Lough Neagh: the site of a Cenozoic pull-apart basin

Quinn, Martyn

doi:10.1144/sjg42020101

Cited by 8 publications

(1 citation statement)

References 29 publications

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“…The stress fields of the igneous centers in northeastern Ireland have locally affected the trend of the dike swarms (Cooper et al, 2012). There is evidence of reactivation of the Paleogene faults in Northern Ireland after the end of magmatic activity, but no major tectonic event occurred in the area of the Mourne Mountains after the emplacement of the granites (Johnston, 2004;Quinn, 2006;Cooper et al, 2012).…”

Section: Paleogene Tectonicsmentioning

confidence: 99%

Host-rock deformation during the emplacement of the Mourne Mountains granite pluton: Insights from the regional fracture pattern

et al. 2019

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The Mourne Mountains magmatic center in Northern Ireland consists of five successively intruded granites emplaced in the upper crust. The Mourne granite pluton has classically been viewed as a type locality of a magma body emplaced by cauldron subsidence. Cauldron subsidence makes space for magma through the emplacement of ring dikes and floor subsidence. However, the Mourne granites were more recently re-interpreted as laccoliths and bysmaliths. Laccolith intrusions form by inflation and dome their host rock. Here we perform a detailed study of the deformation in the host rock to the Mourne granite pluton in order to test its emplacement mechanism. We use the host-rock fracture pattern as a passive marker and microstructures in the contact-metamorphic aureole to constrain large-scale magma emplacement-related deformation. The dip and azimuth of the fractures are very consistent on the roof of the intrusion and can be separated into four steeply inclined sets dominantly striking SE, S, NE, and E, which rules out pluton-wide doming. In contrast, fracture orientations in the northeastern wall to the granites suggest shear parallel to the contact. Additionally, contact-metamorphic segregations along the northeastern contact are brecciated. Based on the host-rock fracture pattern, the contact aureole deformation, and the north-eastward–inclined granite-granite contacts, we propose that mechanisms involving either asymmetric “trap-door” floor subsidence or laccolith and bysmalith intrusion along an inclined or curved floor accommodated the emplacement of the granites and led to deflection of the northeastern wall of the intrusion.

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Section: Paleogene Tectonicsmentioning

confidence: 99%