Metamorphic mineral reactions: Porphyroblast, corona and symplectite growth

2017 ◽  
pp. 469-540 ◽  
Author(s):  
F. Gaidies ◽  
R. Milke ◽  
Wilhelm Heinrich ◽  
Rainer Abart
Keyword(s):  
Metamorphic Mineral

Sur quelques aspects de la zoneographie alpine dans les Alpes cottiennes meridionales

1962 ◽  
Vol S7-IV (4) ◽  
pp. 477-491
Author(s):  
Andre Michard
Keyword(s):  
Tectonic Activity ◽  
Structural Units ◽  
Zonal Distribution ◽  
Rock Types ◽  
Metamorphic Mineral ◽  
Mineral Assemblages ◽  
Alpine Metamorphism

Abstract A Permo-Carboniferous series and a polymetamorphic series are distinguished in the rocks of the southern Cottian Alps, Italy. The metamorphic mineral assemblages and facies of the principal rock types represented in each series and their zonal distribution are discussed. Alpine metamorphism is considered to have occurred after the tectonic activity responsible for superposition of the three structural units recognized in the region between Varaita and Stura.

Vanadium-Bearing Margarite from the Lachlan Fold Belt, New South Wales, Australia

1988 ◽  
Vol 52 (366) ◽  
pp. 341-345 ◽  
Author(s):  
V. J. Morand
Keyword(s):  
Solid Solution ◽  
Local Reaction ◽  
New South ◽  
New South Wales ◽  
Contact Aureole ◽  
Fold Belt ◽  
Metamorphic Mineral ◽  
South Wales ◽  
Lachlan Fold Belt ◽  
Black Slate

AbstractMargarite occurs in Ordovician black slate within the contact aureole of the Wyangala Batholith, in the Lachlan Fold Belt in New South Wales. This occurrence is the first described from New South Wales. It is a regional metamorphic mineral replacing chiastolitic andalusite, and contains up to 1.07% V2O3 and up to 0.37% Cr2O3. Vanadium and chromium here substitute for octahedral aluminium. Margarite is produced by a local reaction in which Ca and H2O are introduced into andalusite grains. There is a significant paragonite component in the margarite but negligible muscovite solid solution.

A metamorphic mineral source for tungsten in the turbidite-hosted orogenic gold deposits of the Otago Schist, New Zealand

2016 ◽  
Vol 52 (4) ◽  
pp. 515-537 ◽  
Author(s):  
Ben J. Cave ◽  
Iain K. Pitcairn ◽  
Dave Craw ◽  
Ross R. Large ◽  
Jay M. Thompson ◽  
...  
Keyword(s):  
New Zealand ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Orogenic Gold Deposits ◽  
Metamorphic Mineral ◽  
Otago Schist

Evolution of regional metamorphism during back-arc stretching and subsequent crustal shortening in the 1.9 Ga Wopmay Orogen, Canada

1987 ◽  
Vol 321 (1557) ◽  
pp. 199-218 ◽  
Keyword(s):  
Regional Metamorphism ◽  
Thermal Relaxation ◽  
Time Interval ◽  
Magmatic Arc ◽  
Mineral Growth ◽  
Metamorphic Mineral ◽  
Mineral Assemblages ◽  
Continental Magmatic Arc ◽  
Uplift And Erosion ◽  
Structural Levels

The stratigraphic units, structural elements and metamorphic mineral assemblages of a regional metamorphic culmination in the 1.9 Ga Wopmay Orogen are exposed over greater than 30 km of composite structural depth, in a series of oblique sections produced by cross folding. Regional metamorphism developed continuously in three sequential, rapidly changing thermo-tectonic régimes within an evolving continental magmatic arc. At ca . 1900 Ma, stretching of intra-arc crust resulted in the accumulation of clastic sediment and bimodal volcanic rift-fill deposits. The onset (first stage) of regional metamorphism is marked by high- T low P mineral assemblages, condensed metamorphic zonal sequences and extensive areas of high-grade gneisses devoid of associated plutons. These features are interpreted in terms of a high thermal gradient related to stretching and thinning of the continental lithosphere. Five to ten million years after stretching, following deposition of a west-facing sedimentary prism, a suite of 1896—1878 Ma plutons was emplaced into the rift and margin deposits as they underwent subhorizontal shortening and deformation during the Calderian Orogeny. Thrusted and folded syn-orogenic foredeep deposits are also intruded by the syn-tectonic plutons. At high and intermediate structural levels, syn-tectonic metamorphic mineral growth and metamorphic zonal sequences which are spatially related to the plutons, document heat advection into the deforming marginal prism and mark a second stage of regional metamorphism related to the emplacement of the plutonic bodies. Inverted mineral isograds in autochthonous Proterozoic units beneath a basal décollement record downward thermal relaxation of isotherms following east-directed Calderian transport of the deformed, thickened, and still hot marginal prism over a relatively cold basement. Derivation of multi-point P - T trajectories from post-tectonic, poikiloblastic garnets charts metamorphic mineral growth during uplift and erosion of the internal zone, documenting the third (final) stage of regional metamorphism in Wopmay Orogen. The short erosional time interval (less than 11 Ma) between tectonic thickening and the end of uplift constrains the heat required for this last metamorphic stage to be inherited from the two preceding thermo-tectonic régimes: epicontinental stretching and the emplacement of the syn-tectonic plutonic suite.

Sign in / Sign up

Export Citation Format

Share Document