Direct40Ar/39Ar dating of Late Ordovician and Silurian brittle faulting in the southwestern Norwegian Caledonides

Terra Nova ◽  
2016 ◽  
Vol 28 (5) ◽  
pp. 374-382 ◽  
Author(s):  
Thomas Scheiber ◽  
Giulio Viola ◽  
Camilla Maya Wilkinson ◽  
Morgan Ganerød ◽  
Øyvind Skår ◽  
...  
Keyword(s):  
Late Ordovician ◽  
Brittle Faulting ◽  
Norwegian Caledonides

Isotopic stratigraphy suggests Neoproterozoic ages and Laurentian ancestry for high-grade marbles from the North-Central Norwegian Caledonides

2002 ◽  
Vol 139 (4) ◽  
pp. 375-393 ◽  
Author(s):  
V. A. MELEZHIK ◽  
M. GOROKHOV ◽  
A. E. FALLICK ◽  
D. ROBERTS ◽  
A. B. KUZNETSOV ◽  
...  
Keyword(s):  
Late Ordovician ◽  
Time Interval ◽  
Low Grade ◽  
High Grade ◽  
North Central ◽  
The North ◽  
Strontium Isotope Stratigraphy ◽  
Dolomite Marble ◽  
Isotope Stratigraphy ◽  
Norwegian Caledonides

Carbon and strontium isotope stratigraphy has been applied to constrain the depositional ages of high-grade marble sequences in the Ofoten district of the North-Central Norwegian Caledonides. Two marble formations hosted by diverse schists from the Bogen Group, all previously correlated over long distances with a Late Ordovician–Early Silurian, low-grade, fossiliferous succession, have been studied for carbon, oxygen and strontium isotopes. The least altered 87Sr/86Sr ratios ranging between 0.7062 and 0.7068, and the best preserved δ13C values falling between +5.0 and +6.5‰ obtained from two marble formations, are consistent with a seawater composition in the time interval 700–600 Ma. The results obtained do not support the previously proposed correlation of the Bogen Group with an Ordovician–Silurian lithostratigraphic succession further north. The apparent depositional ages suggest that the tectonostratigraphic succession studied is inverted and that the tectonostratigraphy of the region requires revision. The Neoproterozoic depositional ages combined with the palaeogeographic position of Baltica imply that carbonates were initially accumulated in seas on a continental shelf, probably Laurentia, and were tectonically transported onto Baltica during Early Silurian, Scandian collision, at c. 425 Ma. Prospecting for new dolomite marble deposits of the Hekkelstrand type and carbonate-hosted manganese–iron ores should be restricted to 700–600 Ma sequences in the Uppermost Allochthon of the Norwegian Caledonides.

A U/Pb age for the Sulitjelma Gabbro, North Norway: further evidence for the development of a Caledonian marginal basin in Ashgill–Llandovery time

1991 ◽  
Vol 128 (2) ◽  
pp. 141-153 ◽  
Author(s):  
Rolf-Birger Pedersen ◽  
Harald Furnes ◽  
Greg Dunning
Keyword(s):  
Continental Margin ◽  
Pillow Lava ◽  
Late Ordovician ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Marginal Basin ◽  
Back Arc ◽  
Dyke Swarms ◽  
North Norway ◽  
Norwegian Caledonides

AbstractThe Sulitjelma Gabbro in the central Norwegian Caledonides has been dated with the U/Pb zircon/sphene method to 437±2 Ma. Geological relationships as well as trace-element geochemistry and Nd and Sr isotopic compositions suggest that the gabbro and associated dyke swarms and pillow lava formed during the initial stages of back-arc spreading. The age constrains the timing of juxtaposition of an older island-arc terrane and continental-margin lithologies exposed within the Caledonian nappes. The age of the gabbro is similar to that of the Solund–Stavfjord Ophiolite in west Norway, and confirms that spreading-related magmatism and marginal-basin development took place along the margin of Iapetus in late Ordovician–early Silurian times.

Late Ordovician (Katian) Graptolites and Shelly Fauna from the Phu Ngu Formation, North-East Vietnam

2020 ◽  
Vol 25 (1) ◽  
Author(s):  
Thomas W. Wong Hearing ◽  
Mark Williams ◽  
Adrian Rushton ◽  
Jan Zalasiewicz ◽  
Toshifumi Komatsu ◽  
...  
Keyword(s):  
Late Ordovician ◽  
North East
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