Abstract:Regional stream sediment geochemistry provides a useful tool for screening relatively large areas for anomalous metal concentrations. Large, open-source governmental datasets represent an affordable option for smaller companies to prioritise areas for follow-up. Equally, such datasets are useful in applied geochemical research. This study investigates recently released Tellus regional stream sediment analyses for Southeast Ireland, focusing on counties Wicklow, Wexford, and parts of Kildare, Carlow, Kilkenny and Waterford. The aim is to: i) apply trace element ratios and vectors to define and confirm key lithologies and types of mineralisation previously mapped in the study area, ii) provide a tool to reconstruct the geological setting at a 1:500k regional scale and iii) outline follow-up areas from a mineral exploration point of view. I demonstrate that governmental geochemical datasets can not only define anomalous areas per se, but also support the recognition of regional geological trends and the definition of a number of ore deposit styles. The Tellus dataset for Southeast Ireland, despite its low-density and regional nature, confirmed the regional geological setting albeit in limited detail. Geochemical vectors for Li-Cs-Ta (LCT) pegmatites in the Leinster Granite as well as Volcanogenic Massive Sulphide (VMS) mineralisation in the Copper Coast and Avoca areas, were established and support previous univariate anomaly detection studies. The workflow will be particularly beneficial in remote and poorly mapped areas where geochemical surveys can add additional value to support ongoing definition of stratigraphy, lithologies and anomalous metal abundances.
{"title":"Using Tellus stream sediment geochemistry to fingerprint regional geology and mineralisation systems in Southeast Ireland","authors":"Benedikt M. Steiner","doi":"10.3318/IJES.2018.36.45","DOIUrl":"https://doi.org/10.3318/IJES.2018.36.45","url":null,"abstract":"Abstract:Regional stream sediment geochemistry provides a useful tool for screening relatively large areas for anomalous metal concentrations. Large, open-source governmental datasets represent an affordable option for smaller companies to prioritise areas for follow-up. Equally, such datasets are useful in applied geochemical research. This study investigates recently released Tellus regional stream sediment analyses for Southeast Ireland, focusing on counties Wicklow, Wexford, and parts of Kildare, Carlow, Kilkenny and Waterford. The aim is to: i) apply trace element ratios and vectors to define and confirm key lithologies and types of mineralisation previously mapped in the study area, ii) provide a tool to reconstruct the geological setting at a 1:500k regional scale and iii) outline follow-up areas from a mineral exploration point of view. I demonstrate that governmental geochemical datasets can not only define anomalous areas per se, but also support the recognition of regional geological trends and the definition of a number of ore deposit styles. The Tellus dataset for Southeast Ireland, despite its low-density and regional nature, confirmed the regional geological setting albeit in limited detail. Geochemical vectors for Li-Cs-Ta (LCT) pegmatites in the Leinster Granite as well as Volcanogenic Massive Sulphide (VMS) mineralisation in the Copper Coast and Avoca areas, were established and support previous univariate anomaly detection studies. The workflow will be particularly beneficial in remote and poorly mapped areas where geochemical surveys can add additional value to support ongoing definition of stratigraphy, lithologies and anomalous metal abundances.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"36 1","pages":"45 - 61"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43983698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract:East-north-east trending amphibolite facies metasedimentary and metaigneous gneisses of the Rosslare Complex, south-east Ireland, have been reconstituted into north-east trending greenschist facies mylonitic shear zones composed mainly of chlorite, sericite and opaque minerals. Modal abundances of feldspar and amphibole in metadiorite decrease and the abundances of sericite and chlorite increase with increasing retrogression. Garnet was altered to chlorite and sheared parallel to the foliation. Plagioclase feldspar underwent brittle deformation whereas quartz experienced syntectonic recrystallisation to finer strain-free grains. Following brittle deformation, feldspar was chloritised during retrogression. Published whole rock chemical analyses indicate that altered metadiorite at Greenore Point gained Mg and lost alkalis (Na, K, Rb), Sr, and Si. Some trace elements (such as Ti, Zr, P) and major elements (Fe, Al and Ca) were immobile. Aqueous fluid inclusions in syntectonic quartz veins have salinities of 5-21 wt% NaCl equivalent, and their first melting temperatures indicate two distinct compositional fluid types are present: KCl and MgCl₂-rich compositions. Balanced retrograde reactions indicate an influx of Mg-rich fluids that exchanged with alkalis in the rock. A simple petrological model involving hydration of periclase to form brucite displays several features analogous to the natural retrograde process, namely, buffering of the fluid salinity and composition by retrograde reaction, reaction-enhanced weakening resulting in retrograde shear zone formation and episodic open and closed system behaviour involving pulsed fluid flow.
{"title":"Coupled Deformation and Reaction Softening Processes: Retrograde Shear Zones in the Rosslare Complex, South-East Ireland","authors":"K. O'Hara","doi":"10.3318/IJES.2007.25.63","DOIUrl":"https://doi.org/10.3318/IJES.2007.25.63","url":null,"abstract":"Abstract:East-north-east trending amphibolite facies metasedimentary and metaigneous gneisses of the Rosslare Complex, south-east Ireland, have been reconstituted into north-east trending greenschist facies mylonitic shear zones composed mainly of chlorite, sericite and opaque minerals. Modal abundances of feldspar and amphibole in metadiorite decrease and the abundances of sericite and chlorite increase with increasing retrogression. Garnet was altered to chlorite and sheared parallel to the foliation. Plagioclase feldspar underwent brittle deformation whereas quartz experienced syntectonic recrystallisation to finer strain-free grains. Following brittle deformation, feldspar was chloritised during retrogression. Published whole rock chemical analyses indicate that altered metadiorite at Greenore Point gained Mg and lost alkalis (Na, K, Rb), Sr, and Si. Some trace elements (such as Ti, Zr, P) and major elements (Fe, Al and Ca) were immobile. Aqueous fluid inclusions in syntectonic quartz veins have salinities of 5-21 wt% NaCl equivalent, and their first melting temperatures indicate two distinct compositional fluid types are present: KCl and MgCl₂-rich compositions. Balanced retrograde reactions indicate an influx of Mg-rich fluids that exchanged with alkalis in the rock. A simple petrological model involving hydration of periclase to form brucite displays several features analogous to the natural retrograde process, namely, buffering of the fluid salinity and composition by retrograde reaction, reaction-enhanced weakening resulting in retrograde shear zone formation and episodic open and closed system behaviour involving pulsed fluid flow.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"25 1","pages":"63 - 80"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69516381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.3318/IJES.2007.25.1.1
D. Cleary, P. W. Jackson
Abstract:A reassessment of the rare trepostome bryozoan Stenophragmidium Bassler, 1952 from the Mississippian (Lower Carboniferous) of Ireland and Britain has utilised traditional morphometric methods as well as multivariate statistical methods, and allowed for the recognition of eleven species of this genus from this region. Full systematic descriptions are given of these taxa, which include the type species of the genus S. lobatum (Munro, 1912), six new combinations, and three new species S. ashfellensis, S. hibernicum and S. bundoranensis.
{"title":"Stenophragmidium Bassler, 1952 (Trepostomida: Bryozoa) from the Mississippian of Ireland and Britain","authors":"D. Cleary, P. W. Jackson","doi":"10.3318/IJES.2007.25.1.1","DOIUrl":"https://doi.org/10.3318/IJES.2007.25.1.1","url":null,"abstract":"Abstract:A reassessment of the rare trepostome bryozoan Stenophragmidium Bassler, 1952 from the Mississippian (Lower Carboniferous) of Ireland and Britain has utilised traditional morphometric methods as well as multivariate statistical methods, and allowed for the recognition of eleven species of this genus from this region. Full systematic descriptions are given of these taxa, which include the type species of the genus S. lobatum (Munro, 1912), six new combinations, and three new species S. ashfellensis, S. hibernicum and S. bundoranensis.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"25 1","pages":"1 - 25"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43420279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract:Small-scale magmatic layers in a minor ultramafic intrusion at Lough Fee, NW Connemara, Ireland, exhibit superb examples of primary adcumulate textures. Two of these monomineralic layers are quantitatively analysed to establish their degree of textural equilibrium. A series of apparent dihedral angles is measured from threegrain junctions, and cumulative frequency curves are plotted for each layer. The curves are compared to theoretical curves for equilibrated and unequilibrated rocks to determine the degree of textural equilibrium of each layer. The results show apparent dihedral angle values that closely approximate those of a system in local textural equilibrium. The importance of adcumulus growth in the development of magmatic layering and the implications of this process for layer formation are briefly discussed with reference to the tectonic setting of the intrusion, and it is concluded that magmatic layering may have developed in a syn-tectonic intrusion.
{"title":"Textural Equilibrium in Magmatic Layers of the Lough Fee Ultramafic Intrusion, NW Connemara, Ireland: Implications for Adcumulus Mineral Growth","authors":"B. O’Driscoll","doi":"10.1353/ijes.2005.0008","DOIUrl":"https://doi.org/10.1353/ijes.2005.0008","url":null,"abstract":"Abstract:Small-scale magmatic layers in a minor ultramafic intrusion at Lough Fee, NW Connemara, Ireland, exhibit superb examples of primary adcumulate textures. Two of these monomineralic layers are quantitatively analysed to establish their degree of textural equilibrium. A series of apparent dihedral angles is measured from threegrain junctions, and cumulative frequency curves are plotted for each layer. The curves are compared to theoretical curves for equilibrated and unequilibrated rocks to determine the degree of textural equilibrium of each layer. The results show apparent dihedral angle values that closely approximate those of a system in local textural equilibrium. The importance of adcumulus growth in the development of magmatic layering and the implications of this process for layer formation are briefly discussed with reference to the tectonic setting of the intrusion, and it is concluded that magmatic layering may have developed in a syn-tectonic intrusion.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"95 ","pages":"39 - 45"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41272856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract:AbstractGeological mapping of the Upper Devonian succession on the northern side of Grab-all Bay in Cork Harbour has led to a new interpretation of the local lithostratigraphy. Rocks previously mapped as the Ballyknock Member of the Gyleen Formation are now reassigned to the Toe Head Sandstone Formation which is here divided into two new members, the Rams Head and Grab-all Bay Members and to the Old Head Sandstone Formation. The axis of the Grab-all Bay Syncline is re-positioned 160m further to the north in Grab-all Bay, revealing a younger and previously undescribed interval of strata here assigned to the Old Head Sandstone Formation. Miospore assemblages recorded from the Toe Head Sandstone and the lower part of the Old Head Sandstone Formation are assigned to the Retispora lepidophyta—Knoxisporites literatus (LL) Miospore Biozone, indicating a late Devonian (Uppermost Famennian) age for the succession. New discoveries of U-shaped burrows, assignable to the trace fossil Diplocraterion, are recorded from several intervals in the Toe Head Sandstone Formation and the lower part of the Old Head Sandstone Formation. These monospecific ichnofaunas are believed to have colonised finely laminated sediments of the intertidal flat environment. In addition, rhythmically laminated sandstone and siltstone beds interpreted as tidal rhythmites are recorded for the first time in the Toe Head Sandstone Formation. The paleoenvironmental significance of the tidal rhythmites and Diplocraterion beds in the Toe Head Sandstone is important in understanding the nature of the fluvial–tidal transition zone in the Cork Harbour region in late Devonian times. It is proposed that in late Devonian (LL Biozone) times the upper Toe Head Sandstone Formation sediments in the Cork Harbour area were deposited in the upper reaches of an estuarine embayment within a low gradient fluvial coastal plain.
{"title":"New Discoveries of Diplocraterion and Tidal Rhythmites in the Upper Devonian Rocks of Grab-all Bay, Cork Harbour: Palaeoenvironmental Implications","authors":"K. Higgs, B. Higgs","doi":"10.3318/IJES.2015.33.35","DOIUrl":"https://doi.org/10.3318/IJES.2015.33.35","url":null,"abstract":"Abstract:AbstractGeological mapping of the Upper Devonian succession on the northern side of Grab-all Bay in Cork Harbour has led to a new interpretation of the local lithostratigraphy. Rocks previously mapped as the Ballyknock Member of the Gyleen Formation are now reassigned to the Toe Head Sandstone Formation which is here divided into two new members, the Rams Head and Grab-all Bay Members and to the Old Head Sandstone Formation. The axis of the Grab-all Bay Syncline is re-positioned 160m further to the north in Grab-all Bay, revealing a younger and previously undescribed interval of strata here assigned to the Old Head Sandstone Formation. Miospore assemblages recorded from the Toe Head Sandstone and the lower part of the Old Head Sandstone Formation are assigned to the Retispora lepidophyta—Knoxisporites literatus (LL) Miospore Biozone, indicating a late Devonian (Uppermost Famennian) age for the succession. New discoveries of U-shaped burrows, assignable to the trace fossil Diplocraterion, are recorded from several intervals in the Toe Head Sandstone Formation and the lower part of the Old Head Sandstone Formation. These monospecific ichnofaunas are believed to have colonised finely laminated sediments of the intertidal flat environment. In addition, rhythmically laminated sandstone and siltstone beds interpreted as tidal rhythmites are recorded for the first time in the Toe Head Sandstone Formation. The paleoenvironmental significance of the tidal rhythmites and Diplocraterion beds in the Toe Head Sandstone is important in understanding the nature of the fluvial–tidal transition zone in the Cork Harbour region in late Devonian times. It is proposed that in late Devonian (LL Biozone) times the upper Toe Head Sandstone Formation sediments in the Cork Harbour area were deposited in the upper reaches of an estuarine embayment within a low gradient fluvial coastal plain.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"33 1","pages":"35 - 54"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3318/IJES.2015.33.35","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42081488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract:William Bookey Brownrigg, who discovered the Upper Carboniferous (Pennsylvanian) vertebrate fossils at Jarrow Colliery, Co. Kilkenny in 1864, published a short paper on the material. Shortly afterwards E.P. Wright, a zoologist from Trinity College Dublin, contacted Thomas Henry Huxley with a view to publishing a full description of the material. In November 1865 Huxley wrote to Brownrigg about his involvement and in his reply Brownrigg agreed to Huxley describing the material. Ultimately, when it came to the publication of the fossil fauna, Brownrigg was side-lined. Brownrigg's letter to Huxley is transcribed here.
{"title":"A LETTER FROM WILLIAM BOOKEY BROWNRIGG TO THOMAS HENRY HUXLEY, DATED 29 NOVEMBER 1865, AUTHORISING HIM TO DESCRIBE HIS FOSSIL VERTEBRATES FROM JARROW COLLIERY, CO. KILKENNY AND GIVING DETAILS OF HIS FIND","authors":"P. W. Jackson, M. DeArce, N. Monaghan","doi":"10.3318/IJES.2011.29.19","DOIUrl":"https://doi.org/10.3318/IJES.2011.29.19","url":null,"abstract":"Abstract:William Bookey Brownrigg, who discovered the Upper Carboniferous (Pennsylvanian) vertebrate fossils at Jarrow Colliery, Co. Kilkenny in 1864, published a short paper on the material. Shortly afterwards E.P. Wright, a zoologist from Trinity College Dublin, contacted Thomas Henry Huxley with a view to publishing a full description of the material. In November 1865 Huxley wrote to Brownrigg about his involvement and in his reply Brownrigg agreed to Huxley describing the material. Ultimately, when it came to the publication of the fossil fauna, Brownrigg was side-lined. Brownrigg's letter to Huxley is transcribed here.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"29 1","pages":"19 - 22"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42835455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract:New geological mapping in the centre of the Galway Granite at Camus, Co. Galway, reveals a major north—south thrust zone, the Furnace Thrust, typically dipping east at 35°, which thrust up westward deeper-crystallised granite, including two minor late intrusions, on top of a higher-level granite footwall. Al-in-hornblende geobarometry of the footwall and the hanging wall confirms the thrusting. At 2km east of the thrust, both the footwall and the hanging wall of the thrust sheet were later substantially further uplifted by the steeper Shannawona Fault. At 6km east of this fault, the granite contains post-400—395Ma, pre-370—378Ma thrusts that moved south-eastward, so a major block of the deep ∼400—395Ma Megacrystic Granite has been squeezed upward. This granite still farther east was later uplifted more by the steep Shannapheasteen Fault, which is connected with the late (?380Ma) central intrusion of the Shannapheasteen Granite, which pushed its roof upward. The uplift of the Central Block with its deeply crystallised Megacrystic Granite was therefore the result of thrusts and faults connected in a complex way with the coeval intrusive pressures of the late emplacement of the Shannapheasteen Granite and six other late granites. All seven late granites are confined to the Central Block and, having low densities, exerted protracted buoyancy uplift forces. This modifies the previous partly correct, but mechanically difficult, explanation for the origin of the Central Block of the Galway Batholith.
{"title":"MAJOR THRUSTING IN THE GRANITE AND THE ROLE OF LATE INTRUSIONS IN EXPOSING THE DEEPER PARTS OF THE CENTRAL BLOCK OF THE GALWAY GRANITE BATHOLITH","authors":"B. Leake","doi":"10.3318/IJES.2012.30.1","DOIUrl":"https://doi.org/10.3318/IJES.2012.30.1","url":null,"abstract":"Abstract:New geological mapping in the centre of the Galway Granite at Camus, Co. Galway, reveals a major north—south thrust zone, the Furnace Thrust, typically dipping east at 35°, which thrust up westward deeper-crystallised granite, including two minor late intrusions, on top of a higher-level granite footwall. Al-in-hornblende geobarometry of the footwall and the hanging wall confirms the thrusting. At 2km east of the thrust, both the footwall and the hanging wall of the thrust sheet were later substantially further uplifted by the steeper Shannawona Fault. At 6km east of this fault, the granite contains post-400—395Ma, pre-370—378Ma thrusts that moved south-eastward, so a major block of the deep ∼400—395Ma Megacrystic Granite has been squeezed upward. This granite still farther east was later uplifted more by the steep Shannapheasteen Fault, which is connected with the late (?380Ma) central intrusion of the Shannapheasteen Granite, which pushed its roof upward. The uplift of the Central Block with its deeply crystallised Megacrystic Granite was therefore the result of thrusts and faults connected in a complex way with the coeval intrusive pressures of the late emplacement of the Shannapheasteen Granite and six other late granites. All seven late granites are confined to the Central Block and, having low densities, exerted protracted buoyancy uplift forces. This modifies the previous partly correct, but mechanically difficult, explanation for the origin of the Central Block of the Galway Batholith.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"30 1","pages":"1 - 12"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42958792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.3318/IJES.2003.21.1.47
D. Naylor, M. Philcox, G. Clayton
Abstract:The stratigraphy encountered in two closely spaced exploration wells drilled on the north-west shore of Lough Neagh, Northern Ireland, is reported. Annaghmore1 was drilled to a depth of 5100ft (1554.5m), and Ballynamullan-1, which was a deviated hole, reached a vertical depth of 4500ft (1371.6m). Both wells drilled through the Antrim Lava Group, the Ulster White Limestone Formation and a Permo-Triassic red-bed sequence comprising the Mercia Mudstone, Sherwood Sandstone, Belfast and Enler groups. The Annaghmore-1 well drilled a thick (542.5m) red-bed section beneath the base of the Belfast Group, which lacked definitive palynomorphs but which is thought to be Permian in age. The upper part of the Triassic sequence and the Lias are absent in the wells, probably as a result of erosion following Late Cimmerian tectonism. Differences of stratigraphical detail between the two wells are attributed to movement on intervening faults at different times. Spore fluorescence studies indicate that the well section is submature to mature for oil generation to 1219m and mature for dry gas beneath 1310m. Apatite fission track analysis suggests that Carboniferous source rocks produced much of their hydrocarbon potential during the Variscan episode.
{"title":"Annaghmore-1 and Ballynamullan-1 Wells, Larne-Lough Neagh Basin, Northern Ireland","authors":"D. Naylor, M. Philcox, G. Clayton","doi":"10.3318/IJES.2003.21.1.47","DOIUrl":"https://doi.org/10.3318/IJES.2003.21.1.47","url":null,"abstract":"Abstract:The stratigraphy encountered in two closely spaced exploration wells drilled on the north-west shore of Lough Neagh, Northern Ireland, is reported. Annaghmore1 was drilled to a depth of 5100ft (1554.5m), and Ballynamullan-1, which was a deviated hole, reached a vertical depth of 4500ft (1371.6m). Both wells drilled through the Antrim Lava Group, the Ulster White Limestone Formation and a Permo-Triassic red-bed sequence comprising the Mercia Mudstone, Sherwood Sandstone, Belfast and Enler groups. The Annaghmore-1 well drilled a thick (542.5m) red-bed section beneath the base of the Belfast Group, which lacked definitive palynomorphs but which is thought to be Permian in age. The upper part of the Triassic sequence and the Lias are absent in the wells, probably as a result of erosion following Late Cimmerian tectonism. Differences of stratigraphical detail between the two wells are attributed to movement on intervening faults at different times. Spore fluorescence studies indicate that the well section is submature to mature for oil generation to 1219m and mature for dry gas beneath 1310m. Apatite fission track analysis suggests that Carboniferous source rocks produced much of their hydrocarbon potential during the Variscan episode.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"21 1","pages":"47 - 69"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45682428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract:The Shankill Fracture Zone is one of several faults that are possibly related, which transect the Devonian-aged Leinster Granite of south-east Ireland. The fault contains epithermal mineralisation, including a hydrothermal breccia that is cemented by the potassium-bearing manganese oxide, cryptomelane. ⁴⁰Ar/³⁹Ar dating of cryptomelane from the breccia yielded a Miocene mineralisation age of 12.1 ± 1.6Ma (2σ), believed to be coincident with tectonohydrothermal activity along the Shankill Fracture Zone. This fracture zone is the only confirmed onshore Neogene fault in Ireland that is not located in the north-east of the country.
{"title":"A Miocene Fault in South-East Ireland Revealed by ⁴⁰Ar-³⁹Ar Dating of Hydrothermal Cryptomelane","authors":"D. Jordan, R. Burgess","doi":"10.3318/IJES.2007.25.55","DOIUrl":"https://doi.org/10.3318/IJES.2007.25.55","url":null,"abstract":"Abstract:The Shankill Fracture Zone is one of several faults that are possibly related, which transect the Devonian-aged Leinster Granite of south-east Ireland. The fault contains epithermal mineralisation, including a hydrothermal breccia that is cemented by the potassium-bearing manganese oxide, cryptomelane. ⁴⁰Ar/³⁹Ar dating of cryptomelane from the breccia yielded a Miocene mineralisation age of 12.1 ± 1.6Ma (2σ), believed to be coincident with tectonohydrothermal activity along the Shankill Fracture Zone. This fracture zone is the only confirmed onshore Neogene fault in Ireland that is not located in the north-east of the country.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"25 1","pages":"55 - 61"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48559632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An appreciation: Charles Hepworth Holland (1923–2019), founding editor of the Irish Journal of Earth Sciences","authors":"P. W. Jackson, M. Parkes, J. Murray","doi":"10.3318/ijes.2020.38.1","DOIUrl":"https://doi.org/10.3318/ijes.2020.38.1","url":null,"abstract":"","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"38 1","pages":"1 - 4"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47876573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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