Carbonatite occurrences of the world: map and database, by AR
... started listing alkaline rocks and carbonatites along with their ages, spatial distribution, and associated rocks types in his volume on the carbonatites of North and South America that appeared in 1987. Since then, other volumes have appeared with Woolley acting as the main driving force. These vol ...
... started listing alkaline rocks and carbonatites along with their ages, spatial distribution, and associated rocks types in his volume on the carbonatites of North and South America that appeared in 1987. Since then, other volumes have appeared with Woolley acting as the main driving force. These vol ...
Lower plate deformation at the Chile Triple Junction from the
... along the axis of segments SCR3 to SCR1 during the past 2–3 Myr exhibits different characteristics. The axial valley of segment SCR3 (Figure 4) is roughly 15 km wide. The maximum depth of the axial seafloor reaches 3000 m while the flanks have an average depth of 2400 m. Linear ridges culminating at 2 ...
... along the axis of segments SCR3 to SCR1 during the past 2–3 Myr exhibits different characteristics. The axial valley of segment SCR3 (Figure 4) is roughly 15 km wide. The maximum depth of the axial seafloor reaches 3000 m while the flanks have an average depth of 2400 m. Linear ridges culminating at 2 ...
Geol Soc London Spec Publ 204 2002
... (e.g. Oxburgh & Turcotte 1970) emphasized magmatism due to frictional heating on the Benioff zone, melting of the subducting slab and compressional shortening of the over-riding plate in the arc-trench gap. In contrast, melts are now seen as originating primarily in the mantle wedge above the subduc ...
... (e.g. Oxburgh & Turcotte 1970) emphasized magmatism due to frictional heating on the Benioff zone, melting of the subducting slab and compressional shortening of the over-riding plate in the arc-trench gap. In contrast, melts are now seen as originating primarily in the mantle wedge above the subduc ...
The ocean-continent transition in the uniform lithospheric stretching
... stretching may occasionally exceed the value corresponding to 2.5 km subsidence, thus producing stretched continental crust that is deeper than the adjacent oceanic crust. As a result, a deep continental rnargin basin will be created. The amount of uniform s t ~ t c h i n gnecessary to bring the sur ...
... stretching may occasionally exceed the value corresponding to 2.5 km subsidence, thus producing stretched continental crust that is deeper than the adjacent oceanic crust. As a result, a deep continental rnargin basin will be created. The amount of uniform s t ~ t c h i n gnecessary to bring the sur ...
Subduction factory 2. Are intermediate
... that intermediate-depth intraslab earthquakes are linked to metamorphic dehydration reactions in the subducting oceanic crust and mantle. We show that there is a correlation between the patterns of intermediate-depth seismicity and the locations of predicted hydrous minerals: Earthquakes occur in su ...
... that intermediate-depth intraslab earthquakes are linked to metamorphic dehydration reactions in the subducting oceanic crust and mantle. We show that there is a correlation between the patterns of intermediate-depth seismicity and the locations of predicted hydrous minerals: Earthquakes occur in su ...
Using Igneous Rocks to Probe the Evolution of the Lithosphere Terry
... There are two ways in which geological studies of rocks can complement the seismic imaging planned for USArray. One is to assist in basic interpretation of the images - by providing geologic maps of surface exposures to correlate with seismic structures at depth, and by providing information on poss ...
... There are two ways in which geological studies of rocks can complement the seismic imaging planned for USArray. One is to assist in basic interpretation of the images - by providing geologic maps of surface exposures to correlate with seismic structures at depth, and by providing information on poss ...
Kimberlites and Lamproites: Primary Sources of Diamond
... minerals present have equilibrated at pressures [50-60 kbar (150-250 km)] and temperatures (900-1400°C) characteristicof the upper mantle. These PT conditions are within the stability field of diamond as defined by the diamond-graphite univariant curve (Figure 2). It is assumed from these data that ...
... minerals present have equilibrated at pressures [50-60 kbar (150-250 km)] and temperatures (900-1400°C) characteristicof the upper mantle. These PT conditions are within the stability field of diamond as defined by the diamond-graphite univariant curve (Figure 2). It is assumed from these data that ...
The Exposed Passive Margin of North America in Western Cuba
... The Mesozoic successions of western Cuba, now exposed in the Guaniguanico terrane, were deposited to the east of the present NE Yucatan coast. The evolution of these passive margin successions encompasses the syn-rift stage (Early Jurassic?Callovian/early Oxfordian), drift stage (?Callovian/middle O ...
... The Mesozoic successions of western Cuba, now exposed in the Guaniguanico terrane, were deposited to the east of the present NE Yucatan coast. The evolution of these passive margin successions encompasses the syn-rift stage (Early Jurassic?Callovian/early Oxfordian), drift stage (?Callovian/middle O ...
GEOTHERMAL SYSTEMS IN GLOBAL PERSPECTIVE
... FIGURE 5: Tectonics of SE-Asia showing eastward escape of large crustal blocks along major strike-slip faults as suggested by Tapponier et al. (1982). Model for comparison (from Pluijm and Marshak 2004) 3. HIGH-TEMPERATURE GEOTHERMAL FIELDS. These are volcanic/intrusive in origin as regards occurren ...
... FIGURE 5: Tectonics of SE-Asia showing eastward escape of large crustal blocks along major strike-slip faults as suggested by Tapponier et al. (1982). Model for comparison (from Pluijm and Marshak 2004) 3. HIGH-TEMPERATURE GEOTHERMAL FIELDS. These are volcanic/intrusive in origin as regards occurren ...
Baltica in the Cryogenian, 850–630 Ma
... passive margin deposition throughout the Cryogenian. In the northeast platformal and deeper-water basin deposits are preserved, whereas the eastern region was later affected by Paleozoic rifting and preserves only shelf deposits. The northeastern and eastern regions define Baltica’s Cryogenian north ...
... passive margin deposition throughout the Cryogenian. In the northeast platformal and deeper-water basin deposits are preserved, whereas the eastern region was later affected by Paleozoic rifting and preserves only shelf deposits. The northeastern and eastern regions define Baltica’s Cryogenian north ...
No Slide Title
... • Continental drift is the idea that a single large landmass broke up into smaller landmasses to form the continents, which then drifted to their present locations. (OLD Theory, no longer relevant) • However, some parts of this theory helped to create the current theory of plate tectonics. • First, ...
... • Continental drift is the idea that a single large landmass broke up into smaller landmasses to form the continents, which then drifted to their present locations. (OLD Theory, no longer relevant) • However, some parts of this theory helped to create the current theory of plate tectonics. • First, ...
Volcanoes, Magma, and Volcanic Eruptions
... As they rise they may encounter a depth or pressure where the dissolved gas no longer can be held in solution in the magma, and the gas begins to form a separate phase (i.e. it makes bubbles just like in a bottle of carbonated beverage when the pressure is reduced). When a gas bubble forms, it will ...
... As they rise they may encounter a depth or pressure where the dissolved gas no longer can be held in solution in the magma, and the gas begins to form a separate phase (i.e. it makes bubbles just like in a bottle of carbonated beverage when the pressure is reduced). When a gas bubble forms, it will ...
Geologic Map of the Prisor Hill Quadrangle, Sierra
... beds consist of inter-bedded tan or reddish-brown conglomerate and conglomeratic sandstone, red sandstone and purple to red mudstone. Higher in the section, conglomerate beds are almost entirely replaced by channels of red to tan sandstone, and the ratio of mudstone to sandstone increases. In the st ...
... beds consist of inter-bedded tan or reddish-brown conglomerate and conglomeratic sandstone, red sandstone and purple to red mudstone. Higher in the section, conglomerate beds are almost entirely replaced by channels of red to tan sandstone, and the ratio of mudstone to sandstone increases. In the st ...
An integrated geophysical analysis of crustal structure in the Wichita
... magnitude lends support to Kluth and Coney’s (1981) interpretation that deformation occurred along discrete fault zones bounding separate uplifts, rather than along one major zone as proposed by Larson et al. (1985) and Budnik ...
... magnitude lends support to Kluth and Coney’s (1981) interpretation that deformation occurred along discrete fault zones bounding separate uplifts, rather than along one major zone as proposed by Larson et al. (1985) and Budnik ...
Introduction to the special issue on “Subduction Zones”
... such as the Andes subduction zone, which is over 100 million years old, whereas others have just initiated, such as the New Hebrides and Puysegur subduction zones. Present-day subduction zones are also diverse in terms of trench motion, slab ...
... such as the Andes subduction zone, which is over 100 million years old, whereas others have just initiated, such as the New Hebrides and Puysegur subduction zones. Present-day subduction zones are also diverse in terms of trench motion, slab ...
Tectónica e Bacias
... the unconformity between them is small to non-existent (Olsen, 1997). TS-IV includes the widespread CAMP basalts that were erupted in a geologically short interval at ~202 Ma (e.g., Olsen et al., 1996; Olsen, 1999) (The CAMP basalts comprise a large-igneous province or L.I.P.; see Section 3.1.3). Si ...
... the unconformity between them is small to non-existent (Olsen, 1997). TS-IV includes the widespread CAMP basalts that were erupted in a geologically short interval at ~202 Ma (e.g., Olsen et al., 1996; Olsen, 1999) (The CAMP basalts comprise a large-igneous province or L.I.P.; see Section 3.1.3). Si ...
K-Fsp can be classified as Sanidine on the basis of low
... pleochroism a phlogopite. Monticellite is Ca olivine (CaMgSiO4) and it resembles olivine in thin sections. It has a high relief, parallel extinction, high birefringence, and can be distinguished from olivine only in large grains by slightly different grain habits (see T/s 262) and the absence of ser ...
... pleochroism a phlogopite. Monticellite is Ca olivine (CaMgSiO4) and it resembles olivine in thin sections. It has a high relief, parallel extinction, high birefringence, and can be distinguished from olivine only in large grains by slightly different grain habits (see T/s 262) and the absence of ser ...
Mantle Exhumation in an Early Paleozoic Passive Margin, Northern
... Orogenic peridotite occurs as a megaboudin structurally juxtaposed with smaller boudined masses of corona troctolite, skarn, and garnet amphibolite in metasedimentary rocks of the Yukon-Tanana Terrane, Yukon. The peridotite shows well-developed plagioclase coronae on spinel and records cooling from ...
... Orogenic peridotite occurs as a megaboudin structurally juxtaposed with smaller boudined masses of corona troctolite, skarn, and garnet amphibolite in metasedimentary rocks of the Yukon-Tanana Terrane, Yukon. The peridotite shows well-developed plagioclase coronae on spinel and records cooling from ...
Chapter 3
... erosional activity. In some regions, volcanic outpourings were confined to a limited time period, leading to flows that cap older nonvolcanic units. The resistance of such volcanic rocks to erosion strongly influences the subsequent history of landscape development as streams penetrate into the unde ...
... erosional activity. In some regions, volcanic outpourings were confined to a limited time period, leading to flows that cap older nonvolcanic units. The resistance of such volcanic rocks to erosion strongly influences the subsequent history of landscape development as streams penetrate into the unde ...
Gabbroic Pegmatite Intrusions, Iberia Abyssal
... of 127 ± 4 Ma, which we interpret as an igneous age. The Site 1070 gabbro pegmatites are the only igneous rocks that are demonstrably coeval with rifting in the southern IAP. As such, they help to document the transition from non-volcanic margin to normal ocean crust formation in this part of the No ...
... of 127 ± 4 Ma, which we interpret as an igneous age. The Site 1070 gabbro pegmatites are the only igneous rocks that are demonstrably coeval with rifting in the southern IAP. As such, they help to document the transition from non-volcanic margin to normal ocean crust formation in this part of the No ...
Unusual nickel and copper to noble
... tive to the high-MgO tholeiite from which the rocks are formed, which is consistent with the petrographic observations that these rocks are olivine and bronzite cumulates with minor chro mite. The relative position of the Tverrfjell and Eiterdalen samples suggests either that the liquid from which ...
... tive to the high-MgO tholeiite from which the rocks are formed, which is consistent with the petrographic observations that these rocks are olivine and bronzite cumulates with minor chro mite. The relative position of the Tverrfjell and Eiterdalen samples suggests either that the liquid from which ...
The role of basement inheritance faults in the recent fracture system
... Reactivation of ancient faults, a common mechanism of deformation in the brittle crust, depends mainly on the action of a new, different stress field and the direction, dip and strength of the faults. In strongly deformed areas, fault reactivation may lead to basin inversion or development of pull-a ...
... Reactivation of ancient faults, a common mechanism of deformation in the brittle crust, depends mainly on the action of a new, different stress field and the direction, dip and strength of the faults. In strongly deformed areas, fault reactivation may lead to basin inversion or development of pull-a ...
accepted manuscript
... et al., 1988; Metcalfe, 2011b; Searle et al., 1987; Yin and Harrison, 2000). Generally, the suture zones presently in Eurasia, demarcating Tethyan terranes (Fig. 2), are nearly eastwest trending. The terranes north of the Himalaya can be divided into east and west partitions by two main faults runni ...
... et al., 1988; Metcalfe, 2011b; Searle et al., 1987; Yin and Harrison, 2000). Generally, the suture zones presently in Eurasia, demarcating Tethyan terranes (Fig. 2), are nearly eastwest trending. The terranes north of the Himalaya can be divided into east and west partitions by two main faults runni ...
Mantle detachment faults and the breakup of cold continental
... of relatively hot and thick (40–60 km) continental crust, an elastic layer develops within the quartz-dominated crust (Rosenbaum et al., 2005; Regenauer-Lieb et al., 2006). The term elastic layer, also known as elastic core, is used here to describe a layer of maximum elastic energy that may also un ...
... of relatively hot and thick (40–60 km) continental crust, an elastic layer develops within the quartz-dominated crust (Rosenbaum et al., 2005; Regenauer-Lieb et al., 2006). The term elastic layer, also known as elastic core, is used here to describe a layer of maximum elastic energy that may also un ...
A study of basement structures and onshore
... the depth to top of the magnetic basement. Structural indices were tested, and an index (SI) of 0.5 (thick step) gave the most focused depth estimates in the eastern platform areas. A structural index of one (l) (sill/dyke) was used in the western part of the Møre Basin and in the Møre Marginal High ...
... the depth to top of the magnetic basement. Structural indices were tested, and an index (SI) of 0.5 (thick step) gave the most focused depth estimates in the eastern platform areas. A structural index of one (l) (sill/dyke) was used in the western part of the Møre Basin and in the Møre Marginal High ...
Algoman orogeny
The Algoman orogeny, known as the Kenoran orogeny in Canada, was an episode of mountain-building (orogeny) during the Late Archean Eon that involved repeated episodes of continental collisions, compressions and subductions. The Superior province and the Minnesota River Valley terrane collided about 2,700 to 2,500 million years ago. The collision folded the Earth's crust and produced enough heat and pressure to metamorphose the rock. Blocks were added to the Superior province along a 1,200 km (750 mi) boundary that stretches from present-day eastern South Dakota into the Lake Huron area. The Algoman orogeny brought the Archaen Eon to a close, about 2,500 million years ago; it lasted less than 100 million years and marks a major change in the development of the earth’s crust.The Canadian shield contains belts of metavolcanic and metasedimentary rocks formed by the action of metamorphism on volcanic and sedimentary rock. The areas between individual belts consist of granites or granitic gneisses that form fault zones. These two types of belts can be seen in the Wabigoon, Quetico and Wawa subprovinces; the Wabigoon and Wawa are of volcanic origin and the Quetico is of sedimentary origin. These three subprovinces lie linearly in southwestern- to northeastern-oriented belts about 140 km (90 mi) wide on the southern portion of the Superior Province.The Slave province and portions of the Nain province were also affected. Between about 2,000 and 1,700 million years ago these combined with the Sask and Wyoming cratons to form the first supercontinent, the Kenorland supercontinent.