Plate Tectonics: This works as a result of hot mantle asthenosphere
... veins. It is thought that these nodules are representative of the subcontinental mantle. This material seems to be rather refractory (could not yield much basalt on melting), but at the same time can be quite enriched in incompatible trace elements such as Sr, Ba, K, Rb and the light rare- earths. ( ...
... veins. It is thought that these nodules are representative of the subcontinental mantle. This material seems to be rather refractory (could not yield much basalt on melting), but at the same time can be quite enriched in incompatible trace elements such as Sr, Ba, K, Rb and the light rare- earths. ( ...
Origin of ocean island basalts: A new perspective from petrology
... Niu et al., 1999, 2002a] suggests that the source materials of these basalts are ancient and have developed their isotopic characteristics over a period in excess of 1.0 Gyr. If recycled ancient oceanic crusts played a role in the source regions of these oceanic basalts, then these ancient oceanic c ...
... Niu et al., 1999, 2002a] suggests that the source materials of these basalts are ancient and have developed their isotopic characteristics over a period in excess of 1.0 Gyr. If recycled ancient oceanic crusts played a role in the source regions of these oceanic basalts, then these ancient oceanic c ...
Gem Corundum in Alkali Basalt: Origin and Occurrence
... 'partial melting," in which minerals with the lowest n~eltingpoints within a rock melt first as the temperature rises, allows the generation of various types of magmas (such as rhyolite, andesite, and tholeiite] from some minerals; other minerals with higher melting points (i.e., that are still soli ...
... 'partial melting," in which minerals with the lowest n~eltingpoints within a rock melt first as the temperature rises, allows the generation of various types of magmas (such as rhyolite, andesite, and tholeiite] from some minerals; other minerals with higher melting points (i.e., that are still soli ...
Subduction zones: observations and
... boundary layer of the mantle. The conceptual picture of a plate as a passive raft that sits on top of the mantle neglects the fact that oceanic plates are created from and return to the mantle. It is generally accepted that the cold, negatively-buoyant slabs provide the dominant force that drives pl ...
... boundary layer of the mantle. The conceptual picture of a plate as a passive raft that sits on top of the mantle neglects the fact that oceanic plates are created from and return to the mantle. It is generally accepted that the cold, negatively-buoyant slabs provide the dominant force that drives pl ...
Furnace of Creation, Cradle of Destruction: A Journey to the
... and causing volcanoes to erupt. Volcanoes have always played a central role in the mythology of Japan—a land with more than a hundred active volcanoes. The most famous of all the Japanese volcanoes is the sacred Mount Fuji (Fujiyama—the Never Dying Mountain). This symmetrical cone-shaped peak is a n ...
... and causing volcanoes to erupt. Volcanoes have always played a central role in the mythology of Japan—a land with more than a hundred active volcanoes. The most famous of all the Japanese volcanoes is the sacred Mount Fuji (Fujiyama—the Never Dying Mountain). This symmetrical cone-shaped peak is a n ...
A source for Icelandic magmas in remelted Iapetus crust
... the MAR ran approximately longitudinally along the Caledonian collision zone. In the area where the Iceland volcanic region later formed, however, the MAR crossed the western frontal thrust, which extends from east Greenland to Britain, and formed a new rift within the continental lithosphere of Gre ...
... the MAR ran approximately longitudinally along the Caledonian collision zone. In the area where the Iceland volcanic region later formed, however, the MAR crossed the western frontal thrust, which extends from east Greenland to Britain, and formed a new rift within the continental lithosphere of Gre ...
Barrovian metamorphism in the central Kootenay Arc, British
... fault (PTF). These Palaeocene–Eocene normal faults truncate Early Cretaceous isogradic surfaces and juxtapose regions with contrasting structural and metamorphic histories. Low-grade rocks in the hanging wall of the GFZ underwent peak regional metamorphism during the Early–Middle Jurassic, prior to ...
... fault (PTF). These Palaeocene–Eocene normal faults truncate Early Cretaceous isogradic surfaces and juxtapose regions with contrasting structural and metamorphic histories. Low-grade rocks in the hanging wall of the GFZ underwent peak regional metamorphism during the Early–Middle Jurassic, prior to ...
The Bent Hawaiian-Emperor Hotspot Track
... Australia, and then through Lord (red); (ii) Australia-Lord Howe Rise circuit (green); (iii) Australia-Lord Howe Rise circuit modified with a revised AntarcticHowe Rise (Fig. 2, B and C). In the Australia spreading history [from (17)] (blue). Note that path (iii) converges to path (i). (D) Trace tha ...
... Australia, and then through Lord (red); (ii) Australia-Lord Howe Rise circuit (green); (iii) Australia-Lord Howe Rise circuit modified with a revised AntarcticHowe Rise (Fig. 2, B and C). In the Australia spreading history [from (17)] (blue). Note that path (iii) converges to path (i). (D) Trace tha ...
Beyond Plate Tectonics: “Plate” Dynamics
... forty years;26 this caught on like wildfire27-29 and became the reigning paradigm, temporarily replacing the more realistic alternative of a fault-based origin. Plumes fail on the basis of the geology and on the basis of first principles. In terms of first principles: “Mantle plumes” don’t burn thro ...
... forty years;26 this caught on like wildfire27-29 and became the reigning paradigm, temporarily replacing the more realistic alternative of a fault-based origin. Plumes fail on the basis of the geology and on the basis of first principles. In terms of first principles: “Mantle plumes” don’t burn thro ...
Mineral Hunters Guide: Ruggles Mine Edition
... Sulfates also occur in hydrothermal vein systems as gangue minerals along with sulfide ore minerals. Another occurrence is as secondary oxidation products of original sulfide minerals. Common sulfates include anhydrite (calcium sulfate), celestine (strontium sulfate), barite (barium sulfate), and gy ...
... Sulfates also occur in hydrothermal vein systems as gangue minerals along with sulfide ore minerals. Another occurrence is as secondary oxidation products of original sulfide minerals. Common sulfates include anhydrite (calcium sulfate), celestine (strontium sulfate), barite (barium sulfate), and gy ...
North Atlantic Igneous Province: A Review of
... The mantle plume concept is currently being challenged as an explanation for North Atlantic Igneous Province formation. Alternative models have been suggested, including delamination, meteorite impact, small-scale rift-related convection, and chemical mantle heterogeneities. We review available data ...
... The mantle plume concept is currently being challenged as an explanation for North Atlantic Igneous Province formation. Alternative models have been suggested, including delamination, meteorite impact, small-scale rift-related convection, and chemical mantle heterogeneities. We review available data ...
The evolving nature of terrestrial crust from the Hadean, through the
... variations of a few parts per million (ppm) is the fact that the early geologists who set foot on Archaean cratons instinctively knew that they were dealing with ‘different’ rocks, even though their mineralogy looked altogether familiar. Having originally been trained as a structural-metamorphic geo ...
... variations of a few parts per million (ppm) is the fact that the early geologists who set foot on Archaean cratons instinctively knew that they were dealing with ‘different’ rocks, even though their mineralogy looked altogether familiar. Having originally been trained as a structural-metamorphic geo ...
Early Ordovician rifting of Avalonia and birth of the Rheic Ocean: U
... Previous studies have shown that single-grain detrital zircon geochronology is a useful method of dating and tracing crustal processes because it can provide information that can be used to: (1) assist stratigraphic correlation of monotonous sedimentary sequences that lack distinctive marker units ( ...
... Previous studies have shown that single-grain detrital zircon geochronology is a useful method of dating and tracing crustal processes because it can provide information that can be used to: (1) assist stratigraphic correlation of monotonous sedimentary sequences that lack distinctive marker units ( ...
The origin and evolution of the Earth`s continental crust
... The continental crust constitutes only 0.40 per cent of the mass of the Earth. Although it might seem so small that it could be ignored to a first approximation, the crust contains over 30 per cent of the bulk Earth budget for several of the most incompatible elements, such as Cs, Rb, K, U, Th and L ...
... The continental crust constitutes only 0.40 per cent of the mass of the Earth. Although it might seem so small that it could be ignored to a first approximation, the crust contains over 30 per cent of the bulk Earth budget for several of the most incompatible elements, such as Cs, Rb, K, U, Th and L ...
Geology - Archean Environment: The habitat of early life.
... the lithosphere. During this period, there has been debate about when Earth adopted a plate tectonics mode of behavior. The appearance of blueschist facies series metamorphism in the Neoproterozoic rock record is regarded as one indicator of the beginning of the modern subduction cycle (Stern, 2005) ...
... the lithosphere. During this period, there has been debate about when Earth adopted a plate tectonics mode of behavior. The appearance of blueschist facies series metamorphism in the Neoproterozoic rock record is regarded as one indicator of the beginning of the modern subduction cycle (Stern, 2005) ...
Plate Tectonics
... Ordinarily, science progresses by incremental improvements in data and theory. This paper is about how science advances through the testing, and discarding of theories, or conventional wisdom. Plate tectonic theory is currently undergoing such a revolution. This paper explains why plate tectonic the ...
... Ordinarily, science progresses by incremental improvements in data and theory. This paper is about how science advances through the testing, and discarding of theories, or conventional wisdom. Plate tectonic theory is currently undergoing such a revolution. This paper explains why plate tectonic the ...
The OIB paradox - Do plumes exist?
... lowest values, most still have ∆Nb>0 suggesting that a relatively Nb-rich component (probably subducted ocean crust) is present in all OIB sources. The OIB source components seem to be present on all scales, from small streaks or blobs of enriched material (with positive ∆Nb) carried in the upper ma ...
... lowest values, most still have ∆Nb>0 suggesting that a relatively Nb-rich component (probably subducted ocean crust) is present in all OIB sources. The OIB source components seem to be present on all scales, from small streaks or blobs of enriched material (with positive ∆Nb) carried in the upper ma ...
Linking continental drift, plate tectonics and the thermal state of the
... The principal aspects of the dynamic feedback between mantle convection and continents have been investigated and described, but very few studies propose a quantitative framework that allows comparison with geological observations and detailed convection characteristics. Recently, on the basis of 3D ...
... The principal aspects of the dynamic feedback between mantle convection and continents have been investigated and described, but very few studies propose a quantitative framework that allows comparison with geological observations and detailed convection characteristics. Recently, on the basis of 3D ...
Mantle mixing - Earth and Environmental Sciences
... quite well if the lithosphere and lower mantle are one or two orders of magnitude more viscous than the upper mantle. This is in line with earlier estimates for the viscosity of the lower mantle based on geoid and gravity anomalies above subduction zones (Hager and Richards, 1989) and geodynamic in ...
... quite well if the lithosphere and lower mantle are one or two orders of magnitude more viscous than the upper mantle. This is in line with earlier estimates for the viscosity of the lower mantle based on geoid and gravity anomalies above subduction zones (Hager and Richards, 1989) and geodynamic in ...
Chapter 1- INTRODUCTION 1.1. Mantle Rocks This study is
... inner core and an outer liquid core, which is the main candidate to be responsible of the Earth’s magnetic field. The mantle-core transition occurs ~2800 km deep. The seismic response also distinguishes seismic discontinuities at 410 km and 660 km depth that mark the expected phase transformations a ...
... inner core and an outer liquid core, which is the main candidate to be responsible of the Earth’s magnetic field. The mantle-core transition occurs ~2800 km deep. The seismic response also distinguishes seismic discontinuities at 410 km and 660 km depth that mark the expected phase transformations a ...
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.