10.6084/m9.figshare.3453947.v1
Jiri Slama
Jiri
Slama
Rolf B. Pedersen
Rolf
B. Pedersen
Zircon provenance of SW Caledonian phyllites reveals a distant Timanian sediment source
Geological Society of London
2016
Jotun Nappe Complex
zircon ages
Baltica
Caledonian orogeny
Middle Ordovician zircon ages
Scandinavian Caledonides
Timanian orogen
Fennoscandian Shield sources
middle Ordovician
middle Ordovician schists
middle Ordovician sediments
Allochthon nappes
ε Hf
Avalonian source
Zircon provenance
detrital zircon
SW Caledonian phyllites
provenance analysis
Timanian sediment source Cambrian
Ordovician phyllites
Geology
2016-06-21 11:47:40
Dataset
https://geolsoc.figshare.com/articles/dataset/Zircon_provenance_of_SW_Caledonian_phyllites_reveals_a_distant_Timanian_sediment_source/3453947
<p>Cambrian to middle Ordovician schists and phyllites in southwestern Baltica, now exposed in the (par-)autochthon to Lower
Allochthon nappes of the Scandinavian Caledonides in southern Norway, contain previously unrecognized far-travelled detrital
zircons with ages in the intervals 0.47–0.8 and 1.85–3.2 Ga and ε<sub>Hf</sub> in the range −27 to +18. These ages are assigned to Timanian and Fennoscandian Shield sources respectively and contrast with
the locally derived detritus with zircon ages of <em>c</em>. 0.9–1.8 Ga and ε<sub>Hf</sub> values <em>c</em>. −13 to +10. The far-travelled zircons provide evidence that a steady, long-haul, source-to-sink drainage system existed
from the northeastern fringe of Baltica to the SW passive margin across the whole palaeocontinent (<em>c</em>. 2000 km) since <em>c</em>. 521 Ma, and that the Timanian orogen shed detritus across large distances towards both its foreland (Baltica) and hinterland
(Arctica). There are several arguments against an Avalonian source for these zircons. Recycling of the detrital zircon from
the Cambrian to middle Ordovician sediments is probably responsible for the presence of Cryogenian to Middle Ordovician zircon
ages in younger sedimentary sequences of southwestern Baltica. The development of an ophiolitic mélange associated with Ordovician
phyllites underlying the Jotun Nappe Complex seems to mark the change to an active continental margin in the middle Ordovician,
heralding the Caledonian orogeny. The study demonstrates that detrital zircon-poor fine-grained (siltstone to mudstone) sediments
are an extremely valuable indicator for distal sources and favourably complement zircon-rich coarser sandstone in provenance
analysis.
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