Low-pressure regional metamorphism in the Omeo Metamorphic Complex, Victoria, Australia

1990 ◽  
Vol 8 (1) ◽  
pp. 1-12 ◽  
Author(s):  
V. J. MORAND
Keyword(s):  
Regional Metamorphism ◽  
Low Pressure ◽  
Metamorphic Complex

Gneissic Alkalic Rocks and Carbonatites in the Frenchman's Cap Gneiss Dome, Shuswap Complex, British Columbia

1974 ◽  
Vol 11 (2) ◽  
pp. 304-318 ◽  
Author(s):  
W. J. McMillan ◽  
J. M. Moore Jr.
Keyword(s):  
Regional Metamorphism ◽  
Lava Flows ◽  
High Grade ◽  
Metamorphic Complex ◽  
Sedimentary Deposits ◽  
Gneiss Domes ◽  
The Core ◽  
Igneous Origin ◽  
Eastern Border ◽  
Shuswap Metamorphic Complex

Frenchman's Cap dome is one of a series of gneiss domes along the eastern border of the high-grade Shuswap metamorphic complex. The granitic gneisses which compose the core of the dome are enclosed in an envelope of metasedimentary rocks.Before Shuswap metamorphism and deformation, the rocks of the sedimentary envelope were intruded by concordant bodies of alkalic rocks and carbonatite. Other carbonatite bodies appear to have formed at or extruded onto the surface. It is not certain whether these are exhalative sedimentary deposits, lava flows, or pyroclastic deposits.Criteria which can be used to distinguish igneous alkalic rocks from those of metasomatic origin were almost entirely destroyed by regional metamorphism. A few relict igneous textures show that at least some of the alkalic gneisses are of igneous origin.

Low-pressure regional metamorphism in the Pyrenees and its implications for the thermal evolution of rifted continental crust

1987 ◽  
Vol 321 (1557) ◽  
pp. 219-242 ◽  
Keyword(s):  
Large Scale ◽  
Thermal Evolution ◽  
Tectonic Setting ◽  
Regional Metamorphism ◽  
Low Pressure ◽  
Maximum Temperature ◽  
Thermal Gradients ◽  
Temperature Heat ◽  
Isotope Studies ◽  
Strike Slip Movement

During late Palaeozoic (Hercynian) low-pressure regional metamorphism in the Pyrenees, exceptionally high thermal gradients existed within the upper crust, and temperatures as high as 700 °C were attained at depths as shallow as 10 km, resulting in large-scale crustal anatexis. Stable isotope studies indicate that the crust was flushed by circulating ground waters to depths of 12 km, but the amount of fluid involved below 8 km was probably not much greater than 50% of the rock mass, and this fluid apparently did not penetrate the pre-Palaeozoic basement below 12 km. There is no evidence for continental collision in the region at that time, and these data, together with other geological and geophysical constraints, suggest that the most plausible tectonic setting for the metamorphism is a zone of continental rifting, possibly associated with strike-slip movement. Thermal modelling suggests that a transient, high-temperature heat source in the lower crust is required to account for the observed metamorphic P - T arrays. Among a range of possible solutions, a basaltic sill, 6-8 km thick and emplaced at 14 km could generate a maximum temperature array similar to those observed in the Pyrenees.

Timing and duration of regional metamorphism in the Kagasawa and Unazuki areas, Hida metamorphic complex, southwest Japan

2018 ◽  
Vol 484 ◽  
pp. 148-167 ◽  
Author(s):  
Kenji Horie ◽  
Yukiyasu Tsutsumi ◽  
Mami Takehara ◽  
Hiroshi Hidaka
Keyword(s):  
Regional Metamorphism ◽  
Metamorphic Complex ◽  
Southwest Japan

scholarly journals Employing contact metamorphism to assess the conditions of pluton emplacement and timing of recrystallization in southwestern Kellys Mountain, Cape Breton Island, Nova Scotia

2017 ◽  
Vol 54 (11) ◽  
pp. 1165-1178 ◽  
Author(s):  
Nabil A. Shawwa ◽  
Robert P. Raeside ◽  
David W.A. McMullin ◽  
Christopher R.M. McFarlane
Keyword(s):  
Nova Scotia ◽  
Regional Metamorphism ◽  
Low Pressure ◽  
Contact Metamorphism ◽  
Contact Aureole ◽  
Low Grade ◽  
Cape Breton Island ◽  
Metasedimentary Rocks ◽  
Cape Breton ◽  
George River

At Kellys Mountain, Cape Breton Island, Nova Scotia, the late Neoproterozoic Glen Tosh formation (a low-grade metapsammite–metapelite unit of the George River Metamorphic Suite) has been intruded by diorite, granodiorite, and granite plutons, and the diorite hosts a narrow contact metamorphic aureole. New mapping and sampling in the contact aureole reveals that the metasedimentary rocks have reached amphibolite-facies metamorphism resulting in the development of neoformed biotite, muscovite, cordierite, ilmenite, garnet, andalusite, sillimanite, monazite, and spinel within the meta-pelite, a mineral assemblage also found in the Kellys Mountain Gneiss as a result of low-pressure regional metamorphism. Neoformed minerals and the disappearance of foliation defines a contact metamorphic aureole within 300 m of the pluton contacts. Petrographic and microprobe analyses of equilibrium assemblages in metapelitic units of the contact aureole yielded metamorphic pressures of 250 MPa, implying an intrusion depth of ∼9 km, with temperatures ranging from 365 to 590 °C. The presence of earlier-formed andalusite and garnet indicates the rocks may have initially undergone a low-pressure regional metamorphic event prior to contact metamorphism. Monazite in the contact aureole was dated using in-situ U–Pb methods and yielded an age of 480.9 ± 3.7 Ma, interpreted as the time of formation of the contact metamorphic aureole.

Achievement in Isolation: A.W. Howitt, Pioneering Investigator of Metamorphism in Australia

1986 ◽  
Vol 5 (1) ◽  
pp. 39-49 ◽  
Author(s):  
T. Vallance
Keyword(s):  
Regional Metamorphism ◽  
Low Pressure ◽  
Formal Training ◽  
Metamorphic Petrology ◽  
Remote Part

The earliest coherent observations of metamorphic phenomena in Australia were made by a policemagistrate, stationed in a remote part of Victoria and largely self-taught in geology. In a series of reports and papers issued between 1875 and 1892 that magistrate, Alfred William Howitt, recorded details of metamorphic progressions found in the mountains of eastern Victoria - from folded Palaeozoic strata to crystalline schists and gneisses, and of different sorts of granitic bodies in the regional metamorphic association.Howitt worked at a time when the metamorphic status of crystalline schists was far from generally accepted in Europe and America; some still regarded them as portions of unchanged Primitive crust. Like George Barrow in Scotland - whose work in some ways he anticipated, Howitt, however, through the influence of Lyell's writings, began as a believer in metamorphism. But whereas Barrow is respected for innovative contributions to metamorphic thought and method, Howitt's isolation in Australia kept his work little known. In fact, as recent studies show, Howitt was investigating a regional metamorphism different in style from that of Barrow. Howitt not only pioneered metamorphic petrology in Australia, he really began the study of what is now termed low-pressure regional metamorphism.This paper seeks to set Howitt's metamorphic investigations in the contexts of his career and the then condition of his chosen subject. The principal influences on his approaches to petrography and metamorphism are seen to be German in origin. Howitt may have had no formal training in science but as a boy he lived in Germany for some years and learned the language. It was to be a most useful acquisition.

Sign in / Sign up

Export Citation Format

Share Document