Rift-Related Transition from Andesite to Rhyolite
... been attributed to lower crustal fractionation processes. Others have suggested that the andesite and rhyolite magmas follow two distinct liquid lines of descent (e.g. Steiner, 1958; Ewart & Stipp, 1968; Graham et al., 1995). As the isotopic compositions are inconsistent with melting of old crustal ...
... been attributed to lower crustal fractionation processes. Others have suggested that the andesite and rhyolite magmas follow two distinct liquid lines of descent (e.g. Steiner, 1958; Ewart & Stipp, 1968; Graham et al., 1995). As the isotopic compositions are inconsistent with melting of old crustal ...
Active tectonism in the intracontinental Middle Atlas Mountains of
... Atlas Mountains, approximately 80 km in width and about 200 km long, are part of the Atlas system of northwestern Africa and represent an inverted rift that developed into an intracratonic mountain system in the foreland of the Alpine collisional zone. The Middle Atlas is composed of two provinces, ...
... Atlas Mountains, approximately 80 km in width and about 200 km long, are part of the Atlas system of northwestern Africa and represent an inverted rift that developed into an intracratonic mountain system in the foreland of the Alpine collisional zone. The Middle Atlas is composed of two provinces, ...
Philippine Sea Plate inception, evolution, and consumption with
... 60–55 Ma likely triggered the Oki-Daito plume occurrence, Mesozoic proto-PSP splitting, shortening and then failure across the paleo-transform boundary between the proto-PSP and the Pacific Plate, Izu-Bonin-Mariana subduction initiation and ultimately PSP inception. (2) The initial splitting phase o ...
... 60–55 Ma likely triggered the Oki-Daito plume occurrence, Mesozoic proto-PSP splitting, shortening and then failure across the paleo-transform boundary between the proto-PSP and the Pacific Plate, Izu-Bonin-Mariana subduction initiation and ultimately PSP inception. (2) The initial splitting phase o ...
44. Mesozoic-Cenozoic Geology of the Eastern Margin of the Grand
... Late Paleozoic reconstructions of the North Atlantic juxtapose the eastern margin of the Grand Banks with the continental margin off Iberia. Comparison of the geology of the Grand Banks region with results from ODP Leg 103 on the Galicia margin improves our understanding of the Mesozoic-cenozoic tec ...
... Late Paleozoic reconstructions of the North Atlantic juxtapose the eastern margin of the Grand Banks with the continental margin off Iberia. Comparison of the geology of the Grand Banks region with results from ODP Leg 103 on the Galicia margin improves our understanding of the Mesozoic-cenozoic tec ...
Structural and biological control of the Cenozoic epithermal uranium
... two episodes of rifting: an early rifting stage at ∼20 Ma producing broad basins and a late, more intense episode of rifting at 10–3 Ma, which increased the overall extension and modified the topography. Tardy et al. (1989) described a N120 strike-slip crustal-scale tectonic feature in the region ca ...
... two episodes of rifting: an early rifting stage at ∼20 Ma producing broad basins and a late, more intense episode of rifting at 10–3 Ma, which increased the overall extension and modified the topography. Tardy et al. (1989) described a N120 strike-slip crustal-scale tectonic feature in the region ca ...
Impact resistance of Illinois limestones and
... to the study of relatively isotropic and nonporous materials, including some limestones. The results of strength tests of solids as measured under slowly applied load (static) are considerably different from those derived from impact or a rapidly applied load. Under static conditions stresses are ge ...
... to the study of relatively isotropic and nonporous materials, including some limestones. The results of strength tests of solids as measured under slowly applied load (static) are considerably different from those derived from impact or a rapidly applied load. Under static conditions stresses are ge ...
A review of the isotopic and trace element evidence for
... Nonetheless, pyroxenitic components are thought to be ubiquitously distributed and are preferentially sampled by melting at low extents as shown by studies of posterosional volcanism at hot spots, off-axis seamounts (Zindler et al., 1984), and magmatism at propagating rifts. Mantle convection calcul ...
... Nonetheless, pyroxenitic components are thought to be ubiquitously distributed and are preferentially sampled by melting at low extents as shown by studies of posterosional volcanism at hot spots, off-axis seamounts (Zindler et al., 1984), and magmatism at propagating rifts. Mantle convection calcul ...
Synthesis of Existing Structural Data for the Auckland Volcanic Field
... Figure 16. Extent of simple and complex structural zones in the Waitemata Group of the Auckland area................................................................................................................ 44 Figure 17. Palaeocurrent directions in the Waitemata Group. ........................ ...
... Figure 16. Extent of simple and complex structural zones in the Waitemata Group of the Auckland area................................................................................................................ 44 Figure 17. Palaeocurrent directions in the Waitemata Group. ........................ ...
Bulletin of the Geological Society of Denmark, Vol. 29/1-2, pp. 77-101
... transgressed, and an eastern area which has suffered continuous crustal foundering and faulting associated with accumulation of Mesozoic continental and marine sediments. The early Permian continental regime was followed by a major transgression in the Late Permian which even covered the marginal pa ...
... transgressed, and an eastern area which has suffered continuous crustal foundering and faulting associated with accumulation of Mesozoic continental and marine sediments. The early Permian continental regime was followed by a major transgression in the Late Permian which even covered the marginal pa ...
Magmatic growth and batholithic root development in the northern
... The Sierra Nevada, one of the largest batholiths in North America, strikes NNW and can be traced ~600 km along the eastern spine of California, varying in width between ~80 and 120 km. The batholith comprises mainly subduction-related intermediate to felsic intrusive rocks and associated metamorphic ...
... The Sierra Nevada, one of the largest batholiths in North America, strikes NNW and can be traced ~600 km along the eastern spine of California, varying in width between ~80 and 120 km. The batholith comprises mainly subduction-related intermediate to felsic intrusive rocks and associated metamorphic ...
Buckling an orogen: The Cantabrian Orocline
... mafic magmatism and melting of the lower crust. The subsequent felsic melts are attributed to melting of the fertile (pelite- and greywacke-rich) middle crust upon upward migration of the thermal anomaly above the high-standing asthenosphere. The study of Sm/Nd isotopes from mantle-derived rocks pro ...
... mafic magmatism and melting of the lower crust. The subsequent felsic melts are attributed to melting of the fertile (pelite- and greywacke-rich) middle crust upon upward migration of the thermal anomaly above the high-standing asthenosphere. The study of Sm/Nd isotopes from mantle-derived rocks pro ...
Geological Activity from Plate Tectonics Processes
... So many natural disasters occur because of plate tectonics processes. By using what we know about plate tectonics we can understand where most earthquakes and volcanic eruptions will strike. We can know where to look for many types of mineral deposits. The scar in this satellite image is of the San ...
... So many natural disasters occur because of plate tectonics processes. By using what we know about plate tectonics we can understand where most earthquakes and volcanic eruptions will strike. We can know where to look for many types of mineral deposits. The scar in this satellite image is of the San ...
Baltica upside down: A new plate tectonic model for Rodinia and the
... Figure 2. Continental distribution on Southern Hemisphere during late Vendian to Cambrian. Rift geometry (seafloor spreading marked by double lines) in peri-Gondwana region generally follows Murphy et al. (1999). A: 550 Ma reconstruction based on paleomagnetic data for Baltica, Laurentia, Gondwana, ...
... Figure 2. Continental distribution on Southern Hemisphere during late Vendian to Cambrian. Rift geometry (seafloor spreading marked by double lines) in peri-Gondwana region generally follows Murphy et al. (1999). A: 550 Ma reconstruction based on paleomagnetic data for Baltica, Laurentia, Gondwana, ...
The American Cordillera: Part III, The North American Taphrogen
... Campanian—Maastrichtian time. This extension produced no known surface-breaking faults, and may have been restricted to mid-crustal rocks. Coeval with extension in the hinterland region, major thinskinned thrust systems propagated eastward into Wyoming in the frontal Sevier belt. The contemporaneity ...
... Campanian—Maastrichtian time. This extension produced no known surface-breaking faults, and may have been restricted to mid-crustal rocks. Coeval with extension in the hinterland region, major thinskinned thrust systems propagated eastward into Wyoming in the frontal Sevier belt. The contemporaneity ...
guide to the geology trail - The Sleeping Giant Park Association
... can be observed along different trails, enabling hikers to appreciate the Park’s natural history in a broader geological context. Because many stations reflect ground-level features, such as rock outcrops located directly on the trail, some may be partially obscured by heavy autumn leaf fall, winter ...
... can be observed along different trails, enabling hikers to appreciate the Park’s natural history in a broader geological context. Because many stations reflect ground-level features, such as rock outcrops located directly on the trail, some may be partially obscured by heavy autumn leaf fall, winter ...
Depositional Environments of Permian Rocks of the
... fossiliferous micrite) consist mainly of microcrystalline quartz, subordinate chalcedonic and megacrystalline quartz, and sparse remnants of both calcareous and dolomite patches. A sequence of thin and grade-bedded calcarenite to calcilutite is favor in the distal part of turbidity grain flows occur ...
... fossiliferous micrite) consist mainly of microcrystalline quartz, subordinate chalcedonic and megacrystalline quartz, and sparse remnants of both calcareous and dolomite patches. A sequence of thin and grade-bedded calcarenite to calcilutite is favor in the distal part of turbidity grain flows occur ...
The Yellowstone magmatic system from the
... southwestward across a mantle plume creates the 16.5 lose resolution with depth quickly due to the limited array million-year old Snake River Plain, a bimodal basalt-rhyolite aperture and the shallowly distributed earthquakes often volcanic system (1). The Yellowstone volcanic field that sits less t ...
... southwestward across a mantle plume creates the 16.5 lose resolution with depth quickly due to the limited array million-year old Snake River Plain, a bimodal basalt-rhyolite aperture and the shallowly distributed earthquakes often volcanic system (1). The Yellowstone volcanic field that sits less t ...
Finite source modelling of magmatic unrest in Socorro, New Mexico
... A nearly constant inflation rate of several millimetres per year inferred from the geodetic and geomorphic studies in the Socorro area is perhaps surprising, given that geodetic data from other active crustal magma chambers reveal episodic uplift and subsidence on timescales from days to years (see ...
... A nearly constant inflation rate of several millimetres per year inferred from the geodetic and geomorphic studies in the Socorro area is perhaps surprising, given that geodetic data from other active crustal magma chambers reveal episodic uplift and subsidence on timescales from days to years (see ...
imp prefaz.qxp - Istituto Nazionale di Oceanografia e di Geofisica
... Dinarides is left undetermined because of the lack of data east of the Udine-Trieste line. The main divide along the Alps and the Italian peninsula is marked by a broken black line representing the over-thrusting fronts of the Moho boundary, the European crust being subducted beneath the Adriatic-Pa ...
... Dinarides is left undetermined because of the lack of data east of the Udine-Trieste line. The main divide along the Alps and the Italian peninsula is marked by a broken black line representing the over-thrusting fronts of the Moho boundary, the European crust being subducted beneath the Adriatic-Pa ...
ATLAS of plutonic rocks and orthogneisses in the Bohemian Massif
... Granitoids are the most abundant rocks (about 86 vol %) in the Earth´s upper continental crust; Wedepohl 1991). Even now, the proportion of granitoids and associated volcanic rocks present on Earth is low, about 0.1 % of the bulk Earth (Clarke 1996). Like other igneous rocks, they represent probes i ...
... Granitoids are the most abundant rocks (about 86 vol %) in the Earth´s upper continental crust; Wedepohl 1991). Even now, the proportion of granitoids and associated volcanic rocks present on Earth is low, about 0.1 % of the bulk Earth (Clarke 1996). Like other igneous rocks, they represent probes i ...
Modeling the thermal evolution of fault
... models: implications for the solidi®cation of granitoid plutons AARON S. YOSHINOBU*, DAVID A. OKAYA and SCOTT R. PATERSON Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740, U.S.A. (Received 1 July 1997; accepted in revised form 20 April 1998) AbstractÐA two- ...
... models: implications for the solidi®cation of granitoid plutons AARON S. YOSHINOBU*, DAVID A. OKAYA and SCOTT R. PATERSON Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740, U.S.A. (Received 1 July 1997; accepted in revised form 20 April 1998) AbstractÐA two- ...
Chapter 8 Let`s take it from the top: the crust and upper mantle
... The Moho is a sharp seismological boundary and in some regions appears to be laminated. There are three major crustal types- continental, transitional and oceanic. Oceanic crust generally ranges from 5-15 km in thickness and comprises 60% of the total crust by area and more than 20% by volume. In so ...
... The Moho is a sharp seismological boundary and in some regions appears to be laminated. There are three major crustal types- continental, transitional and oceanic. Oceanic crust generally ranges from 5-15 km in thickness and comprises 60% of the total crust by area and more than 20% by volume. In so ...
Geomorphic analysis of transient landscapes in the Sierra
... and Motagua faults as the space between the two faults is left “empty” by the moving Caribbean Plate. According to their model, the Tonalá shear zone is a suture resulting from this “zipper” process. However, both the Motagua and Jalpatagua fault traces are lost west of 91◦ W. The western terminatio ...
... and Motagua faults as the space between the two faults is left “empty” by the moving Caribbean Plate. According to their model, the Tonalá shear zone is a suture resulting from this “zipper” process. However, both the Motagua and Jalpatagua fault traces are lost west of 91◦ W. The western terminatio ...
Contrasting origins of Cenozoic silicic volcanic rocks from the
... may dominate some of the volcanic fields in the western Snake River Plain (Bonnichsen 1982). However, the easternmost volcanic fields are centered on large collapse calderas. Throughout much of the central part of the plain, the silicic rocks are buried by a few 100 m to as much as 1 km of basaltic ...
... may dominate some of the volcanic fields in the western Snake River Plain (Bonnichsen 1982). However, the easternmost volcanic fields are centered on large collapse calderas. Throughout much of the central part of the plain, the silicic rocks are buried by a few 100 m to as much as 1 km of basaltic ...
GB06 - Geology and scenery, Killarney Provincial
... store, 880 Bay Street, Toronto. Orders for publications should be accompanied by cheque or money order, payable to the Treasurer of Ontario. Parts of this publication may be quoted if credit is given. It is rec ommended that reference to this guidebook be made in the follow ing form: Debicki, R.L. 1 ...
... store, 880 Bay Street, Toronto. Orders for publications should be accompanied by cheque or money order, payable to the Treasurer of Ontario. Parts of this publication may be quoted if credit is given. It is rec ommended that reference to this guidebook be made in the follow ing form: Debicki, R.L. 1 ...
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.