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| Detailed Reference Information |
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Forbes, R.B. and Kuno, H. (1965). The regional petrology of peridotite inclusions and basaltic host rocks. In: International Union Geol. Sci. Upper Mantle Symposium, New Delhi. Berlingske Bogtrykkeri, Copenhagen. 1964: 161-179. |
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Peridotite inclusion-bearing basaltic rocks occur in regional belts on the continents and the island archipelagos of the ocean basins. In some regions, oceanic and continental belts appear to be contiguous. Over 200 inclusion localities are known, and with the exception of Carboniferous occurrences in Great Britain, and a possible Mesozoic locality in east Australia, the basaltic host rocks are of post-Cretaceous age. The mechanism is currently active, as historic eruptions have produced peridotite inclusion bearing basalts. Most host rocks have alkalic affinities, and they tend to be silica undersaturated with nepheline and/or leucite in the norm. Although the host basalts are more alkalic, as a group, than average basalts, inclusion bearing basalts have been sub-divided into high and low alkali groups. High alumina basalts have not been reported as host rocks, but rarely, tholeiitic basalts contain peridotite inclusions. TiO (sub 2) and K (sub 2) O show considerable variation in the bulk chemical composition of the host rocks, and regional trends have been detected, which may be genetically significant. The assemblage enstatite-chromian augite-olivine-spinel seems to occur with the greatest frequency, but other peridotite assemblages prevail at some localities. Although little studied, gabbroic inclusions are the most ubiquitous of all inclusion types. Granulite and eclogite inclusions occur with or without peridotite inclusions in a few localities. Recent findings concerning the chemistry of certain inclusions and mineral phases are discussed. The world-wide scope of the inclusion problem is expanding, as many new localities are being reported. A coordinated international research program is suggested. |
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