Lower Continental Crust. - UCSB Earth Science
... (1990) assembled a database of rock compositions from Archean and post-Archean terrains recrystallized at >0.6 GPa. Huang et al. (2013) updated this database and added a compilation of amphibolite-facies samples. We augmented their granulite data with additional analyses from the literature, and her ...
... (1990) assembled a database of rock compositions from Archean and post-Archean terrains recrystallized at >0.6 GPa. Huang et al. (2013) updated this database and added a compilation of amphibolite-facies samples. We augmented their granulite data with additional analyses from the literature, and her ...
PETROLOGY AND GEOCHEMISTRY OF THE WILDCAT GULCH
... This study provides a petrological and geochemical characterization and assessment of the informally named Wildcat Gulch syenite to aid the placement of these syenitoid intrusions within the regional geology of Colorado. Through petrologic and geochemical analyses this study finds that the Wildcat G ...
... This study provides a petrological and geochemical characterization and assessment of the informally named Wildcat Gulch syenite to aid the placement of these syenitoid intrusions within the regional geology of Colorado. Through petrologic and geochemical analyses this study finds that the Wildcat G ...
Fulltext - ETH E-Collection
... Prof. Dr. Christoph A. Heinrich, examiner Dr. Albrecht von Quadt, co-examiner Prof. emeritus Dr. Stefan M. Schmid, co-examiner Prof. Dr. Gerhard Wörner, co-examiner ...
... Prof. Dr. Christoph A. Heinrich, examiner Dr. Albrecht von Quadt, co-examiner Prof. emeritus Dr. Stefan M. Schmid, co-examiner Prof. Dr. Gerhard Wörner, co-examiner ...
Evolution of the continental crust
... sedimentary and igneous records for crustal evolution indicates that it may take up to one billion years for new crust to dominate the sedimentary record. Combining models for the differentiation of the crust and the residence time of elements in the upper crust indicates that the average rate of cr ...
... sedimentary and igneous records for crustal evolution indicates that it may take up to one billion years for new crust to dominate the sedimentary record. Combining models for the differentiation of the crust and the residence time of elements in the upper crust indicates that the average rate of cr ...
Geology and petrology of the felsic intrusions in the
... “Rocks are records of events that took place at the time they formed. They are books. They have a different vocabulary, a different alphabet, but you learn how to read them.” -John McPhee- ...
... “Rocks are records of events that took place at the time they formed. They are books. They have a different vocabulary, a different alphabet, but you learn how to read them.” -John McPhee- ...
Sublayer and Offset Dikes of the Sudbury Igneous
... Supplementing existing data with new measurements made along most of the Lithoprobe transect lines, McGrath and Broome (1994) have re-interpreted the gravity map of the Sudbury structure. They conclude that the sub-surface disposition of rock-types that are exposed at surface, as revealed in the sei ...
... Supplementing existing data with new measurements made along most of the Lithoprobe transect lines, McGrath and Broome (1994) have re-interpreted the gravity map of the Sudbury structure. They conclude that the sub-surface disposition of rock-types that are exposed at surface, as revealed in the sei ...
34 - School of Ocean and Earth Science and Technology
... the crust largely formed after core formation. (It’s possible that an early crust existed while the core was forming; if so, it must have been destroyed later by plate tectonics or late-stage bombardment of planetesimals.) The overall shape of the primitive-mantle-normalized concentration profiles h ...
... the crust largely formed after core formation. (It’s possible that an early crust existed while the core was forming; if so, it must have been destroyed later by plate tectonics or late-stage bombardment of planetesimals.) The overall shape of the primitive-mantle-normalized concentration profiles h ...
Setting Based Classification
... Polymetamorphic rocks are common, usually representing an orogenic event followed by a contact one • Spotted phyllite (or slate) • Overprint may be due to: – Lag time between the creation of the magma at depth during T maximum, and its migration to the lower grade rocks above ...
... Polymetamorphic rocks are common, usually representing an orogenic event followed by a contact one • Spotted phyllite (or slate) • Overprint may be due to: – Lag time between the creation of the magma at depth during T maximum, and its migration to the lower grade rocks above ...
The origin and evolution of the Earth`s continental crust
... The Archaean crust The composition of the Archaean upper crust as revealed in the sedimentary record stands in marked contrast to that of the post-Archaean crust (Taylor & McLennan 1995, table 3). A significant difference is shown by the REE patterns in the Archaean sedimentary rocks, which, relativ ...
... The Archaean crust The composition of the Archaean upper crust as revealed in the sedimentary record stands in marked contrast to that of the post-Archaean crust (Taylor & McLennan 1995, table 3). A significant difference is shown by the REE patterns in the Archaean sedimentary rocks, which, relativ ...
Remobilization of granitoid rocks through mafic recharge: evidence
... Gorai area (Fig. 1), the study area of this paper, these shallow-level trachytic intrusions form good outcrops, though extensive mudflats within the area unfortunately hide all contact relationships between them, so that it is not possible to determine their exact geometry. Few radioisotopic dates e ...
... Gorai area (Fig. 1), the study area of this paper, these shallow-level trachytic intrusions form good outcrops, though extensive mudflats within the area unfortunately hide all contact relationships between them, so that it is not possible to determine their exact geometry. Few radioisotopic dates e ...
Crustal contamination of mafic magmas: evidence from a
... The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe – Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs ...
... The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe – Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs ...
Anomalous Occurrence of Cretaceous Placer Deposits: A
... During the Cretaceous, the CO2 content of the global atmosphere drastically increased in response to volcanism associated with the disintegration of the former continents. This increase in the global atmospheric CO2 level subsequently led to a considerable rise in global temperatures. The interactio ...
... During the Cretaceous, the CO2 content of the global atmosphere drastically increased in response to volcanism associated with the disintegration of the former continents. This increase in the global atmospheric CO2 level subsequently led to a considerable rise in global temperatures. The interactio ...
Geology of granite - Royal Society of Western Australia
... Granite was also generated from melting of continental crust where continents collided and thickened as one was pushed over the other (Fig 2). This situation is still active in the Himalayas and beneath the Tibetan Plateau where the Indian continent has already been pushed for 2000 km under the edge ...
... Granite was also generated from melting of continental crust where continents collided and thickened as one was pushed over the other (Fig 2). This situation is still active in the Himalayas and beneath the Tibetan Plateau where the Indian continent has already been pushed for 2000 km under the edge ...
Formation and Evolution of Granite Magmas During
... (1991), and maximizes the geochemical signature of crustal differentiation. In contrast, the diatexite model can produce residuum-rich granites, and so reduce the geochemical effect of crustal differentiation, as Chappell (1996) noted. How anatectic magmas formed in the deeper crust evolve to the gr ...
... (1991), and maximizes the geochemical signature of crustal differentiation. In contrast, the diatexite model can produce residuum-rich granites, and so reduce the geochemical effect of crustal differentiation, as Chappell (1996) noted. How anatectic magmas formed in the deeper crust evolve to the gr ...
Oxygen and hydrogen isotope compositions of oceanic plutonic rocks
... hydrothermal metamorphism by seawater. Maximum temperatures of alteration are above 600°C; lower temperatures of alteration, greenschist and below, are not characteristic. Whole-rock samples and plagioclaseseparates have undergone 180 depletions associated with deformation and development of metamor ...
... hydrothermal metamorphism by seawater. Maximum temperatures of alteration are above 600°C; lower temperatures of alteration, greenschist and below, are not characteristic. Whole-rock samples and plagioclaseseparates have undergone 180 depletions associated with deformation and development of metamor ...
A Comparative Study of the Badger Pass Igneous Intrusion and the
... of Bannack. The area has a history of mining that dates back over 100 years, and includes gold, silver, and copper mining (Geach, 1972). PVC claim posts, denoting private claims, still dot the landscape, and several mining companies operate intermittently. Recently, several local residents have expa ...
... of Bannack. The area has a history of mining that dates back over 100 years, and includes gold, silver, and copper mining (Geach, 1972). PVC claim posts, denoting private claims, still dot the landscape, and several mining companies operate intermittently. Recently, several local residents have expa ...
Geochemistry of Jurassic Oceanic Crust beneath
... beneath Gran Canaria. As the Canary Islands are located on some of the oldest oceanic crust, this crust serves as an end-member for evaluating the effects of (1) alteration processes, (2) radiogenic ingrowth and (3) contamination of plume-derived, ocean-island melts. Furthermore, because of the prox ...
... beneath Gran Canaria. As the Canary Islands are located on some of the oldest oceanic crust, this crust serves as an end-member for evaluating the effects of (1) alteration processes, (2) radiogenic ingrowth and (3) contamination of plume-derived, ocean-island melts. Furthermore, because of the prox ...
WalkerJ_JGR_95(B13)21483 - KU ScholarWorks
... [Burchfiel et al., 1989] of the earliest intrusive rocks within the suite suggestcrustal thickening began in the northernTibetan Plateaubefore 10.5 Ma, with maximum averageunroofingrates in this part of the Tibetan Plateaufor the period between 10.5 and 4 Ma at approximately< 2 mm/yr. The Ulugh Muzt ...
... [Burchfiel et al., 1989] of the earliest intrusive rocks within the suite suggestcrustal thickening began in the northernTibetan Plateaubefore 10.5 Ma, with maximum averageunroofingrates in this part of the Tibetan Plateaufor the period between 10.5 and 4 Ma at approximately< 2 mm/yr. The Ulugh Muzt ...
Evolution of early continental crust
... known 147Sm/144Nd ratio must have evolved along the growth curve with time (Figure 3). If the sample was derived from CHUR, then the separation event occurred at 1.5 Ga ago. If the source was a DM, the separation took place 2.0 Ga ago. If the granite source formed at 0.8 Ga ago from a crustal source ...
... known 147Sm/144Nd ratio must have evolved along the growth curve with time (Figure 3). If the sample was derived from CHUR, then the separation event occurred at 1.5 Ga ago. If the source was a DM, the separation took place 2.0 Ga ago. If the granite source formed at 0.8 Ga ago from a crustal source ...
A model of intracratonic basin formation, entailing deep crustal
... change of this thickness with time, A L / A t , determined numerically using finite differences. Given that the densities of greenschist and amphibolite are pg and pa, respectively, then the Earth’s surface experiences a downward displacement, Z(t), according to the equation: ...
... change of this thickness with time, A L / A t , determined numerically using finite differences. Given that the densities of greenschist and amphibolite are pg and pa, respectively, then the Earth’s surface experiences a downward displacement, Z(t), according to the equation: ...
What is the meaning of ophiolites? - Creation Ministries International
... the current ocean crust is believed to have formed by CPT. Ophiolites are mostly younger than 1 billion years with the oldest believed to be about 2 billion years old within the uniformitarian timescale.19 However, there is now a claim of a 3.8 billion-year-old ophiolite in southwest Greenland.20 So ...
... the current ocean crust is believed to have formed by CPT. Ophiolites are mostly younger than 1 billion years with the oldest believed to be about 2 billion years old within the uniformitarian timescale.19 However, there is now a claim of a 3.8 billion-year-old ophiolite in southwest Greenland.20 So ...
The Composition of the Continental Crust
... 75% Archean crust Archean crust: Mixture of Archean basalt & Archean granite* Assume 50% of 40 mWm-2 surface heat flow derives from crust: 66% basalt, 33% granite *A special type of granite called tonalite, with relatively low K, Th and U ...
... 75% Archean crust Archean crust: Mixture of Archean basalt & Archean granite* Assume 50% of 40 mWm-2 surface heat flow derives from crust: 66% basalt, 33% granite *A special type of granite called tonalite, with relatively low K, Th and U ...
Micro-Raman study of Precambrian Permineralized Cells from the
... In general we search for self-replicating systems made with organic molecules in contact with liquid water and the remains of these systems. On Mars: - Mars was habitable during the Noachian (~3.8 Ga ago). ...
... In general we search for self-replicating systems made with organic molecules in contact with liquid water and the remains of these systems. On Mars: - Mars was habitable during the Noachian (~3.8 Ga ago). ...
... elements and geochemically similar elements) form when normal eucrite magmas pass through regions that were heated enough to partially melt. Such partial melts would contain higher levels of elements that are not incorporated readily into major minerals, so have higher concentrations in melted regio ...
Sample Chapter 2 - Investigating Geologic Questions
... m (5,000 to 10,000 ft) below sea level. Rivers draining into this new deep basin eroded down through the land and cut canyons hundred of meters deep. The drying of the Mediterranean Sea caused profound climate changes in the region, and perhaps across much of the planet, leading to extinction of loc ...
... m (5,000 to 10,000 ft) below sea level. Rivers draining into this new deep basin eroded down through the land and cut canyons hundred of meters deep. The drying of the Mediterranean Sea caused profound climate changes in the region, and perhaps across much of the planet, leading to extinction of loc ...
Chicxulub crater
The Chicxulub crater (/ˈtʃiːkʃʉluːb/; Mayan pronunciation: [tʃʼikʃuluɓ]) is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named. The age of the Chicxulub asteroid impact and the Cretaceous–Paleogene boundary (K–Pg boundary) coincide precisely. The crater is more than 180 kilometers (110 miles) in diameter and 20 km (12 mi) in depth, making the feature one of the largest confirmed impact structures on Earth; the impacting bolide that formed the crater was at least 10 km (6 mi) in diameter.The crater was discovered by Antonio Camargo and Glen Penfield, geophysicists who had been looking for petroleum in the Yucatán during the late 1970s. Penfield was initially unable to obtain evidence that the geological feature was a crater, and gave up his search. Through contact with Alan Hildebrand, Penfield obtained samples that suggested it was an impact feature. Evidence for the impact origin of the crater includes shocked quartz, a gravity anomaly, and tektites in surrounding areas.The age of the rocks marked by the impact shows that this impact structure dates from roughly 66 million years ago, the end of the Cretaceous period, and the start of the Paleogene period. It coincides with the K-Pg boundary, the geological boundary between the Cretaceous and Paleogene. The impact associated with the crater is thus implicated in the Cretaceous–Paleogene extinction event, including the worldwide extinction of non-avian dinosaurs. This conclusion has been the source of controversy. In March 2010, 41 experts from many countries reviewed the available evidence: 20 years' worth of data spanning a variety of fields. They concluded that the impact at Chicxulub triggered the mass extinctions at the K–Pg boundary. In 2013 a study compared isotopes in impact glass from the Chicxulub impact with the same isotopes in ash from the boundary where the extinction event occurred in the fossil record; the study concluded that the impact glasses were dated at 66.038±0.049 Ma, and the deposits immediately above the discontinuity in the geological and fossil record was dated to 66.019±0.021, the two dates being within 32,000 years of each other, or almost exactly the same within experimental error.