Unravelling the Neoproterozoic oceanic sedimentary record: Insights from the Mona Complex Ocean Plate Stratigraphy, Wales

Santolík, Václav, Ackerman, Lukás, Buchs, David ORCID: https://orcid.org/0000-0001-8866-8125 and Groome, Niall 2025. Unravelling the Neoproterozoic oceanic sedimentary record: Insights from the Mona Complex Ocean Plate Stratigraphy, Wales. Precambrian Research 418 , 107708. 10.1016/j.precamres.2025.107708 Item availability restricted.

PDF - Accepted Post-Print Version Restricted to Repository staff only until 23 January 2026 due to copyright restrictions. Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (4MB)

Abstract

Ocean Plate Stratigraphy (OPS) represents a sequence of volcanic and sedimentary rocks of the uppermost part of an oceanic plate typically preserved in tectonic stacks of an accretionary wedge. While the characteristics of Phanerozoic OPS are generally well-known, those of Neoproterozoic OPS, especially their sedimentary components, remain underexplored. We combined field observations with petrography and geochemistry (major and trace elements, Sr–Nd isotopes) of sedimentary rocks from the Gwna Group (Mona Complex, Wales, UK) representing a well-preserved example of Neoproterozoic OPS. The rocks were subdivided into five groups: (1) red chert/jasper, (2) carbonate/dolostone, (3) black mudstone, (4) red/green mudstone, and (5) turbiditic/volcaniclastic rocks. The carbonate rock and red chert fill interpillow spaces or form less than 2-meter-thick layers above a basaltic base. These rocks formed as chemical precipitates from hydrothermal fluid (εNd = −2.4 to −1.2) or hydrothermally fluxed seawater (εNd = −8.3 to −7.4) related to magmatic activity on the seafloor. Unlike Phanerozoic OPS, the studied OPS does not include a thick bedded chert sequence resulting from the accumulation of plankton remains. The red, green, and black mudstones were deposited on the ocean floor in a pelagic or hemipelagic environment under oxygenated and anoxic conditions. They were predominantly sourced from distal mature continental crust as exemplified by their low εNd values (−11.3 to −3.5). In contrast, the turbiditic and volcaniclastic rocks (εNd = −1.9 to +0.8) that form most of the Gwna Group were sourced from an adjacent volcanic arc and deposited in a trench. We show that the OPS lithological and compositional changes relate to Neoproterozoic plate motion and increasing proximity to a subduction zone. The OPS of the Gwna Group serves as a crucial paleooceanographic and paleogeographic indicator in the Neoproterozoic.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Earth and Environmental Sciences
Publisher:	Elsevier
ISSN:	0301-9268
Date of First Compliant Deposit:	25 February 2025
Date of Acceptance:	19 January 2025
Last Modified:	26 Feb 2025 13:15
URI:	https://orca.cardiff.ac.uk/id/eprint/176472

Actions (repository staff only)

Edit Item