Marginal and Contact Phenomena of the Dorback Granite

1935 ◽  
Vol 72 (2) ◽  
pp. 49-63 ◽  
Author(s):  
Frederick Walker ◽  
Charles F. Davidson
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
Eastern Margin ◽  
Plutonic Rocks ◽  
Central Highlands ◽  
The Village ◽  
Granite Mass ◽  
Great Mass

The granite mass of Dorback in the Braes of Abernethy, a few miles east of the village of Tomintoul, occupies an area of from 5 to 6 square miles, the plutonic rocks outcropping through the siliceous schists and granulites of the Central Highlands of Scotland. For a highland district the exposures are rather poor, since the igneous rocks only rarely appear from under a thick covering of peat and glacial drift, but towards the eastern margin of the mass the complex is well exposed in the valleys trenched by the Allt Iomadaidh and tributary streams. Here the interest of the plutonic rocks is twofold, for they form a complex of acid, intermediate, and basic types exhibiting considerable variation in petrography, and they include a series of xenoliths of quartzite, schist, and limestone which range from a few inches in diameter to a great mass of limestone 1½ miles in length. This xenolith has been mapped by the Geological Survey of Scotland, and it was the occurrence of a contact between limestone and plutonic rocks at this locality that led to the investigations of the authors.

The aegirine-granulites of Glen Lui, Braemar, Aberdeenshire

1951 ◽  
Vol 29 (212) ◽  
pp. 476-495 ◽  
Author(s):  
G. R. McLachlan
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
Central Highlands

In the explanation of sheet 65 of the Geological Survey of Scotland an outcrop of aegirine-granulites was described from Glen Lui, 1¼ miles SSE. of Derry Lodge. Brief descriptions of some of the rocks were given and it was suggested that they might be metamorphosed igneous rocks having distinct affinities with the borolanites of Assynt. Such a correlation, it was felt, would be of importance in assessing the age of metamorphism in the Central Highlands. Harker (1932) made the further suggestion that these rocks might originally have been a tuff which had subsequently become metamorphosed.

III.—The Gneissose-Granite of the Himalayas

1887 ◽  
Vol 4 (5) ◽  
pp. 212-220
Author(s):  
C. A. McMahon
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
Short Account ◽  
Near Future

The cause, or causes, which result in the foliation of igneous rocks is a subject which at present occupies the attention of many geologists, and seems likely, in the near future, to lead to some discussion. In view of this, a short account of the foliated granite of the Himalayas may be of interest. It may be as well, however, to preface my remarks by saying that I believe that foliation may be produced in several distinct ways, and the explanation which I offer of the mode in which the foliation of the Himalayan granite has been brought about is only intended to apply to the case of that granite.In the following pages I propose to give a brief summary only of some of the more important results worked out in detail in a series of papers published in the Eecords of the Geological Survey of India; and to add thereto a brief consideration of the question whether the foliation of the gneissose-granite of the Himalayas

Rb/Sr Ages and a profile of initial Sr87/Sr86 ratios for plutonic rocks across the Yukon Crystalline Terrane

1976 ◽  
Vol 13 (2) ◽  
pp. 319-330 ◽  
Author(s):  
P. C. Le Couteur ◽  
D. J. Tempelman-Kluit
Keyword(s):  
Quartz Diorite ◽  
Igneous Rocks ◽  
Slow Cooling ◽  
Precambrian Rocks ◽  
Quartz Monzonite ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Plutonic Rocks

Nine Rb/Sr apparent ages are reported for igneous rocks of the Yukon Crystalline Terrane. The oldest age (144 m.y.) is from the Triassic? Klotassin quartz diorite and is thought to be a hybrid age that probably reflects the effects of younger intrusives on rocks at least 190 m.y. old. Five ages of about 100 m.y. presumably reflect the cooling of the Coffee Creek quartz monzonite. K/Ar ages for this event are slightly younger than the Rb/Sr ages, suggesting slow cooling. Rb/Sr ages of 53 and 67 m.y. were obtained for the Ruby Range batholith and an age of 61–67 m.y. for the Nisling Range alaskite. The Rb/Sr ages obtained generally confirm recently determined K/Ar ages. There is a regional decrease in initial Sr87/Sr86 ratios, southwestward across the Yukon Crystalline Terrane. This may mean that Precambrian rocks extend under the Yukon Crystalline Terrane, but are absent under the adjoining Coast Plutonic Complex.

scholarly journals V.—Note on the Highland Border Series, near Aberfoyle

1914 ◽  
Vol 1 (9) ◽  
pp. 402-404 ◽  
Author(s):  
T. J. Jehu
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
The West ◽  
Series Form ◽  
Lower Silurian ◽  
Close Resemblance ◽  
Southern Border

The rocks of this series form an interrupted belt along the southern border of the Highlands from Stonehaven on the east to the island of Arran on the west, and they appear again on a more extensive scale in Ireland. In Scotland the series consists of cherts or jaspers and shales, sometimes associated with limestones and with some peculiar igneous rocks. The age of the series has been for years a matter of controversy. Many geologists have held that these rocks are of pre-Cambrian age, but Messrs. Peach & Horne in their volume on The Silurian Rocks of Britain (Mem. Geol. Surv., 1899) remarked on the close resemblance of the rocks of this belt to some of the Arenig rocks in the Southern Uplands of Scotland, and the belt has been marked on the Geological Survey maps as doubtfully Lower Silurian.

Chronology of the Red Wine alkaline province, central Labrador

1977 ◽  
Vol 14 (8) ◽  
pp. 1940-1946 ◽  
Author(s):  
Alan B. Blaxland ◽  
Laurence W. Curtis
Keyword(s):  
Red Wine ◽  
Early Stage ◽  
Regional Metamorphism ◽  
Strong Support ◽  
New Age ◽  
Igneous Rocks ◽  
Rift System ◽  
Alkaline Rocks ◽  
Plutonic Rocks ◽  
Basaltic Lavas

An 11-point Rb–Sr whole-rock isochron for the regionally metamorphosed Red Wine alkaline province gives an age of intrusion of 1345 ± 75 Ma (errors quoted at 2σ) and an initial 87Sr/86Sr ratio of (1.7021 ± 0.0103. Two 5-point mineral isochrons give ages of ~1000 Ma that represent metamorphic 'resetting' of the alkaline rocks. The whole-rock intrusion age compares closely with the early stage of magmatism in the Gardar Province of south Greenland where un-metamorphosed agpaitic igneous rocks, similar to those of the Red Wine Province, occur. In both provinces, alkaline plutonic rocks are associated, both spatially and chronologically, with thick sequences of continental sediments and basaltic lavas, and the new age data lend strong support to the supposition that the Gardar and Red Wine rocks are parts of the same pre-drift magmatic province and inferred rift system. The Gardar Province has, however, escaped the effects of the Grenville regional metamorphism which severely affected the Red Wine rocks.

The Contaminated Gabbro of Easter Saphook near Old Meldrum in Aberdeenshire

1921 ◽  
Vol 58 (4) ◽  
pp. 177-183 ◽  
Author(s):  
H. H. Read
Keyword(s):  
Igneous Rocks ◽  
Geological Survey ◽  
North East ◽  
Rock Types

In North-East Scotland the igneous rocks have been divided into two series, whose times of intrusion were separated by the movements responsible for the foliation and disposition of the crystalline schists of that area.2 With the older series, intruded prior to or during those movements, this paper is not concerned. The younger, or non-foliated, series supplies rock types ranging from peridotite to granite. Gabbro is the chief rock in the large independent basic masses formed by the younger igneous rocks; to the more important of these masses may be given the names of the Huntly, Insch, Boganloch, Haddo, Arnage, Maud, and Belhelvie Masses. For the most part they lie within Sheets 76, 77, 86, and 87 of the 1 inch Geological Survey Map of Scotland.

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