Rock Types - Perils of Classification
... composition and particular fabric. • In practice, only a few major names are unambiguous and used uniformly by petrologists. Option 1: Adopt a flexible strategy for naming and classification because of the continuous chemical spectrum observed for igneous rocks on Earth. Option 2: Use IUGS approach ...
... composition and particular fabric. • In practice, only a few major names are unambiguous and used uniformly by petrologists. Option 1: Adopt a flexible strategy for naming and classification because of the continuous chemical spectrum observed for igneous rocks on Earth. Option 2: Use IUGS approach ...
North Cascades National Park (10 May)
... Arc complex in British Columbia (now offset along the Eocene Fraser Fault). It is uncertain whether they developed on the oceanic rocks of the Bridge River plate, but were likely part of the Insular Belt by late Jurassic time. The rock is metamorphosed at amphibolite facies. This stop illustrates th ...
... Arc complex in British Columbia (now offset along the Eocene Fraser Fault). It is uncertain whether they developed on the oceanic rocks of the Bridge River plate, but were likely part of the Insular Belt by late Jurassic time. The rock is metamorphosed at amphibolite facies. This stop illustrates th ...
The Early Cretaceous Arperos oceanic basin
... At Valle de Santiago, Guanajuato, granulitic xenoliths with TDM D 1:5 Ga in Neogene volcanics support the presence of Precambrian crust there (UribeCifuentes and Urrutia-Fucugauchi, 1995). At La Goleta Oligocene volcanic field, 45 km south from Valle de Bravo, high-grade gneiss xenoliths with "Nd.0/ ...
... At Valle de Santiago, Guanajuato, granulitic xenoliths with TDM D 1:5 Ga in Neogene volcanics support the presence of Precambrian crust there (UribeCifuentes and Urrutia-Fucugauchi, 1995). At La Goleta Oligocene volcanic field, 45 km south from Valle de Bravo, high-grade gneiss xenoliths with "Nd.0/ ...
Structure and Tectonic Framework of Kachchh
... Cenozoic sedimentary rocks are seen to have been folded. Sedimentary beds belonging to as young as Kankawati formation (Pliocene) are seen intensely folded. The region has preserved various fold-thrust belt related features resulted on account of intense N-S compressional tresses, such as, 1) faultp ...
... Cenozoic sedimentary rocks are seen to have been folded. Sedimentary beds belonging to as young as Kankawati formation (Pliocene) are seen intensely folded. The region has preserved various fold-thrust belt related features resulted on account of intense N-S compressional tresses, such as, 1) faultp ...
DESTRUCTIVE CONVERGENT PLATE MARGINS: SUBDUCTION
... Why do magmas produced at subduction zones not have the same compositions the original basaltic rocks of the oceanic crust? Partial melting: lowest ‘C of melting minerals ...
... Why do magmas produced at subduction zones not have the same compositions the original basaltic rocks of the oceanic crust? Partial melting: lowest ‘C of melting minerals ...
Draft Museum Guide - Valley Geology
... exposed to higher temperatures and pressures. This occurs during mountain building. As rocks are exposed to higher temperatures and pressure metamorphic reactions can occur, where elements in certain minerals re ...
... exposed to higher temperatures and pressures. This occurs during mountain building. As rocks are exposed to higher temperatures and pressure metamorphic reactions can occur, where elements in certain minerals re ...
Geology of the New Jersey Highlands and Valley and Ridge Provinces
... Geologic Map of the Highlands Distribution of Proterozoic rocks More than 30 different Proterozoic rock units recognized (mainly granites, gneisses, marble) Complex folding and faulting ...
... Geologic Map of the Highlands Distribution of Proterozoic rocks More than 30 different Proterozoic rock units recognized (mainly granites, gneisses, marble) Complex folding and faulting ...
The metamorphic evolution of the Mozambique Belt in Central
... path, dominated by decompression during final stages of exhumation. The IBC segment of the Eastern Granulites forms a ‘beta’-shaped retrograde path accompanied by strike-slip tectonics at granulite facies metamorphic conditions. We interpret this highly dynamic initial cooling stage at a particular ...
... path, dominated by decompression during final stages of exhumation. The IBC segment of the Eastern Granulites forms a ‘beta’-shaped retrograde path accompanied by strike-slip tectonics at granulite facies metamorphic conditions. We interpret this highly dynamic initial cooling stage at a particular ...
Basin processes
... It is debated if heating and magmatic processes cause rifting or if rifting processes cause magmatic activity. However, rifting is always accompanied by magmatic intrusion into the crust and volcanism at the surface, although usually considered a secondary process. The stretching factor in rift zone ...
... It is debated if heating and magmatic processes cause rifting or if rifting processes cause magmatic activity. However, rifting is always accompanied by magmatic intrusion into the crust and volcanism at the surface, although usually considered a secondary process. The stretching factor in rift zone ...
Rocks
... Metamorphic Rocks: Classification • Foliated – layered looking. These layers have different densities EX. Shale • Non-foliated – no layers or bands. Usually have only one mineral EX. Marble ...
... Metamorphic Rocks: Classification • Foliated – layered looking. These layers have different densities EX. Shale • Non-foliated – no layers or bands. Usually have only one mineral EX. Marble ...
An Introduction to Terrane Analysis in the Western North American
... Nevada, Idaho; Coast Plutonic complex built on Baja BC); plutonic complexes may have been fed by volatiles from underthrusting of North American miogeocline South-moving Baja BC approached maximum S position at latitude of southern Arizona Baja BC west of classic Great Valley and Franciscan complexe ...
... Nevada, Idaho; Coast Plutonic complex built on Baja BC); plutonic complexes may have been fed by volatiles from underthrusting of North American miogeocline South-moving Baja BC approached maximum S position at latitude of southern Arizona Baja BC west of classic Great Valley and Franciscan complexe ...
Getting to Know: Why Earthquakes Occur
... Tectonic plate movement is the primary cause of earthquakes. As tectonic plates move, they grind against each other or push into each other. The edges of the plates rub against each other with a lot of friction, and the edges can become stuck for awhile. If this happens, pressure builds up in the cr ...
... Tectonic plate movement is the primary cause of earthquakes. As tectonic plates move, they grind against each other or push into each other. The edges of the plates rub against each other with a lot of friction, and the edges can become stuck for awhile. If this happens, pressure builds up in the cr ...
THEME 8: The Mokolian Era Namaqualand Metamorphic Complex
... metasediments north of Groblershoop in Northern Cape. 1350-1150 Ma, 2000m thick. Koras Gp: alluvial sedimentary rocks, lavas, pyroclastics, deposited in grabens. 1180-1080 Ma ...
... metasediments north of Groblershoop in Northern Cape. 1350-1150 Ma, 2000m thick. Koras Gp: alluvial sedimentary rocks, lavas, pyroclastics, deposited in grabens. 1180-1080 Ma ...
Petrogenetic Types, Tectonic Settings and Mineral Potential of
... types of granitoid rocks may have potential for different type of mineral deposits, some of which are among the largest mineral deposits on Earth. Despite this, granitoid rocks have generally not been explored to the same extent as the belts of volcanic and sedimentary rocks that host the majority o ...
... types of granitoid rocks may have potential for different type of mineral deposits, some of which are among the largest mineral deposits on Earth. Despite this, granitoid rocks have generally not been explored to the same extent as the belts of volcanic and sedimentary rocks that host the majority o ...
Long-term continental areal reduction produced by tectonic processes
... continental collision events and increased during rifting and extension. But what is the net effect: reduction, expansion, or neither? We use a global strain-rate model and a finite-element approach with over 24,000 grid elements to define the velocity gradient tensor field within all plate boundary ...
... continental collision events and increased during rifting and extension. But what is the net effect: reduction, expansion, or neither? We use a global strain-rate model and a finite-element approach with over 24,000 grid elements to define the velocity gradient tensor field within all plate boundary ...
Plate boudaries II
... granite. Over time it volumetrically overwhelms the amount of granite in the rift, and you have primarily just mafic igneous crust. • This crust subsides (Pratt isostacy) as a function of its density, which means that it floats lower in the mantle, topographically lower than continental crust. • By ...
... granite. Over time it volumetrically overwhelms the amount of granite in the rift, and you have primarily just mafic igneous crust. • This crust subsides (Pratt isostacy) as a function of its density, which means that it floats lower in the mantle, topographically lower than continental crust. • By ...
Overheads for background on mantle minerals
... (calcium carbonate) and dolomite (calcium-magnesium carbonate) • As low pressure minerals are squeezed, they may suddenly transform to a denser high-pressure phase. ...
... (calcium carbonate) and dolomite (calcium-magnesium carbonate) • As low pressure minerals are squeezed, they may suddenly transform to a denser high-pressure phase. ...
Marine Environments
... blades over much of the zone – the organisms that live here are tolerate only to brief exposures to air. – brown, red, and a few species of green algae provide the canopy and tufts of filamentous brown and red algae carpet many of the rocks. – anemones, snails, sea spiders, nudibranchs, hydroids, se ...
... blades over much of the zone – the organisms that live here are tolerate only to brief exposures to air. – brown, red, and a few species of green algae provide the canopy and tufts of filamentous brown and red algae carpet many of the rocks. – anemones, snails, sea spiders, nudibranchs, hydroids, se ...
AN EXAMPLE FROM SURGHAR RANGE, NORTH PAKISTAN
... range owes its evolution to frontal ramping from decollement thrusting within the Paleozoic-Mesozoic rocks and emerges as an low angle frontal thrust named as the Surghar Fault. The hanging wall of Surghar Fault is moderately to tightly folded with Surghar Anticline being the most prominent fault be ...
... range owes its evolution to frontal ramping from decollement thrusting within the Paleozoic-Mesozoic rocks and emerges as an low angle frontal thrust named as the Surghar Fault. The hanging wall of Surghar Fault is moderately to tightly folded with Surghar Anticline being the most prominent fault be ...
Read the Abstract
... oceans formed since the breakup of Pangaea suggests that spontaneous subduction initiation at passive margins (or margin inversion) is rare. In the Appalachian-Caledonide system, rifting continued to at least ~550 Ma, producing an ocean with numerous hyperextended passive margins and microcontinenta ...
... oceans formed since the breakup of Pangaea suggests that spontaneous subduction initiation at passive margins (or margin inversion) is rare. In the Appalachian-Caledonide system, rifting continued to at least ~550 Ma, producing an ocean with numerous hyperextended passive margins and microcontinenta ...
Combined field trip guide/program with abstracts
... sequence of sedimentary rocks that was intruded by mafic sheets. A psammitic layer at a similar outcrop gave a few detrital ages in the Precambrian and Paleozoic, but mainly zircon crystallization ages of 50 Ma. We have dated the amphibolite sheets at ~159 Ma with metamorphism recorded at 98 and 50 ...
... sequence of sedimentary rocks that was intruded by mafic sheets. A psammitic layer at a similar outcrop gave a few detrital ages in the Precambrian and Paleozoic, but mainly zircon crystallization ages of 50 Ma. We have dated the amphibolite sheets at ~159 Ma with metamorphism recorded at 98 and 50 ...
Investigations Into The Sources of K and Th Decoupling Across
... between two different types of crusts. Class 6, is island-arc volcanism during oceanic-oceanic subduction, such as in the Marianas Island volcanics [11]. Class 7 is represented by continental-arc volcanism during oceanic-continental subduction such as in the Northern Andean mountain range of South A ...
... between two different types of crusts. Class 6, is island-arc volcanism during oceanic-oceanic subduction, such as in the Marianas Island volcanics [11]. Class 7 is represented by continental-arc volcanism during oceanic-continental subduction such as in the Northern Andean mountain range of South A ...
Chlorine cycling during subduction of altered oceanic crust
... exospheric C1 that can be transfered back to the mantle remains largely unknown, however. The aim of this study is to show that eclogitic rocks, that have experienced devolatilisation, with little or no interaction with external fluid sources, can be viewed as relevant analogues for crustal material ...
... exospheric C1 that can be transfered back to the mantle remains largely unknown, however. The aim of this study is to show that eclogitic rocks, that have experienced devolatilisation, with little or no interaction with external fluid sources, can be viewed as relevant analogues for crustal material ...
Great Lakes tectonic zone
The Great Lakes tectonic zone is bounded by South Dakota at its tip and heads northeast to south of Duluth, Minnesota, then heads east through northern Wisconsin, Marquette, Michigan, and then trends more northeasterly to skim the northern-most shores of lakes Michigan and Huron before ending in the Sudbury, Ontario, Canada, area.During the Late Archean Era the Algoman orogeny added landmass to the Superior province by volcanic activity and continental collision along a boundary that stretches from present-day South Dakota, U.S., into the Lake Huron region near Sudbury, Ontario, Canada.This crustal boundary is the Great Lakes tectonic zone. It is 1,400 km (870 mi) long, and separates the older Archean gneissic terrane to the south from younger Late Archean greenstone-granite terrane to the north.The zone is characterized by active compression during the Algoman orogeny (about 2,700 million years ago), a pulling-apart (extensional) tectonics (2,450 to 2,100 million years ago), a second compression during the Penokean orogeny (1,900 to 1,850 million years ago), a second extension during Middle Proterozoic time (1,600 million years ago) and minor reactivation during Phanerozoic time (the past 500 million years).Collision began along the Great Lakes tectonic zone (GLTZ) with the Algoman mountain-building event and continued for tens of millions of years. During the formation of the GLTZ, the gneissic Minnesota River Valley subprovince was thrust up onto the Superior province's edge as it consumed the Superior province's oceanic crust. Fragmentation of the Kenorland supercontinent began 2,450 million years ago and was completed by 2,100 million years ago. The Wyoming province is the continental landmass that is hypothesized to have rifted away from the southern Superior province portion of Kenorland, before moving rapidly west and docking with the Laurentia supercontinent 1,850 to 1,715 million years ago. Sedimentation from the GLTZ-rifting environment continued into the Penokean orogeny, which is the next major tectonic event in the Great Lakes region. Several earthquakes have been documented in Minnesota, Michigan's Upper Peninsula and Sudbury in the last 120 years along the GLTZ.