The psammites and conglomerates have locally preserved their primary bedding (Photos 7, 10, 12); thin pelitic interbeds display
a foliation defined by – from macroscopic observations to judge – a low-grade mineral assemblage with sericite and chlorite. In psammitic-pelitic alternations, minor intrafolial, isoclinal folds are observed (Photos 107, 131). No attempt has been made to verify Piepjohn's et al. (2000) subdivision into two interfolial phases (see above).
No foliation is seen in massive carbonate rocks, but intercalated, competent lithologic bands like chert layers may be boudinaged and veins show ptygmatic folds (Photo 108). Heterogeneous carbonate rocks show intensive, irregular shearing and folding at small scale (Photo 109) and large-scale (Photo 110) – it is not clear whether these structures were formed at the same time as the early ductile structures, or alternatively formed during a younger, semi-brittle event.
Non-calcareous, metapelitic lithologies mainly occurring in the Kaggen Formation, display a penetrative foliation. When primary bedding is seen, the bedding is either shear-folded (Photo 111) or cut obliquely by the foliation (Photos 112, 113).
Map-scale isoclinal repetions of strata have not been observed, apart from a refolded syncline in the Finneryggen area (close to Selvågen) that has been mapped in the Scotiafjellet Group (Fig. 9).
The superimposed folds refold the main foliation and are probably younger, but the primary syncline may be near isoclional, with the main, ductile foliation equalling the shear foliation of the structure.
High-strain zones have been seen in several places. They are par-allel with the penetrative foliation and seem to belong to the same deformational episode. They are easy to detect where they affect psammitic and psephitic rocks, which elsewhere are less deformed and show primary bedding. One of these zones occurs in coastal exposurs just south of Kapp Sietoe, seaward of a younger fault sepa-rating it from the Sutor conglomerate. The host lithology is most likely the Conquerorfjellet Formation and consists of quartz schists with conglomeratic layers. The zone is several metres thick and dis-plays a strong foliation with cross-cutting shear bands, elongate and boudinaged pebbles and quartz rods (Photos 114-117).
Another high-strain zone occurs at the thrust contact above the Macnairrabbane Window, where it has been observed in both the upper reaches of the valleys Glenmoredalen (Photo 118), Glenbeg- dalen (Photos 38, 119) and Gjelet (Photos 120-123). In the two for-mer places, it displays calcareous greenschists with stretched and boudinaged quartz pebbles belonging to the lithology of the lower nappe in the window. At Gjelet, the zone is observed in the psammi-tic lithologies of the overlying nappe (Conquerorfjellet Formation).
Here it displays strongly sheared slates (Photo 120), boudinaged psammitic layers within slates (Photos 121-122), locally refolded and overprinted by a well-developed crenulation cleavage (Pho-tos 123-124). The orientation of the shear zone is roughly parallel with the lithological boundary between the rocks of the window and rocks of the overlying nappe. These observations suggest an early, ductile phase of nappe emplacement, while detached semi-brittle folds in the overlying nappe indicate a later reactivation of the thrust under cooler conditions (see Macnairrabbane Window).
The special structures in the contact zone between the Craigtoppane and Pinkie units and the correlated mega-boudinage structures at Richardlaguna are dealt with in a separate section below, where also the age of the ductile fabric of the basement rocks is discussed.
Photo 107: Ductile fabric of the basement rocks: Foliation and isoclinal folds in the Fuglehuken Formation, Mosehjellen, west of Fuglehukfjellet.
Photo 109: Ductile fabric of the basement rocks: Sheared and irregularly folded in an Omondryggen facies marble, west of Conquerorfjellet.
Photo 108: Ductile fabric of the basement rocks: Boudinage (chert bands) and ptygmatic folds (quartz vein) in the Baklia facies calcareous rock, east of Finneryggen (Selvågen).
Photo 110: Ductile fabric of the basement rocks: Sheared and irregularly folded marbles at large scale on western Conquerorfjellet (compare Photo 20).
Photo 111: Ductile fabric of the basement rocks: Shear folds in sandy slate of the Kaggen Formation, showing a penetrative foliation at an angle with primary bedding.
Photo 112: Ductile fabric of the basement rocks: Lithological banding in a purple slate of the Kaggen Formation, obliquely cut by a penetrative foliation.
Northern shore of Selvågen.
Photo 113: Ductile fabric of the basement rocks: Layer-parallel foliation in a slate of the Kaggen Formation, obliquely cut by a tightly spaced cleavage.
(part of Photo 27). Northern shore of Selvågen.
Photo 115: Ductile fabric of the basement rocks: Detail of the high-strain zone (Photo 114) in a conglomeratic layer.
Photo 117: Ductile fabric of the basement rocks: Detail of the high-strain zone (Photo 114) in a conglomeratic layer showing mylonitic foliation surrounding a competent pegmatitic pebble.
Photo 114: Ductile fabric of the basement rocks: high-strain zone in quartz schists with conglomeratic layers, Conquerorfjellet Formation south of Sutor- fjellet.
Photo 116: Ductile fabric of the basement rocks: Detail of the high-strain zone (Photo 114) showing mylonitic foliation, boudinaged quartz veins and rods.
Photo 118: Ductile fabric of the basement rocks: High-strain zone in a green-schist at the upper thrust boundary of the Macnairrabbane Window, upper Glenmoredalen.
Photo 119: Ductile fabric of the basement rocks: High-strain zone in a green-schist at the upper thrust boundary of the Macnairrabbane Window, upper Glenbegdalen.
Photo 122: Ductile fabric of the basement rocks: High-strain zone at the upper thrust boundary of the Macnairrabbane Window at Gjelet (Photo 120), displaying large-scale boudinage of pegmatitic dykes.
Photo 124: Ductile fabric of the basement rocks: High-strain zone in a green-schist at the upper thrust boundary of the Macnairrabbane Window at Gjelet (Photo 120) ― mylonitic foliation, boudinage and crenulation.
Photo 125: Selvågen conglomerate, exceptionally ductile deformed with folia-ted matrix and stretched pebbles, on Sesshøgda.
Photo 123: Ductile fabric of the basement rocks: High-strain zone at the upper thrust boundary of the Macnairrabbane Window at Gjelet (Photo 120), displaying a mylonitic foliation and a superimposed, tightly spaced cleavage.
Photo 120: Ductile fabric of the basement rocks: High-strain zone at the upper thrust boundary of the Macnairrabbane Window, here situated in the overlying metapsammitic lithologies (Conquerorfjellet Formation) at Gjelet.
Photo 121: Ductile fabric of the basement rocks: High-strain zone at the upper thrust boundary of the Macnairrabbane Window at Gjelet (Photo 120), displaying boudinage and superimposed crenulation.
An important observation is that ductile deformed zones are also seen in the Palaeogene Selvågen conglomerate on Sesshøgda, which exhibits stretched dolomite and other carbonate pebbles in a local high-strain zone with a well-developed foliation (Photos 125-126).