Composition of the depleted mantle
... 1985]. One possibility is that the DM is an open system whereby U, Th and Pb have different exchange rates, and therefore have different residence times in non-DM mantle and CC [Galer et al., 1989; Galer and O’Nions, 1985; Paul et al., 2002]. A second class of models argues that the discrepancy betw ...
... 1985]. One possibility is that the DM is an open system whereby U, Th and Pb have different exchange rates, and therefore have different residence times in non-DM mantle and CC [Galer et al., 1989; Galer and O’Nions, 1985; Paul et al., 2002]. A second class of models argues that the discrepancy betw ...
Can slab melting be caused by flat subduction
... Although prolonged flat subduction generally produces a cooler thermal structure (i.e., both upper and lower lithospheres are cooler) (Fig. 3D), (Sacks, 1983; Vlaar, 1983; Henry and Pollack, 1988; Dumitru et al., 1991), during the initiation of flat subduction the leading edge of the undersliding sl ...
... Although prolonged flat subduction generally produces a cooler thermal structure (i.e., both upper and lower lithospheres are cooler) (Fig. 3D), (Sacks, 1983; Vlaar, 1983; Henry and Pollack, 1988; Dumitru et al., 1991), during the initiation of flat subduction the leading edge of the undersliding sl ...
Convergent plate margin dynamics
... landmasses. Wegener compiled much of the pre-drift geological data to show that the continuity of older structures, formations and fossil floras and faunas located along the shorelines of many continents could be explained on a pre-drift reconstruction of Pangea. The geoscience community received the ...
... landmasses. Wegener compiled much of the pre-drift geological data to show that the continuity of older structures, formations and fossil floras and faunas located along the shorelines of many continents could be explained on a pre-drift reconstruction of Pangea. The geoscience community received the ...
CK-12 Earth Science For High School - Workbook
... Read this passage based on the text and answer the questions that follow. The Importance of Community in Science Although each scientist may perform experiments in her lab alone or with a few helpers, she will write up her results and present her work to the community of scientists in her field. Ini ...
... Read this passage based on the text and answer the questions that follow. The Importance of Community in Science Although each scientist may perform experiments in her lab alone or with a few helpers, she will write up her results and present her work to the community of scientists in her field. Ini ...
Convergence of tectonic reconstructions and mantle - HAL-Insu
... involving changes in ridge length and global tectonic reorganisations. Although independent, both convection models and kinematic reconstructions suggest that changes in ridge length are at least as significant as spreading rate fluctuations in driving changes in the seafloor area-age distribution t ...
... involving changes in ridge length and global tectonic reorganisations. Although independent, both convection models and kinematic reconstructions suggest that changes in ridge length are at least as significant as spreading rate fluctuations in driving changes in the seafloor area-age distribution t ...
FREE Sample Here
... A) a massive nickle iron asteroid that was the nucleus upon which Earth condensed B) the left over nickle and iron that would not fit into the earlier formed crust and mantle C) molten iron and nickle that separated from silicates and sank due to its higher density D) high density radioactive carbon ...
... A) a massive nickle iron asteroid that was the nucleus upon which Earth condensed B) the left over nickle and iron that would not fit into the earlier formed crust and mantle C) molten iron and nickle that separated from silicates and sank due to its higher density D) high density radioactive carbon ...
Fluid release from the subducted Cocos plate and partial melting of
... Belt (TMVB). The isolated conductivity anomalies in the southern profile are interpreted as slab fluids stored in the overlying deep continental crust. These fluids were released by progressive metamorphic dehydration of the basaltic oceanic crust. The conductivity anomalies may be related to the ma ...
... Belt (TMVB). The isolated conductivity anomalies in the southern profile are interpreted as slab fluids stored in the overlying deep continental crust. These fluids were released by progressive metamorphic dehydration of the basaltic oceanic crust. The conductivity anomalies may be related to the ma ...
Fluid release from the subducted Cocos plate and
... Belt (TMVB). The isolated conductivity anomalies in the southern profile are interpreted as slab fluids stored in the overlying deep continental crust. These fluids were released by progressive metamorphic dehydration of the basaltic oceanic crust. The conductivity anomalies may be related to the ma ...
... Belt (TMVB). The isolated conductivity anomalies in the southern profile are interpreted as slab fluids stored in the overlying deep continental crust. These fluids were released by progressive metamorphic dehydration of the basaltic oceanic crust. The conductivity anomalies may be related to the ma ...
Earth`s first two billion years—The era of internally
... Pearce and Cann (1973). When, as often is the case, the Archean analyses cannot be fitted into desired chemotectonic pigeonholes, hypothetical mixtures and derivatives of criteria are devised to postulate hybrid tectonic settings with no modern analogues. That the discriminants for modern rocks lack ...
... Pearce and Cann (1973). When, as often is the case, the Archean analyses cannot be fitted into desired chemotectonic pigeonholes, hypothetical mixtures and derivatives of criteria are devised to postulate hybrid tectonic settings with no modern analogues. That the discriminants for modern rocks lack ...
Erosion, Himalayan Geodynamics, and the Geomorphology of
... Nanga Parbat which show the massif to be developed atop weak crust that is hot, dry, and thin by overthickened Himalayan standards (Meltzer et al., 1998; Park and Mackie, 2000). Coupled thermal-mechanical-erosional modeling (Koons , 1998) shows that in a deforming orogen, local rheological variation ...
... Nanga Parbat which show the massif to be developed atop weak crust that is hot, dry, and thin by overthickened Himalayan standards (Meltzer et al., 1998; Park and Mackie, 2000). Coupled thermal-mechanical-erosional modeling (Koons , 1998) shows that in a deforming orogen, local rheological variation ...
Origin of Mesoproterozoic A-type granites in Laurentia
... Laurentian A-type granitoids that must be explained by any petrogenetic model include: (1) low degree of partial melting (10–30%; [1]), but a high fraction of juvenile crustal source material; (2) Nd-, Sr- and Oisotope compositions that indicate derivation from 1.9 to 1.7 Ga crust with little eviden ...
... Laurentian A-type granitoids that must be explained by any petrogenetic model include: (1) low degree of partial melting (10–30%; [1]), but a high fraction of juvenile crustal source material; (2) Nd-, Sr- and Oisotope compositions that indicate derivation from 1.9 to 1.7 Ga crust with little eviden ...
Mantle plumes and dynamics of the Earth interior — towards a new
... plumes as the assumption of the convection process in the Earth’s mantle, mantle convection versus data on both its viscosity and the existence of global seismic discontinuities, possibility of horizontal displacements of lithospheric plates above the discontinuous LVZ zone which disappears under de ...
... plumes as the assumption of the convection process in the Earth’s mantle, mantle convection versus data on both its viscosity and the existence of global seismic discontinuities, possibility of horizontal displacements of lithospheric plates above the discontinuous LVZ zone which disappears under de ...
Radiogenic Isotope Geochemistry of the Mantle
... A principal objective of geology is to understand how the Earth evolved from its initial state to its present one. Radiogenic isotope geochemistry is uniquely suited for this sort of study because an isotope ratio such as 87Sr/86Sr is a function not only of the differentiation processes which fracti ...
... A principal objective of geology is to understand how the Earth evolved from its initial state to its present one. Radiogenic isotope geochemistry is uniquely suited for this sort of study because an isotope ratio such as 87Sr/86Sr is a function not only of the differentiation processes which fracti ...
GEO144_mid_term_I_so..
... C) rift zones along mid-ocean ridges D) sites of long-lived, hot spot volcanism in the ocean basins (1) 2 pts. The ________ is an example of an active, continent-continent collision. A) westward movement of the South American plate over the Nazca plate B) Arabian Peninsula slamming into North Africa ...
... C) rift zones along mid-ocean ridges D) sites of long-lived, hot spot volcanism in the ocean basins (1) 2 pts. The ________ is an example of an active, continent-continent collision. A) westward movement of the South American plate over the Nazca plate B) Arabian Peninsula slamming into North Africa ...
Thick-Structured Proterozoic Lithosphere of the Rocky Mountain
... Fig. 4), and it has a 45° dip. The second possibility is dismissed because this feature is more than 1000 km inboard of the western United States plate margin and orientated at a high angle to the Cenozoic plate boundary. Therefore, because the velocity anomaly is correlated directly with an old sut ...
... Fig. 4), and it has a 45° dip. The second possibility is dismissed because this feature is more than 1000 km inboard of the western United States plate margin and orientated at a high angle to the Cenozoic plate boundary. Therefore, because the velocity anomaly is correlated directly with an old sut ...
Geochemistry of near-EPR seamounts: importance of source vs
... lavas erupted on the nearby EPR axis. These isotopic ratios correlate with each other, with the abundances and ratios of incompatible elements, with the abundances of measured major elements such as MgO, CaO, Na2 O and TiO2 contents, and with the abundances and ratios of major elements corrected for ...
... lavas erupted on the nearby EPR axis. These isotopic ratios correlate with each other, with the abundances and ratios of incompatible elements, with the abundances of measured major elements such as MgO, CaO, Na2 O and TiO2 contents, and with the abundances and ratios of major elements corrected for ...
middle cambrian stratigraphy in the røyken area, oslo region
... Cambrian rocks are penetrated by numerous sills, some of them of different types to those found at Slemmestad. BRøGGER (1882) has given a description of some of the types, which occur both as sills and dikes. The tectonics of the oldest beds are therefore very compli cated, and in the same way as a ...
... Cambrian rocks are penetrated by numerous sills, some of them of different types to those found at Slemmestad. BRøGGER (1882) has given a description of some of the types, which occur both as sills and dikes. The tectonics of the oldest beds are therefore very compli cated, and in the same way as a ...
On the origin of noble gases in mantle plumes
... a residence time F =M comparable with the age of the Earth (where M is the mantle mass and F the mass ®ux of subducted material). Stirring is certainly more complex than simple random redistribution, but all numerical simulations agree that a small but signi cant volume of material (from 10 to 35%) ...
... a residence time F =M comparable with the age of the Earth (where M is the mantle mass and F the mass ®ux of subducted material). Stirring is certainly more complex than simple random redistribution, but all numerical simulations agree that a small but signi cant volume of material (from 10 to 35%) ...
Synthesis of Results From the CD-ROM Experiment
... An alternative hypothesis, presented in this paper, is that the lithospheric mantle under the Rocky Mountains, although extensively modified and reactivated by younger events, is primarily Proterozoic in age, and that Proterozoic structures are controlling some of the major velocity contrasts in the ...
... An alternative hypothesis, presented in this paper, is that the lithospheric mantle under the Rocky Mountains, although extensively modified and reactivated by younger events, is primarily Proterozoic in age, and that Proterozoic structures are controlling some of the major velocity contrasts in the ...
Earth and Planetary Science Letters Recycled crust in the
... to correct for instrumental drift. A summary of the primary standards, statistics for the secondary standards, and statistics for the olivine analyses are given in Table S1B in Supplementary Materials. All oxide totals from the olivine analyses were normalized to 100%. Olivine data are also reported ...
... to correct for instrumental drift. A summary of the primary standards, statistics for the secondary standards, and statistics for the olivine analyses are given in Table S1B in Supplementary Materials. All oxide totals from the olivine analyses were normalized to 100%. Olivine data are also reported ...
Recycled crust in the Galápagos Plume source at 70 Ma
... additionally, we examine olivines from the older CLIP lavas from Curacao in order to provide constraints on how the source lithology changed from ∼90 to 70 Ma. A detailed description of the method that was adopted for petrological modeling was provided previously (Herzberg, 2011; Herzberg et al., 20 ...
... additionally, we examine olivines from the older CLIP lavas from Curacao in order to provide constraints on how the source lithology changed from ∼90 to 70 Ma. A detailed description of the method that was adopted for petrological modeling was provided previously (Herzberg, 2011; Herzberg et al., 20 ...
sample test
... Magnetic stripes in the oceanic crust show the direction of Earth’s magnetic field when the oceanic crust formed. Oceanic crust contains iron. As new crust cools and hardens, the iron atoms line up according to the direction of Earth’s magnetic field at that time. But Earth’s magnetic field occasion ...
... Magnetic stripes in the oceanic crust show the direction of Earth’s magnetic field when the oceanic crust formed. Oceanic crust contains iron. As new crust cools and hardens, the iron atoms line up according to the direction of Earth’s magnetic field at that time. But Earth’s magnetic field occasion ...
Earth & Space Science An open source text edited by MPS teachers
... This book is adapted primarily from the excellent materials created by the CK-12 Foundation – http://ck12.org/ – which are licensed under the Creative Commons Attribution NonCommercial ShareAlike license. We express our gratitude to the CK-12 Foundation for their pioneering work on secondary scienc ...
... This book is adapted primarily from the excellent materials created by the CK-12 Foundation – http://ck12.org/ – which are licensed under the Creative Commons Attribution NonCommercial ShareAlike license. We express our gratitude to the CK-12 Foundation for their pioneering work on secondary scienc ...
Evolution of the continental crust
... OIB and IAB end-members (Table 1), but their apparent proportions are much less significant than the proposal that the model new continental crust lies at the intersection of the two arrays. As highlighted by Rudnick13, the striking conclusion from Fig. 1 is that the bulk continental crust cannot be ...
... OIB and IAB end-members (Table 1), but their apparent proportions are much less significant than the proposal that the model new continental crust lies at the intersection of the two arrays. As highlighted by Rudnick13, the striking conclusion from Fig. 1 is that the bulk continental crust cannot be ...
Experimental_laboratory_files/2004_The source of Granites
... However, due to the fact that granite rocks have a composition close to the thermodynamic minimum in the system quartz–albite–orthoclase (Tuttle & Bowen 1958; Holtz et al. 2001a), a wide variety of rock compositions are theoretically suitable as source materials for the production of granite melts u ...
... However, due to the fact that granite rocks have a composition close to the thermodynamic minimum in the system quartz–albite–orthoclase (Tuttle & Bowen 1958; Holtz et al. 2001a), a wide variety of rock compositions are theoretically suitable as source materials for the production of granite melts u ...
History of Earth
The history of Earth concerns the development of the planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's past. The age of Earth is approximately one-third of the age of the universe. An immense amount of biological and geological change has occurred in that time span.Earth formed around 4.54 billion years ago by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere, but it contained almost no oxygen and would have been toxic to humans and most modern life. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. One very large collision is thought to have been responsible for tilting the Earth at an angle and forming the Moon. Over time, the planet cooled and formed a solid crust, allowing liquid water to exist on the surface.The first life forms appeared between 3.8 and 3.5 billion years ago. The earliest evidences for life on Earth are graphite found to be biogenic in 3.7-billion-year-old metasedimentary rocks discovered in Western Greenland and microbial mat fossils found in 3.48-billion-year-old sandstone discovered in Western Australia. Photosynthetic life appeared around 2 billion years ago, enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago, when complex multicellular life arose. During the Cambrian period it experienced a rapid diversification into most major phyla. More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described.Geological change has been constantly occurring on Earth since the time of its formation and biological change since the first appearance of life. Species continuously evolve, taking on new forms, splitting into daughter species, or going extinct in response to an ever-changing planet. The process of plate tectonics has played a major role in the shaping of Earth's oceans and continents, as well as the life they harbor. The biosphere, in turn, has had a significant effect on the atmosphere and other abiotic conditions on the planet, such as the formation of the ozone layer, the proliferation of oxygen, and the creation of soil.