Hafnium isotope evidence for slab melt contributions in the Central
... oceanic crust to eclogite. Isotopic and chemical mass balance considerations indicate that the slab melts are ~80% basaltic oceanic crust and ~20% subducted sediment. The calc-alkaline lavas have higher SiO2 at a given Mg# compared to the high-Nb alkaline lavas, also reflecting melt contributions fro ...
... oceanic crust to eclogite. Isotopic and chemical mass balance considerations indicate that the slab melts are ~80% basaltic oceanic crust and ~20% subducted sediment. The calc-alkaline lavas have higher SiO2 at a given Mg# compared to the high-Nb alkaline lavas, also reflecting melt contributions fro ...
Ocean ridges - dynamicearth.de
... the high may arise from the buoyancy of hot rock at shallow depth, but on slowly spreading ridges it is clearly formed by the coalescence of small volcanoes 1–2 km in width, and hence is known as an axial volcanic ridge (Smith & Cann, 1993). A detailed study of a median rift valley was made in the A ...
... the high may arise from the buoyancy of hot rock at shallow depth, but on slowly spreading ridges it is clearly formed by the coalescence of small volcanoes 1–2 km in width, and hence is known as an axial volcanic ridge (Smith & Cann, 1993). A detailed study of a median rift valley was made in the A ...
Osmium-isotope variations in Hawaiian lavas: evidence
... Hawaiian plume, both from the same packet of recycled oceanic lithosphere. Radiogenic Os-isotopes and anomalously heavy oxygen-isotopes in Koolau lavas reflect melt generation from recycled oceanic crust plus pelagic sediment. In contrast, Kea lavas have unradiogenic Os-isotopes but anomalously ligh ...
... Hawaiian plume, both from the same packet of recycled oceanic lithosphere. Radiogenic Os-isotopes and anomalously heavy oxygen-isotopes in Koolau lavas reflect melt generation from recycled oceanic crust plus pelagic sediment. In contrast, Kea lavas have unradiogenic Os-isotopes but anomalously ligh ...
Geological Society of America Bulletin
... In a uniformitarian approach, ophiolite geologists then started reconstructing the evolution of fossil oceanic lithosphere exposed on land as a product of paleo–mid-ocean ridges using the ophiolite–ocean crust analogy (Gass, 1968; Coleman, 1971; Moores and Vine, 1971; Cann, 2003, and references ther ...
... In a uniformitarian approach, ophiolite geologists then started reconstructing the evolution of fossil oceanic lithosphere exposed on land as a product of paleo–mid-ocean ridges using the ophiolite–ocean crust analogy (Gass, 1968; Coleman, 1971; Moores and Vine, 1971; Cann, 2003, and references ther ...
Are `hot spots` - Durham University Community
... The term ‘hot spot’ emerged in the 1960s from speculations that Hawaii might have its origins in an unusually hot source region in the mantle. It subsequently became widely used to refer to volcanic regions considered to be anomalous in the then-new plate tectonic paradigm. It carried with it the im ...
... The term ‘hot spot’ emerged in the 1960s from speculations that Hawaii might have its origins in an unusually hot source region in the mantle. It subsequently became widely used to refer to volcanic regions considered to be anomalous in the then-new plate tectonic paradigm. It carried with it the im ...
- Mineralogical Society of America
... we conceptualize it, the conversion of low-permeability bedrock to regolith generally begins due to the transport of meteoric water into protolith through the large-scale fractures that are present as a result of regional tectonic factors or exhumation (Wyrick and Borchers 1981; Molnar et al. 2007). ...
... we conceptualize it, the conversion of low-permeability bedrock to regolith generally begins due to the transport of meteoric water into protolith through the large-scale fractures that are present as a result of regional tectonic factors or exhumation (Wyrick and Borchers 1981; Molnar et al. 2007). ...
A new model of lunar crust: asymmetry in crustal composition... Tomoko Arai , Hiroshi Takeda , Akira Yamaguchi
... (FAN), while those of the latter include Mg-suite rocks plus some rocks enriched in alkali elements, termed alkali-suite rocks. There is another outstanding group, called KREEP, which is extremely enriched in alkalis and incompatible trace elements, such as K, rare earth elements (REEs) and P. They ...
... (FAN), while those of the latter include Mg-suite rocks plus some rocks enriched in alkali elements, termed alkali-suite rocks. There is another outstanding group, called KREEP, which is extremely enriched in alkalis and incompatible trace elements, such as K, rare earth elements (REEs) and P. They ...
Science Article PDF - Geological Society of America
... on authors’ or organizational Web sites, except that permission is granted to authors to post the abstracts only of their science articles on their own or their organization’s Web site providing the posting includes this reference: “The full paper was published in the Geological Society of America’s ...
... on authors’ or organizational Web sites, except that permission is granted to authors to post the abstracts only of their science articles on their own or their organization’s Web site providing the posting includes this reference: “The full paper was published in the Geological Society of America’s ...
A cool model for the Iceland hot spot
... A holistic appraisal of the evidence available from the Iceland melt anomaly suggests that, if the assumption of a plume is dropped, an upper-mantle, moderate-temperature model is natural, reasonable and not without support. The primary observations that require explanation are the local production ...
... A holistic appraisal of the evidence available from the Iceland melt anomaly suggests that, if the assumption of a plume is dropped, an upper-mantle, moderate-temperature model is natural, reasonable and not without support. The primary observations that require explanation are the local production ...
PNAS-2014-Anderson-1..
... detail, they also violate the first and second laws of thermodynamics because they require noncooling boundaries and external sources of energy, material, and information (e.g., Maxwell demons); that is, the model planets are not closed, isolated, selforganizing systems living off of their own resou ...
... detail, they also violate the first and second laws of thermodynamics because they require noncooling boundaries and external sources of energy, material, and information (e.g., Maxwell demons); that is, the model planets are not closed, isolated, selforganizing systems living off of their own resou ...
34 - School of Ocean and Earth Science and Technology
... G Siderophiles (with metallic bonding) are much less abundant in the crust. They’re mostly in the core. G Chalcophiles (with mostly covalent bonding) are split between mantle, crust and core. The major elements in the crust are the same as those in the mantle, but the proportions are different. Beca ...
... G Siderophiles (with metallic bonding) are much less abundant in the crust. They’re mostly in the core. G Chalcophiles (with mostly covalent bonding) are split between mantle, crust and core. The major elements in the crust are the same as those in the mantle, but the proportions are different. Beca ...
compositional and thermal differences between lithospheric and
... variations upon changes of P-T parameters. Our attention is focused on effects of phase and density changes that may be very important and even dominant when compared with the effect of a simple change of the thermal mantle structure. The paper presents the results of numerical modeling for eclogiti ...
... variations upon changes of P-T parameters. Our attention is focused on effects of phase and density changes that may be very important and even dominant when compared with the effect of a simple change of the thermal mantle structure. The paper presents the results of numerical modeling for eclogiti ...
On the origin of noble gases in mantle plumes
... the mantle, potentially satis es trace-element as well as noble-gas constraints. Keywords: mantle; noble gas; plumes; recycling; convection ...
... the mantle, potentially satis es trace-element as well as noble-gas constraints. Keywords: mantle; noble gas; plumes; recycling; convection ...
North Atlantic Igneous Province: A Review of
... The MgO content of the rocks analyzed by Gill et al. (1992) range between 15 to 30 wt.%. Petrologists debate the nature of these rocks: do the melts represent unmodified high-MgO mantle melts (e.g. Clarke, 1970; Clarke and O’Hara, 1979), or are they derived from a primary mantle magma modified by on ...
... The MgO content of the rocks analyzed by Gill et al. (1992) range between 15 to 30 wt.%. Petrologists debate the nature of these rocks: do the melts represent unmodified high-MgO mantle melts (e.g. Clarke, 1970; Clarke and O’Hara, 1979), or are they derived from a primary mantle magma modified by on ...
as a PDF
... late veneer. The same may hold true for the noble gas budget of the Earth. Deep sea sediments today are high in noble gases because of the high concentration of interplanetary dust particles (IDPs). The sediments are retentive of trapped 3He but not 4He [Farley, 1995]. Therefore sediments are subduc ...
... late veneer. The same may hold true for the noble gas budget of the Earth. Deep sea sediments today are high in noble gases because of the high concentration of interplanetary dust particles (IDPs). The sediments are retentive of trapped 3He but not 4He [Farley, 1995]. Therefore sediments are subduc ...
The Statistical Upper Mantle Assemblage, Earth
... in terms of abundances and isotopic compositions of lithophile trace elements [4^6] and noble gases [7] has led to the widespread (but not universally adopted) notion that the source region for ‘normal’ MORB (N-MORB), referred to as depleted MORB mantle (DMM), is a large-scale (i.e. global), homogen ...
... in terms of abundances and isotopic compositions of lithophile trace elements [4^6] and noble gases [7] has led to the widespread (but not universally adopted) notion that the source region for ‘normal’ MORB (N-MORB), referred to as depleted MORB mantle (DMM), is a large-scale (i.e. global), homogen ...
Some Thermal Constraints on Crustal
... The liquidus curve (liquid line of descent) relates the equilibrium composition of the melt to the magma temperature. A first stage (point c to point b in Fig. 1c) includes the cooling of the magma (Tm), heating and melting of the crustal assimilate (Ta), and mixing of this assimilate with the man ...
... The liquidus curve (liquid line of descent) relates the equilibrium composition of the melt to the magma temperature. A first stage (point c to point b in Fig. 1c) includes the cooling of the magma (Tm), heating and melting of the crustal assimilate (Ta), and mixing of this assimilate with the man ...
Plate tectonics began in Neoproterozoic time
... model and regarded the olivine as residual after partial melting to exhaustion of orthopyroxene.) The fertile lherzolite, pyroxenite, eclogite, and other rocks that now accompany dunite and harzburgite as mantle xenoliths (Griffin et al., 2009) could not have formed in high-temperature equilibrium wi ...
... model and regarded the olivine as residual after partial melting to exhaustion of orthopyroxene.) The fertile lherzolite, pyroxenite, eclogite, and other rocks that now accompany dunite and harzburgite as mantle xenoliths (Griffin et al., 2009) could not have formed in high-temperature equilibrium wi ...
Crustal growth at active continental margins: Numerical
... dependent on the pore fluid pressure (Davies, 1983) that varies according to the nature (coarse terrigeneous sedimentation versus finer pelagic sedimentation) and history (fast and slow sedimentation) of the rock column considered (Le Pichon et al., 1993). At greater depth mineral dehydration reaction ...
... dependent on the pore fluid pressure (Davies, 1983) that varies according to the nature (coarse terrigeneous sedimentation versus finer pelagic sedimentation) and history (fast and slow sedimentation) of the rock column considered (Le Pichon et al., 1993). At greater depth mineral dehydration reaction ...
Sabzevar Ophiolite, NE Iran - The University of Texas at Dallas
... a b s t r a c t The poorly known Sabzevar–Torbat-e-Heydarieh ophiolite belt (STOB) covers a large region in NE Iran, over 400 km E-W and almost 200 km N-S. The Sabzevar mantle sequence includes harzburgite, lherzolite, dunite and chromitite. Spinel Cr# (100Cr/(Cr + Al)) in harzburgites and lherzolit ...
... a b s t r a c t The poorly known Sabzevar–Torbat-e-Heydarieh ophiolite belt (STOB) covers a large region in NE Iran, over 400 km E-W and almost 200 km N-S. The Sabzevar mantle sequence includes harzburgite, lherzolite, dunite and chromitite. Spinel Cr# (100Cr/(Cr + Al)) in harzburgites and lherzolit ...
Earth`s heterogeneous mantle: A product of convection
... analyses of oceanic basalts. Despite the ever-increasing amount of data, the way in which compositional heterogeneity is manifest in the Earth's mantle, as well as the processes leading to mantle heterogeneity remain fundamental questions. The large amount of available isotope data in oceanic basalt ...
... analyses of oceanic basalts. Despite the ever-increasing amount of data, the way in which compositional heterogeneity is manifest in the Earth's mantle, as well as the processes leading to mantle heterogeneity remain fundamental questions. The large amount of available isotope data in oceanic basalt ...
Late Palaeozoic lam pro phyres and as so ci ated mafic subvolcanic
... evolved (Mg# down to 30 in some micromonzodiorites). Some richterite minettes show Nb-enriched trace element patterns, but negative Nb anomalies are more typical. Richterite minettes posesess eNd300 and 87Sr/86Sr300 values that range from +1.9 to –8.3, and from 0.7037 to 0.715, respectively. The oth ...
... evolved (Mg# down to 30 in some micromonzodiorites). Some richterite minettes show Nb-enriched trace element patterns, but negative Nb anomalies are more typical. Richterite minettes posesess eNd300 and 87Sr/86Sr300 values that range from +1.9 to –8.3, and from 0.7037 to 0.715, respectively. The oth ...
Introduction to Metamorphism
... Cpx + plag ( olivine, ilmenite…) Or any combination of melt + minerals along the liquid line of descent ...
... Cpx + plag ( olivine, ilmenite…) Or any combination of melt + minerals along the liquid line of descent ...
Chapter 21: Metamorphism
... Cpx + plag ( olivine, ilmenite…) Or any combination of melt + minerals along the liquid line of descent ...
... Cpx + plag ( olivine, ilmenite…) Or any combination of melt + minerals along the liquid line of descent ...
Basalt
Basalt (pronounced /bəˈsɔːlt/, /ˈbæsɒlt/, /ˈbæsɔːlt/, or /ˈbeɪsɔːlt/)is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of lava basalt flows.