Abstract
The thickest section of Early Jurassic strata known from onshore Ireland (total Jurassic thickness 566 m) is reported from the Ballinlea-1 well (Rathlin Basin) on the north coast of Northern Ireland. A detailed biostratigraphical and palaeoenvironmental assessment is presented for this section largely based on calcareous benthic microfossils (foraminifera and ostracods). The Early Jurassic Waterloo Mudstone Formation (Lias Group) of Northern Ireland has previously received little micropalaeontological attention, therefore this work provides an opportunity to enhance palaeogeographic and palaeoenvironmental understanding for the Early Jurassic of the province, and this paper illustrates key microfossil taxa of this age from Ireland for the first time. The records, based on ditch-cuttings samples, demonstrate a stratigraphical range from Hettangian to Early Pliensbachian, consistent with other wells and boreholes in this basin. The assemblage compositions are comparable to those elsewhere in the European boreal Atlantic realm. Hettangian to earliest Sinemurian microfossil assemblages are generally of low diversity and are numerically dominated by metacopid ostracods with occasional influxes of foraminifera. Gradually, foraminiferal abundance (often dominated by species of the Lagenida) come to exceed those of the ostracods in the Early Sinemurian reaching greatest diversity in the Late Sinemurian. The sediments are considered to represent an inner to mid-shelf environment throughout while the record thickness for this region indicates ongoing syn-sedimentary fault movement along the basin margins throughout this period
Original language | English |
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Pages (from-to) | 657-666 |
Number of pages | 10 |
Journal | Proceedings of the Geologists' Association |
Volume | 132 |
Issue number | 6 |
Early online date | 11 Jul 2020 |
DOIs | |
Publication status | Published - Dec 2021 |
Bibliographical note
Publisher Copyright:© 2020 The Geologists' Association
Keywords
- Foraminifera
- Hettangian
- Ostracoda
- Pliensbachian
- Sinemurian
- Waterloo Mudstone Formation
ASJC Scopus subject areas
- Geology
- Palaeontology
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Microfossil biostratigraphy data supporting "Lower Jurassic (Hettangian–Pliensbachian) microfossil biostratigraphy of the Ballinlea-1 well, Rathlin Basin, Northern Ireland, United Kingdom"
Boomer, I. (Creator), Binti Azmi, A. (Creator), Copestake, P. (Creator) & Raine, R. (Creator), University of Birmingham, 5 Jun 2020
DOI: 10.25500/edata.bham.00000492
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