Unconventional Isotopes and Approaches
... chondrites is also statistically significant and could also not result from equilibrium fractionation during core formation. It is possible, however, that some as yet unrecognized form of kinetic fractionation could account for the difference; if so that could provide clues to the details of the cor ...
... chondrites is also statistically significant and could also not result from equilibrium fractionation during core formation. It is possible, however, that some as yet unrecognized form of kinetic fractionation could account for the difference; if so that could provide clues to the details of the cor ...
Global geochemical variation of mid-ocean ridge basalts - UiO
... 1.1. A brief introduction to MORB and mantle geochemistry The mid ocean ridges (MORs) are the Earth’s longest mountain chain and are present at all divergent plate boundaries. At the MORs the lithosphere that gets recycled into the mantle at the subduction zones, their plate tectonical counterparts, ...
... 1.1. A brief introduction to MORB and mantle geochemistry The mid ocean ridges (MORs) are the Earth’s longest mountain chain and are present at all divergent plate boundaries. At the MORs the lithosphere that gets recycled into the mantle at the subduction zones, their plate tectonical counterparts, ...
Are the Earth and the Moon compositionally alike? Inferences on
... crust. However, enough potassium and uranium must be retained in the deep interior to provide the typical values of 500 ppm potassium and 200 ppb uranium in mare basalts, derived later by partial melting. In addition, much of the potassium and uranium in the Moon ends up being concentrated in the fi ...
... crust. However, enough potassium and uranium must be retained in the deep interior to provide the typical values of 500 ppm potassium and 200 ppb uranium in mare basalts, derived later by partial melting. In addition, much of the potassium and uranium in the Moon ends up being concentrated in the fi ...
Chapter 2
... collision. Previously existing geologic structures and differences in depositional history along the system produce a variety of features that are characteristic of large-scale continent/continent convergence and whose recognition may be useful in the study of other similar systems. Western North Am ...
... collision. Previously existing geologic structures and differences in depositional history along the system produce a variety of features that are characteristic of large-scale continent/continent convergence and whose recognition may be useful in the study of other similar systems. Western North Am ...
Types of Metamorphism
... - where?: Localized at interaction of hot, largely aqueous fluids (from igneous source) with country rocks. - Similar to regional ocean-floor metamorphism - the aqueous hydrothermal fluids usually transported via fractures and shear zones at some distance either near or far from their source - The y ...
... - where?: Localized at interaction of hot, largely aqueous fluids (from igneous source) with country rocks. - Similar to regional ocean-floor metamorphism - the aqueous hydrothermal fluids usually transported via fractures and shear zones at some distance either near or far from their source - The y ...
Metamorphic reworking of a high pressure–low temperature
... of ocean basins as part of the Wilson Cycle (Wilson, 1960). Most sutures were assumed to be perpendicular to convergent directions since major dip slip motion is required to form HP rocks. However, many modern compressional terrane boundaries are not perpendicular to convergent directions, but obliq ...
... of ocean basins as part of the Wilson Cycle (Wilson, 1960). Most sutures were assumed to be perpendicular to convergent directions since major dip slip motion is required to form HP rocks. However, many modern compressional terrane boundaries are not perpendicular to convergent directions, but obliq ...
- BIROn - Birkbeck Institutional Research Online
... have experienced tectono-thermal events within the last 300-400 Myr (e.g. the Variscan belt of Europe); these typically have higher heat flow and thinner lithosphere than the surrounding cratons (e.g. Baltic Shield) (Prodehl et al, 1992). A number are located on uplifted basement massifs (e.g. Massi ...
... have experienced tectono-thermal events within the last 300-400 Myr (e.g. the Variscan belt of Europe); these typically have higher heat flow and thinner lithosphere than the surrounding cratons (e.g. Baltic Shield) (Prodehl et al, 1992). A number are located on uplifted basement massifs (e.g. Massi ...
Igneous Geology - Illinois Wesleyan University
... pressure decreases, like most materials. A mafic magma gets further above its melting range as it ascends, so mafic magmas usually erupt, at temperatures well above melting. • Granites have a PT melting curve that causes them to freeze as pressure decreases, like water. As a felsic melt ascends, it ...
... pressure decreases, like most materials. A mafic magma gets further above its melting range as it ascends, so mafic magmas usually erupt, at temperatures well above melting. • Granites have a PT melting curve that causes them to freeze as pressure decreases, like water. As a felsic melt ascends, it ...
Chiarenzelli, J., Regan, S., Peck, W., Selleck, B., Cousens, B., Baird, G. and Shrady, C. (2010)
... Lowlands, it is proposed the ARS formed as a consequence of subduction related to closure of a backarc basin that once extended between the Frontenac terrane and the Southern Adirondacks. INTRODUCTION The Mesoproterozoic Grenville Province is a portion of one of the Earth’s major orogenic belts that ...
... Lowlands, it is proposed the ARS formed as a consequence of subduction related to closure of a backarc basin that once extended between the Frontenac terrane and the Southern Adirondacks. INTRODUCTION The Mesoproterozoic Grenville Province is a portion of one of the Earth’s major orogenic belts that ...
FOSI BeritaSedimentologi BS 23 March2012
... and Middle Triassic so was uplifted and eroded supplying significant volumes of Triassic sediment. The Neogene tectonic model used here follows that of Hall (2002), which shows old oceanic crust in the Banda Sea consumed by subduction rollback from 10 Ma to the Present. Hall’s (2002) model shows ove ...
... and Middle Triassic so was uplifted and eroded supplying significant volumes of Triassic sediment. The Neogene tectonic model used here follows that of Hall (2002), which shows old oceanic crust in the Banda Sea consumed by subduction rollback from 10 Ma to the Present. Hall’s (2002) model shows ove ...
The Seismic Structure of Island Arc Crust
... forearc, resulting in the latter case in the two magma sources, associated with subducting slab and upwelling asthenosphere, migrating past one another as backarc spreading develops (Martinez and Taylor 2006). When rifting occurs on the back-arc side of the arc massif, the remnant arc separates from ...
... forearc, resulting in the latter case in the two magma sources, associated with subducting slab and upwelling asthenosphere, migrating past one another as backarc spreading develops (Martinez and Taylor 2006). When rifting occurs on the back-arc side of the arc massif, the remnant arc separates from ...
Seismic and aseismic deformation along the East African Rift
... Western and the Eastern (Kenya Rift) branches surrounding the Tanzanian craton the Malawi Rift and the Davie Ridge (Fig. 2). The second-order segmentation delimits 50–100-km-long segments (Chorowicz 2005), concentrating the tectonic or/and the volcanic activity (Ebinger 1989a,b; Ebinger et al. 1993; ...
... Western and the Eastern (Kenya Rift) branches surrounding the Tanzanian craton the Malawi Rift and the Davie Ridge (Fig. 2). The second-order segmentation delimits 50–100-km-long segments (Chorowicz 2005), concentrating the tectonic or/and the volcanic activity (Ebinger 1989a,b; Ebinger et al. 1993; ...
Insights into extensional processes during magma assisted rifting
... eruptions emanating from scoria cones and fissures located within the Wonji Fault Belt and Silti-Debre Zeyit Fault Zone (Figs. 1B, 2). 3. Magmatic–tectonic fault belts in Ethiopia 3.1. Structural features of the Wonji Fault Belt The topographic expression of the northern MER is defined by ~ NE strikin ...
... eruptions emanating from scoria cones and fissures located within the Wonji Fault Belt and Silti-Debre Zeyit Fault Zone (Figs. 1B, 2). 3. Magmatic–tectonic fault belts in Ethiopia 3.1. Structural features of the Wonji Fault Belt The topographic expression of the northern MER is defined by ~ NE strikin ...
Alpine Granites
... represent the feeder zone of the pluton (ROSENBERG, 2004). After the emplacement of the tonalitic feeder zone, the intrusion of the central granodiorite occurred, resulting in a boudinage and mineral alignment within the tonalite and country rocks (BUCHER, 1977). The pluton formed due to ballooning ...
... represent the feeder zone of the pluton (ROSENBERG, 2004). After the emplacement of the tonalitic feeder zone, the intrusion of the central granodiorite occurred, resulting in a boudinage and mineral alignment within the tonalite and country rocks (BUCHER, 1977). The pluton formed due to ballooning ...
Mechanics of active magmatic intraplating in the Rio Grande Rift
... with earlier data. To quantify the time dependence of surface deformation in the Socorro area, we processed the whole catalog of European Remote‐Sensing Satellites ERS‐1 and 2 data from the descending satellite track 98. The catalog data consists of several tens of radar acquisitions collected over ...
... with earlier data. To quantify the time dependence of surface deformation in the Socorro area, we processed the whole catalog of European Remote‐Sensing Satellites ERS‐1 and 2 data from the descending satellite track 98. The catalog data consists of several tens of radar acquisitions collected over ...
bulletin of marine science
... years of a scientist's lifetime. The prospects for the unraveling of the past two hundred million years of planetary history from the study of such an active area seem exceptionally good. This is due in large part to the fact that a model exists to be tested, the outlines of which were suggested by ...
... years of a scientist's lifetime. The prospects for the unraveling of the past two hundred million years of planetary history from the study of such an active area seem exceptionally good. This is due in large part to the fact that a model exists to be tested, the outlines of which were suggested by ...
Phase Transitions and Mineralogy of the Upper Mantle
... convective mantle, that is, the source of primary basaltic magmas, which implies significant heterogeneities also in the convecting mantle. Over the last decades, many studies addressed processes that may cause heterogeneities in the upper mantle, using both field-based and experimental investigatio ...
... convective mantle, that is, the source of primary basaltic magmas, which implies significant heterogeneities also in the convecting mantle. Over the last decades, many studies addressed processes that may cause heterogeneities in the upper mantle, using both field-based and experimental investigatio ...
CHAPTER 4 GEOCHRONOLOGY AND ISOTOPIC CHARACTER OF
... 1:500,000-scale geologic mapping of the Precambrian basement. The ages were reported on USGS maps I-200-A, I-204-A, I-206-A, and I-211-A (Bramkamp, Brown and others 1963; Bramkamp, Ramirez and others, 1963; Brown and others 1963a, 1963b; and Jackson and others, 1963), and supporting analytic data we ...
... 1:500,000-scale geologic mapping of the Precambrian basement. The ages were reported on USGS maps I-200-A, I-204-A, I-206-A, and I-211-A (Bramkamp, Brown and others 1963; Bramkamp, Ramirez and others, 1963; Brown and others 1963a, 1963b; and Jackson and others, 1963), and supporting analytic data we ...
The nature of the crust beneath the Afar triple junction: Evidence
... plateau (∼40 km) and southeastern plateau (∼35 km). The western plateau shows VP/VS ranging between 1.7–1.9, suggesting a mafic altered crust, likely associated with Cenozoic flood basalts, or current magmatism. The southeastern plateau shows VP/VS more typical of silicic continental crust (∼1.78). ...
... plateau (∼40 km) and southeastern plateau (∼35 km). The western plateau shows VP/VS ranging between 1.7–1.9, suggesting a mafic altered crust, likely associated with Cenozoic flood basalts, or current magmatism. The southeastern plateau shows VP/VS more typical of silicic continental crust (∼1.78). ...
Poisson`s ratio in the lower mantle beneath Alaska: Evidence for
... [4] There are, at least, two major difficulties with seismological studies of compositional heterogeneity that rely on wave speed ratios. First, without absolute values the trade-off between temperature and compositional effects cannot be resolved, so that the interpretation in terms of the origin o ...
... [4] There are, at least, two major difficulties with seismological studies of compositional heterogeneity that rely on wave speed ratios. First, without absolute values the trade-off between temperature and compositional effects cannot be resolved, so that the interpretation in terms of the origin o ...
Plate tectonics
Plate tectonics (from the Late Latin tectonicus, from the Greek: τεκτονικός ""pertaining to building"") is a scientific theory that describes the large-scale motion of Earth's lithosphere. This theoretical model builds on the concept of continental drift which was developed during the first few decades of the 20th century. The geoscientific community accepted the theory after the concepts of seafloor spreading were later developed in the late 1950s and early 1960s.The lithosphere, which is the rigid outermost shell of a planet (on Earth, the crust and upper mantle), is broken up into tectonic plates. On Earth, there are seven or eight major plates (depending on how they are defined) and many minor plates. Where plates meet, their relative motion determines the type of boundary; convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates typically varies from zero to 100 mm annually.Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some supporters) propose gradual shrinking (contraction) or gradual expansion of the globe.Tectonic plates are able to move because the Earth's lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topography and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by the rotation of the globe and the tidal forces of the Sun and Moon. The relative importance of each of these factors and their relationship to each other is unclear, and still the subject of much debate.