Multiple high-pressure metamorphic events and crustal telescoping in the NW Highlands of Scotland
C.D. Storey
T.S. Brewer
R. Anczkiewicz
R.R. Parrish
M.F. Thirlwall
10.6084/m9.figshare.3454784.v1
https://geolsoc.figshare.com/articles/dataset/Multiple_high-pressure_metamorphic_events_and_crustal_telescoping_in_the_NW_Highlands_of_Scotland/3454784
<p>The Glenelg–Attadale Inlier is the largest basement inlier within the Caledonian orogen in NW Scotland. A Western Unit consists
of trondhjemite–tonalite–granodiorite (TTG) gneisses and subordinate mafic intrusions with locally preserved mafic high-pressure
granulite and eclogite assemblages. An Eastern Unit comprises TTG gneisses, Grenville-age (<em>c</em>. 1.1 Ga) eclogite and metasediments. U–Pb zircon ages from the Western Unit TTG gneisses are highly disturbed with Neoarchaean
upper intercepts and Palaeo- to Mesoproterozoic lower intercepts, suggesting strong reworking at these times. U–Pb zircon,
Sm–Nd and Lu–Hf garnet–clinopyroxene dates from the Western Unit high-pressure granulite and eclogite yield Neoarchaean (<em>c</em>. 2.6–2.8 Ga) and Palaeoproterozoic (<em>c</em>. 1.75 Ga) ages, respectively. These ages correspond to the ages of partial resetting of the TTG gneisses. The eclogite in
the Western Unit may represent the high-pressure convergent margin to the lower-pressure Laxfordian events within the Lewisian
Gneiss Complex, whereas the Mesoproterozoic eclogites in the Eastern Unit may represent a farther eastward Grenville-age margin.
Further east, Ordovician high-pressure granulites within the Moine Supergroup may represent another, later, Grampian convergent
margin. These high-pressure belts were developed sequentially towards the east and telescoped westwards from Palaeoproterozoic
to Early Palaeozoic times.
</p>
2016-06-21 12:21:01
TTG gneisses
Eastern Unit
granulite
Ga
Western Unit
NW
eclogite
Grampian convergent margin
Western Unit TTG gneisses
Lewisian Gneiss Complex
Geology