Thrust sequences and the significance of low-angle, out-of-sequence faults in the northernmost Moine Nappe and Moine thrust zone, NW Scotland

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doi: 10.1144/0016-76492005-076
Authors:Holdsworth, R. E.; Strachan, R. A.; Alsop, G. I.; Grant, C. J.; Wilson, R. W.
Author Affiliations:Primary:
University of Durham, Department of Geological Sciences, Durham, United Kingdom
University of Portsmouth, United Kingdom
University of St. Andrews, United Kingdom
Shell, United States
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 163(5), p.801-814. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2006
Note:In English. 58 refs.; illus., incl. geol. sketch maps, sects.
Summary:In common with most thrust belts, the Moine Thrust Zone, Scotland, preserves a foreland-propagating sequence of thrusting. However, significant examples of local to regional overstep sequences are also recognized and their interpretation remains controversial. Remapping of the northernmost Moine Thrust Zone has defined a thick belt of mylonites in the centre of which lies the ductile WNW-directed Moine Thrust. The base of the mylonite belt, however, is marked by a regionally significant, low-angle, west-directed brittle fault, here termed the Lochan Riabhach Thrust, that truncates thrust-related structures in its footwall. Comparison of the tectonic stratigraphy of the mylonite belt with that preserved in a downfaulted outlier to the west at Durness indicates that the Lochan Riabhach Thrust cuts down-section in its footwall and therefore appears to be extensional. Locally, it is unequivocally breached by underlying imbricate thrusts. We prefer to interpret the Lochan Riabhach "Thrust" as an extensional fault that formed during a hiatus in thrust stacking. We relate this faulting episode to the changes in the stability of the evolving orogenic wedge and reiterate that such extensional faults may be common, although possibly unrecognized, features in many other thrust belts.
Subjects:Brittle deformation; Cambrian; Decollement; Deformation; Ductile deformation; Extension tectonics; Faults; Imbricate tectonics; Lewisian; Low-angle faults; Metamorphic rocks; Models; Mylonites; Nappes; Paleozoic; Precambrian; Proterozoic; Protoliths; Tectonics; Thrust faults; Upper Precambrian; Europe; Great Britain; Moine thrust zone; Scotland; United Kingdom; Western Europe; Lochan Riabhach Thrust; Moine Nappe
Coordinates:N581500 N583000 W0041500 W0044500
Abstract Numbers:06M/3593
Record ID:2006069723
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data from The Geological Society, London
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