The Highland Boundary Fault : Reverse or Wrench Fault?
DETAILED work which I have done in the Loch Lomond area suggests a definite answer to the above problem which is of some importance since it concerns one of the major geological features of the British Isles. The direction in which the principal stress acted in the production of the fault can be approximately determined from the pattern of structures in the Lower Old Red Sandstone conglomerates, and this supports the contention put forward in stratigraphical accounts (summarized by J. G. C. Anderson1) that the Highland Boundary Fault is a reverse fault of Caledonian age and not a Proto-Armorican wrench fault as envisaged by E. M. Anderson2.
Neotectonic rotations in the Orava-Nowy Targ Intramontane Basin (Western Carpathians): An integrated palaeomagnetic and fractured clasts study
Abstract The objectives of this contribution are: (1) to promote the application of fractured clasts analysis in conglomerates for regional stress reconstructions and (2) to advance reconstruction of the Western Carpathians structural development. Our results show that the Neogene fill of the Orava-Nowy Targ Intramontane Basin underwent CCW rotation of about 30°. We infer that the rotation terminated after 8 Ma and was related to shift along NW-SE to NNW-SSE trending faults at the NE termination of the sinistral Mur-Žilina Fault Zone. Our results show that, fractured clasts analysis can be good tool for regional tectonic reconstructions. The tool is especially useful when other tectonic tools are scarce or absent. Results of our palaeomagnetic study and fractured clasts analysis verify and supplement each others. In the studied case, palaeomagnetic results allow to distinguish between regional stress field rotation and rotation of the Orava-Nowy Targ Basin Neogene fill, whereas, results of fractured clast analysis help to constrain the age of rotation.
Contact-Metamorphism in the Comrie Area of the Perthshire Highlands
British petrographic literature is now so enriched by the detailed descriptions of contact-metamorphic aureoles, associated with plutonic intrusions—investigations largely conducted by the officers of the Geological Survey, and partly by independent workers—that it might appear that an investigation of an additional contact-zone would bring to light little but the usual well-known mineral-assemblage of aureoles already investigated: In the case of the aureole surrounding the Carn Chois diorite-complex of Perthshire, moreover, an inspection of the 1-inch Geological Survey map would tend to confirm this view—not only as to the nature of the mineral-assemblages, but also as to their apparently restricted variety. The diorite-complex is shown as intruded almost completely within the Ben Ledi Grit stratigraphical zone, touching only at its southernmost point rocks essentially of argillaceous composition— the Aberfoyle Slate-band. Here, then, are presumably sediments of a restricted range of composition; the hornfelses derived from them may be expected to show the same limit of variation. The examination that I have been able to make of this aureole shows quite clearly, however, that such a restriction in chemical composition is far from being the case. The thermal products show a wide range of composition, and the mineral-assemblages in the inner zone of hornfelses include types which (I believe) have not been previously recorded from British contact-zones, and some that I have not been able to match with any of the thermal products of extra-British contact-aureoles. Moreover, these unusual mineral-assemblages are by no means rare in the aureole itself, but have been