Seismological observations in Northwestern South America
... the Panama–Choco Block collision, which steepens at the location of the Bucaramanga nest. Hypocentral relocations by Ojeda and Havskov (2001) also suggest the existence of two segments, but their association with subducted slabs is still unclear. There are still open questions about the spatial exte ...
... the Panama–Choco Block collision, which steepens at the location of the Bucaramanga nest. Hypocentral relocations by Ojeda and Havskov (2001) also suggest the existence of two segments, but their association with subducted slabs is still unclear. There are still open questions about the spatial exte ...
Unit 1 Searching for Evidence
... the edges of the continents, or both? (Hint: Use the Zoom In tool to take a closer look.) ...
... the edges of the continents, or both? (Hint: Use the Zoom In tool to take a closer look.) ...
Geosphere - Do plumes exist?
... discussed mechanisms contributing to this uplift include phase transitions, dynamic uplift from mantle plumes, and magmatic underplated bodies. We show in this study that dynamic uplift resulting from passive upwelling asthenosphere below the rift is limited (~200 m). Isostatic arguments suggest tha ...
... discussed mechanisms contributing to this uplift include phase transitions, dynamic uplift from mantle plumes, and magmatic underplated bodies. We show in this study that dynamic uplift resulting from passive upwelling asthenosphere below the rift is limited (~200 m). Isostatic arguments suggest tha ...
Lecture 38
... This diagram generalizes the REE patterns for the three main tectonic settings where volcanism occurs on earth: spreading centers, convergent margins, and intra-plate (both oceanic and continental). The difference between REE patterns in BCR-1 and MORB is common in many igneous rocks from around the ...
... This diagram generalizes the REE patterns for the three main tectonic settings where volcanism occurs on earth: spreading centers, convergent margins, and intra-plate (both oceanic and continental). The difference between REE patterns in BCR-1 and MORB is common in many igneous rocks from around the ...
Melting Relations of MORB^Sediment Me
... emplaced into the supra-subduction zone mantle wedge by diapiric structures rooted in the subduction channel (Gerya & Stoeckhert, 2006; Gorczyk et al., 2007a). Annen et al. (2006) discussed the role of differentiation of mantle-derived wet basalt or basaltic andesite magmas in producing silicic magm ...
... emplaced into the supra-subduction zone mantle wedge by diapiric structures rooted in the subduction channel (Gerya & Stoeckhert, 2006; Gorczyk et al., 2007a). Annen et al. (2006) discussed the role of differentiation of mantle-derived wet basalt or basaltic andesite magmas in producing silicic magm ...
Seismic character of volcanic activity at the ultraslow
... ridges (Smith and Cann, 1999). It has long been postulated that certain types of swarm activity on slow-spreading ridges relate to volcanism (Sykes, 1970; Blackman et al., 2000), the time scales of activity being tens to hundreds of days. However, without field confirmation, the cause of these swarm ...
... ridges (Smith and Cann, 1999). It has long been postulated that certain types of swarm activity on slow-spreading ridges relate to volcanism (Sykes, 1970; Blackman et al., 2000), the time scales of activity being tens to hundreds of days. However, without field confirmation, the cause of these swarm ...
Mantle hotspot neon in basalts from the Northwest Lau Back
... hotspot appears to be the ultimate source of the high 3He/4He signature in the Northwest Lau Back-arc Basin, it is surprising that the 3He/4He ratios are so consistently elevated along the entire length of the RR–NWLSC. The question remains as to whether the elevated 3He/4He ratios along the RR–NWLS ...
... hotspot appears to be the ultimate source of the high 3He/4He signature in the Northwest Lau Back-arc Basin, it is surprising that the 3He/4He ratios are so consistently elevated along the entire length of the RR–NWLSC. The question remains as to whether the elevated 3He/4He ratios along the RR–NWLS ...
Stress distribution within subducting slabs and their deformation in
... are replaced by those of mantle peridotite at the depth of 200 km mainly for numerical reasons. Sketch of the setup of the fault area is given in Fig. 1. Thermal boundary conditions are T = 0 ◦ C at the surface, and T = 2300 ◦ C at the bottom of the model domain. On the left hand side boundary a man ...
... are replaced by those of mantle peridotite at the depth of 200 km mainly for numerical reasons. Sketch of the setup of the fault area is given in Fig. 1. Thermal boundary conditions are T = 0 ◦ C at the surface, and T = 2300 ◦ C at the bottom of the model domain. On the left hand side boundary a man ...
Geodynamical interpretation of crustal and upper mantle electrical conductivity
... the asthenosphere (Kiselev and Popov, 1992). Mantle xenoliths drawn to the surface by basaltic eruptions in different parts of the rift bear evidence of thermal and compositional heterogeneity of the underlying mantle. The most widely spread are spinel lherzolites that give way to garnet varieties d ...
... the asthenosphere (Kiselev and Popov, 1992). Mantle xenoliths drawn to the surface by basaltic eruptions in different parts of the rift bear evidence of thermal and compositional heterogeneity of the underlying mantle. The most widely spread are spinel lherzolites that give way to garnet varieties d ...
Mineralogy and petrology of rocks from Kamen Volcano, Kamchatka
... numerous of papers during last decades [e.g. Kersting & Arculus, 1995; Pineau et al., 1999; Ozerov, 2000; Dorendorf et al., 2000; Mironov et al., 2001; Churikova et al., 2001; Portnyagin et al., 2007; Turner et al., 2007]. However, modern geochemical studies of Kamen volcano, which is located betwee ...
... numerous of papers during last decades [e.g. Kersting & Arculus, 1995; Pineau et al., 1999; Ozerov, 2000; Dorendorf et al., 2000; Mironov et al., 2001; Churikova et al., 2001; Portnyagin et al., 2007; Turner et al., 2007]. However, modern geochemical studies of Kamen volcano, which is located betwee ...
Deep-mantle contributions to the surface dynamics of the North
... A.M. Forte et al. / Tectonophysics xxx (2009) xxx–xxx ...
... A.M. Forte et al. / Tectonophysics xxx (2009) xxx–xxx ...
Modelling stress accumulation and crustal deformation associated
... loading processes at a seismic zone on a transform plate boundary subject to steady relative plate motion (Matsu'ura and Sato 1997[2]). In this model, the seismic zone is represented by a locked patch with a nite length on an in nitely long plate interface. The simulation shows that stress accumula ...
... loading processes at a seismic zone on a transform plate boundary subject to steady relative plate motion (Matsu'ura and Sato 1997[2]). In this model, the seismic zone is represented by a locked patch with a nite length on an in nitely long plate interface. The simulation shows that stress accumula ...
Summary of Research Projects John W. Shervais Department of Geology Professor and Head
... overlying crust was extracted, and its mineralogy and composition reflect the processes that have affected it through time, including melt extraction, fluid phase enrichment, and subsequent interactions with melt derived from lower in the mantle tectosphere. These processes have been frozen in place ...
... overlying crust was extracted, and its mineralogy and composition reflect the processes that have affected it through time, including melt extraction, fluid phase enrichment, and subsequent interactions with melt derived from lower in the mantle tectosphere. These processes have been frozen in place ...
Evolution of the Earth as an andesite planet: water
... Once the chemical compositions of each layer of the subIBM arc crust and mantle were defined, the mineral assemblages and physical properties of these layers were obtained and compared to the observed layered structure. The amount of H2O in magma governs the amount of hydrous phases in a solidified ...
... Once the chemical compositions of each layer of the subIBM arc crust and mantle were defined, the mineral assemblages and physical properties of these layers were obtained and compared to the observed layered structure. The amount of H2O in magma governs the amount of hydrous phases in a solidified ...
Workman, Hart, 2005 - University of Maryland, Department of Geology
... and differentiation processes that have affected these upper mantle melts. Unfortunately, it is just these processes that we are trying to understand, rather than assume a priori. The most compelling evidence for upper mantle depletion comes from the heavy-element isotopic composition of MORBs. Alth ...
... and differentiation processes that have affected these upper mantle melts. Unfortunately, it is just these processes that we are trying to understand, rather than assume a priori. The most compelling evidence for upper mantle depletion comes from the heavy-element isotopic composition of MORBs. Alth ...
Temporal evolution of continental lithospheric strength in actively
... 103 yr) and glacio-isostatic adjustment (GIA, ~103 to 104 yr) time scales. Topography and gravity field correlations indicate that lithosphere isostatic adjustment (LIA) on ~106 –107 yr time scales occurs with most lithospheric stress supported by an upper crust overlying a much weaker ductile subst ...
... 103 yr) and glacio-isostatic adjustment (GIA, ~103 to 104 yr) time scales. Topography and gravity field correlations indicate that lithosphere isostatic adjustment (LIA) on ~106 –107 yr time scales occurs with most lithospheric stress supported by an upper crust overlying a much weaker ductile subst ...
Water transportation from the subducting slab into the mantle
... However, if the temperature is above 650 °C at 30–90 km depths, subducting oceanic crust reaches the solidus temperature condition, causing the partial melting of amphibole-bearing metamorphosed oceanic crust. The released H2O dissolves in the melt; then the remaining subducting oceanic crust transf ...
... However, if the temperature is above 650 °C at 30–90 km depths, subducting oceanic crust reaches the solidus temperature condition, causing the partial melting of amphibole-bearing metamorphosed oceanic crust. The released H2O dissolves in the melt; then the remaining subducting oceanic crust transf ...
Lithosphere and Asthenosphere
... The definition of the lithosphere is based on how Earth materials behave, so it includes the crust and the uppermost mantle, which are both brittle. Since it is rigid and brittle, when stresses act on the lithosphere, it breaks. This is what we experience as an earthquake. Although we sometimes refe ...
... The definition of the lithosphere is based on how Earth materials behave, so it includes the crust and the uppermost mantle, which are both brittle. Since it is rigid and brittle, when stresses act on the lithosphere, it breaks. This is what we experience as an earthquake. Although we sometimes refe ...
Author`s personal copy
... western U.S., during the mid-Tertiary “ignimbrite flare-up”, principally at the San Juan and Mogollon-Datil volcanic fields. At both volcanic centers, radiogenic isotope data have been interpreted as evidence that 50% or more of the volcanic rocks (by mass) were derived from mantle-derived, mafic pa ...
... western U.S., during the mid-Tertiary “ignimbrite flare-up”, principally at the San Juan and Mogollon-Datil volcanic fields. At both volcanic centers, radiogenic isotope data have been interpreted as evidence that 50% or more of the volcanic rocks (by mass) were derived from mantle-derived, mafic pa ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.