Journal of the Geological Society; October 1989; v. 146; no. 5;
p. 798; DOI: 10.1144/gsjgs.146.5.0798
© 1989 Geological Society of London
Discussion
A. L. Harris writes: The work reported by Rogers et al confirms the conclusions of Bradbury et al. (1976) that the Ben Vuirich granite intruded Dalradian rocks which had already suffered two episodes of deformation (Dl-D2) and that subsequent deformation (D3) imposed a strong LS fabric on country rocks and granite alike. An age of 590 ± 2 Ma for the granite, reported by Rogers et al. means that the status and setting of the Dalradian stratigraphic units from which Phanerozoic fossils had been reported should be re-examined and that early orogenesis, at least, was Precambrian.
The Leny Limestone from the Highland Border zone of the Callander area, Perthshire yielded topmost Lower Cambrian Pagetides trilobites and was regarded by Harris (1969) on structural grounds as likely to be part of the Dalradian sequence. The limestones which yielded the fossils crop out in Leny Quarry [NN618100], a locality where there is much evidence of faulting. Consequently, only a tenuous link exists between it and the stream section in the Keltie Water [NN644124] some 3.4 km to the ENE where structural and stratigraphic relationships between the supposed, but unfossiliferous Leny Limestone and Shales and adjacent Dalradian strata are less equivocal. (see fig. 2 in BGS 1970 Stirling District Memoir). Examination of this stream section shows that multiply deformed, locally calcareous dark and bluish-grey phyllites are both overlain and underlain by moderately northerly dipping but inverted granular sandstones, the Lower and Upper Leny Grits respectively. Both grit units contain upward-and downward facing, spaced pressure
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