1 Accretion of terranes and growth of continental crust along the
... orogenic contraction and terrane accretion within the Ouachita embayment at ~309 Ma (Nicholas and Waddell, 1989). The orthogonal intersection of the northwest-striking Alabama-Oklahoma transform fault with the northeast-striking southern segment of the Blue Ridge rift outline the Alabama promontory ...
... orogenic contraction and terrane accretion within the Ouachita embayment at ~309 Ma (Nicholas and Waddell, 1989). The orthogonal intersection of the northwest-striking Alabama-Oklahoma transform fault with the northeast-striking southern segment of the Blue Ridge rift outline the Alabama promontory ...
Review of the Current State of Development and the Potential for
... activity. It is thought that hundreds, if not thousands, of hydrothermal vent sites may exist along the Mid-Oceanic Ridge but as yet only about 100 sites have been identified because they are very difficult to find (Glowka, 2003). In 1977, scientists discovered that vents were populated with an extr ...
... activity. It is thought that hundreds, if not thousands, of hydrothermal vent sites may exist along the Mid-Oceanic Ridge but as yet only about 100 sites have been identified because they are very difficult to find (Glowka, 2003). In 1977, scientists discovered that vents were populated with an extr ...
Density constraints on the formation of the continental Moho and crust
... Regardless of whether the mass of the continental crust has grown or has been conserved with time, the isotopic data indicate that large volumes of calcalkaline magmas could have originated from the mantle during certain episodes. For a detailed discussion of the relationship between isotopic "age p ...
... Regardless of whether the mass of the continental crust has grown or has been conserved with time, the isotopic data indicate that large volumes of calcalkaline magmas could have originated from the mantle during certain episodes. For a detailed discussion of the relationship between isotopic "age p ...
Volcanism in the Afar Rift sustained by decompression melting with
... Cynthia Ebinger4 , Ian D. Bastow3 , Atalay Ayele5 , Manahloh Belachew4,5 and Graham Stuart6 Continental breakup is caused by some combination of heating and stretching1,2 . The Afar Rift system in Africa is an example of active continental rifting, where a mantle plume probably weakened the lithosph ...
... Cynthia Ebinger4 , Ian D. Bastow3 , Atalay Ayele5 , Manahloh Belachew4,5 and Graham Stuart6 Continental breakup is caused by some combination of heating and stretching1,2 . The Afar Rift system in Africa is an example of active continental rifting, where a mantle plume probably weakened the lithosph ...
The Origins of Magma PowerPoint
... The Formation of Magma Observe these settings where large magma chambers form, and propose causes of melting for each site ...
... The Formation of Magma Observe these settings where large magma chambers form, and propose causes of melting for each site ...
INTRODUCTION TO TECTONICS
... Westward drift implies that plates have a general sense of motion, and are not moving randomly. Geophysical and geodetic analyses suggest that plates move along sinusoidal flow lines with different velocities, yet with the general westward direction. Therefore plates are more or less mechanically de ...
... Westward drift implies that plates have a general sense of motion, and are not moving randomly. Geophysical and geodetic analyses suggest that plates move along sinusoidal flow lines with different velocities, yet with the general westward direction. Therefore plates are more or less mechanically de ...
Microbial community structure in the
North Pacific ocean
... a remarkably low degree of overlap between communities at each depth. The 444 147 sequence tags analyzed represented 62 975 unique sequences. Of these, 3707 (5.9%) occurred at two depths, and only 298 (0.5%) were observed at all three depths. At this level of phylogenetic resolution, Bacteria divers ...
North Pacific ocean
... a remarkably low degree of overlap between communities at each depth. The 444 147 sequence tags analyzed represented 62 975 unique sequences. Of these, 3707 (5.9%) occurred at two depths, and only 298 (0.5%) were observed at all three depths. At this level of phylogenetic resolution, Bacteria divers ...
Bathymetry of Mariana trench-arc system and formation of the
... 2002; Gvirtzman and Nur, 1999b; Lachenbruch and Morgan, 1990] and thus the base of the lithosphere should be at a depth of about 31 km, nearly 70 km above the top of the subducting plate. We thus conclude that 70 km of asthenosphere lies between the two plates under the ridge and that the overriding ...
... 2002; Gvirtzman and Nur, 1999b; Lachenbruch and Morgan, 1990] and thus the base of the lithosphere should be at a depth of about 31 km, nearly 70 km above the top of the subducting plate. We thus conclude that 70 km of asthenosphere lies between the two plates under the ridge and that the overriding ...
Geodynamic evolution of the Earth over the Phanerozoic: Plate
... tonics. Any change in plate motion must then be related to evolution of the boundary conditions. We stress that plate boundaries are lithospheric discontinuities which cannot appear spontaneously by themselves. In the UNIL model (v.2011, © Neftex), new plate boundaries can be created in the followin ...
... tonics. Any change in plate motion must then be related to evolution of the boundary conditions. We stress that plate boundaries are lithospheric discontinuities which cannot appear spontaneously by themselves. In the UNIL model (v.2011, © Neftex), new plate boundaries can be created in the followin ...
1 The role of the mantle wedge in subduction zone dynamics and
... framework is reasonably well understood from the near-surface observations (Figure 1). Pressure-release melting of the Earth’s mantle at mid-oceanic ridges causes a differentiation into a basaltic crust overlying depleted peridotite. Interaction with seawater by hydrothermal circulation, potentially ...
... framework is reasonably well understood from the near-surface observations (Figure 1). Pressure-release melting of the Earth’s mantle at mid-oceanic ridges causes a differentiation into a basaltic crust overlying depleted peridotite. Interaction with seawater by hydrothermal circulation, potentially ...
The discovery of a conjugate system of faults in the Wharton Basin
... Wharton Basin is east-west, but the shear zones are oblique to these preexisting structures, suggesting that the shear zones are new and not reactivated spreading-related normal faults. The sediment thickness over the normal oceanic crust, away from the fracture zones, is ~2.2 km (Figs. 4 and 5). A ...
... Wharton Basin is east-west, but the shear zones are oblique to these preexisting structures, suggesting that the shear zones are new and not reactivated spreading-related normal faults. The sediment thickness over the normal oceanic crust, away from the fracture zones, is ~2.2 km (Figs. 4 and 5). A ...
Speculations on the Consequences and Causes of Plate Motions*
... caused by a lack of knowledge, and do not demonstrate that plate theory is wrong. Indeed there is a similar difficulty in relating the detailed topography of ridges to the creation of oceanic crust on their axes (Atwater & Mudie 1968). It is therefore clear from this work on plate theory that the li ...
... caused by a lack of knowledge, and do not demonstrate that plate theory is wrong. Indeed there is a similar difficulty in relating the detailed topography of ridges to the creation of oceanic crust on their axes (Atwater & Mudie 1968). It is therefore clear from this work on plate theory that the li ...
The Research Fleet
... however, they are generally smaller in size and a Global Class vessel. tend to have lower operating costs. Regional/ Ocean Class ships are a new class of research Coastal ships include: R/V F. G. Walton Smith, R/V Hugh vessel. These ships will fulfill a critical need in fleet R. Sharp, R/V Pelican a ...
... however, they are generally smaller in size and a Global Class vessel. tend to have lower operating costs. Regional/ Ocean Class ships are a new class of research Coastal ships include: R/V F. G. Walton Smith, R/V Hugh vessel. These ships will fulfill a critical need in fleet R. Sharp, R/V Pelican a ...
- World Ocean Observatory
... worldwide; fifty volumes of results are published beginning in 1880, ushering in new era of science Image: HMS Challenger ...
... worldwide; fifty volumes of results are published beginning in 1880, ushering in new era of science Image: HMS Challenger ...
Terrigenous Sediments - Lamont
... the most widely distributed terrigenous components in pelagic marine sediments, and their occurrence and distribution is well reviewed by Kennett (1982) (see Eolian Records, Deep-Sea Sediments). Some clays are formed as weathering or alteration products of primary silicate minerals, and others are r ...
... the most widely distributed terrigenous components in pelagic marine sediments, and their occurrence and distribution is well reviewed by Kennett (1982) (see Eolian Records, Deep-Sea Sediments). Some clays are formed as weathering or alteration products of primary silicate minerals, and others are r ...
Dehydration of serpentinized slab mantle: Seismic evidence from southwest Japan
... The occurrence of intermediate-depth and deep earthquakes at 60–670 km depth range in the Wadati-Benioff zone is one of the enigmas of earth sciences because the lithostatic pressure at such depths appears to be too high for brittle fracture (see Kirby, 1995 for review). In some slabs, double seismi ...
... The occurrence of intermediate-depth and deep earthquakes at 60–670 km depth range in the Wadati-Benioff zone is one of the enigmas of earth sciences because the lithostatic pressure at such depths appears to be too high for brittle fracture (see Kirby, 1995 for review). In some slabs, double seismi ...
Earth and Planetary Science Letters
... from a high MgO and CaO primary magma will not only have low contents of CaO, but they will also be low in SiO2. This is in contrast to observed high MgO lavas that contain both low CaO and high SiO2. Therefore, some other process is controlling the substantial ...
... from a high MgO and CaO primary magma will not only have low contents of CaO, but they will also be low in SiO2. This is in contrast to observed high MgO lavas that contain both low CaO and high SiO2. Therefore, some other process is controlling the substantial ...
Mid Term I: KEY - earthjay science
... (28) 2 pts. All of the following are evidence supporting the theory of plate tectonics EXCEPT for ________. A) hot spots B) paleomagnetism C) ocean floor drilling D) changes in the Moon's orbit due to shifting plates ...
... (28) 2 pts. All of the following are evidence supporting the theory of plate tectonics EXCEPT for ________. A) hot spots B) paleomagnetism C) ocean floor drilling D) changes in the Moon's orbit due to shifting plates ...
Constraints on shallow mantle viscosity from morphology and
... unconstrained magma column will reach a shallower level than zt. Therefore, zm is conceptualized as the potential height of the top of magma column relative to zt and is called magma top. For instance, zm of 200 m means that internal pressure can push magma up to 200 m above the dike top. z0 is the ...
... unconstrained magma column will reach a shallower level than zt. Therefore, zm is conceptualized as the potential height of the top of magma column relative to zt and is called magma top. For instance, zm of 200 m means that internal pressure can push magma up to 200 m above the dike top. z0 is the ...
A multiphase seismic investigation of the shallow subduction zone
... The seismic velocities and depths of the five layers are parametrized in terms of 2-D B-splines. The B-spline functions are expressed as a linear combination of B-spline basis functions (Powell 1991) and interpolate between knot points of specified layer depth to form surfaces approximating the laye ...
... The seismic velocities and depths of the five layers are parametrized in terms of 2-D B-splines. The B-spline functions are expressed as a linear combination of B-spline basis functions (Powell 1991) and interpolate between knot points of specified layer depth to form surfaces approximating the laye ...
Web page 1
... paleomagnetics and show a simplified timeline of events. Readers can find more detailed information in subsequent pages which concentrate on slab gaps and the deformation caused within the continental US due to forces without. ...
... paleomagnetics and show a simplified timeline of events. Readers can find more detailed information in subsequent pages which concentrate on slab gaps and the deformation caused within the continental US due to forces without. ...
E ects of Lithospheric Strength on Convection in the Earth`s Mantle
... Convection in Earth's mantle is driven largely by horizontal density gradients that form when cold, dense, mantle lithosphere descends into the mantle interior, either through subduction for plate-scale ow, or as localized convective instability beneath lithospheric plates. The deformation associat ...
... Convection in Earth's mantle is driven largely by horizontal density gradients that form when cold, dense, mantle lithosphere descends into the mantle interior, either through subduction for plate-scale ow, or as localized convective instability beneath lithospheric plates. The deformation associat ...
Vertical distribution and population structure of the three dominant
... cophora, which implied it has an annual life-cycle. Attempts to follow similar sequences in the other two species were unsuccessful. The annual mean of the integrated total biomass of the three ostra ...
... cophora, which implied it has an annual life-cycle. Attempts to follow similar sequences in the other two species were unsuccessful. The annual mean of the integrated total biomass of the three ostra ...
univERsity oF copEnhAGEn
... (1.1–0.9 Ga). The Caledonian orogeny (500–400 Ma) along the present western margin of the Baltic Shield and the eastern margin of Greenland resulted from collision of two main plates of Baltica and Laurentia. In the North Sea area, a micro-continent or a series of accreted terranes (Avalonia) formed ...
... (1.1–0.9 Ga). The Caledonian orogeny (500–400 Ma) along the present western margin of the Baltic Shield and the eastern margin of Greenland resulted from collision of two main plates of Baltica and Laurentia. In the North Sea area, a micro-continent or a series of accreted terranes (Avalonia) formed ...
Convergent plate boundaries
... • Most divergent plate boundaries are associated with oceanic ridges – Elevated seafloor with high heat flow and volcanism – Longest topographic feature on Earth’s surface (covers 20% of surface) – Crest is 2 to 3 km higher than adjacent basin and can be 1000 to 4000 km wide • Rift valley is a deep ...
... • Most divergent plate boundaries are associated with oceanic ridges – Elevated seafloor with high heat flow and volcanism – Longest topographic feature on Earth’s surface (covers 20% of surface) – Crest is 2 to 3 km higher than adjacent basin and can be 1000 to 4000 km wide • Rift valley is a deep ...
Abyssal plain
An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 m. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins (the other elements being an elevated mid-ocean ridge and flanking abyssal hills). In addition to these elements, active oceanic basins (those that are associated with a moving plate tectonic boundary) also typically include an oceanic trench and a subduction zone.Abyssal plains were not recognized as distinct physiographic features of the sea floor until the late 1940s and, until very recently, none had been studied on a systematic basis. They are poorly preserved in the sedimentary record, because they tend to be consumed by the subduction process. The creation of the abyssal plain is the end result of spreading of the seafloor (plate tectonics) and melting of the lower oceanic crust. Magma rises from above the asthenosphere (a layer of the upper mantle) and as this basaltic material reaches the surface at mid-ocean ridges it forms new oceanic crust. This is constantly pulled sideways by spreading of the seafloor. Abyssal plains result from the blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited by turbidity currents that have been channelled from the continental margins along submarine canyons down into deeper water. The remainder of the sediment is composed chiefly of pelagic sediments. Metallic nodules are common in some areas of the plains, with varying concentrations of metals, including manganese, iron, nickel, cobalt, and copper. These nodules may provide a significant resource for future mining ventures.Owing in part to their vast size, abyssal plains are currently believed to be a major reservoir of biodiversity. The abyss also exerts significant influence upon ocean carbon cycling, dissolution of calcium carbonate, and atmospheric CO2 concentrations over timescales of 100–1000 years. The structure and function of abyssal ecosystems are strongly influenced by the rate of flux of food to the seafloor and the composition of the material that settles. Factors such as climate change, fishing practices, and ocean fertilization are expected to have a substantial effect on patterns of primary production in the euphotic zone. This will undoubtedly impact the flux of organic material to the abyss in a similar manner and thus have a profound effect on the structure, function and diversity of abyssal ecosystems.