Abstract
The Krummedal supracrustal sequence is a lower to middle Proterozoic sedimentary succession widely represented in the Caledonian fold belt of the Scoresby Sund region. Around inner Nordvestfjord laterally variable sequences of pelitic, semipelitic and psammitic rocks occur. The sequences of different areas ranging from 2500 m to more than 8000 m in thickness are described but no formal subdivision is attempted. High amphibolite facies metamorphism, migmatisation, emplacement of granite intrusions and several phases of deformation appear to relate to an orogenic episode giving dates in the range 900-1200 m.y. Caledonian orogenesis is represented by a relatively weak retrogressive metamorphic phase, westward displacements on major thrusts and emplacement of granite intrusions.
Highlights
The East Greenland fold belt dominates the ice-free stretch of land between latitudes 70° and 82°N
Phillips et al (1973) have used this age data as a basis for a detailed succession of structural and metamorphic events in the southem part of the gneiss and schist zone. These results indicate deposition of the Krummedal supracrustal sequence fairly early in the Proterozoic, in which case the similarity in development with the lower part of the Eleonore Bay Group is no more than coincidenta1
The thick sequence of pelitic, semipelitic and psammitic rocks which makes up the Krummedal supracrustal sequence was deposited in a trough or subsiding shelf environment of great extent
Summary
The East Greenland fold belt dominates the ice-free stretch of land between latitudes 70° and 82°N. A 50 m marble and· amphibolite unit is found locally and comprises layers of marble or sandy marble 10-250 cm thick alternating with basic layers 10-300 cm thick This varied sequence massive brown or red, coarse-grained garnet-biotite gneisses occur, developing eastwards and upwards a progressively coarser grain and more prominent feldspathic augen-like leucocratic sweats. There are obvious similarities with the T-Sø-Nordbugt region in that part of the sequence is characterised by massive augen granite sheets, and further east a development of at least 2000 m of homogeneous siliceous gneisses occurs in the cliffs of northern Renland The latter form a monotonous well banded succession in steep walls exhibiting a number of major flat-lying folds.
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