain approximately constant at 87±.53MPa along ridge segments to the north of the Cleft. Two magma lenses were identified at depths of 4.47±.89km and 4.08±1.5km. Pressures calculated for samples from single lava flows along the Cleft segment described by Stakes et al (2006) allow identification of two magma chambers at depths of 4.91±.77km and 4.33±1.07km which agree well with the depth of 5 to 6 km for a seismically imaged sill (Canales et al 2009). The average depth of partial crystallization of both ridges increase with increasing heat flux. While calculated pressures provide evidence for some crystallization in axial melt lenses, results obtained for some samples from virtually every locality also suggest partial crystallization in the crust beneath these lenses, and therefore the results support the many sill or crystal mush models for accretion of oceanic crust for both ridges. The average difference between pressures calculated with both methods within the uncertainty in the calculation. The Herzberg method returns slightly lower pressures for most samples.
The Role Of Halogens In Terrestrial And Extraterrestrial Geochemical Processes
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Author : Daniel E. Harlov
language : en
Publisher: Springer
Release Date : 2018-01-30
The Role Of Halogens In Terrestrial And Extraterrestrial Geochemical Processes written by Daniel E. Harlov and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-01-30 with Science categories.
The book summarizes the knowledge and experiences concerning the role of halogens during various geochemical processes, such as diagenesis, ore-formation, magma evolution, metasomatism, mineralization, and metamorphism in the crust and mantle of the Earth. It comprises the role of halogens in other terrestrial worlds like volatile-rich asteroids, Mars, and the ice moons of Jupiter and Saturn. Review chapters outline and expand upon the basis of our current understanding regarding how halogens contribute to the geochemical/geophysical evolution and stability of terrestrial worlds overall.
Proceedings Of The Ocean Drilling Program
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Author : Scripps Institution of Oceanography
language : en
Publisher:
Release Date : 1983
Proceedings Of The Ocean Drilling Program written by Scripps Institution of Oceanography and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with Submarine geology categories.