physical, chemical, and chronological characteristics of
... of the convecting mantle across a broad transition region. This zone of velocity transition, in general not well resolved, ranges from 200 to perhaps 400 km deep beneath different cratons. The largest craton, the Superior Province of North America, also has the deepest seismically fast root into the ...
... of the convecting mantle across a broad transition region. This zone of velocity transition, in general not well resolved, ranges from 200 to perhaps 400 km deep beneath different cratons. The largest craton, the Superior Province of North America, also has the deepest seismically fast root into the ...
Absolute velocity of North America during the Mesozoic from
... Myrl E. Beck Jr. *, Bernard A. Housen Department of Geology, Western Washington University, Bellingham, WA 98225, USA ...
... Myrl E. Beck Jr. *, Bernard A. Housen Department of Geology, Western Washington University, Bellingham, WA 98225, USA ...
2 Regional Geological Setting
... is still controversially discussed as chemostratigraphic data (Fölling et al. 1998) indicate that the Gumchavib Formation might be a facies equivalent of the Pickelhaube Formation in the Hilda Subgroup (Frimmel 2000b). Extensive carbonate rocks appeared the first time at the base of the Upper Hilda ...
... is still controversially discussed as chemostratigraphic data (Fölling et al. 1998) indicate that the Gumchavib Formation might be a facies equivalent of the Pickelhaube Formation in the Hilda Subgroup (Frimmel 2000b). Extensive carbonate rocks appeared the first time at the base of the Upper Hilda ...
Intrusive vs. Extrusive Volcanic Eruptions
... • Gases come out of solution as the magma rises to the surface and the _________drops • Gas bubbles which become frozen in a lava are termed ______________ • Vesicles which are eventually filled, as a result of secondary processes, are termed _______________ ERSC 2P17 Brock University ...
... • Gases come out of solution as the magma rises to the surface and the _________drops • Gas bubbles which become frozen in a lava are termed ______________ • Vesicles which are eventually filled, as a result of secondary processes, are termed _______________ ERSC 2P17 Brock University ...
Shear wave anisotropy beneath the Cascadia subduction zone and
... front (trench), which may be indicative of 3–5 per cent anisotropy within the forearc mantle wedge, with a fast direction parallel to the subduction direction. Above the Explorer Plate at the northern end of the CSZ, the fast directions are N25◦ E. This may reflect either the more northerly subducti ...
... front (trench), which may be indicative of 3–5 per cent anisotropy within the forearc mantle wedge, with a fast direction parallel to the subduction direction. Above the Explorer Plate at the northern end of the CSZ, the fast directions are N25◦ E. This may reflect either the more northerly subducti ...
Paleoproterozoic Metamorphism in the Northern Wyoming Province
... observations suggest that the western part of the GFTZ may have experienced a distinct Paleoproterozoic episode of metamorphism and tectonism at 1.77 Ga that may not be directly related to the Wyoming-Hearne collision. If so, this younger event has important implications for the assembly of southern ...
... observations suggest that the western part of the GFTZ may have experienced a distinct Paleoproterozoic episode of metamorphism and tectonism at 1.77 Ga that may not be directly related to the Wyoming-Hearne collision. If so, this younger event has important implications for the assembly of southern ...
Bedrock Geology along the Northern Margin of the Athabasca Basin
... of metasedimentary rocks, although alternatively some could represent sheared varieties of the mixed garnetiferous granite gneiss and tonalite. A distinctive highly magnetic unit (magnetic susceptibility of unit averages 18.5 x 10-3 SI; average of unit core 31 x 10-3 SI) extends southwestward from a ...
... of metasedimentary rocks, although alternatively some could represent sheared varieties of the mixed garnetiferous granite gneiss and tonalite. A distinctive highly magnetic unit (magnetic susceptibility of unit averages 18.5 x 10-3 SI; average of unit core 31 x 10-3 SI) extends southwestward from a ...
Simple Kinematics of Subduction Zones
... ments typical of W-directed subduction zones with respect to the deeper lithospheric-rooted decollements occurring along E- and NE-directed subduction zones. The asymmetry can be recognized not simply comparing W- versus E-directed subduction zones, but subductions along the sinusoidal flow of absol ...
... ments typical of W-directed subduction zones with respect to the deeper lithospheric-rooted decollements occurring along E- and NE-directed subduction zones. The asymmetry can be recognized not simply comparing W- versus E-directed subduction zones, but subductions along the sinusoidal flow of absol ...
Chortis block: where did it come from - Centro de Geociencias
... absence of supracrustal rocks of Paleozoic age throughout the Chortís block. These metamorphic rocks were included in his more recent work (Manton and Manton, 1999). Along the northern limit of the Chortís block in Guatemala, between the Motagua and Jocotán faults, orthogneissic units of Las Ovejas ...
... absence of supracrustal rocks of Paleozoic age throughout the Chortís block. These metamorphic rocks were included in his more recent work (Manton and Manton, 1999). Along the northern limit of the Chortís block in Guatemala, between the Motagua and Jocotán faults, orthogneissic units of Las Ovejas ...
2012 Americas School of Mines
... Notes: Igneous – hydrothermal ore deposits – 2 Magma may melt enough rock to form a chamber where it accumulates. Fractionation continues in the chamber as lighter low melting point minerals remain as fluids and heavier sulfide and oxide minerals precipitate. Sulfur is leached from the walls of the ...
... Notes: Igneous – hydrothermal ore deposits – 2 Magma may melt enough rock to form a chamber where it accumulates. Fractionation continues in the chamber as lighter low melting point minerals remain as fluids and heavier sulfide and oxide minerals precipitate. Sulfur is leached from the walls of the ...
Two- and three-dimensional gravity modeling along western
... delineated by high angle (65◦ –70◦ ) northward dipping normal faults of the Tapti rift on the southern side and southward dipping Narmada step-like listric normal faults (Bhattacharji et al 1996) of the Narmada rift zone. The width of the intraplate Narmada-Tapti rift ranges from 30–40 km at the wes ...
... delineated by high angle (65◦ –70◦ ) northward dipping normal faults of the Tapti rift on the southern side and southward dipping Narmada step-like listric normal faults (Bhattacharji et al 1996) of the Narmada rift zone. The width of the intraplate Narmada-Tapti rift ranges from 30–40 km at the wes ...
Unconventional Isotopes and Approaches
... Terrestrial peridotites have a mean δ56FeIRMM-14 of 0.00 ±0.11‰. Oceanic basalts average slightly heavier, δ56FeIRMM-14 = +0.11‰ ±0.03‰. This consistent with a small (∆56Fe ≈ -0.2‰) fractionation between olivine and silicate liquid during partial melting and fractional crystallization. Lunar basalts ...
... Terrestrial peridotites have a mean δ56FeIRMM-14 of 0.00 ±0.11‰. Oceanic basalts average slightly heavier, δ56FeIRMM-14 = +0.11‰ ±0.03‰. This consistent with a small (∆56Fe ≈ -0.2‰) fractionation between olivine and silicate liquid during partial melting and fractional crystallization. Lunar basalts ...
Mesozoic fill-sequences in Hefei Basin: Implication for Dabie
... 3 Basin-fill sequence and evolution It is found that the fill-sequences of Hefei basin show obviously distinct lithofacies, depositional architectures and regional geodynamics in the Jurassic and the late Jurassic-Cretaceous respectively, which may be divided by angular unconformities (fig. 4). 3.1 ...
... 3 Basin-fill sequence and evolution It is found that the fill-sequences of Hefei basin show obviously distinct lithofacies, depositional architectures and regional geodynamics in the Jurassic and the late Jurassic-Cretaceous respectively, which may be divided by angular unconformities (fig. 4). 3.1 ...
Where and why do large shallow intraslab earthquakes occur?
... depth) of a subducting slab. Searching for events in published individual studies and the Harvard University centroid moment tensor catalogue, we find twenty such events in E. Hokkaido, Kyushu-SW, Japan, S. Mariana, Manila, Sumatra, Vanuatu, N. Chile, C. Peru, El Salvador, Mexico, N. Cascadia and Al ...
... depth) of a subducting slab. Searching for events in published individual studies and the Harvard University centroid moment tensor catalogue, we find twenty such events in E. Hokkaido, Kyushu-SW, Japan, S. Mariana, Manila, Sumatra, Vanuatu, N. Chile, C. Peru, El Salvador, Mexico, N. Cascadia and Al ...
Kinematic Evolution of the Gulf of Mexico and Caribbean James
... seismic data (e.g. Driscoll and Diebold, 1999) argue against seafloor spreading in the Caribbean Plate as young as Campanian, indicating instead that widespread oceanic plateau basalts were built up on a pre-exisiting ocean floor from ca. 90 Ma. Limited age data from areas such as the Piñon Terrane ...
... seismic data (e.g. Driscoll and Diebold, 1999) argue against seafloor spreading in the Caribbean Plate as young as Campanian, indicating instead that widespread oceanic plateau basalts were built up on a pre-exisiting ocean floor from ca. 90 Ma. Limited age data from areas such as the Piñon Terrane ...
08_chapter 2
... Lichens are the association between fungus and a photosynthetic partner either green algae or cyanobacteria. Lichens which dwell on rocks are known as saxicolous species and fall under distinct groups such as (i) Crustose (ii) Fruticose and (iii) Foliose based on their mode of attachment to rocks (J ...
... Lichens are the association between fungus and a photosynthetic partner either green algae or cyanobacteria. Lichens which dwell on rocks are known as saxicolous species and fall under distinct groups such as (i) Crustose (ii) Fruticose and (iii) Foliose based on their mode of attachment to rocks (J ...
alps vs apennines - Dipartimento di Scienze della Terra
... (BOCCALETTI et alii, 1990). The Alps grew laterally and vertically expanding first the retrobelt and then the forebelt during the subduction stage, eventually involving the footwall continental lithosphere during collision, and amplifying the elevation and the lateral expansion of both sides (Figs 2 ...
... (BOCCALETTI et alii, 1990). The Alps grew laterally and vertically expanding first the retrobelt and then the forebelt during the subduction stage, eventually involving the footwall continental lithosphere during collision, and amplifying the elevation and the lateral expansion of both sides (Figs 2 ...
Deep Sea Drilling Project Initial Reports Volume 87
... forearc area, and its main part is Pliocene to upper Miocene. The Lower Layer on the multichannel seismic profile unconformably covers the pre-Tertiary basement, and its thickness changes by thinning or erosion, von Huene and others (1980; 1982) considered the change of the thickness to be due to th ...
... forearc area, and its main part is Pliocene to upper Miocene. The Lower Layer on the multichannel seismic profile unconformably covers the pre-Tertiary basement, and its thickness changes by thinning or erosion, von Huene and others (1980; 1982) considered the change of the thickness to be due to th ...
Palaeocene–Recent plate boundaries in the NE Atlantic and the
... might have been precluded by various ridge propagations and/or short-lived triple junctions NE and possibly SW of the Jan Mayen microcontinent from the inception of sea-floor spreading (54 Ma) to C18 (40 Ma). Our model implies a series of failed ridges offshore the Faeroe Islands, a northern propaga ...
... might have been precluded by various ridge propagations and/or short-lived triple junctions NE and possibly SW of the Jan Mayen microcontinent from the inception of sea-floor spreading (54 Ma) to C18 (40 Ma). Our model implies a series of failed ridges offshore the Faeroe Islands, a northern propaga ...
Crustal Shortening and Extension in the Central Andes: Insights
... The Andes resulted mainly from crustal shortening associated with the South America-Nazca plate convergence in the past ~30 Myr. The GPS data indicate 30-40 mm yr-1 crustal shortening across the entire Andean mountain belt and no significant extension in the High Andes, but the seismic data show cru ...
... The Andes resulted mainly from crustal shortening associated with the South America-Nazca plate convergence in the past ~30 Myr. The GPS data indicate 30-40 mm yr-1 crustal shortening across the entire Andean mountain belt and no significant extension in the High Andes, but the seismic data show cru ...
Is the Asian lithosphere underthrusting beneath northeastern
... We stacked the moveout corrected P and S receiver functions of all stations as a function of the longitude of P-to-S (or S-to-P) pierce points at 100 km depth (Fig. 4). The S-to-P phases from the Moho and LAB in S receiver functions are consistent with those in P receiver functions, indicating that ...
... We stacked the moveout corrected P and S receiver functions of all stations as a function of the longitude of P-to-S (or S-to-P) pierce points at 100 km depth (Fig. 4). The S-to-P phases from the Moho and LAB in S receiver functions are consistent with those in P receiver functions, indicating that ...
Petrology and geochemistry of Neoproterozoic volcanic arc terranes
... from 57 deep wells at the Department of Energy’s Savannah River Site. Southeast of the eastern Piedmont in central South Carolina and Georgia, these cores provide most of the known samples of crystalline basement and, along with structural trends defined by aeromagnetic lineaments, allow us to defin ...
... from 57 deep wells at the Department of Energy’s Savannah River Site. Southeast of the eastern Piedmont in central South Carolina and Georgia, these cores provide most of the known samples of crystalline basement and, along with structural trends defined by aeromagnetic lineaments, allow us to defin ...
Large igneous province
A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including liquid rock (intrusive) or volcanic rock formations (extrusive), when hot magma extrudes from inside the Earth and flows out. The source of many or all LIPs is variously attributed to mantle plumes or to processes associated with plate tectonics. Types of LIPs can include large volcanic provinces (LVP), created through flood basalt and large plutonic provinces (LPP). Eleven distinct flood basalt episodes occurred in the past 250 million years, creating volcanic provinces, which coincided with mass extinctions in prehistoric times. Formation depends on a range of factors, such as continental configuration, latitude, volume, rate, duration of eruption, style and setting (continental vs. oceanic), the preexisting climate state, and the biota resilience to change.