Fluid infiltration and regional metamorphism of the Waits River Formation, north-east Vermont, USA

1993 ◽  
Vol 11 (1) ◽  
pp. 3-29 ◽  
Author(s):  
A. LÉGER ◽  
J. M. FERRY
2020 ◽  
Author(s):  
Bjørn Jamtveit ◽  
Kristina G. Dunkel ◽  
Arianne Petley-Ragan ◽  
Fernando Corfu ◽  
Dani W. Schmid

<p>Caledonian eclogite- and amphibolite-facies metamorphism of initially dry Proterozoic granulites in the Lindås Nappe of the Bergen Arcs, Western Norway, is driven by fluid infiltration along faults and shear zones. The granulites are also cut by numerous dykes and pegmatites that are spatially associated with metamorphosed host rocks. U-Pb geochronology was performed to constrain the age of fluid infiltration and metamorphism. The ages obtained demonstrate that eclogite- and amphibolite-facies metamorphism were synchronous within the uncertainties of our results and occurred within a maximum time interval of 5 Myr, with a mean age of ca. 426 Ma.  Caledonian dykes and pegmatites are granitic rocks characterised by a high Na/K-ration, low REE-abundance and positive anomalies of Eu, Ba, Pb, and Sr. The most REE-poor compositions show HREE-enrichment. Melt compositions are consistent with wet melting of plagioclase- and garnet-bearing source rocks. The most likely fluid source is dehydration of Paleozoic metapelites, located immediately below the Lindås part of the Jotun-Lindås microcontinent, during eastward thrusting over the extended margin of Baltica. Melt compositions and thermal modelling suggest that short-lived fluid-driven metamorphism of the Lindås Nappe granulites was related to shear heating at lithostatic pressures in the range 1.0-1.5 GPa. High-P (≈2 GPa) metamorphism within the Nappe was related to weakening-induced pressure perturbations, not to deep burial. Our results emphasize that both prograde and retrograde metamorphism may proceed rapidly during regional metamorphism and that their time-scales may be coupled through local production and consumption of fluids.</p>


1944 ◽  
Vol 61 (1) ◽  
pp. 221-246 ◽  
Author(s):  
N. E. Odell

In the introduction to his previous paper on the Structure (Odell, 1939) the author included a short description of the stratigraphy of the region under review, and the briefest account only is therefore here deemed necessary.A principal feature of north-east Greenland is the considerable number of representatives of the Geological Succession which lie exposed in the ice-free mountainous tract between the Inland Ice Cap and the Greenland Sea. These formations include Pre-Cambrian, Palæozoic, and Mesozoic sedimentaries with Kainozoic eruptives. They have a general trend north and south, and while the older rocks are situated mainly inland, the younger ones lie along the fringes of the coast-line. Consequently, as one sails westward up the immense fjords which cut transversely across the formations, one moves downwards in the succession towards the older rocks. The older rocks, however, underlie by far the greater part of the ice-free area, and of these, sandstones and coarse elastics of Old Red type, quartzites, slates, and limestones ranging from Ordovician to Pre-Cambrian, and metamorphic rocks with granites comprising a Metamorphic Complex, are found in three great belts in order from east to west, between latitudes 72° and 74°. Within these limiting latitudes, the numerous inlets and deeply entrenched fjords, whose great bare walls display in remarkable fashion the multi-coloured formations and their structures, have yielded a considerable amount of information in recent years to the British, Scandinavian, and other geologists who have studied them.


1996 ◽  
Vol 81 (5-6) ◽  
pp. 696-705 ◽  
Author(s):  
Donna L. Whitney ◽  
Trudy A. Mechum ◽  
Yildirim Dilek ◽  
Scott M. Kuehner

1966 ◽  
Vol 103 (3) ◽  
pp. 231-239 ◽  
Author(s):  
J. R. Vail

AbstractInvestigations of the sedimentary rocks of the Umkondo System have enabled six zones of eastwardly increasing metamorphic grade to be delineated on the basis of index mineral assemblages in pelite horizons.Chlorite, garnet (almandine), staurolite, kyanite, and sillimanite isograds have been recognized over a distance of 500 km. along the eastern border of Southern Rhodesia and are plotted on a map. More detailed reconnaissance work has been confined to the Barué highlands north-east of Inyanga. In addition, a “zone of intermediate isotopic age measurements” is proposed to the west of the lowermost chlorite zone. The isograds lie parallel to the structural edge of the north-south trending Mozambique orogenic belt and can be joined with those of similar metamorphic rocks in the east-west trending Zambesi orogenic belt, suggesting contemporaneity of the c. 500 m.y. regional tectono-thermal event in these two belts.


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