Structures in the southern part of the Cabrach Igneous Area, Banffshire

The structure of the eastern part of the Insch Mafic Intrusion Aberdeenshire

“…Thus, Read (1951Read ( , 1956 has shown that, to the west of the area of the present investigation, a zone of strong deformation involving both igneous and country rocks occurs at, or near, the southern margin of the mass (Fig. 7), and Blyth (1969) has identified a similar zone at the southern margin of the Boganclogh mass (the probable western extension of the Insch mass). Similar E-W trending zones of shearing have also been recognized (Read 1956) in the interior of the Insch mass, and it is noteworthy that Read (1956, pp.…”

“…Elsewhere, on the NE contact of the intrusion the metasedimentary specimen from drillhole 53 is too highly altered for satisfactory petrological assessment, but the occurrence of a xenolithic, 'mixed' rock in drillhole 50 may indicate that this portion of the outer boundary of the intrusion has not been disturbed by later events. Ashcroft and Boyd 1976;Ashcroft and Wilson 1976;Blyth 1969;Boyd and Munro 1978;Duncan 1974;Johnson and Stewart 1960;Munro 1970;Read 1956. The trends of the late cleavage in the Cabrach area are as shown in Fettes 1971.…”

The igneous rocks of the Boganclogh area, N.E. Scotland

“…The ultrabasic rocks are quite distinctive in the field, displaying characteristic pale brown weathered surfaces and rather sparse vegetational cover. A detailed description of the field relationships and certain structural aspects (particularly the pattern of jointing and shearing directions) of the Ultrabasic Group is given by Blyth (1969), who interprets this 'serpentine belt' as an extension of the dislocated southern margin of the main Insch intrusion, with its similar tectonically-emplaced ultrabasic masses (Read 1956).…”

“…The average composition of the plagioclase cores is close to Ari 50 , but the normative (and bulk modal) composition of the feldspars is in the andesine range. On this basis Clarke (1965) chose to use the term quartz-diorite, but Blyth (1969) refers to the rocks of this group as (hypersthene) gabbros, presumably because pyroxene is the dominant ferromagnesian constituent. In this account the term quartz-biotite norite is preferred, despite the fact that orthopyroxene is generally less abundant than clinopyroxene (see Read 1966), mainly on the grounds that these rocks show certain affinities to the quartzbiotite-norites of Morven-Cabrach (Allan 1970) and Haddo House (Gribble 1967).…”

“…The only recently published account dealing with the Boganclogh area is by Blyth (1969); this work was particularly concerned with the structures in the ultrabasic rocks along the southern margin. The country rocks associated with the western end of the Insch mass (including Boganclogh) have been briefly described by Fettes (1970) as part of a more general account of the Dalradian envelope around the basic intrusions, while the geophysical context of the Boganclogh mass is referred to by McGregor and Wilson (1967) and Wilson (1970).…”