Geology, petrography, and geochemistry of granitic rocks from the Coast Mountains Complex near Juneau, southeastern Alaska

1995 ◽  
Author(s):  
J.L. Drinkwater ◽  
A. B. Ford ◽  
D.A. Brew
Keyword(s):  
Granitic Rocks ◽  
Coast Mountains

Model of evolution of the Bella Coola – Ocean Falls Region, Coast Mountains, British Columbia

1968 ◽  
Vol 5 (6) ◽  
pp. 1429-1441 ◽  
Author(s):  
A. J. Baer
Keyword(s):  
British Columbia ◽  
Granitic Rocks ◽  
Coast Mountains ◽  
Early Tertiary ◽  
Upper Paleozoic ◽  
Late Tertiary ◽  
Bella Coola

Granitic rocks and metavolcanics underlie most of the Coast Mountains of British Columbia between the fifty-second and the fifty-third parallel, about half-way between Vancouver and Prince Rupert. The age of most rocks is unknown. The area has been involved in at least two orogenic cycles. The oldest known supracrustal rocks (Upper Paleozoic?) have been metamorphosed to gneisses, deformed along northeasterly trends, and intruded by granitic plutons, probably early in the Mesozoic Era. These rocks formed the basement of disconformable Mesozoic sediments and volcanics. The basement and its Mesozoic cover were metamorphosed and deformed along northwesterly trends in the early Tertiary. In the late Tertiary (Pliocene?) post-kinematic granites were emplaced and basalts were extruded for a period extending to postglacial times. The model is possibly applicable to all of the Coast Mountains in Canada.

A northern Cordilleran ocean–continent transect: Sitka Sound, Alaska, to Atlin Lake, British Columbia

1991 ◽  
Vol 28 (6) ◽  
pp. 840-853 ◽  
Author(s):  
David A. Brew ◽  
Susan M. Karl ◽  
David F. Barnes ◽  
Robert C. Jachens ◽  
Arthur B. Ford ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
High Rate ◽  
Granitic Rocks ◽  
Coast Mountains ◽  
Glacier Bay ◽  
Denali Fault ◽  
Queen Charlotte Islands ◽  
Sitka Sound ◽  
Almost All ◽  
Alexander Terrane

The 155 km wide, 310 km long Sitka Sound – Atlin Lake continent–ocean transect includes almost all the geologic, geophysical, and geotectonic elements of the Canadian Cordillera. It crosses the Chugach, Wrangellia, Alexander, Stikine, and Cache Creek terranes, the Gravina and Laberge overlap assemblages, intrusive and metamorphic belts, and neotectonic faults that bound major blocks. Linear belts of magnetic highs are associated with Jurassic and Cretaceous granitic belts in Wrangellia and the western and central parts of the Alexander terrane and with the granitic rocks of the Coast plutonic–metamorphic complex (CPMC). The Border Ranges fault may be expressed at depth on either side of the Peril Strait fault. An enigmatic northeast-trending gradient in the CPMC and adjacent rocks separates a regional magnetic low to the northwest from a 300 nT high field to the southeast. The Bouguer gravity field decreases in broad steps from Pacific crust high values to lows at the international boundary, with pronounced gradients at the east edge of Chugach terrane and west edge of of CPMC. It indicates that the crust thickens from about 20 to 40 km from southwest to northeast. Ultramafic bodies in the Chugach, Alexander, and Wrangellia terranes and Gravina assemblage underlie local highs. Most of the accumulated seismic strain is released by large earthquakes on the Fairweather – Queen Charlotte Islands plate-margin fault, but the northern part of the Glacier Bay region, the Denali fault zone, and the Coast Mountains also have significant seismicity. Part of the Glacier Bay region is being uplifted at a high rate. Most of these features are related to the joining of (i) Wrangellia to Alexander terrane (Carboniferous), (ii) Stikine to Cache Creek terrane (Early Jurassic), (iii) Alexander terrane and Gravina assemblage to Stikine (Late Cretaceous), and (iv) Chugach to Wrangellia and Alexander terrane (Late Cretaceous or Paleogene).

Degradation of Rocks, Through Cracking Caused by Differential Thermal Expansion, in Relation to Nuclear Waste Repositories

1981 ◽  
Vol 6 ◽  
Author(s):  
J.R. Mclaren ◽  
R.W. Davidge ◽  
I. Titchell ◽  
K. Sincock ◽  
A. Bromley
Keyword(s):  
Thermal Expansion ◽  
Grain Boundary ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Crack Density ◽  
Granitic Rocks ◽  
Multiphase Materials ◽  
Thermal Expansion Behaviour ◽  
Waste Repositories ◽  
Expansion Behaviour

ABSTRACTHeating to temperatures up to 500°C, gives a reduction in Young's modulus and increase in permeability of granitic rocks and it is likely that a major reason is grain boundary cracking. The cracking of grain boundary facets in polycrystalline multiphase materials showing anisotropic thermal expansion behaviour is controlled by several microstructural factors in addition to the intrinsic thermal and elastic properties. Of specific interest are the relative orientations of the two grains meeting at the facet, and the size of the facet; these factors thus introduce two statistical aspects to the problem and these are introduced to give quantitative data on crack density versus temperature. The theory is compared with experimental measurements of Young's modulus and permeability for various rocks as a function of temperature. There is good qualitative agreement, and the additional (mainly microstructural) data required for a quantitative comparison are defined.

IDENTIFICAÇÃO DAS FEIÇÔES GRANÍTICAS DO MUNICÍPO DE IRAUÇUBA-CEARÁ

2019 ◽  
Vol 21 (2) ◽  
pp. 51-61
Author(s):  
Abner Monteiro Nunes Cordeiro ◽  
Rayane Barroso Araújo ◽  
Frederico De Holanda Bastos ◽  
Augusto César Praciano Sampaio
Keyword(s):  
Field Work ◽  
Granitic Rocks ◽  
Surface Erosion ◽  
Climatic Fluctuations ◽  
Geological Faults ◽  
Dry Climates ◽  
Evolution Understanding ◽  
Geomorphological Features

A exumação de rochas graníticas do Complexo Tamboril-Santa Quitéria, especificamente, na superfície de aplainamento do município de Irauçuba, Ceará, tem revelado uma grande variedade de feições geomorfológicas que se justificam por fatores litológicos e evidentes flutuações climáticas cenozoicas, comandadas, sobretudo, por morfogênese mecânica, associada a climas secos. São relevos residuais como, maciços, cristas, inselbergs, inselguebergs, lajedos e blocos saprolitizados (boulders) em diferentes graus de desenvolvimento que se sobressaem em meio à superfície erosiva rebaixada, regionalmente conhecida como depressão sertaneja. Nesse trabalho, foram identificadas diferentes formas de relevo granítico condicionadas, sobretudo por intempéries de subsuperfície, controladas por falhas e fraturas, e por remoção do regolito através da erosão superficial, além de eventos de esfoliação. Essas formas graníticas constituem peças fundamentais na compreensão da evolução paleoclimática do município de Irauçuba. Para a realização do presente trabalho foram usadas as seguintes metodologias: revisão bibliográfica, levantamento cartográfico e trabalho de campo.Palavras-chave: Feições graníticas; Superfícies de aplainamento; Erosão diferencial. ABSTRACTThe granitic rocks exhumation of Complexo Tamboril-Santa Quitéria, specifically, on the planing surface of Irauçuba county, Ceará, has revealed a great variety of geomorphological features that are justified by lithologic factors and evident Cenozoic climatic fluctuations, mainly, headed by mechanical morphogenesis, associated with dry climates. Residual reliefs like rocky massives, residual ridges, inselbergs and inselguebergs, slab stones and boulders in different degrees of development stand out in the middle of the lowered erosive surface, regionally known by “depressão sertaneja”. In this study, different forms of granite relief were identified, specially conditioned by subsurface erosion, controlled by geological faults and fractures, but also by regolith removal through surface erosion, plus exfoliation spheroidal events. These granitic features are fundamental in paleoclimatic evolution understanding of Irauçuba municipality. For the accomplishment of the present work the following methodology was used: bibliographical revision, cartographic survey and field work. For the accomplishment of the present work the following methodology was used: bibliographical revision, cartographic survey and field work.Keywords: Granitic features; Planing surface; Differential erosion.RESUMENLa exhumación de rocas graníticas del Complejo tamboril-Santa Quitéria, específicamente en la superficie de aplanado del municipio de Irauçuba, Ceará, ha revelado una gran variedad de rasgos geomorfológicos que se justifican por factores litológicos y evidentes fluctuaciones climáticas cenozoicas, comandadas principalmente por morfogénesis mecánica, asociada a climas secos. Son relieves residuales como, macizos, crestas, Inselbergs, inselguebergs, losas y bloques saprolitizados (Boulders) en diferentes grados de desarrollo que sobresalen en medio de la superficie erosiva rebajada, regionalmente conocida como depresión sertaneja. En este trabajo, se identificaron diferentes formas de relieve granítico condicionadas, principalmente por intemperies de subsuperficie, controladas por fallas y fracturas, y por eliminación del regolito a través de la erosión superficial, además de eventos de exfoliación. Estas formas graníticas constituyen piezas fundamentales en la comprensión de la evolución paleoclimática del municipio de Irauçuba. Para la realización del presente trabajo se utilizaron las siguientes metodologías: revisión bibliográfica, levantamiento cartográfico y trabajo de campo.Palabras clave: Facciones graníticas; Superficies de aplanado; Erosión diferencial.

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