Oceanic Crust
... • It is also more dense than continental crust and considerably thinner averaging 5-10 km versus the average continental crust thickness of around 20 to 80 km. • Oceanic crust is coarsest at its bottom and is finer grained at its top. • About 60% of the Earth's surface is underlain by oceanic crust. ...
... • It is also more dense than continental crust and considerably thinner averaging 5-10 km versus the average continental crust thickness of around 20 to 80 km. • Oceanic crust is coarsest at its bottom and is finer grained at its top. • About 60% of the Earth's surface is underlain by oceanic crust. ...
An outline of the East African Rift Volcanism
... Ethiopia volcanic province is characterized by episodic volcanism that becomes increasingly silica-saturated through time, ranging from essentially tholeiitic compositions 40-45 Ma to nephelinenormative basalts since ~19 Ma. These features are similar to those displayed by contemporaneous lavas from ...
... Ethiopia volcanic province is characterized by episodic volcanism that becomes increasingly silica-saturated through time, ranging from essentially tholeiitic compositions 40-45 Ma to nephelinenormative basalts since ~19 Ma. These features are similar to those displayed by contemporaneous lavas from ...
The effect of the large-scale mantle flow field on the Iceland hotspot
... perpendicular to the flow directions (see: Ruedas and Schmeling, this issue, and references therein). The experimental and numerical models to date make simplifying assumptions, or are of low resolution, and a direct ...
... perpendicular to the flow directions (see: Ruedas and Schmeling, this issue, and references therein). The experimental and numerical models to date make simplifying assumptions, or are of low resolution, and a direct ...
olivia Earthquake Re..
... the USGS, “the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80mm/yr in the south, to approximately 65 mm/yr in the north.” ...
... the USGS, “the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80mm/yr in the south, to approximately 65 mm/yr in the north.” ...
Dynamic topography and long-term sea-level variations
... Backstripping of one or more wells to derive long-term sea level variations have, to date, been restricted to a small number of sites (New Jersey, Nova Scotia, and northwest Africa). The presumption that the sea-level trends represent eustatic signals (after correction for effects such as sediment c ...
... Backstripping of one or more wells to derive long-term sea level variations have, to date, been restricted to a small number of sites (New Jersey, Nova Scotia, and northwest Africa). The presumption that the sea-level trends represent eustatic signals (after correction for effects such as sediment c ...
ON THE SCALE OF MANTLE CONVECTION The relative motion of
... greater than that of the upper mantle and that sinking lithospheric slabs do not penetrate deeper than the deepest earthquakes. While such models can produce reasonable agreement with geophysical observations this does not mean that the models are correct or that other models could not satisfy the o ...
... greater than that of the upper mantle and that sinking lithospheric slabs do not penetrate deeper than the deepest earthquakes. While such models can produce reasonable agreement with geophysical observations this does not mean that the models are correct or that other models could not satisfy the o ...
Subduction origin on early Earth: A hypothesis
... Inception of plate tectonics by the proposed hypothesis would not require strictly serendipitous occurrence of exogenic and endogenic processes. Rather, initiation of plate tectonics might be a function of planet size, which in turn influences both endogenic (heat budget, cooling rate, and lithosphe ...
... Inception of plate tectonics by the proposed hypothesis would not require strictly serendipitous occurrence of exogenic and endogenic processes. Rather, initiation of plate tectonics might be a function of planet size, which in turn influences both endogenic (heat budget, cooling rate, and lithosphe ...
Earth`s Crust Name
... Earth has three layers: the crust, the mantle, and the core. The crust is made of solid rocks and minerals. Beneath the crust is the mantle, which is also mostly solid rocks and minerals, but punctuated by malleable areas of semi-solid magma. At the center of the Earth is a hot, dense, mostly iron a ...
... Earth has three layers: the crust, the mantle, and the core. The crust is made of solid rocks and minerals. Beneath the crust is the mantle, which is also mostly solid rocks and minerals, but punctuated by malleable areas of semi-solid magma. At the center of the Earth is a hot, dense, mostly iron a ...
Plate Tectonics PPT
... atmosphere. As these convection currents in the mantle circulate, they cause the continents above them to move. What Wegener had no way of knowing is that the force that is driving plate tectonics is convection currents in the mantle. ...
... atmosphere. As these convection currents in the mantle circulate, they cause the continents above them to move. What Wegener had no way of knowing is that the force that is driving plate tectonics is convection currents in the mantle. ...
Chapter 11: The Archean Eon of Precambrian Time
... – mafic and ultra-mafic meta-volcanics (inc. pillow basalts) – some felsic volcanics – turbidites and mudstones ...
... – mafic and ultra-mafic meta-volcanics (inc. pillow basalts) – some felsic volcanics – turbidites and mudstones ...
Seismic wave speed structure of the Ontong
... waveforms and an iterative finite-frequency tomography methodology. The combination of datasets allow us to best exploit the limited station distribution in the Pacific and image wave speed structures between 35 km and 300 km into the Earth. We image a region of fast shear wave speeds, greater than 4. ...
... waveforms and an iterative finite-frequency tomography methodology. The combination of datasets allow us to best exploit the limited station distribution in the Pacific and image wave speed structures between 35 km and 300 km into the Earth. We image a region of fast shear wave speeds, greater than 4. ...
Subduction-driven recycling of continental margin lithosphere
... Whereas subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, the recycling of continental lithosphere appears to be far more complicated and less well understood1. Delamination and convective downwelling are two widely recognized processes invoked to explain t ...
... Whereas subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, the recycling of continental lithosphere appears to be far more complicated and less well understood1. Delamination and convective downwelling are two widely recognized processes invoked to explain t ...
Mantle flow, melting, and dehydration of the Iceland mantle plume
... servations [10,11]. This second model, however, predicted unreasonably high crustal thicknesses (>160 km) at Iceland, and therefore over-predicted bathymetric and gravity anomalies along the MAR. A narrow, hot plume model would only be feasible if large volumes of melt migrate several hundreds of ki ...
... servations [10,11]. This second model, however, predicted unreasonably high crustal thicknesses (>160 km) at Iceland, and therefore over-predicted bathymetric and gravity anomalies along the MAR. A narrow, hot plume model would only be feasible if large volumes of melt migrate several hundreds of ki ...
A, Adam, Relation of mantle conductivity to physical conditions in the
... both on old crystalline shields (Early Rise, Manitoba) and on normal continents (Bretagne SE). The velocity increase is attributed to dunite and eclogite intruded into the peridotite (see Pal" PI' Pit in Figure 5). In my opinion the low-velocity zones of the P waves cannot be identified with the con ...
... both on old crystalline shields (Early Rise, Manitoba) and on normal continents (Bretagne SE). The velocity increase is attributed to dunite and eclogite intruded into the peridotite (see Pal" PI' Pit in Figure 5). In my opinion the low-velocity zones of the P waves cannot be identified with the con ...
Energetics Energetics of the Earth and the Missing Heat Source
... could break through and create “heat pipes” to carry magma and heat to the surface. Io and Venus may utilize this mechanism of heat transfer. The surface boundary condition in these cases can be viewed as a permeable plate. Present day plates can be penetrated by sills and dikes and are therefore p ...
... could break through and create “heat pipes” to carry magma and heat to the surface. Io and Venus may utilize this mechanism of heat transfer. The surface boundary condition in these cases can be viewed as a permeable plate. Present day plates can be penetrated by sills and dikes and are therefore p ...
Exploring Active Tectonics in the Dominican Republic
... is especially important because the islands of the northeastern Caribbean are densely ...
... is especially important because the islands of the northeastern Caribbean are densely ...
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.