Geochemical Constraints on the Evolution of the Proterozoic Continental Crust in Southern Norway (Telemark Sector)

Summary. Upper Riphean/Vendian basalt lavas within the Hedmark Group of the Osen-Røa Nappe Complex, the lowest tectonostratigraphic unit within the Scandinavian Caledonides, are typical continental tholeiites. Differences in their REE patterns may reflect source heterogeneities, while the general lack of correlation between incompatible trace element ratios may be due to contamination of the basalts by continental crust. Their association with fluvial deposits in NNW-trending graben, and some geochemical disparities with time-equivalent basalt dykes of MORB-like character in tectonically higher units, may indicate their formation in an aulacogen related to the central rift zone of the lapetus Ocean.

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A Discussion on global tectonics in Proterozoic times - Introductory remarks

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1976.0003 ◽

1976 ◽

Vol 280 (1298) ◽

pp. 399-403

Keyword(s):

Continental Crust ◽

Horizontal Displacement ◽

Polar Wander ◽

Igneous Activity ◽

Order Of Magnitude ◽

Global Tectonics ◽

Horizontal Displacements ◽

Proterozoic Continental Crust

Palaeomagnetic measurements show that horizontal displacements of the crust occurred throughout the Proterozoic at rates comparable to those recorded from the Mesozoic to the present day. However, examination of Proterozoic continental crust reveals some structures which cannot be matched precisely at the present time. Proterozoic stable blocks are smaller and more numerous than the plates of the present day. Those blocks were surrounded by belts in which deformation and igneous activity occurred during times when the blocks behaved as rigid masses. When the apparent polar wander paths of these stable blocks are compared, they are seen to follow rather similar tracks implying that a number of isolated blocks followed approximately the same course. Bearing in mind the uncertainties in establishing pole positions and in dating the rocks concerned, Precambrian apparent polar wander paths are still not precisely located. Despite these uncertainties it would appear that a genuine phenomenon has been revealed which can be described in these terms. During Proterozoic times rates of divergence between stable blocks within a continental mass were an order of magnitude smaller than the overall rate of horizontal displacement of that mass.

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Geochemical constraints on the composition of Archaean lower continental crust: Partial melting in the Lewisian granulites

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2012.07.018 ◽

2012 ◽

Vol 351-352 ◽

pp. 1-12 ◽

Cited By ~ 22

Author(s):

Hugh Rollinson

Keyword(s):

Partial Melting ◽

Continental Crust ◽

Lower Continental Crust ◽

Geochemical Constraints

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