Fig. 1
... Whitmarsh et al., 2001). However, it is difficult to interpret the geological record unambiguously because the tectonic activity that characterised breakup has long-since ceased and the continent– ocean transition (COT) is sometimes masked by up to several kilometres of late-to-syn rift interbedded b ...
... Whitmarsh et al., 2001). However, it is difficult to interpret the geological record unambiguously because the tectonic activity that characterised breakup has long-since ceased and the continent– ocean transition (COT) is sometimes masked by up to several kilometres of late-to-syn rift interbedded b ...
Chapter 1- INTRODUCTION 1.1. Mantle Rocks This study is
... but the melt removal causes the continental lithospheric mantle to become cold and strong but also buoyant compared to convecting mantle, characteristic caused by the loss of heavy elements as Fe and Ca. These characteristics allow thick sections of cold mantle to persist beneath continental crust i ...
... but the melt removal causes the continental lithospheric mantle to become cold and strong but also buoyant compared to convecting mantle, characteristic caused by the loss of heavy elements as Fe and Ca. These characteristics allow thick sections of cold mantle to persist beneath continental crust i ...
Plate Tectonics - The Open University
... considerable amount of data in a concerted exposition of his theory, and suggested that during the late Permian all the continents were once assembled into a supercontinent that he named Pangaea, meaning 'all Earth'. He drew maps showing how the continents have since moved to today's positions. He p ...
... considerable amount of data in a concerted exposition of his theory, and suggested that during the late Permian all the continents were once assembled into a supercontinent that he named Pangaea, meaning 'all Earth'. He drew maps showing how the continents have since moved to today's positions. He p ...
Lithosphere delamination in continental collisional orogens: A
... numerical studies, lithosphere delamination was usually induced by prescribed weak zones in the initial model configuration [e.g., Bird, 1979; Schott and Schmeling, 1998; Gogus and Pysklywec, 2008a, 2008b; Bajolet et al., 2012; Wang and Currie, 2015]. These models focus on the consequences of lithosp ...
... numerical studies, lithosphere delamination was usually induced by prescribed weak zones in the initial model configuration [e.g., Bird, 1979; Schott and Schmeling, 1998; Gogus and Pysklywec, 2008a, 2008b; Bajolet et al., 2012; Wang and Currie, 2015]. These models focus on the consequences of lithosp ...
ABSTRACT The gneiss complex around and north of Pouso Alegre
... feeling that we are still probing in the dark, and in addition to trying to answer the questions in a geochmeical way, one is plagued by doubts such as arise from our ignorance of the role of physical properties of crustal materiais, tectonics and heat flow. Although some of these parameters have be ...
... feeling that we are still probing in the dark, and in addition to trying to answer the questions in a geochmeical way, one is plagued by doubts such as arise from our ignorance of the role of physical properties of crustal materiais, tectonics and heat flow. Although some of these parameters have be ...
Temporal variation in relative zircon abundance throughout Earth
... lower magma water contents display lower total zircon abundance at any given time, as shown in Figure 1b. Nonetheless, common temporal trends are revealed across a wide range of P and H 2O values, with the mass of zircon saturated per mass of magma increasing substantially since the early Archean (F ...
... lower magma water contents display lower total zircon abundance at any given time, as shown in Figure 1b. Nonetheless, common temporal trends are revealed across a wide range of P and H 2O values, with the mass of zircon saturated per mass of magma increasing substantially since the early Archean (F ...
Anomalous Occurrence of Cretaceous Placer Deposits: A
... continents of the Earth were sutured together into one supergiant continent, Pangea. The disintegration of this supergiant continent started in the early Jurassic and subsequently resulted in two giant continents: Laurasia and Gondwana. The disintegration of Laurasia opened up what eventually became ...
... continents of the Earth were sutured together into one supergiant continent, Pangea. The disintegration of this supergiant continent started in the early Jurassic and subsequently resulted in two giant continents: Laurasia and Gondwana. The disintegration of Laurasia opened up what eventually became ...
Full text PDF - Geochemical Perspectives
... remains incompatible-element enriched. Other studies, particularly geophysical ones, indicate that this subduction flux is substantially augmented by subduction erosion of the overriding plate. Over Earth’s history these processes together with continental crustal founding may have delivered a volum ...
... remains incompatible-element enriched. Other studies, particularly geophysical ones, indicate that this subduction flux is substantially augmented by subduction erosion of the overriding plate. Over Earth’s history these processes together with continental crustal founding may have delivered a volum ...
Earth`s heterogeneous mantle: A product of convection
... fundamental questions. The large amount of available isotope data in oceanic basalts shows that, statistically, only two principal compositional vectors capture the essential features of the data. Care must be taken, however, when estimating the isotopic composition of mantle from basalt samples. Th ...
... fundamental questions. The large amount of available isotope data in oceanic basalts shows that, statistically, only two principal compositional vectors capture the essential features of the data. Care must be taken, however, when estimating the isotopic composition of mantle from basalt samples. Th ...
Age, Origin and Emplacement of Diamonds
... disciplines related to the physical, chemical, and mineralogic properties of diamonds, the roclzs in which they crystallize, as well as the roclzs that brought them to the surface and in which they now are found as primary deposits. Clearly, such a broad survey is beyond the scope of this article. T ...
... disciplines related to the physical, chemical, and mineralogic properties of diamonds, the roclzs in which they crystallize, as well as the roclzs that brought them to the surface and in which they now are found as primary deposits. Clearly, such a broad survey is beyond the scope of this article. T ...
A. M. Celâl ŞENGÖR, Boris A. NATAL`IN, Gürsel
... The Altaids are one of the largest superorogenic complexes in the world in which two genetically closely related orogenic complexes ended up generating much of northern Asia during the Palaeozoic and the early and medial Mesozoic. This immense superorogenic complex evolved as a consequence of the de ...
... The Altaids are one of the largest superorogenic complexes in the world in which two genetically closely related orogenic complexes ended up generating much of northern Asia during the Palaeozoic and the early and medial Mesozoic. This immense superorogenic complex evolved as a consequence of the de ...
Lower Continental Crust. - UCSB Earth Science
... terrains noted by Rudnick & Presper (1990): The younger terrains are enriched relative to the older terrains in Fe, Mg, Ca, P, Ti, Sc, V, middle rare earth elements (MREEs), heavy rare earth elements (HREEs), Hf, Ta, and U and depleted in Si and some large-ion lithophile elements, including K, Pb, a ...
... terrains noted by Rudnick & Presper (1990): The younger terrains are enriched relative to the older terrains in Fe, Mg, Ca, P, Ti, Sc, V, middle rare earth elements (MREEs), heavy rare earth elements (HREEs), Hf, Ta, and U and depleted in Si and some large-ion lithophile elements, including K, Pb, a ...
McLelland, JM, Selleck, BW, and Bickford, ME, 2010
... ca. 1050 Ma, followed by orogen collapse at ca. 1020 Ma. A final contractional pulse (ca. 1010–980 Ma) ending with extensional collapse gave rise to the Grenville Front thrust. The Allochthonous Monocyclic Belt consists of rocks younger than ca. 1.35 Ga. Details of these belts and the orogenic seque ...
... ca. 1050 Ma, followed by orogen collapse at ca. 1020 Ma. A final contractional pulse (ca. 1010–980 Ma) ending with extensional collapse gave rise to the Grenville Front thrust. The Allochthonous Monocyclic Belt consists of rocks younger than ca. 1.35 Ga. Details of these belts and the orogenic seque ...
Ophiolites and Their Origins
... Ophiolites are the remnants of ancient oceanic crust the Troodos oceanic crust on Cyprus was a product of and upper mantle that were tectonically emplaced into island arc magmatism. This was a revolutionary but controcontinental margins. They display the only evidence for versial development in the ...
... Ophiolites are the remnants of ancient oceanic crust the Troodos oceanic crust on Cyprus was a product of and upper mantle that were tectonically emplaced into island arc magmatism. This was a revolutionary but controcontinental margins. They display the only evidence for versial development in the ...
Geological Society of America Bulletin
... and the allochthonous nature of ophiolites by the mid-1960s was instrumental in the formulation of the ophiolite model and the ophiolite– ocean crust analogy within the framework of the new plate-tectonic theory. The ophiolite suite became an ideal analogue to explain the seismic velocity structure ...
... and the allochthonous nature of ophiolites by the mid-1960s was instrumental in the formulation of the ophiolite model and the ophiolite– ocean crust analogy within the framework of the new plate-tectonic theory. The ophiolite suite became an ideal analogue to explain the seismic velocity structure ...
Magma genesis, plate tectonics, and chemical
... also provide clues about the nature of the source material at (volume 25, numbers 2, 3, 5, and 6, 1987). Volcanoes have played a significant role in the development depth. The theme common to the different parts of this review of geology sinceAbraham Werner at the beginning of the last relates to th ...
... also provide clues about the nature of the source material at (volume 25, numbers 2, 3, 5, and 6, 1987). Volcanoes have played a significant role in the development depth. The theme common to the different parts of this review of geology sinceAbraham Werner at the beginning of the last relates to th ...
2.03 Sampling Mantle Heterogeneity through Oceanic Basalts
... abundances, particularly rare-earth element (REE) abundances, it became clear that not only some particular parent–daughter element abundance ratios but also the light-to-heavy REE ratios of the Earth’s mantle are quite heterogeneous. The interpretation of these heterogeneities has occupied mantle g ...
... abundances, particularly rare-earth element (REE) abundances, it became clear that not only some particular parent–daughter element abundance ratios but also the light-to-heavy REE ratios of the Earth’s mantle are quite heterogeneous. The interpretation of these heterogeneities has occupied mantle g ...
Hafnium isotope evidence for slab melt contributions in the Central
... sediment, based on chemical and Hf–Nd isotope data. The CMVB includes both calc-alkaline lavas with arctype trace element patterns such as aqueous fluid mobile element enrichments and high field strength element depletions; and “high-Nb” alkaline lavas with trace element patterns similar to ocean isla ...
... sediment, based on chemical and Hf–Nd isotope data. The CMVB includes both calc-alkaline lavas with arctype trace element patterns such as aqueous fluid mobile element enrichments and high field strength element depletions; and “high-Nb” alkaline lavas with trace element patterns similar to ocean isla ...
The Architecture, Chemistry, and Evolution of Continental Magmatic
... 2.4.1. Extinct arcs. The western North American Cordillera comprises a continuous belt of arc products (mostly intrusive) from Alaska to Baja California (Figure 3a). These are the great North American batholiths, with ages ranging from Triassic to Eocene (Table 1) (Anderson 1990). All these batholit ...
... 2.4.1. Extinct arcs. The western North American Cordillera comprises a continuous belt of arc products (mostly intrusive) from Alaska to Baja California (Figure 3a). These are the great North American batholiths, with ages ranging from Triassic to Eocene (Table 1) (Anderson 1990). All these batholit ...
IODP Proposal Cover Sheet
... major proportion of intra-oceanic arc lava are basaltic (50 wt.% SiO2). There is no pre-existing continental crust in the IBM upper plate, yet recent seismic studies of this arc reveal a thick middle crust layer with 6.0-6.8 km/s Vp that is hypothesized to be intermediate in composition. The primary ...
... major proportion of intra-oceanic arc lava are basaltic (50 wt.% SiO2). There is no pre-existing continental crust in the IBM upper plate, yet recent seismic studies of this arc reveal a thick middle crust layer with 6.0-6.8 km/s Vp that is hypothesized to be intermediate in composition. The primary ...
The Río de la Plata Craton: a review of units, boundaries, ages and
... Cufré Granite. Post-orogenic gabbros are also frequently associated (e.g. Mahoma, Rospide and Carreta Quemada Gabbros). U–Pb SHRIMP ages for zircons from the Rospide Gabbro yielded 2,076 ± 6 and 2,086 ± 7 Ma (Hartmann et al. 2008a). The similar ages of gabbros and granites point to a coeval magmati ...
... Cufré Granite. Post-orogenic gabbros are also frequently associated (e.g. Mahoma, Rospide and Carreta Quemada Gabbros). U–Pb SHRIMP ages for zircons from the Rospide Gabbro yielded 2,076 ± 6 and 2,086 ± 7 Ma (Hartmann et al. 2008a). The similar ages of gabbros and granites point to a coeval magmati ...
full text - NWT Protected Area Strategy
... receives numerous requests each year to provide samples of Acasta gneiss to schools, museums, and individuals from around the world. In addition, media interest over the years attests to the public’s ongoing interest in these rocks. Geologists consider the scientific value of the Acasta gneisses to ...
... receives numerous requests each year to provide samples of Acasta gneiss to schools, museums, and individuals from around the world. In addition, media interest over the years attests to the public’s ongoing interest in these rocks. Geologists consider the scientific value of the Acasta gneisses to ...
Ringwood Phase transformations and their bearing on the
... bulk chemical composition of the Upper Mantle (“pyrolite”) is derived from experimental and petrological studies of the complementary relationships between basaltic magmas and refractory peridotites. The phase transformations which are experienced by pyrolite between depths of 100-800 km are reviewe ...
... bulk chemical composition of the Upper Mantle (“pyrolite”) is derived from experimental and petrological studies of the complementary relationships between basaltic magmas and refractory peridotites. The phase transformations which are experienced by pyrolite between depths of 100-800 km are reviewe ...
nature and composition of the continental crust
... middle crust (i.e., between 10-15 and 20-25 km depth) may contain rocks in the amphibolite facies, which are also found in surface outcrop or as xenoliths. Amphibolite facies rocks may also be important in the lowermost crust in areas of high water flux (such as in island arc settings where hydrous ...
... middle crust (i.e., between 10-15 and 20-25 km depth) may contain rocks in the amphibolite facies, which are also found in surface outcrop or as xenoliths. Amphibolite facies rocks may also be important in the lowermost crust in areas of high water flux (such as in island arc settings where hydrous ...
Article
... any older strata and so to narrow down potential sources the younger portion of the age spectrum is subdivided into 750–600 Ma, 600–500 Ma, 500–350 Ma, and 350–200 Ma (Fig 4). The Upper Cretaceous spectrum has peaks ranging from 600–350 Ma that only overlap comprehensively with the Upper Mississippi ...
... any older strata and so to narrow down potential sources the younger portion of the age spectrum is subdivided into 750–600 Ma, 600–500 Ma, 500–350 Ma, and 350–200 Ma (Fig 4). The Upper Cretaceous spectrum has peaks ranging from 600–350 Ma that only overlap comprehensively with the Upper Mississippi ...
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.