Neoproterozoic recycling of the sveconorwegian orogenic belt:detrital-zircon data from the sparagmite basins in the scandinavian caledonides

• Published in: Precambrian Research
• Main Authors: Bingen, B., Belousova, E. A., Griffin, W. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2011
• Subjects: Greenland; Moelv; Norway; Osen; Røa; Svalbard; East Greenland; Fennoscandia
• Online Access: https://researchers.mq.edu.au/en/publications/a481530e-bf31-42b4-a84c-9585dc7e0cfb; https://doi.org/10.1016/j.precamres.2011.07.005; http://www.scopus.com/inward/record.url?scp=80052725492&partnerID=8YFLogxK

Arkose-dominated sequences exposed in the Lower and Middle Allochthons of the Scandinavian Caledonides, known as the Sparagmites, are the product of sedimentation along the Baltoscandian (northwestern) margin of Baltica during Cryogenian and Ediacaran times; they notably include the glaciogenic Moelv Formation. These sequences were thrusted southeastward during the Caledonian orogeny. U-Pb and Lu-Hf LA-ICP-MS data from detrital zircons are reported from five samples of arkose or greywacke distributed over the Hedmark Group, to represent the Lower Allochthon Osen-Røa Nappes in southeast Norway. Three samples of arkose from the Särv, Kvitvola and Valdres Nappes represent the Middle Allochthon. All samples share a multimodal detrital-zircon age distribution ranging from 1988 to 862 Ma. Zircons older than 2000 Ma are very rare. Zircons with ages between 677 and 620 Ma are present in only one sample. Mesoproterozoic detrital zircons generally have positive e{open}Hf values, and a general trend of decreasing e{open}Hf with decreasing age reflects crustal recycling. Most detrital-zircon populations in the samples can be attributed to primary magmatic sources exposed in the Sveconorwegian orogenic belt sensu lato (including the Paleo- to Mesoproterozoic crust in western Baltica affected by Sveconorwegian reworking). A 1580-1380 Ma detrital population with negative e{open}Hf, found in several samples of the Hedmark Group, is nevertheless unknown from this belt, and may reflect sourcing from granitoids located in Fennoscandia east of the Sveconorwegian belt. The correspondence between known magmatic events in the Sveconorwegian belt and the ages of detrital zircons is strongest in the samples of the Middle Allochthon. The pooled distribution of new and published detrital-zircon data in arkose from the Middle Allochthon has age modes at 1645, 1600, 1490, 1280, 1155, 965 and 930 Ma. Thick Tonian to Cryogenian siliciclastic sediments exposed in the Caledonides of Scandinavia, East Greenland, Scotland and Svalbard all have ...