10.6084/m9.figshare.3454064.v1
Andrew J. Mason
Andrew J.
Mason
The Palaeoproterozoic anatomy of the Lewisian Complex, NW Scotland: evidence for two ‘Laxfordian’ tectonothermal cycles
Geological Society of London
2016
South Harris
Lewisian Complex
Laxfordian
deformation
tectonothermal
Palaeoproterozoic
SW
continuation
orogen
Ga
NW Scotland
Geology
2016-06-21 11:52:29
Journal contribution
https://geolsoc.figshare.com/articles/journal_contribution/The_Palaeoproterozoic_anatomy_of_the_Lewisian_Complex_NW_Scotland_evidence_for_two_Laxfordian_tectonothermal_cycles/3454064
<p>A new structural examination of Palaeoproterozoic high-<em>P</em> granulites on South Harris, NW Scotland, when integrated with previous geochronological, structural and metamorphic studies
on key areas of the Lewisian Complex, suggests the existence of two distinct tectonothermal cycles within the Palaeoproterozoic
‘Laxfordian Event’, which on South Harris are separated by a >100 myr hiatus in deformation. The older cycle, from <em>c</em>. 1.91 to 1.85 Ga, records the development of an active continental margin on the Archaean gneisses that dominate the Complex,
and the subsequent onset of continent–continent collision; this represents the continuation of the Nagssugtoqidian orogen
of Greenland. Evidence for this is concentrated in allochthonous slivers of the former active continental margin displaced
during the younger cycle. The younger cycle, around 1.75–1.65 Ga, began with thrust-related crustal thickening that initiated
regionally extensive amphibolite-facies metamorphism and ductile deformation, which dominates the preserved ‘Laxfordian’ deformation
history. This may be the peripheral expression of the accretion of the Malin block to the SW of the Lewisian, and represents
the lateral continuation of the Labradorian–Ketilidian orogen of North America.
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