Topic
Borolanite
About: Borolanite is a research topic. Over the lifetime, 6 publications have been published within this topic receiving 57 citations.
Papers
TL;DR: Analcite-syenite is one of the most abundant types of syenite in the British Isles as mentioned in this paper, and it is the most common type of borolanite in Ayrshire.
Abstract: The petrographical province of analcite-rich rocks in Ayrshire is thoroughly basic in character. The most abundant type is teschenite, which frequently passes into picrite and peridotite. Other thoroughly basic types, such as kylite, essexite, crinanite, and monchiquite, are known ; while the effusive phase of this igneous episode has, in the Mauchline basin, given rise to olivine-basalts, analcite-basanites, nepheline-basalts, monchiquite-lavas, and limburgites, which verge on the ultrabasic. It is all the more interesting, therefore, to find in a few localities subacid rocks rich in analcite, evidently belonging to the same suite. This rock constitutes a new type, analcite-syenite. The rock is so fresh, and the primary character of the analcite so undeniable, that this occurrence must take its place as the principal type of this rock-species. Alkali-syenites and felspathoidal syenites of any description are rare in the British Isles. The best-known examples are found in the remarkable masses of Cnoc-na-Sroine and Loch Ailsh (Suther-land). Prof. S. J. Shand described one of the rocks from the first-named locality as ‘analcite-syenite ’; but in a later paper he withdrew this term, as the analcite was found to be secondary, and he then regarded the rock as merely a leucocratic unspotted variety of borolanite. An analcite-syenite was also described by Hibsch from Grosspriesen in the Bohemian Mittelgebirge, but later the rock was described as sodalite-syenite with a little secondary analcite. Many nepheline-syenites, as, for example, those of Madagascar, contain analcite, some of which Prof. A. Lacroix now believes to be of primary
24 citations
TL;DR: The main part of the mass has the form of a laccolith which appears to rest on a floor of limestone as mentioned in this paper, and the silica content of the rocks decreases progressively from the top to the base of the Laccolith, and the rocks near the base develop melanite, diopside and nepheline.
Abstract: The scattered literature relating to this eruptive mass has been brought together and condensed into a connected account. The main part of the mass has the form of a laccolith which appears to rest on a floor of limestone. The silica content of the rocks decreases progressively from the top to the base of the laccolith, and the rocks near the base develop melanite, diopside, and nepheline. The variety known as "borolanite" contains also what appear to be pseudomorphs after leucite. Fundamental problems of petrogenesis are involved in the interpretation of the evidence.
19 citations
TL;DR: Cancrinite is a common constituent of the spots in some types of borolanite, and further work will have to be done to determine its importance in this connexion as discussed by the authors.
Abstract: The minerals to be described in this paper were collected, in conjunction with W. E. Fraser, who was carrying out a detailed study of the borolanite, from the road-metal quarry, opened in 1938, at Allt a' Mhuillin, Loch Borolan, Assynt, Scotland. They occur in pegmatitic patches and veins in borolanite. This mineral is one of the chief constituents of the pegmatites. It forms large cleavable masses, associated with orthoclase, melanite, and a little dark mica. Calcite, sphene, zircon, and orthite are present as accessories. It often fills interstices between crystals of orthoclase. A preliminary examination has indicated that it is a common constituent of the spots in some types of borolanite, and further work will have to be done to determine its importance in this connexion. This is the first definite record of the occurrence of cancrinite in Britain.
11 citations
TL;DR: The remarkable development of igneous rocks associated with the Torridon sandstone and Cambrian strata in Assynt, Sutherlandshire, forms one of the striking geological features of that region.
Abstract: The remarkable development of igneous rocks associated with the Torridon sandstone and Cambrian strata in Assynt, Sutherlandshire, forms one of the striking geological features of that region. In the various papers descriptive of the ancient sedimentary formations of the North-West Highlands by former observers, references are made to the lithological characters of these crystalline rocks and to their mode of occurrence.
8 citations
TL;DR: The geology of Scotland has been studied extensively in the last few decades as discussed by the authors, and the amount of work that has been done, in spite of the labours of Zirkel, Allport, Judd, Geikie, Teall, Harker and others, is very little in comparison with the great amount that still remains for petrographers to do.
Abstract: I. Introduction. No one studying the geological maps of Scotland, on whatever scale, can fail to be impressed by the enormous amount of igneous activity they disclose in the geological history of that country. The broad areas of pink or brown, indicating great lava plateaux, and the splashes and stripes of crimson, indicating intrusive rocks, are literally everywhere. Not only are the igneous rocks widely distributed in space, but also in time. Practically every formation up to the Permian supplies its quota. In the Archaean we have the great foundation of gneiss, with its inextricable tangle of acid and basic igneous rocks. The Dalradian schists and gneisses of the Grampians are everywhere penetrated by igneous masses now largely metamorphosed to massive epidiorites and hornblende schists. The Cambrian of the north-west Highlands contains an interesting complex of highly alkaline rocks, including borolanite and several other rare types. The Ordovician, Devonian, Carboniferous, and Permian in Scotland each exhibit a great series of extrusive and intrusive igneous rocks. Finally, after a long period of quiescence in the Mesozoic, an enormous outburst of igneous activity in the Tertiary gave rise to the great lava plateaux of the Western Isles.
This richness in material makes Scotland a petrographer's paradise. The amount of work that has been done, however, in spite of the labours of Zirkel, Allport, Judd, Geikie, Teall, Harker and others, is very little in comparison with the great amount that still remains for petrographers to do. “No adequate investigation,”
This 250-word extract was created in the absence of an abstract
7 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 1958 | 1 |
| 1941 | 1 |
| 1939 | 1 |
| 1928 | 1 |
| 1909 | 1 |
| 1895 | 1 |