U–Pb dating of calcite in ancient carbonates for age estimates of syn- to post-depositional processes: a case study from the upper Ediacaran strata of Finnmark, Arctic Norway. (10th August 2020)

• Record Type: Journal Article
• Authors: Meinhold, Guido; Roberts, Nick M. W.; Arslan, Arzu; Jensen, Sören; Ebbestad, Jan Ove R.; Högström, Anette E. S.; Høyberget, Magne; Agić, Heda; Palacios, Teodoro; Taylor, Wendy L.
• Is Part Of: Geological magazine. Volume 157:Number 8(2020)
• Page Start: 1367
• Page End: 1372
• Publication Date: 2020-08-10
• Subjects: U–Pb calcite geochronology, -- calcite spherulites, -- cone-in-cone calcite, -- Ediacaran, -- Caledonides, -- Norway; Geology -- Periodicals; 551.05
• DOI: 10.1017/S0016756820000564
• Languages: English
• ISSNs: 0016-7568

Abstract

Abstract: Results of in situ U–Pb dating of calcite spherulites, cone-in-cone (CIC) calcite and calcite fibres from a calcareous concretion of the upper Ediacaran of Finnmark, Arctic Norway, are reported. Calcite spherulites from the innermost layers of the concretion yielded a lower intercept age of 563 ± 70 Ma, which, although imprecise, is within uncertainty of the age of sedimentation based on fossil assemblages. Non-deformed CIC calcite from the bottom part of the concretion yielded an age of 475 ± 25 Ma, which is interpreted as the age of CIC calcite formation during a period of fluid overpressure induced during burial of the sediments. Deformed CIC calcite from the top part of the concretion yielded an age of 418 ± 23 Ma, which overlaps with a known Caledonian tectono-metamorphic event, and indicates a potential post-depositional overprint at this time. Calcite fibres that grew in small fissures along spherulite rims, which are interpreted as a recrystallization feature during deformation and formation of a cleavage, gave an imprecise age of 486 ± 161 Ma. Our results show that U–Pb dating of calcite can provide age constraints for ancient carbonates and syn- to post-depositional processes that operated during burial and metamorphic overprinting.