The origin of Upper Palaeozoic sedimentary basins in Northern Ireland and relationships with the Canadian Maritime Provinces

Abstract

The evolution of Carboniferous and early Permian sedimentary basins in Northern Ireland is related to a rapidly changing pattern of tectonic episodes. Characteristic sedimentary assemblages and facies changes are associated with discrete phases of basin formation and were related to tectonic events that can be correlated with events in a wide zone of dextral strike-slip in the Canadian Maritime Provinces. Small, localized nonmarine basins developed during late Asbian-early Brigantian and Westphalian B times. These data support the extension of the Canadian Maritime transform fault system into Northern Ireland in late Silesian times.

Lower carboniferous (Dinantian) stratigraphy and structure in the Kingscourt Outlier, Ireland

“…In the Armagh and Lough Allen Basins to the north of the Longford-Down massif there were two periods of tectonic activity at broadly the same time intervals -latest Courceyan to early Chadian and late Asbian to early Brigantian, with a prolonged period of quiescence in between (Mitchell 1992). However, these basins did not have a Courceyan sag phase; the very earliest sedimentation was controlled by syn-sedimentary faulting.…”

Correlation of Mississippian (Upper Viséan) foraminiferan, conodont, miospore and ammonoid zonal schemes, and correlation with the Asbian–Brigantian boundary in northwest Ireland

“…In northwest Ireland this boundary was placed at the base of the Glenade Sandstone Formation by George et al (1976), and at the top of the Bellavally Formation by Brandon and Hodson (1984). If the regressive/transgressive curve of the Dartry Limestone, Meenymore, Glenade Sandstone and Bellavally formations is analysed (figure 2b in Brandon and Hodson 1984), the most significant marine regression occurs at the top of the Dartry Limestone Formation (West et al 1968;Brandon 1977;Brunton and Mason 1979;Kelly 1989Kelly , 1996Mitchell 1992). At this level, relatively deep-water mid-to outer-shelf cherty limestones are succeeded abruptly by very shallow-water sediments deposited in intertidal/supratidal environments in the Meenymore Formation (see Legg et al 1998).…”

“…in the Carn Limestone and Cloghany Limestone members; see Kelly 1996). Mitchell (1992) also considered that the Meenymore Formation was deposited on an extensive coastal plain in a tectonically active regime. He also interpreted the southward thinning of the Glenade Sandstone Formation (from 300 m to 4 m) as indicating deposition in an asymmetrical half-graben.…”

“…He also interpreted the southward thinning of the Glenade Sandstone Formation (from 300 m to 4 m) as indicating deposition in an asymmetrical half-graben. Tectonic activity continued during deposition of the Larkfield Shale and Lugasnaghta Shale members of the Bellavally Formation, which were deposited in the northern part but not the southern part of the basin (Brandon and Hodson 1984;Mitchell 1992). In consequence, Mitchell (1992) interpreted the non-sequence observed in some parts of the succession as a result of tectonism, not eustatically driven regression, and the cyclic sedimentation in the Bellavally and Carraun Shale formations as a combination of minor fault movement plus subsidence.…”

“…The upper Viséan-Namurian succession of the Lough Allen Basin (Mitchell 1992;Philcox et al 1992) in northwest Ireland comprises the Tyrone and Leitrim groups (Brandon and Hodson 1984;Legg et al 1998). The upper part of the Tyrone Group consists mostly of limestone, whereas the Leitrim Group is mainly mudstone with accessory limestone and sandstone.…”