10.6084/m9.figshare.3453401.v1
Steven P. Hollis
Steven P.
Hollis
Mark R. Cooper
Mark R.
Cooper
Stephen Roberts
Stephen
Roberts
Garth Earls
Garth
Earls
Richard Herrington
Richard
Herrington
Daniel J. Condon
Daniel J.
Condon
Stratigraphic, geochemical and U–Pb zircon constraints from Slieve Gallion, Northern Ireland: a correlation of the Irish Caledonian
arcs
Geological Society of London
2016
correlation
Grampian orogeny
LREE
Charlestown
Tyrone Volcanic Group
Irish Caledonian arcs
biostratigraphic age constraints
Lough Nafooey Group
Ma
geochemical
biostratigraphic age constraint
geochronology
zircon
Slieve Gallion Inlier
Northern Ireland
Geology
2016-06-21 11:22:48
Journal contribution
https://geolsoc.figshare.com/articles/journal_contribution/Stratigraphic_geochemical_and_U_Pb_zircon_constraints_from_Slieve_Gallion_Northern_Ireland_a_correlation_of_the_Irish_Caledonian___arcs/3453401
<p>Recent Ar–Ar and U–Pb zircon geochronology from across the British and Irish Caledonides has revealed a prolonged period of
arc-ophiolite formation (<em>c</em>. 514–464 Ma) and accretion (<em>c</em>. 490–470 Ma) to the Laurentian margin during the Grampian orogeny. The Slieve Gallion Inlier of Northern Ireland, an isolated
occurrence of the Tyrone Volcanic Group, records the development of a peri-Laurentian island arc–backarc and its obduction
to an outboard microcontinental block. Although a previous biostratigraphic age constraint provides a firm correlation of
at least part of the volcanic succession to the Ca1 Stage of the Arenig (<em>c</em>. 475–474 Ma), there is uncertainty on its exact statigraphic position in the Tyrone Volcanic Group. Earliest magmatism is
characterized by light rare earth element (LREE) depleted island-arc tholeiite. Overlying deposits are dominated by large
ion lithophile and LREE-enriched, hornblende-phyric and feldspathic calc-alkaline basaltic andesites and andesitic tuffs with
strongly negative ϵNd<sub>t</sub> values. Previously published biostratigraphic age constraints, combined with recent U–Pb zircon geochronology and new petrochemical
correlations, suggest that the Slieve Gallion Inlier is equivalent to the lower Tyrone Volcanic Group. Temporal and geochemical
correlations between the Slieve Gallion Inlier and Charlestown Group of Ireland suggest that they may be part of the same
arc system, which was accreted at a late stage (<em>c</em>. 470 Ma) in the Grampian orogeny. A switch from tholeiitic volcanism to calc-alkaline dominated activity within the Lough
Nafooey Group of western Ireland occurred prior to <em>c</em>. 490 Ma, some 15–20 Myr earlier than at Tyrone and Charlestown.
</p>