4.7 Article

In search of the Rheic suture: detrital zircon geochronology of Neoproterozoic to Lower Paleozoic metasedimentary units in the Balkan fold-and-thrust belt in Bulgaria

Journal

GONDWANA RESEARCH
Volume 121, Issue -, Pages 196-214

Publisher

ELSEVIER
DOI: 10.1016/j.gr.2023.04.010

Keywords

Avalonian-Cadomian belt; Cadomian orogeny; Cambro-Ordovician rifting; detrital zircon U-Pb geochronology; Rheic Ocean

Ask authors/readers for more resources

This paper attempts to locate the unknown provenance of pre-Darriwillian basement slivers along the boundary of the Avalonian-type Moesia microplate attached to the southeastern margin of Baltica and the Balkan fold-and-thrust belt in Bulgaria. The U-Pb detrital zircon ages analysis suggests that the pre-Darriwillian units were deposited in an accretionary wedge/forearc basin setting or in an incipient rift superposed on the Cadomian forearc/arc region, while the overlying formations indicate sustained delivery of cratonic detritus. The detrital zircon ages possibly define the Rheic suture and imply the possibility of Cadomian terranes remaining attached to Gondwana during the Early Paleozoic.
The Rheic Ocean opened between Avalonia and Gondwana in the late Cambrian to early Ordovician, triggering break-up of other terranes from the former Avalonian-Cadomian belt. In turn, the Gondwana-derived terranes recorded contrasting drift histories and were variably reworked within the younger orogens, tracing the Rheic suture thus remains challenging. In this paper, we attempt to locate the enigmatic easterly trace of the suture along the boundary of the Avalonian-type Moesia microplate attached to the southeastern margin of Baltica and the Balkan fold-and-thrust belt in Bulgaria, which con-tains Neoproterozoic to Early Paleozoic basement slivers of unknown provenance. We present new U-Pb detrital zircon ages from several pre-Darriwillian low-grade units (Lakavitsa, Berkovitsa, Bilo, Diabase- Phyllitoid Complex) but also from the overlying Darriwillian Grohoten and Famennian-Frasnian Katina formations. The age spectra and the maximum depositional ages of the pre-Darriwillian units suggest deposition in an accretionary wedge/forearc basin setting, or in an incipient rift superposed on the Cadomian forearc/arc region, from the latest Ediacaran to late Cambrian. The basins were sourced from a magmatic arc with a limited input of cratonic detritus, presumably adjacent to the Trans-Saharan belt or Saharan metacraton. In contrast, samples from the overlying formations indicate a sustained delivery of the cratonic detritus, perhaps first into passive-margin basins of the 'Gondwana super-fan' system and then into a Variscan foreland basin. Our statistical analysis shows that the sampled units exhibit age spectra compatible with the Cadomian terranes and that they differ significantly from those reported from Moesia. The detrital zircon ages thus possibly define the Rheic suture and also suggest that the east-erly Cadomian terranes may have remained attached to Gondwana during the Early Paleozoic. It cannot be excluded, however, that the Rheic suture even did not reach that far east and terminated at an intrao-ceanic transform plate boundary.(c) 2023 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.7
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available