U-Pb Monazite Geochronology of Granitic Rocks from Maine: Implications for Late Paleozoic Tectonics in the Northern Appalachians

1996 ◽  
Vol 104 (2) ◽  
pp. 185-195 ◽  
Author(s):  
Paul B. Tomascak ◽  
Eirik J. Krogstad ◽  
Richard J. Walker
Keyword(s):  
Granitic Rocks ◽  
Late Paleozoic

Paleomagnetism and geochronology of late Paleozoic granitic rocks from the Lake District of southern Chile:Implications for accretionary tectonics

Geology ◽  
1991 ◽  
Vol 19 (4) ◽  
pp. 332 ◽  
Author(s):  
Myrl E. Beck, Jr. ◽  
Alfredo Garcia R. ◽  
Russell F. Burmester ◽  
Francisco Munizaga H. ◽  
Francisco Hervé A. ◽  
...  
Keyword(s):  
Granitic Rocks ◽  
Late Paleozoic ◽  
Lake District

40Ar/39Ar ages of detrital muscovite within early Paleozoic overstep sequences, Avalon composite terrane, southern New Brunswick: implications for extent of late Paleozoic tectonothermal overprint

1990 ◽  
Vol 27 (9) ◽  
pp. 1209-1214 ◽  
Author(s):  
R. D. Dallmeyer ◽  
R. D. Nance
Keyword(s):  
New Brunswick ◽  
Coarse Grained ◽  
Granitic Rocks ◽  
Late Paleozoic ◽  
Low Grade ◽  
Early Paleozoic ◽  
Late Precambrian ◽  
Pelitic Schist ◽  
Gas Fractions ◽  
Thermal Overprint

Concentrates of coarse-grained detrital muscovite from the Ratcliffe Brook Formation (lowermost Cambrian) display internally discordant 40Ar/39Ar age spectra. Gas fractions evolved at intermediate and high experimental temperatures record apparent ages of ca. 610–620 Ma. These are interpreted as dating initial cooling through temperatures appropriate for intracrystalline retention of 40Ar and may indicate derivation from mylonite zones developed within proximal late Precambrian granitic rocks. Gas fractions evolved at lower experimental temperatures record patterns of spectra discordance that suggest the constituent grains experienced partial, intracrystalline diffusive loss of 40Ar during a late Paleozoic, low-grade thermal overprint. A muscovite concentrate from pelitic schist beneath the allochthonous, latest Precambrian Cranberry Head granite records a 40Ar/39Ar plateau age of 318 ± 1 Ma. This is interpreted as closely dating Late Carboniferous thrust emplacement of the allochthon.

Late Paleozoic granitic rocks of the Chukchi Peninsula: Composition and location in the structure of the Russian Arctic

Geotectonics ◽  
2015 ◽  
Vol 49 (4) ◽  
pp. 243-268 ◽  
Author(s):  
M. V. Luchitskaya ◽  
S. D. Sokolov ◽  
A. B. Kotov ◽  
L. M. Natapov ◽  
E. A. Belousova ◽  
...  
Keyword(s):  
Granitic Rocks ◽  
Late Paleozoic ◽  
Chukchi Peninsula ◽  
Russian Arctic

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.

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