Download or read book Integrating Volatile and Trace Element Geochemistry to Evaluate Sources of Volcanism in Oceanic and Continental Rift Environments written by Erica Lynn Maletic and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A close relationship between lithospheric extension and mantle plumes is commonly assumed as the driving force for evolving divergent plate boundaries that manifest as a rift in either oceanic or continental settings. While lithospheric extension is robustly supported by geophysical and geochemical evidence, the role of mantle plumes is often less clear. In fact, in many cases, ongoing integrated geochemical and geophysical work suggest that heterogenous asthenospheric and sub-continental lithospheric mantle components or complex interactions between those two reservoirs (i.e., variable asthenospheric erosion or delamination of lithospheric mantle, especially the SCLM associated with continental rifts) may more robustly account for geological, geochemical, and geophysical observations at many of the prominent rifts, including each of the three rifts explored as part of this thesis. Herein, we integrate trace element and gas geochemistry from three prominent rift zones, including: 1) the Equatorial Mid-Atlantic Ridge (MAR) (5°N to 7°S), 2) the West Antarctic Rift System (WARS), and 3) the East African Rift System (EARS), to evaluate magmatic sources and processes that influence their evolution. Basalts from the Equatorial MAR provide an ideal setting to study the compositional variations in the upper mantle related to mixing and investigate interactions between mantle plumes and ridges without the risks of crustal contamination associated with working in continental settings. MORBs from the northern Equatorial MAR (5°N to 3°S) display trace element, radiogenic isotope, and helium isotopic characteristics indicative of mixing between the depleted mantle (DM) and a HIMU plume while the southern Equatorial MAR (3°S to 7°S) exhibit extremely depleted MORB compositions. The DM basalts have significantly lower (factor of 2) volatile (H2O and Cl)/Pb ratios in samples with the extremely non-radiogenic Pb isotope ratios, but vary by less than ~50% when volatile concentrations are normalized to 204Pb to control for partial melting/fractional crystallization, suggesting the volatile contents fluctuate with the degree of partial melting and source variation. In contrast to the MAR, the WARS and EARS are both continental rifts with ample opportunity for influence by crustal contamination. WARS volcanics in Victoria Land exhibit OIB-like trace element compositions with dominantly MORB-like gas signatures (e.g., La/Lu up to 155; 3He/4He ~7RA). Elevated CO2/3He cannot be accounted for strictly by the influences of magmatic degassing, indicating an addition of CO2 from the more alkaline source in the magmatic mixture. Based on the positive correlations between CO2 and several trace element ratios (e.g., Zr/Hf, Rb/Sr, Th/U), we suggest that subduction-related alteration of the mantle induced metasomatism of the SCLM across the region and eventually led to the formation of alkaline-rich volcanics, contrary to previous suggestions of a prolonged HIMU (high 238U/204Pb) plume in the region. Mantle upwelling in this region entrained magma bodies with noble gases derived from the uprising asthenosphere, which can be characterized by higher 3He/4He than typical subduction, SCLM, or HIMU sources. Volcanics in the Virunga Volcanic Province in the EARS (specifically at Mount Nyiragongo and Mount Nyamuragira) exhibit highly alkaline, silica-undersaturated lavas with even more extreme enrichments of incompatible elements (e.g., high field strength elements) than the WARS. Although VVP volcanics consistently display these atypical, but starkly similar compositions, we note significant and corresponding changes in both helium isotopes and trace elements even over the course of a few years in the region. To a first order, volcanics from the VVP region are consistent with WARS volcanism, and we envision a similar conceptual model for the evolution of the SCLM and associated volcanics in this region. We suggest that subduction-related alteration of the mantle during the Proterozoic accretion of the Tanzania Craton induced metasomatic enrichment of incompatible elements into the SCLM across the region and formed the basis for the formation of alkaline-rich volcanics. Next, we hypothesize that following the cessation of subduction during the Proterozoic, asthenospheric upwelling, and lithospheric delamination led to partial melting of highly devolatilized and incompatible-rich SCLM to generate the volcanic products we observe today. With this conceptual model in mind, we envision that the helium isotopic values observed in the current study area result from the influence of dominantly asthenospheric mantle interacting with and generating variable degrees of partial melts of the SCLM instead of a HIMU (high 238U/204Pb) plume in the region.
Download or read book Petrology and Geochemistry of Continental Rifts written by E.R. Neumann and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the NATO Advanced Study Institute, Oslo, Norway, July 27-August 5, 1977
Download or read book Isotopic Geochemical and Geochronological Constraints on the Origin and Evolution of Cenozoic Volcanism Baikal Rift Zone Siberia written by Nancy Ruth Harris and published by . This book was released on 1998 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Volcanism in Antarctica 200 Million Years of Subduction Rifting and Continental Break up written by J.L. Smellie and published by Geological Society of London. This book was released on 2021-06-09 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt: This memoir is the first to review all of Antarctica’s volcanism between 200 million years ago and the Present. The region is still volcanically active. The volume is an amalgamation of in-depth syntheses, which are presented within distinctly different tectonic settings. Each is described in terms of (1) the volcanology and eruptive palaeoenvironments; (2) petrology and origin of magma; and (3) active volcanism, including tephrochronology. Important volcanic episodes include: astonishingly voluminous mafic and felsic volcanic deposits associated with the Jurassic break-up of Gondwana; the construction and progressive demise of a major Jurassic to Present continental arc, including back-arc alkaline basalts and volcanism in a young ensialic marginal basin; Miocene to Pleistocene mafic volcanism associated with post-subduction slab-window formation; numerous Neogene alkaline volcanoes, including the massive Erebus volcano and its persistent phonolitic lava lake, that are widely distributed within and adjacent to one of the world’s major zones of lithospheric extension (the West Antarctic Rift System); and very young ultrapotassic volcanism erupted subglacially and forming a world-wide type example (Gaussberg).
Download or read book Minerals Inclusions And Volcanic Processes written by Keith D. Putirka and published by Walter de Gruyter GmbH & Co KG. This book was released on 2018-12-17 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 69 of Reviews in Mineralogy and Geochemistry covers the fundamental issues of volcanology: At what depths are eruptions triggered, and over what time scales? Where and why do magmas coalesce before ascent? If magmas stagnate for thousands of years, what forces are responsible for initiating final ascent, or the degassing processes that accelerate upward motion? To the extent that we can answer these questions, we move towards formulating tests of mechanistic models of volcanic eruptions (e.g., Wilson, 1980; Slezin, 2003; Scandone et al., 2007), and hypotheses of the tectonic controls on magma transport (e.g., ten Brink and Brocher, 1987; Takada, 1994; Putirka and Busby, 2007). Our goal, in part, is to review how minerals can be used to understand volcanic systems and the processes that shape them; we also hope that this work will spur new and integrated studies of volcanic systems.
Download or read book Trace Element Geochemistry of Volcanic Rocks written by D. A. Wyman and published by . This book was released on 1996 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geochronology Geochemistry and Isotopic Compositions of the Volcanic Rocks from Oceanic Hawaii and Continental Eifel Intra plate Environments written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Eifel volcanism is part of the Central European Volcanic Province (CEVP) and is located in the Rhenish Massif, close to the Rhine and Leine Grabens. The Quaternary Eifel volcanism appears to be related to a mantle plume activity. However, the causes of the Tertiary Hocheifel volcanism remain debated. We present geochronological, geochemical and isotope data to assess the geotectonic settings of the Tertiary Eifel volcanism. Based on 40Ar/39Ar dating, we were able to identify two periods in the Hocheifel activity: from 43.6 to 39.0 Ma and from 37.5 to 35.0 Ma. We also show that the pre-rifting volcanism in the northernmost Upper Rhine Graben (59 to 47 Ma) closely precede the Hocheifel volcanic activity. In addition, the volcanism propagates from south to north within the older phase of the Hocheifel activity. At the time of Hocheifel volcanism, the tectonic activity in the Hocheifel was controlled by stress field conditions identical to those of the Upper Rhine Graben. Therefore, magma generation in the Hocheifel appears to be caused by decompression due to Middle to Late Eocene extension. Our geochemical data indicate that the Hocheifel magmas were produced by partial melting of a garnet peridotite at 75-90 km depth. We also show that crustal contamination is minor although the magmas erupted through a relatively thick continental lithosphere. Sr, Nd and Pb isotopic compositions suggest that the source of the Hocheifel magmas is a mixing between depleted FOZO or HIMU-like material and enriched EM2-like material. The Tertiary Hocheifel and the Quaternary Eifel lavas appear to have a common enriched end-member. However, the other sources are likely to be distinct. In addition, the Hocheifel lavas share a depleted component with the other Tertiary CEVP lavas. Although the Tertiary Hocheifel and the Quaternary Eifel lavas appear to originate from different sources, the potential involvement of a FOZO-like component would indicate the contribution of deep mantle mate.
Download or read book Magma Redox Geochemistry written by Roberto Moretti and published by John Wiley & Sons. This book was released on 2021-09-14 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores the many facets of redox exchanges that drive magma's behavior and evolution, from the origin of the Earth until today The redox state is one of the master variables behind the Earth's forming processes, which at depth concern magma as the major transport agent. Understanding redox exchanges in magmas is pivotal for reconstructing the history and compositional make-up of our planet, for exploring its mineral resources, and for monitoring and forecasting volcanic activity. Magma Redox Geochemistry describes the multiple facets of redox reactions in the magmatic realm and presents experimental results, theoretical approaches, and unconventional and novel techniques. Volume highlights include: Redox state and oxygen fugacity: so close, so far Redox processes from Earth’s accretion to global geodynamics Redox evolution from the magma source to volcanic emissions Redox characterization of elements and their isotopes The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Download or read book Volcanoes and the Environment written by Joan Marti and published by Cambridge University Press. This book was released on 2008-01-21 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volcanoes and the Environment is a comprehensive and accessible text incorporating contributions from some of the world's authorities in volcanology. This book is an indispensable guide for those interested in how volcanism affects our planet's environment. It spans a wide variety of topics from geology to climatology and ecology; it also considers the economic and social impacts of volcanic activity on humans. Topics covered include how volcanoes shape the environment, their effect on the geological cycle, atmosphere and climate, impacts on health of living on active volcanoes, volcanism and early life, effects of eruptions on plant and animal life, large eruptions and mass extinctions, and the impact of volcanic disasters on the economy. This book is intended for students and researchers interested in environmental change from the fields of earth and environmental science, geography, ecology and social science. It will also interest policy makers and professionals working on natural hazards.
Download or read book Volatile Mobility of Trace Metals in Volcanic Systems written by Matthew W. Loewen and published by . This book was released on 2014 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semi-volatile trace metals like Li, Cu, Mo, Sn, In, and Pb have the potential to track mobility of a volatile phase in volcanic systems. In this dissertation four studies are presented that either directly investigate or are motivated by observations of trace metal behavior in volcanic systems. A common tool for trace element determination in solid materials is laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Although this technique has the potential to measure concentrations of many elements to “1 ppm, it also has the potential to fractionate elements of different volatility resulting in increased analytical uncertainty. Potential sources of fractionation in two different laser ablation systems are characterized, including a previously unrecognized source of fractionation related to differential carrier gas flow at the site of ablation. Glass and melt inclusions from the 1959 eruption of Kilauea Iki record little evidence for volatile behavior of metals, but do record variations related to mixing of distinct batches of magma. Variations in concentrations of metals like Cu, Zn, and Mo can be explained with olivine fractionation. Only Sn variations appear to be compatible with volatile mobility. Lithophile element variations in both glass and melt inclusions require that the Kilauea Iki magma was a mixture of melts generated from different mantle sources by variable degrees of melting. Amphibole phenocrysts from Mt. Pinatubo, Mt. Hood, Mt. St. Helens, and Shiveluch Volcano record a variety of trace element signatures related to the sources and fractionation processes acting in each of these systems. Variations in Li and Cu in amphiboles are decoupled from any other trace element but positively correlate with each other. Their behavior appears to be consistent with mobility in volatile-rich fluids followed by rapid equilibration with amphibole phenocrysts. New 40Ar-39Ar incremental heating age determinations and whole rock major and trace element analyses from the Curaçao Lava Formation and the Dumisseau Formation have provided a revision of the timing and geochemical character of the Caribbean Large Igneous Province. These data provide evidence for almost 30 million years of volcanic history beginning around 94-60 Ma with mantle plume-like geochemical character. To reconcile the duration of volcanism and the observed geochemical signature with models of mantle plume impingement, a new model for development of the Caribbean Large Igneous Province is proposed that calls on nearby subduction zones to induce asthenospheric flow in the mantle that allows for continuous tapping of plume-influenced mantle for a 30 million year period.
Download or read book Late Cenozoic Volcanism in the Rio Grande Rift written by Susan Williams and published by . This book was released on 1984 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Secular and Recent Trends in the Geochemistry of the R union Hotspot and Other Global Hotspots written by Bradley Peters and published by . This book was released on 2016 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: The origins of volcanic activity at intraplate "hotspot" localities cannot be easily explained by fundamental principles of plate tectonics. Decades of geochemical and geophysical research have produced controversial hypotheses that attempt to explain the physical mechanism of magma generation and the origin of the magmas in the deep Earth. The mantle plume hypothesis conjectures that hotspot volcanism results from upwelling of buoyant mantle material from the deep Earth, which may carry recycled crust and lithosphere that resided on Earth's surface billions of years ago. One requirement of the xviii plume hypothesis is that initial, intense stages of hotspot volcanism, which exist only in the geologic record, are genetically linked to later, waning stages of volcanism observed on Earth today. Physiographic evidence exists in several global localities, including the Réunion hotspot, that appears to link large igneous province volcanism to oceanic volcanism, however geochemical evidence linking the two is tenuous. Here, I demonstrate that certain trace element signatures of global hotspots are unlikely to reflect their mantle source in the same way as isotope systems. Next, I show that igneous rocks on Réunion possess a unique geochemical and isotopic signature that make them distinct from igneous rocks from other global hotspots. Finally, I interrogate the composition of the Deccan Traps mantle source in two ways. First, I use early-formed mineral phases to evaluate the presence of recycled material in the Deccan Traps mantle source. Second, I use lava compositions to re-construct a lithospheric and crustal assimilation history for Deccan Traps parental magmas and attempt to relate the composition of this parental magma to that of Réunion. Considering all chapters together, I show that these two volcanic provinces likely share a mantle source with a common composition, and that this source contains a small amount of recycled material. In addition, I provide new evidence that the Réunion mantle source was formed early in Earth's history and remained isolated from other mantle domains for long periods of geologic time.
Download or read book Tectonic magmatic Controls on Volcanism Rifting and Volatile Release written by James D. Muirhead and published by . This book was released on 2016 with total page 738 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation examines the interplay between tectonic and magmatic processes that influence the nature of volcanically active regions. In particular, I address how faulting, fluid transport, and magma intrusion interact in a variety of settings, including continental rifts, large igneous provinces (LIPs), and monogenetic volcanic fields. In the East African Rift (EAR), I combine structural measurements and field observations with geochronology, geochemistry, and seismicity data to investigate how continental breakup initiates and evolves. Analyses of volcanic cone lineaments illustrate variations in the geometries and distributions of dike intrusions along the rift. In early stage basins (10 Ma), dikes begin to accommodate extension along the entire length of the basin. Measurements of diffuse gas flux in the EAR demonstrate that significant volumes of magmatic CO2 (>4 Mt yr−1) are rising along faults from upper mantle/lower crustal magma bodies. Over the entire EAR, this tectonic degassing (~71+/-33 Mt yr−1) contributes significantly to Earth's natural CO2 budget. Moreover, the release of magmatic volatiles assists strain localization and the development of new rift segmentation within existing half-graben depressions. Newly developing segments become kinematically linked with existing rift segments through the reactivation of rift-oblique basement fabrics. Resulting transverse faults postdate rift-parallel fault systems, indicating that preexisting weaknesses play a critical role at all stages of rift development. A regional synthesis of sill-fed dikes of the Ferrar LIP, Antarctica, and field and remote-sensing analysis of the Hopi Buttes volcanic field, Arizona, highlights the role of interconnected dike-sill systems in feeding eruptions. Measurements reveal a previously unrecognized feeder system to LIP eruptions----analogous to a "cracked lid" atop a sill network----that may be the archetypal model for LIPs that intrude sedimentary basins undergoing negligible regional extension. At Hopi Buttes, several characteristic shallow feeder systems are identified: (1) dike-dominated, (2) sill-dominated, and (3) interconnected dike-sill networks. Dike-fed eruptions are common, but sills also modulate the flow of magma toward and away from eruptive conduits, providing a novel mechanism for lateral vent migration and changes in magma-water ratios that lead to explosive volcanism.
Download or read book The Petrology Geochemistry and Geochronology of Hotspot Seamounts in the North Pacific and Arc backarc Volcanism on the Northern Antarctic Peninsula written by Randall Arthur Keller and published by . This book was released on 1996 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volcanic rocks from hotspots and island arcs/backarcs typically have enriched trace element and isotopic compositions that contain a contribution from subducted oceanic crust. Isotopic and trace element data suggest that the enriched components in hotspot volcanism are ancient subducted sediment and crust, and the enriched components in arc/backarc volcanism are hydrous fluids and melts from the subducting slab. This thesis examines the origins of these enriched components, and how they change in time and space. The Hawaiian-Emperor seamount chain records over 81 million years of volcanism from the Hawaiian hotspot. Seamounts at the old (northern) end of the chain have isotopic compositions more depleted then anything previously reported from the Hawaiian hotspot. Detroit seamount (81 Ma) has the most depleted composition, and was created while an active spreading ridge was close to the hotspot. Proximity to a spreading ridge must have caused the hotspot to entrain and melt more of the depleted upper mantle. The Patton-Murray seamount platform, at the old end of the Cobb hotspot track in the Gulf of Alaska, was volcanically active at 33 Ma, 27 Ma, and 17 Ma. The 33 Ma tholeiitic phase and 27 Ma alkalic phase are related to passage over the hotspot. The 17 Ma phase erupted too late to be directly related to the hotspot, but may have been caused by minor extension along a zone of weakness originally created by passage over the hotspot. On the northern Antarctic Peninsula, volcanism occurred above a subducting slab up to 360 km from the South Shetland Trench. Volcanism on the South Shetland Arc has enriched trace element and isotopic compositions that can be modeled by mixing of subducted sediments and depleted mantle. Backarc basin volcanism in Bransfield Strait contains less of the subducted component, and the most depleted samples are distinguishable from MORB only by their slightly elevated Cs and Pb concentrations. Extreme-backarc volcanism on James Ross Island (360 km from the trench) shows no evidence for the subducted component in its trace element compositions, but its Pb isotopic ratios are affected by Pb from subducted sediment.
Download or read book The Geochemistry and Geophysics of the Antarctic Mantle written by A.P. Martin and published by Geological Society of London. This book was released on 2023-02-14 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Memoir is the first dedicated to the Antarctic mantle. It is a cross-disciplinary reference work combining geochemistry and geophysics to characterize Antarctic mantle properties. Through observations and modelling the mantle structures, compositions and dynamics are characterized at regional and continental scales by subject experts. The Memoir reviews all known occurrences of sub-continental mantle xenoliths in igneous rocks. These studies are presented by region as southern or northern Victoria Land, Marie Byrd Land, the Antarctic Peninsula, East Antarctica and the sub-Antarctic Islands. Sub-oceanic mantle in tectonically emplaced and abyssal settings is also considered where known. This is complemented by a continental-scale mantle xenolith overview, mantle characteristics from igneous rocks and a quantitative mantle fabric study. State-of-the-art, continental-scale geophysical overviews of the Antarctic mantle are presented by discipline as seismology, gravity and magnetics, magnetotellurics, rheology, glacial isostatic adjustment, mantle convection and palaeotopography. This Memoir will be the reference for all researchers interested in the Antarctic mantle and its role in dynamics that shape the Antarctic surface and ice sheets.
Download or read book Volcanic Geothermal and Ore forming Fluids written by Stuart Frank Simmons and published by . This book was released on 2003 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Timing Extent and Sources of Marine Volcanism Through U series Disequilibrium written by Kenneth Howard Rubin and published by . This book was released on 1991 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
