Geology - Central Washington University Geological Sciences
... A geophysical transect across the central Gulf of Mexico coastal plain shows that the early Paleozoic continental margin of southern Laurentia is preserved in a nearly pristine state beneath younger strata that were emplaced during the late Paleozoic Ouachita orogeny and formation of the modern Gulf ...
... A geophysical transect across the central Gulf of Mexico coastal plain shows that the early Paleozoic continental margin of southern Laurentia is preserved in a nearly pristine state beneath younger strata that were emplaced during the late Paleozoic Ouachita orogeny and formation of the modern Gulf ...
Collision of continental corner from 3
... in the ‘sticky air’ viscosity and/or increase in its thickness are precluded by numerical limitations of the multigrid solver convergence. Indeed, the large viscosity contrast caused by this lowviscosity boundary layer minimizes shear stresses (<105 Pa) at the top of the solid portion of the model ( ...
... in the ‘sticky air’ viscosity and/or increase in its thickness are precluded by numerical limitations of the multigrid solver convergence. Indeed, the large viscosity contrast caused by this lowviscosity boundary layer minimizes shear stresses (<105 Pa) at the top of the solid portion of the model ( ...
Characteristic thermal regimes of plate tectonics
... From a geological perspective, we may break down into several components the question of when plate tectonics began on Earth. For example, we may ask when did the lithosphere first behave as a mosaic of plates—that is, a mosaic of largely torsionally rigid lithosphere elements bounded by zones of ge ...
... From a geological perspective, we may break down into several components the question of when plate tectonics began on Earth. For example, we may ask when did the lithosphere first behave as a mosaic of plates—that is, a mosaic of largely torsionally rigid lithosphere elements bounded by zones of ge ...
Unraveling the Tapestry of Ocean Crust
... “float” high atop the viscous mantle, forming dry land. Conversely, dense oceanic crust does not “float” as high—forming lower-lying ocean basins. As oceanic crust cools, it becomes denser and ultimately sinks back into the mantle under its own weight after about 200 million years. Earth’s continent ...
... “float” high atop the viscous mantle, forming dry land. Conversely, dense oceanic crust does not “float” as high—forming lower-lying ocean basins. As oceanic crust cools, it becomes denser and ultimately sinks back into the mantle under its own weight after about 200 million years. Earth’s continent ...
Plate Tectonics: A Unifying Theory
... What do these three recent tragic events have in common? They are part of the dynamic interactions involving Earth’s plates. When two plates come together, one plate is pushed or pulled under the other plate, triggering large earthquakes such as the one that shook India in 2001, Iran in 2003, and Pa ...
... What do these three recent tragic events have in common? They are part of the dynamic interactions involving Earth’s plates. When two plates come together, one plate is pushed or pulled under the other plate, triggering large earthquakes such as the one that shook India in 2001, Iran in 2003, and Pa ...
The South-east African margin and its marine basins and ridge
... controversial. Continental breakup along the eastern coast involved important elements of shear (Falkland Plateau) as well as extreme LIP magmatism (Karoo event). The significance of the Karoo event to the breakup process is still enigmatic because some characteristic hallmarks of a mantle plume are ...
... controversial. Continental breakup along the eastern coast involved important elements of shear (Falkland Plateau) as well as extreme LIP magmatism (Karoo event). The significance of the Karoo event to the breakup process is still enigmatic because some characteristic hallmarks of a mantle plume are ...
Seismic reflection image of the Great Sumatra
... with the dehydration transition from clay (stable sliding) to illite-chlorite (stick-slip), and the latter with the onset of plastic flow in crustal rocks. For a mantle megathrust however, such inferences ought to be reconsidered, with the upper limit lying farther upwards, including at the seafloor ...
... with the dehydration transition from clay (stable sliding) to illite-chlorite (stick-slip), and the latter with the onset of plastic flow in crustal rocks. For a mantle megathrust however, such inferences ought to be reconsidered, with the upper limit lying farther upwards, including at the seafloor ...
Plate Tectonics
... occasionally think to yourself “That’s obvious.” In fact, you may have muttered the same sentiment during at least some portion of the opening exercise. For some, the following paragraphs may accomplish nothing more than adding descriptive terminology to intuitive knowledge. On the other hand, this ...
... occasionally think to yourself “That’s obvious.” In fact, you may have muttered the same sentiment during at least some portion of the opening exercise. For some, the following paragraphs may accomplish nothing more than adding descriptive terminology to intuitive knowledge. On the other hand, this ...
A relatively reduced Hadean continental crust and - HAL
... (McCammon, 2005; Rohrbach et al., 2007). The atmosphere also experienced changes in fO2, being initially low, and rising markedly at ~2.3 Ga, during the so-called Great Oxidation Event (GOE) (Collerson and Kamber, 1999; Holland, 2002; Zahnle et al., 2010), progressively reaching its present oxidati ...
... (McCammon, 2005; Rohrbach et al., 2007). The atmosphere also experienced changes in fO2, being initially low, and rising markedly at ~2.3 Ga, during the so-called Great Oxidation Event (GOE) (Collerson and Kamber, 1999; Holland, 2002; Zahnle et al., 2010), progressively reaching its present oxidati ...
Banda Arc Experiment—Transitions in the Banda Arc
... both in terms of frequency content and maximum amplitudes. These results do not appear to be a result of site/local geology effects, but suggest that we may be able to image a change in subducted lithospheric structure or composition along strike. Additional preliminary results on local and teleseis ...
... both in terms of frequency content and maximum amplitudes. These results do not appear to be a result of site/local geology effects, but suggest that we may be able to image a change in subducted lithospheric structure or composition along strike. Additional preliminary results on local and teleseis ...
Oceanic Lithosphere
... Assumption they are old oceanic lithosphere, so may not represent true oceanic lithosphere. Most likely to have formed in back-arc settings. ...
... Assumption they are old oceanic lithosphere, so may not represent true oceanic lithosphere. Most likely to have formed in back-arc settings. ...
Convergence of tectonic reconstructions and mantle - HAL-Insu
... by the incomplete preservation of very old seafloor, and therefore the timedependence of the production of new seafloor is controversial. There is no consensus on how much it has varied in the past 200 My, and how it could have fluctuated over longer timescales. We explore how seafloor spreading and ...
... by the incomplete preservation of very old seafloor, and therefore the timedependence of the production of new seafloor is controversial. There is no consensus on how much it has varied in the past 200 My, and how it could have fluctuated over longer timescales. We explore how seafloor spreading and ...
Densities of metapelitic rocks at high to ultrahigh
... pressures had increased to 12 kbar and more (T N 500 °C). This density increase is, among others, due to garnet- and Na-clinopyroxene-forming reactions as is best demonstrated by basic rock compositions transforming to eclogites which are significantly denser than the lherzolites of the Earth's uppe ...
... pressures had increased to 12 kbar and more (T N 500 °C). This density increase is, among others, due to garnet- and Na-clinopyroxene-forming reactions as is best demonstrated by basic rock compositions transforming to eclogites which are significantly denser than the lherzolites of the Earth's uppe ...
Structure of the Lithosphere and the Sedimentary Record: Where do
... Embayment is quite different from N.J. and requires several tectonic events, including a long-term subsidence event in the mid to Late Miocene. The center of the Eocene impact crater is showing the opposite sense of motion, suggesting an in-plane stress event. Besides the subducted Farallon slab are ...
... Embayment is quite different from N.J. and requires several tectonic events, including a long-term subsidence event in the mid to Late Miocene. The center of the Eocene impact crater is showing the opposite sense of motion, suggesting an in-plane stress event. Besides the subducted Farallon slab are ...
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... well new material from particular critical episodes of biotic change such as the Triassic-Jurassic boundary. There is now growing evidence that the Triassic-Jurassic mass extinction was of very large magnitude and very abrupt. The cause is as yet unknown as is the temporal scale outside the Newark b ...
... well new material from particular critical episodes of biotic change such as the Triassic-Jurassic boundary. There is now growing evidence that the Triassic-Jurassic mass extinction was of very large magnitude and very abrupt. The cause is as yet unknown as is the temporal scale outside the Newark b ...
Plate Tectonics: A Paradigm Under Threat
... boundaries, where they converge, diverge, or slide past one another. Such interactions are believed to be responsible for most of the seismic and volcanic activity of the earth. Plates cause mountains to rise where they push together, and continents to fracture and oceans to form where they rift apa ...
... boundaries, where they converge, diverge, or slide past one another. Such interactions are believed to be responsible for most of the seismic and volcanic activity of the earth. Plates cause mountains to rise where they push together, and continents to fracture and oceans to form where they rift apa ...
Density of Oceanic Crust
... Density of Oceanic Crust Background Certain properties of a substance are both distinctive and relatively easy to determine. Density, the ratio between a sample’s mass and volume at a specific temperature and pressure (like standard ambient temperature and pressure), is one such property. Regardless ...
... Density of Oceanic Crust Background Certain properties of a substance are both distinctive and relatively easy to determine. Density, the ratio between a sample’s mass and volume at a specific temperature and pressure (like standard ambient temperature and pressure), is one such property. Regardless ...
Plate Tectonics
... Fundamental Geologic Principle #1: Law of Original Horizontality As early as the 17th century, Nicolas Steno (1638-1686) fi rst proposed two concepts that fi eld geologists use every day. The fi rst concept stated that regardless of how intricately the sedimentary rocks exposed in an outcrop are ...
... Fundamental Geologic Principle #1: Law of Original Horizontality As early as the 17th century, Nicolas Steno (1638-1686) fi rst proposed two concepts that fi eld geologists use every day. The fi rst concept stated that regardless of how intricately the sedimentary rocks exposed in an outcrop are ...
(Cambridge: Cambridge University Press, 1988), 1-2, 37
... Alfred L. Wegener proposed in 1912 that all the continents had once been united, had broken apart, and had drifted through the ocean floor to their current locations. This 'Drift' theory' conflicted with the two prevailing views. 'Permanentists' believed that continents and ocean basins had remained ...
... Alfred L. Wegener proposed in 1912 that all the continents had once been united, had broken apart, and had drifted through the ocean floor to their current locations. This 'Drift' theory' conflicted with the two prevailing views. 'Permanentists' believed that continents and ocean basins had remained ...
Are lithospheres forever?
... the major TanLu fault zone suggest that this fault penetrates the lithospheric mantle and separates two Archaean terranes. In Ordovician time, each of these terranes had a thick cold, diamondiferous and typically Archaean type of SCLM, which probably had survived plate-tectonic movements for at leas ...
... the major TanLu fault zone suggest that this fault penetrates the lithospheric mantle and separates two Archaean terranes. In Ordovician time, each of these terranes had a thick cold, diamondiferous and typically Archaean type of SCLM, which probably had survived plate-tectonic movements for at leas ...
Opening of the North Atlantic and Norwegian
... Along the length of the divergent boundary of the Atlantic Mid-Ocean Ridge, the spreading center is offset by regularly spaced transform boundaries. These can be traced shoreward as deep-seated continental fracture zones beneath the sediment cover. Lister et al. (1986) described upper plate and lowe ...
... Along the length of the divergent boundary of the Atlantic Mid-Ocean Ridge, the spreading center is offset by regularly spaced transform boundaries. These can be traced shoreward as deep-seated continental fracture zones beneath the sediment cover. Lister et al. (1986) described upper plate and lowe ...
Earth`s Climate System Today
... Parts of Gondwana lay over the South Pole for ~100 my Evidence for glaciations exist Ordovician (~430 my) glaciations lasted less than 10 my and probably less than 1 my ...
... Parts of Gondwana lay over the South Pole for ~100 my Evidence for glaciations exist Ordovician (~430 my) glaciations lasted less than 10 my and probably less than 1 my ...
proposal
... In the following we will highlight some possibilities, either because there are already some projects running (or data have been acquired in recent years) ore because groups are very much interested in a particular area. These project ideas show the wealth of possibilities. Of course is this list of ...
... In the following we will highlight some possibilities, either because there are already some projects running (or data have been acquired in recent years) ore because groups are very much interested in a particular area. These project ideas show the wealth of possibilities. Of course is this list of ...
Trace element evidence from seamounts for recycled oceanic crust
... basalts provide fundamental constraints for models of earth’s differentiation and convection processes Že.g. w1–7x.. It is generally thought that mid-ocean ridge basalts ŽMORB. are derived from a mantle source that was depleted early in earth history to produce the continental crust. Hofmann and col ...
... basalts provide fundamental constraints for models of earth’s differentiation and convection processes Že.g. w1–7x.. It is generally thought that mid-ocean ridge basalts ŽMORB. are derived from a mantle source that was depleted early in earth history to produce the continental crust. Hofmann and col ...
Supercontinent
In geology, a supercontinent is the assembly of most or all of the Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many tectonicists such as P.F. Hoffman (1999) use the term ""supercontinent"" to mean ""a clustering of nearly all continents"". This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times. Using the first definition provided here, Gondwana (aka Gondwanaland) is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were in a close proximity to one another. This would classify Pangaea as a supercontinent. According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain.