Chronology and geochemistry of late Svecofennian processes in northern Sweden

• Radiometric and geochemical data have been used to characterize the concluding stages of the Svecofennian orogeny in northern Sweden. U-Pb zircon ages of 1879 +- 7 and 1858 +- 9 Ma have been obtained from two unfoliated granitoids of the North Svecofennian Sub-province. The ages are distinctly different from each other and indicate late- to post-orogenic Svecofennian magmatic activity 1860 Ma ago. The older rock type forms a diorite-quartz monzonite-adamellite trend, while samples of the younger type are adamellitic. Trace element data are not in accordance with a model age where the younger type is formed by continuous magmatic differentiation from rocks of the older type. We propose a new 1910-1860 Ma delimitation for the emplacement of all igneous Svecofennian rocks in northern Sweden and conclude that the widespread potassic 1800-1770 Ma granites of that area should not be considered part of the Svecofennian orogeny, but of some later and separate event.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)

Nyckelord

Applied Geology

Tillämpad geologi

Publikations- och innehållstyp

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