the fate of subducted oceanic crust and the origin
... composition had been suggested from crust-mantle evolution models in which the upper mantle MORB-source was considered the residue from formation of the continental crust (e.g. Allègre 1982). A primitive lower mantle had also been suggested from the chondritic Nd-Sr isotope compositions measured in ...
... composition had been suggested from crust-mantle evolution models in which the upper mantle MORB-source was considered the residue from formation of the continental crust (e.g. Allègre 1982). A primitive lower mantle had also been suggested from the chondritic Nd-Sr isotope compositions measured in ...
Mapping of Structurally Controlled Uranium Mineralization in
... been investigated through several studies dealing with its magma source, mineralogy, radioactivity and physical dressing [10-21]. The use of gamma ray spectrometry as a tool for mapping and exploring radioelement concentrations has found widespread acceptance in diverse fields. The method has evolve ...
... been investigated through several studies dealing with its magma source, mineralogy, radioactivity and physical dressing [10-21]. The use of gamma ray spectrometry as a tool for mapping and exploring radioelement concentrations has found widespread acceptance in diverse fields. The method has evolve ...
Intrusive and Extrusive Igneous Rocks - cK-12
... These rocks don’t even look like they’re the same type! They are, at least in the same way that fish and mice are both vertebrates. They both cooled from magma, but the similarities end there. Can you tell what’s different? Cooling ...
... These rocks don’t even look like they’re the same type! They are, at least in the same way that fish and mice are both vertebrates. They both cooled from magma, but the similarities end there. Can you tell what’s different? Cooling ...
Osmium-isotope variations in Hawaiian lavas: evidence
... lavas possess systematically higher δ18 O values than olivines from other Hawaiian volcanoes (e.g., Fig. 3) or from upper mantle peridotites. Koolau olivines have δ18 O D 5.7–6.0‰, compared with 5.2 š 0.1‰ for olivines in equilibrium with upper mantle peridotites or fresh MORB [5,35]. The elevated δ ...
... lavas possess systematically higher δ18 O values than olivines from other Hawaiian volcanoes (e.g., Fig. 3) or from upper mantle peridotites. Koolau olivines have δ18 O D 5.7–6.0‰, compared with 5.2 š 0.1‰ for olivines in equilibrium with upper mantle peridotites or fresh MORB [5,35]. The elevated δ ...
Intrusive and Extrusive Igneous Rocks
... These rocks don’t even look like they’re the same type! They are, at least in the same way that fish and mice are both vertebrates. They both cooled from magma, but the similarities end there. Can you tell what’s different? Cooling ...
... These rocks don’t even look like they’re the same type! They are, at least in the same way that fish and mice are both vertebrates. They both cooled from magma, but the similarities end there. Can you tell what’s different? Cooling ...
Differentiated impact melt sheets may be a
... effects of the anomalously thick overlying crater fill; and (4) our new SIMS Ti and T values for the Sudbury impact melt sheet fully overlap with the range of values observed in detrital Hadean zircons. In their Comment, Wielicki et al. used a particular statistical method (p-values for Kolmogorov-S ...
... effects of the anomalously thick overlying crater fill; and (4) our new SIMS Ti and T values for the Sudbury impact melt sheet fully overlap with the range of values observed in detrital Hadean zircons. In their Comment, Wielicki et al. used a particular statistical method (p-values for Kolmogorov-S ...
Dynamic Earth: crustal and mantle heterogeneity
... Both geophysical and geochemical techniques contribute to understanding of the complex nature of the Earth’s mantle and the processes operating within it, but these two sources of information provide very different viewpoints on structure. Most geophysical evidence provides an instantaneous snapshot ...
... Both geophysical and geochemical techniques contribute to understanding of the complex nature of the Earth’s mantle and the processes operating within it, but these two sources of information provide very different viewpoints on structure. Most geophysical evidence provides an instantaneous snapshot ...
joseph barrell - National Academy of Sciences
... Barrell was first an engineer in Geology, since his training had led him to precise habits of thought, and it is this characteristic that especially distinguishes his work. He himself has said that "geologic research in the past generation has been passing out of the qualitative stage and has partak ...
... Barrell was first an engineer in Geology, since his training had led him to precise habits of thought, and it is this characteristic that especially distinguishes his work. He himself has said that "geologic research in the past generation has been passing out of the qualitative stage and has partak ...
Basaltic and Gabbroic Rocks
... Volcanism occurs at three different settings on the ocean floor. 1. Oceanic Ridges - these are the oceanic spreading centers where a relatively small range of chemical compositions of basalts are erupted to form the basaltic layer of the oceanic crust. This chemical type of basalt is referred to as ...
... Volcanism occurs at three different settings on the ocean floor. 1. Oceanic Ridges - these are the oceanic spreading centers where a relatively small range of chemical compositions of basalts are erupted to form the basaltic layer of the oceanic crust. This chemical type of basalt is referred to as ...
TECTONIC PLATES
... The crust beneath Earth’s continents is less dense than the crust beneath the ocean. As a result, at subduction zones continental crust is not usually forced deep enough into the mantle to be melted. Instead, the continents move or drift across Earth’s surface over time. The continents have not alwa ...
... The crust beneath Earth’s continents is less dense than the crust beneath the ocean. As a result, at subduction zones continental crust is not usually forced deep enough into the mantle to be melted. Instead, the continents move or drift across Earth’s surface over time. The continents have not alwa ...
P R E L I M I N A R Y P R O O F S Unpublished Work © 2008 by
... History. Within the uppermost portion of the mantle, near the surface of Earth our terminology becomes more complicated. For example, the cool, strong outermost layer of Earth is also called the lithosphere (lithos means “rock”). It is much stronger and more rigid than the material underlying it, th ...
... History. Within the uppermost portion of the mantle, near the surface of Earth our terminology becomes more complicated. For example, the cool, strong outermost layer of Earth is also called the lithosphere (lithos means “rock”). It is much stronger and more rigid than the material underlying it, th ...
the dynamic earth - Mater Academy Lakes High School
... The evidence that Wegener needed to support his hypothesis was discovered nearly two decades after his death. The evidence lay on the ocean floor. In 1947, a group of scientists set out to map the Mid-Atlantic Ridge. The Mid-Atlantic Ridge is part of a system of mid-ocean ridges, which are undersea ...
... The evidence that Wegener needed to support his hypothesis was discovered nearly two decades after his death. The evidence lay on the ocean floor. In 1947, a group of scientists set out to map the Mid-Atlantic Ridge. The Mid-Atlantic Ridge is part of a system of mid-ocean ridges, which are undersea ...
MORB13
... Many MORB basalts (especially EMORB) have (Sm/Yb)n ratios of 1.3 to 1.5, suggesting slight depletion in the heavy rare earths (HREE). This has been interpreted as a residual garnet effect. The effect is small, however, and MORB have relatively high and unfractionated HREE in comparison to all OIB ba ...
... Many MORB basalts (especially EMORB) have (Sm/Yb)n ratios of 1.3 to 1.5, suggesting slight depletion in the heavy rare earths (HREE). This has been interpreted as a residual garnet effect. The effect is small, however, and MORB have relatively high and unfractionated HREE in comparison to all OIB ba ...
IgPetMORB13
... Approximately 60% of the surface of the Earth is composed of basalt or its gabbroic intrusive equivalent, which are composed largely of pyroxene and feldspar (< 50%). The oceanic crust averages about 6 km in thickness, but ranges from 0 km at mid-ocean ridges to 10 km near the continents. Ophiolites ...
... Approximately 60% of the surface of the Earth is composed of basalt or its gabbroic intrusive equivalent, which are composed largely of pyroxene and feldspar (< 50%). The oceanic crust averages about 6 km in thickness, but ranges from 0 km at mid-ocean ridges to 10 km near the continents. Ophiolites ...
The Rock Cycle
... located at depths ranging from near the surface to about 150 km below the surface. Temperatures of magmas range from about 650°C to 1,200°C, depending on their chemical compositions and pressures exerted on them. The heat that melts rocks comes from sources within Earth’s interior. One source is the ...
... located at depths ranging from near the surface to about 150 km below the surface. Temperatures of magmas range from about 650°C to 1,200°C, depending on their chemical compositions and pressures exerted on them. The heat that melts rocks comes from sources within Earth’s interior. One source is the ...
Continent formation through time
... proportion of continental arcs from old to new. However, if microcratons are ignored, as these themselves must have originated as crust formed in a particular setting, then it can be seen that the general dominance of continental arc settings has not changed greatly through time. Extending this diag ...
... proportion of continental arcs from old to new. However, if microcratons are ignored, as these themselves must have originated as crust formed in a particular setting, then it can be seen that the general dominance of continental arc settings has not changed greatly through time. Extending this diag ...
Evolution of young oceanic lithosphere and the meaning of seafloor
... depth, respectively. The model spans from the seafloor (z = 0) to the depth of 300 km, which is sufficiently deep to model half-space cooling for the duration of 100 Myr. The above equation is solved with a finite difference approximation, using the vertical spacing of 1 km and the time step of 5000 year ...
... depth, respectively. The model spans from the seafloor (z = 0) to the depth of 300 km, which is sufficiently deep to model half-space cooling for the duration of 100 Myr. The above equation is solved with a finite difference approximation, using the vertical spacing of 1 km and the time step of 5000 year ...
Next Generation Sunshine State Standards Chapter 3
... tually, all of the liquid is transformed into a solid mass of inmasses within the upper crust have a fine-grained texture, terlocking crystals. The rate of cooling strongly influences crystal size. If magma cools very slowly, relatively few centers of crystal growth develop. Slow cooling also allows ...
... tually, all of the liquid is transformed into a solid mass of inmasses within the upper crust have a fine-grained texture, terlocking crystals. The rate of cooling strongly influences crystal size. If magma cools very slowly, relatively few centers of crystal growth develop. Slow cooling also allows ...
Age of the Earth
The age of the Earth is 4.54 ± 0.05 billion years (4.54 × 109 years ± 1%). This age is based on evidence from radiometric age dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.Following the development of radiometric age dating in the early 20th century, measurements of lead in uranium-rich minerals showed that some were in excess of a billion years old.The oldest such minerals analyzed to date—small crystals of zircon from the Jack Hills of Western Australia—are at least 4.404 billion years old. Comparing the mass and luminosity of the Sun to those of other stars, it appears that the Solar System cannot be much older than those rocks. Calcium-aluminium-rich inclusions – the oldest known solid constituents within meteorites that are formed within the Solar System – are 4.567 billion years old, giving an age for the solar system and an upper limit for the age of Earth.It is hypothesised that the accretion of Earth began soon after the formation of the calcium-aluminium-rich inclusions and the meteorites. Because the exact amount of time this accretion process took is not yet known, and the predictions from different accretion models range from a few millions up to about 100 million years, the exact age of Earth is difficult to determine. It is also difficult to determine the exact age of the oldest rocks on Earth, exposed at the surface, as they are aggregates of minerals of possibly different ages.