Evidence from detrital zircons for sedimentary links between the onshore Palaeozoic and offshore Mesozoic basins of southern Ireland.

Abstract

Understanding the history of sedimentary basins is fundamental to improving exploration models for hydrocarbons. A key part of this history is revealed by defining the sediment source and elucidating processes of sediment recycling. Determining the links between source areas and ultimate sediment sinks is not a trivial task particularly when dealing with multiple sediment cycles. This study considers the provenance of five ancient onshore and offshore sedimentary basins in southern Ireland. The onshore basins include the Upper Palaeozoic Dingle and Munster Basins and the offshore basins include the Mesozoic North Celtic Sea, Fastnet and Porcupine Basins. Previous work has shown that the Munster Basin had, at least in part, sourced material from the Dingle Basin. In the case of the offshore basins, it is postulated that basin-fill includes reworked sediment from the Munster and Dingle Basins. This implies that offshore Mesozoic basin fill sediments passed through at least two erosional/depositional cycles. Geochronological techniques are very useful in assessing sediment source-to-sink routing paths and the use of detrital zircon geochronology is a novel approach for provenance research in the study region. This study aims to establish the source of offshore basin fill in the Mesozoic South Porcupine, Fastnet and North Celtic Sea Basins; helping to constrain a tectonostratigraphic model for basin evolution. This involves LA ICPMS detrital zircon dating of field and offshore samples from Devonian to Cretaceous intervals across the Dingle, Munster, Porcupine, Fastnet and North Celtic Sea Basins. This work, coupled with petrographic analysis, augments previous studies by expanding onshore detrital mica and zircon geochronology data sets to offshore basins. Deposition into these offshore basins may represent the final stage of ‘triple distilled’ sediment recycling driven by a series of major orogenic events.

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015