The development of a regional-scale intraplate strike-slip fault system; Alpine deformation in the north of Ireland

Anderson, Hugh; Walsh, John J.; Cooper, Mark

doi:10.1016/j.jsg.2018.07.002

Cited by 20 publications

(20 citation statements)

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“…Outcrop and mine studies, together with newly acquired aeromagnetic Tellus dataset in Ireland's onshore, also highlight the prevalence of ubiquitous newly formed NNW‐trending dextral strike‐slip faults (Carboni, Walsh, Stewart, Güven, & Eliopoulos, ; Fusciardi, Guven, Stewart, Carboni, & Walshe, ; Moore & Walsh, ) and the development of more localised Cenozoic sinistral strike‐slip fault displacement (up to 2.5 km) on pre‐existing Carboniferous normal faults. This conjugate configuration of faults has been attributed to two principal phases of Alpine‐Pyrenean deformation, one in the Early Paleocene or Late Cretaceous, and another in the Oligocene (Anderson, Walsh, & Cooper, ; Anderson et al, ; Cooper et al, ): given the absence of additional temporal constraints (e.g. fault‐related sedimentation or offset volcanic/magmatic bodies) other phases cannot, however, be ruled out.…”

Section: Discussionmentioning

confidence: 98%

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Structural evolution and the partitioning of deformation during basin growth and inversion: A case study from the Mizen Basin Celtic Sea, offshore Ireland

et al. 2019

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The Celtic Sea basins lie on the continental shelf between Ireland and northwest France and consist of a series of ENE-WSW trending elongate basins that extend from St George's Channel Basin in the east to the Fastnet Basin in the west. The basins, which contain Triassic to Neogene stratigraphic sequences, evolved through a complex geological history that includes multiple Mesozoic rift stages and later Cenozoic inversion. The Mizen Basin represents the NW termination of the Celtic Sea basins and consists of two NE-SW-trending half-grabens developed as a result of the reactivation of Palaeozoic (Caledonian, Lower Carboniferous and Variscan) faults. The faults bounding the Mizen Basin were active as normal faults from Early Triassic to Late Cretaceous times. Most of the fault displacement took place during Berriasian to Hauterivian (Early Cretaceous) times, with a NW-SE direction of extension. A later phase of Aptian to Cenomanian (Early to Late Cretaceous) N-S-oriented extension gave rise to E-Wstriking minor normal faults and reactivation of the pre-existing basin bounding faults that propagated upwards as left-stepping arrays of segmented normal faults. In common with most of the Celtic Sea basins, the Mizen Basin experienced a period of major erosion, attributed to tectonic uplift, during the Paleocene. Approximately N-S Alpine regional compression-causing basin inversion is dated as Middle Eocene to Miocene by a well-preserved syn-inversion stratigraphy. Reverse reactivation of the basin bounding faults was broadly synchronous with the formation of a set of near-orthogonal NW-SE dextral strike-slip faults so that compression was partitioned onto two fault sets, the geometrical configuration of which is partly inherited from Palaeozoic basement structure. The segmented character of the fault forming the southern boundary of the Mizen Basin was preserved during Alpine inversion so that Cenozoic reverse displacement distribution on syn-inversion horizons mirrors the earlier extensional displacements. Segmentation of normal faults therefore controls the geometry and location of inversion structures, including inversion anticlines and the back rotation of earlier relay ramps.

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Section: Discussionmentioning

confidence: 98%

“…9 km (e.g. the Codling Fault; Anderson, Walsh, & Cooper, ), combining with the inversion of pre‐existing normal faults, of Permo–Triassic and possibly Carboniferous age, involving sinistral transpression (i.e. compression and sinistral strike‐slip displacements).…”

Section: Discussionmentioning

confidence: 99%

Structural evolution and the partitioning of deformation during basin growth and inversion: A case study from the Mizen Basin Celtic Sea, offshore Ireland

et al. 2019

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“…At Lisheen and Silvermines, these faults have a displacement of up to 50 m, but usually less than 10 m, and act as major conduits for present-day groundwater flow at the scale of individual deposits (Carboni et al, 2003;Fusciardi et al, 2004). These and other NNW-trending dextral strike-slip faults have been attributed to north-south Alpine-Pyrenean compression during the Paleocene and Oligocene (Carboni et al, 2003;Fusciardi et al, 2004;Cooper et al, 2012;Anderson et al, 2016Anderson et al, , 2018…”

Section: Structural Evolution Of the Irish Ore Fieldmentioning

confidence: 98%

3-D Modeling of the Lisheen and Silvermines Deposits, County Tipperary, Ireland:Insights into Structural Controls on the Formation of Irish Zn-Pb Deposits

et al. 2019

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Faults are important structures in the formation of many mineral deposits, often acting as conduits for oreforming fluids and sometimes providing, or generating, the bounding structures to associated mineralizing sites. Using 3-D analysis and modeling of the Lisheen and Silvermines deposits within the Irish ore field, we investigate the geometry of normal fault systems and their implications on the origin and nature of associated deposits. These Irish-type deposits are carbonate hosted and developed within the hanging walls of normal faults arising from an Early Carboniferous episode of north-south rifting, with relatively limited amounts of later deformation. Structural analysis of high-quality mine datasets indicates that fault segmentation is ubiquitous with left-stepping segments arising from north-south stretching developed above generally ENE-NE-trending fault arrays, which are subparallel to older Caledonian penetrative fabrics and structure within underlying Silurian and Ordovician rocks. Fault segments occur on different scales and have a profound impact on structural evolution, with larger scale segments and intervening relay ramps defining distinct orebodies within deposits and smaller scale segments and relays potentially providing paths for upfault fluid flow. The difference in behavior is attributed to the integrity of associated relay ramps where intact ramps represent orebody-bounding structures, and smaller breached ramps provide enhanced associated hydraulic properties and act as vertical conduits. Hanging-wall deformation along the rheological boundary between host-rock limestones and underlying shales has an important control on the localization of earlier dolomitization and/or brecciation and later mineralization adjacent to this contact, and on the migration pathways for basinal brines and mineralizing fluids.Roisin Kyne is a structural geologist specializing in the formation of sedimentary rock-hosted base metal deposits. After receiving her HB.Sc. degree from Lakehead University (2009), Roisin completed a Ph.D. at CODES, University of Tasmania (2014), followed by a post-doc at iCRAG, University College Dublin (2018). Her work focused on structural controls of Zn-Pb-Cu deposits in Cobar, NSW, and the Irish ore field and implications for formation, fluid flow, and mineralization. In her current role as project geologist at Teck Resources, Roisin is applying her knowledge of 3-D modeling, basin analysis, and deposit formation to explore for Zn-Pb deposits in North America.

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“…As rifting in the Rockall Basin ceased towards the end of the Cretaceous, the basin underwent thermal subsidence, with the western margins of the northern Slyne and the Erris basins that had been subject to rift-shoulder uplift now experiencing large-scale subsidence. Post-rift tectonic activity continued throughout the Paleocene, Eocene and Early Miocene, expressed as subtle normal and reverse movement on faults throughout the basins, and in the formation of E-W oriented strike-slip faults, likely related to along-strike movement on major Caledonian crustal lineaments like the Great Glen and Fair Head-Clew Bay lineaments (Cooper et al, 2012;Le Breton et al, 2013;Anderson et al, 2018). The development of the North Atlantic Igneous Province during the mid-Eocene had an impact on the Slyne and Erris basins, with the intrusion of several sills and the extrusion of thick basaltic lavas of the Druid Formation (Jolley & Bell, 2002).…”

Section: Basinsmentioning

confidence: 99%

Multi-layered salt-prone stratigraphy and its influence on rift-basin development; The Slyne and Erris basins, offshore NW Ireland

O’Sullivan¹,

Childs²,

Saqab³

et al. 2024

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While salt-influenced rift basins have been identified across the European Atlantic margin, the Irish Atlantic margin remains the exception despite salt being proven in several boreholes. Using an extensive seismic database coupled with data from exploration wells and shallow boreholes, this study maps the distribution and composition of salt layers and investigates their role in the structural evolution of the Slyne and Erris basins offshore west of Ireland. Two salt-prone intervals have been proven: The Upper Permian Zechstein Group and the Upper Triassic Uilleann Halite Member. The Zechstein Group is present throughout the Slyne and Erris basins, while the Uilleann Halite Member is only developed in the Northern Slyne and Southern Erris sub-basins. Where salt-prone, both layers mechanically detach pre-, post-, and intra-salt stratigraphy. Both layers underwent halokinesis during basin development, creating a variety of salt-related structures; The Zechstein Group forms salt pillows and salt rollers, causing folding and rafting in the overlying Mesozoic section, driven by active faulting within the pre-salt basement. The Uilleann Halite Member caused thinskinned crestal collapse of the overlying Jurassic section above anticlines cored by Zechstein salt. Where both Triassic and Permian salt are present, unique structural geometries are formed when two stratigraphically discrete but kinematically linked halokinetic structures develop. The most common structural configuration consists of a Zechstein salt pillow and an Uilleann Halite salt wall separated by Lower Triassic sandstones. The fold-axis of the salt pillow trends parallel to the strike of the salt wall. The results of this study provide a framework for the evolution of halokinetic structures in other basins on the Irish Atlantic margin, greater insight into the Permian and Triassic paleogeography of the region, as well as having more general implications for the evolution of salt-related structures in rift basins with multiple stratigraphically discrete salt layers. This research is funded in part by a research grant from Science Foundation Ireland (SFI) under Grant Number 13/RC/2092 and is co-funded under the European Regional Development Fund, and by the Petroleum Infrastructure Programme (PIP) and its member companies. Efstratios Delogkos is thanked for thoughtful discussions regarding the links between the Slyne and Erris basins and the Bróna and Pádraig basins. Neil Jones and Kristian Lomas are thanked for engaging discussions on the structural evolution of the Slyne and Goban Spur basins respectively. The authors would like to thank the Petroleum Affairs Division (PAD) of the Department of Communications, Climate Action and Environment (DCCAE), Ireland, for providing access to released well, seismic, and potential field datasets. Europa Oil & Gas are thanked for providing access to the Inishkea 2018 reprocessed seismic volume and allowing a section from the volume to be shown. Shell Exploration & Production Ireland Ltd. are thanked for providing acc...

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The development of a regional-scale intraplate strike-slip fault system; Alpine deformation in the north of Ireland

Cited by 20 publications

References 69 publications

Structural evolution and the partitioning of deformation during basin growth and inversion: A case study from the Mizen Basin Celtic Sea, offshore Ireland

Structural evolution and the partitioning of deformation during basin growth and inversion: A case study from the Mizen Basin Celtic Sea, offshore Ireland

3-D Modeling of the Lisheen and Silvermines Deposits, County Tipperary, Ireland:Insights into Structural Controls on the Formation of Irish Zn-Pb Deposits

Multi-layered salt-prone stratigraphy and its influence on rift-basin development; The Slyne and Erris basins, offshore NW Ireland

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