Pub Date : 2022-01-01DOI: 10.3318/IJES.2006.24.1.1
M. Feely, J. Conliffe, K. Faure, Siobhain Power
Abstract:The results of fluid inclusion petrography and microthermometry of Oughterard Granite quartz reveals the presence of a dominant and ubiquitous population of liquid rich (degree of fill ∼ 0.70-0.95) saline (<11 equivalent wt% NaCl) fluid inclusions. Temperature of homogenisation (to the liquid phase) ranges between 140°C and 380°C with the majority in the range 175°C to 250°C. These aqueous fluid inclusions invariably occur in annealed fractures that transverse the granite quartz. These represent evidence of saline hydrothermal fluid infiltration post crystallisation of granite quartz. Microthermometry also reveals that within this population rare CaCl₂-bearing fluid inclusions occur. Oxygen isotope $Delta _{text{quartz-feldspar}}$ values are lower than 0.70, reflecting isotope disequilibrium. The isotope data supports the fluid inclusion evidence for the influx of post crystallisation hydrothermal fluids, possibly related to granite emplacement, or to a later incursion of relatively low temperature (<200°C) meteoric waters.
{"title":"Fluid Inclusion Trails in Granite Quartz: Evidence for Aqueous Fluid Infiltration in the Oughterard Granite, Eastern Connemara","authors":"M. Feely, J. Conliffe, K. Faure, Siobhain Power","doi":"10.3318/IJES.2006.24.1.1","DOIUrl":"https://doi.org/10.3318/IJES.2006.24.1.1","url":null,"abstract":"Abstract:The results of fluid inclusion petrography and microthermometry of Oughterard Granite quartz reveals the presence of a dominant and ubiquitous population of liquid rich (degree of fill ∼ 0.70-0.95) saline (<11 equivalent wt% NaCl) fluid inclusions. Temperature of homogenisation (to the liquid phase) ranges between 140°C and 380°C with the majority in the range 175°C to 250°C. These aqueous fluid inclusions invariably occur in annealed fractures that transverse the granite quartz. These represent evidence of saline hydrothermal fluid infiltration post crystallisation of granite quartz. Microthermometry also reveals that within this population rare CaCl₂-bearing fluid inclusions occur. Oxygen isotope $Delta _{text{quartz-feldspar}}$ values are lower than 0.70, reflecting isotope disequilibrium. The isotope data supports the fluid inclusion evidence for the influx of post crystallisation hydrothermal fluids, possibly related to granite emplacement, or to a later incursion of relatively low temperature (<200°C) meteoric waters.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"24 1","pages":"1 - 11"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47936297","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.2003.21.1.71
P. Mohr
Abstract:The Galway Granite is singular among the Irish latest Caledonian (-400Ma) batholiths for the number and variety of syn- and post-consolidation sheet intrusions. The most numerous and persistent are microphyric dacitic dikes, typically arranged in sets trending N-NNE, perpendicular to the long axis of the batholith. The sets cut the eastern and western blocks of the batholith, in contrast to their absence from the uplifted and eroded central block. Dacite geochemistry is similar to that of the megacrystic granodiorite that comprises the greater part of the batholith. However, the longer dike sets manifest mineralogical and chemical gradients along strike, from rhyodacite at the batholith axis to andesitic dacite outside the batholith. Hybridisation of granitoid magma with a more mafic magma is considered to have produced the dike magmas. Diking was induced by east-west stress relaxation of the batholith, coeval with a final plutonic episode involving high-level intrusion of alkali leucogranite sills. Regional ENE-WNW transcurrent faulting became active before the diking had concluded.
{"title":"Late Magmatism of the Galway Granite Batholith: I. Dacite Dikes","authors":"P. Mohr","doi":"10.3318/IJES.2003.21.1.71","DOIUrl":"https://doi.org/10.3318/IJES.2003.21.1.71","url":null,"abstract":"Abstract:The Galway Granite is singular among the Irish latest Caledonian (-400Ma) batholiths for the number and variety of syn- and post-consolidation sheet intrusions. The most numerous and persistent are microphyric dacitic dikes, typically arranged in sets trending N-NNE, perpendicular to the long axis of the batholith. The sets cut the eastern and western blocks of the batholith, in contrast to their absence from the uplifted and eroded central block. Dacite geochemistry is similar to that of the megacrystic granodiorite that comprises the greater part of the batholith. However, the longer dike sets manifest mineralogical and chemical gradients along strike, from rhyodacite at the batholith axis to andesitic dacite outside the batholith. Hybridisation of granitoid magma with a more mafic magma is considered to have produced the dike magmas. Diking was induced by east-west stress relaxation of the batholith, coeval with a final plutonic episode involving high-level intrusion of alkali leucogranite sills. Regional ENE-WNW transcurrent faulting became active before the diking had concluded.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"21 1","pages":"104 - 71"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48147283","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 petrochemistry of the major elements (33 new rock analyses) of the Dalradian Glencolumbkille metadolerite sills, now amphibolite, shows them to have been quartz tholeiites like those of most of Donegal. Their compositions overlap with those of Connemara (Co. Galway) and Knapdale (Scotland), except the latter two also extend into the olivine tholeiite field. The syn-D2 (~470Ma) sheared schistose margins of the Glencolumbkille bodies are garnet amphibolites, unlike the generally garnet-free centres, and have suffered fluid-derived metasomatism and garnet growth. Garnets are postulated to have been nucleated by the activation energy from the shearing, but the main garnet growth and metamorphism was under static post-D2 pre-D3 conditions in certain favourable rock compositions. Garnet growth in the Glencolumbkille and Connemara amphibolites was generally restricted to rocks with low Mg/Fe, low Fe2O3/FeO and high MnO compositions, whether original or metasomatic. The long-standing puzzle as to why amphibolites that were originally dolerite sills in the Dalradian succession are clustered at certain horizons (at Glencolumbkille in and near the 654–635Ma Marinoan glaciation Portaskaig Tillite Formation) is examined. The clustering is suggested to be partly explained by recent structural research showing that the intrusion of widespread lateral sheets of basaltic magma is restricted to closely interbedded competent beds with thin incompetent pelites. The former act as lids, while the latter allow lateral expansion of the original sills. The whole magmatic suite studied intruded sediments deposited before 600Ma. It is thought to be part of the major ~600Ma magmatism and crustal extension that affected the Scottish Highlands and eastern North America as the supercontinent Rodinia split apart and the Iapetus Ocean opened. Of the metabasites, only the Knapdale ones have been U-Pb dated, yielding a magmatic 600Ma age and thus definitely shown to be pre-D1.
{"title":"The metabasites and garnet amphibolites of Glencolumbkille, Co. Donegal and the early mafic intrusions into the Dalradian rocks of Donegal, Connemara and Scotland","authors":"B. Leake","doi":"10.3318/IJES.2016.34.27","DOIUrl":"https://doi.org/10.3318/IJES.2016.34.27","url":null,"abstract":"Abstract:The petrochemistry of the major elements (33 new rock analyses) of the Dalradian Glencolumbkille metadolerite sills, now amphibolite, shows them to have been quartz tholeiites like those of most of Donegal. Their compositions overlap with those of Connemara (Co. Galway) and Knapdale (Scotland), except the latter two also extend into the olivine tholeiite field. The syn-D2 (~470Ma) sheared schistose margins of the Glencolumbkille bodies are garnet amphibolites, unlike the generally garnet-free centres, and have suffered fluid-derived metasomatism and garnet growth. Garnets are postulated to have been nucleated by the activation energy from the shearing, but the main garnet growth and metamorphism was under static post-D2 pre-D3 conditions in certain favourable rock compositions. Garnet growth in the Glencolumbkille and Connemara amphibolites was generally restricted to rocks with low Mg/Fe, low Fe2O3/FeO and high MnO compositions, whether original or metasomatic. The long-standing puzzle as to why amphibolites that were originally dolerite sills in the Dalradian succession are clustered at certain horizons (at Glencolumbkille in and near the 654–635Ma Marinoan glaciation Portaskaig Tillite Formation) is examined. The clustering is suggested to be partly explained by recent structural research showing that the intrusion of widespread lateral sheets of basaltic magma is restricted to closely interbedded competent beds with thin incompetent pelites. The former act as lids, while the latter allow lateral expansion of the original sills. The whole magmatic suite studied intruded sediments deposited before 600Ma. It is thought to be part of the major ~600Ma magmatism and crustal extension that affected the Scottish Highlands and eastern North America as the supercontinent Rodinia split apart and the Iapetus Ocean opened. Of the metabasites, only the Knapdale ones have been U-Pb dated, yielding a magmatic 600Ma age and thus definitely shown to be pre-D1.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"34 1","pages":"27 - 43"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3318/IJES.2016.34.27","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42300492","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:A contact zone between porphyritic microgranite of the early ring-complex of the Paleocene Slieve Gullion igneous centre and Lower Palaeozoic metasedimentary rocks of the Longford—Down inlier was exposed along a 300m section excavated during construction of the new M 1 motorway. The outcrop displays a thin sliver of Longford—Down metasediment in contact with porphyritic microgranite in a steep, and locally intensely crushed, contact zone that dips away from the ring-complex. This outcrop pattern is reminiscent of a 'caldera-superfault'. Given the recent discussion on sheet versus ring-dyke emplacement of the early ring-complex at Slieve Gullion, this new evidence argues in favour of the traditional ring-dyke model with magma ascending along an active ring fracture associated with caldera subsidence.
{"title":"A NEW EXPOSURE OF A CALDERA FAULT SEGMENT AT THE SLIEVE GULLION IGNEOUS CENTRE: IMPLICATIONS FOR THE EMPLACEMENT OF THE EARLY RING-COMPLEX","authors":"V. Troll, F. Meade, D. Chew, C. H. Emeleus","doi":"10.3318/IJES.2008.26.1","DOIUrl":"https://doi.org/10.3318/IJES.2008.26.1","url":null,"abstract":"Abstract:A contact zone between porphyritic microgranite of the early ring-complex of the Paleocene Slieve Gullion igneous centre and Lower Palaeozoic metasedimentary rocks of the Longford—Down inlier was exposed along a 300m section excavated during construction of the new M 1 motorway. The outcrop displays a thin sliver of Longford—Down metasediment in contact with porphyritic microgranite in a steep, and locally intensely crushed, contact zone that dips away from the ring-complex. This outcrop pattern is reminiscent of a 'caldera-superfault'. Given the recent discussion on sheet versus ring-dyke emplacement of the early ring-complex at Slieve Gullion, this new evidence argues in favour of the traditional ring-dyke model with magma ascending along an active ring fracture associated with caldera subsidence.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"26 1","pages":"1 - 16"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48833700","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:Penniretepora d'Orbigny, 1849, is a widespread and distinctive Upper Palaeozoic acanthocladiid bryozoan. A syntype of the type species Retepora pluma Phillips, 1836, has been located, illustrated and designated lectotype, and the neotype designated in 1974 is set-aside.
{"title":"REDISCOVERY OF A TYPE SPECIMEN OF RETEPORA PLUMA PHILLIPS, 1836, THE TYPE SPECIES OF PENNIRETEPORA D'ORBIGNY, 1849 (FENESTRATA, BRYOZOA), AND REPLACEMENT OF ITS NEOTYPE","authors":"P. W. Jackson","doi":"10.3318/IJES.2011.29.15","DOIUrl":"https://doi.org/10.3318/IJES.2011.29.15","url":null,"abstract":"Abstract:Penniretepora d'Orbigny, 1849, is a widespread and distinctive Upper Palaeozoic acanthocladiid bryozoan. A syntype of the type species Retepora pluma Phillips, 1836, has been located, illustrated and designated lectotype, and the neotype designated in 1974 is set-aside.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"29 1","pages":"15 - 18"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48838181","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.2005.23.1.65
K. Higgs, G. O'connor
Abstract:The Leinster Coalfield is the largest of the onshore coalfields in southern Ireland. Topographically and geologically the coalfield is an upland basin and the Westphalian sediments occupy the centre of the coalfield, while the older Namurian sediments form the rim. The Westphalian succession is approximately 320m thick and is subdivided into three lithostratigraphic formations: in ascending stratigraphic order these are the Moyadd Coal Formation, the Clay Gall Sandstone Formation and the Coolbaun Coal Formation. The latter formation is formally defined here and described, together with several new lithostratigraphic members. The first palynological study of the Westphalian strata in the coalfield has been carned out. The lower part of the Westphalian succession has been sampled palynologically from a stream section in the north of the coalfield, while the rest of the Westphalian strata have been sampled from three boreholes situated in the centre of the coalfield. Forty two miospore taxa have been identified from thirty productive samples. The miospore assemblages recorded are assigned to the Triquitrites sinani - Cirratriradites saturni (SS) and Radiizonates aligerens (RA) biozones (Clayton et al. 1977) of Westphalian A (Langsettian) age. The stratigraphically important species Radiizonates aligerens first occurs within the Double Fireclay Member in the lower part of the Coolbaun Coal Formation. The SS / RA Miospore Biozonal boundary in the Leinster Coalfield is shown to closely correlate with the Lenisulcata-Communis non-marine bivalve Chronozone boundary.
{"title":"Stratigraphy and Palynology of the Westphalian Strata of the Leinster Coalfield, Ireland","authors":"K. Higgs, G. O'connor","doi":"10.3318/IJES.2005.23.1.65","DOIUrl":"https://doi.org/10.3318/IJES.2005.23.1.65","url":null,"abstract":"Abstract:The Leinster Coalfield is the largest of the onshore coalfields in southern Ireland. Topographically and geologically the coalfield is an upland basin and the Westphalian sediments occupy the centre of the coalfield, while the older Namurian sediments form the rim. The Westphalian succession is approximately 320m thick and is subdivided into three lithostratigraphic formations: in ascending stratigraphic order these are the Moyadd Coal Formation, the Clay Gall Sandstone Formation and the Coolbaun Coal Formation. The latter formation is formally defined here and described, together with several new lithostratigraphic members. The first palynological study of the Westphalian strata in the coalfield has been carned out. The lower part of the Westphalian succession has been sampled palynologically from a stream section in the north of the coalfield, while the rest of the Westphalian strata have been sampled from three boreholes situated in the centre of the coalfield. Forty two miospore taxa have been identified from thirty productive samples. The miospore assemblages recorded are assigned to the Triquitrites sinani - Cirratriradites saturni (SS) and Radiizonates aligerens (RA) biozones (Clayton et al. 1977) of Westphalian A (Langsettian) age. The stratigraphically important species Radiizonates aligerens first occurs within the Double Fireclay Member in the lower part of the Coolbaun Coal Formation. The SS / RA Miospore Biozonal boundary in the Leinster Coalfield is shown to closely correlate with the Lenisulcata-Communis non-marine bivalve Chronozone boundary.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"23 1","pages":"65 - 84"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49483772","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:AbstractThe Connemara Antiform has iconic status in the geology of western Ireland. With its east-to-west trend and eastward plunge and the disposition of Dalradian stratigraphy about its axis, it forms the dominant structure in the present-day landscape and is a focal feature of geological maps of the area. Its genesis has long been ascribed to D4, the last main major deformation phase of the Ordovician Grampian Orogeny that affected the Dalradian rocks of Connemara. But does the structure have such a straightforward and simple origin? This paper investigates the possible role of middle–late Silurian deformation in the origin of the Connemara Antiform.
{"title":"The Connemara Antiform and its possible Silurian history","authors":"M. Badley","doi":"10.3318/IJES.2014.32.71","DOIUrl":"https://doi.org/10.3318/IJES.2014.32.71","url":null,"abstract":"Abstract:AbstractThe Connemara Antiform has iconic status in the geology of western Ireland. With its east-to-west trend and eastward plunge and the disposition of Dalradian stratigraphy about its axis, it forms the dominant structure in the present-day landscape and is a focal feature of geological maps of the area. Its genesis has long been ascribed to D4, the last main major deformation phase of the Ordovician Grampian Orogeny that affected the Dalradian rocks of Connemara. But does the structure have such a straightforward and simple origin? This paper investigates the possible role of middle–late Silurian deformation in the origin of the Connemara Antiform.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"32 1","pages":"71 - 78"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3318/IJES.2014.32.71","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44954140","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}
In Volume 29 of the Irish Journal of Earth Sciences, geology of the Chalk outlier. The meeting was brief, Professor Gordon Herries Davies paints a fascinatlasting only an hour or so. O'Meara was accom ing picture of the events which led to my 1960 panied by his GSI colleague, Francis Synge, and recognition of the white limestone outlier at they explained that meeting me was a detour from Ballydeenlea, Co. Kerry, as Cretaceous Chalk, other business which the Survey had elsewhere in Although I am credited as having provided 'full Munster that day. To the best of my recollection, and generous co-operation' in the preparation of the O'Meara told me that, certainly, he had mapped the paper, I nevertheless feel it necessary to add to this chalk pit in 1942 but had not then identified the rock as follows. as Chalk. In the ensuing conversation, he stated that The detail of the first half of the paper is based he had never seen the Chalk in Antrim, and had on an account, provided by me, of my role in the never actually visited Northern Ireland. I had no events which led to the recognition of the Chalk, subsequent dealings with him on any matter. Herries Davies is to be congratulated on making a An apology is due, therefore, to Professor fine summary of my much longer biography. The Herries Davies by me in respect that, in the notes second half of the paper concerns the role which the which I gave him in the early stages of our GSI officer, Michael O'Meara, played in mapping collaboration, I made no mention of my meeting the area in 1942 when searching for rock phosphate with O'Meara in 1960—in retrospect, it was simply in the local Namurian sediments, and whether or a question that he didn't ask and I didn't offer, not he recognised the chalk as Chalk eighteen years Herries Davies's analysis of the comments made before I did. Herries Davies makes the case that by D.V. Ager in his 1980 book The geology of O'Meara may have priority here, having changed Europe is taken as support for the notion that the original record when ordered to do so by the O'Meara may have recognised the Chalk in 1942 but then director, Douglas Bishopp, and then, at a later this was suppressed by office politics. Ager's sources date, re-inscribing it back to the original wording. for the comments may have included my own two In 2000, when I sent my biographical notes to publications about the Chalk (1960 and 1966) in Herries Davies, I mentioned that I could not recall which the record of a 'dirty white phosphatic whether or not I had ever met O'Meara (which was limestone' at Ballydeenlea is erroneously attributed true at the time). In fact, it was not until recently, on to a nineteenth-century surveyor. When Herries seeing the portrait of O'Meara in his office at Hume Davies interpreted Ager's comments as relating to Street, which was published in Herries Davies's 1995 a supposed Bishopp/O'Meara clash, this came as a book North from the Hook, that the floodgates of surprise, because
{"title":"DISCUSSION OF 'THE CHALK OUTLIER AT BALLYDEENLEA, CO. KERRY: A STORY OF DISCOVERY' BY GORDON L. HERRIES DAVIES (2011)","authors":"P. Walsh","doi":"10.3318/IJES.2012.30.59","DOIUrl":"https://doi.org/10.3318/IJES.2012.30.59","url":null,"abstract":"In Volume 29 of the Irish Journal of Earth Sciences, geology of the Chalk outlier. The meeting was brief, Professor Gordon Herries Davies paints a fascinatlasting only an hour or so. O'Meara was accom ing picture of the events which led to my 1960 panied by his GSI colleague, Francis Synge, and recognition of the white limestone outlier at they explained that meeting me was a detour from Ballydeenlea, Co. Kerry, as Cretaceous Chalk, other business which the Survey had elsewhere in Although I am credited as having provided 'full Munster that day. To the best of my recollection, and generous co-operation' in the preparation of the O'Meara told me that, certainly, he had mapped the paper, I nevertheless feel it necessary to add to this chalk pit in 1942 but had not then identified the rock as follows. as Chalk. In the ensuing conversation, he stated that The detail of the first half of the paper is based he had never seen the Chalk in Antrim, and had on an account, provided by me, of my role in the never actually visited Northern Ireland. I had no events which led to the recognition of the Chalk, subsequent dealings with him on any matter. Herries Davies is to be congratulated on making a An apology is due, therefore, to Professor fine summary of my much longer biography. The Herries Davies by me in respect that, in the notes second half of the paper concerns the role which the which I gave him in the early stages of our GSI officer, Michael O'Meara, played in mapping collaboration, I made no mention of my meeting the area in 1942 when searching for rock phosphate with O'Meara in 1960—in retrospect, it was simply in the local Namurian sediments, and whether or a question that he didn't ask and I didn't offer, not he recognised the chalk as Chalk eighteen years Herries Davies's analysis of the comments made before I did. Herries Davies makes the case that by D.V. Ager in his 1980 book The geology of O'Meara may have priority here, having changed Europe is taken as support for the notion that the original record when ordered to do so by the O'Meara may have recognised the Chalk in 1942 but then director, Douglas Bishopp, and then, at a later this was suppressed by office politics. Ager's sources date, re-inscribing it back to the original wording. for the comments may have included my own two In 2000, when I sent my biographical notes to publications about the Chalk (1960 and 1966) in Herries Davies, I mentioned that I could not recall which the record of a 'dirty white phosphatic whether or not I had ever met O'Meara (which was limestone' at Ballydeenlea is erroneously attributed true at the time). In fact, it was not until recently, on to a nineteenth-century surveyor. When Herries seeing the portrait of O'Meara in his office at Hume Davies interpreted Ager's comments as relating to Street, which was published in Herries Davies's 1995 a supposed Bishopp/O'Meara clash, this came as a book North from the Hook, that the floodgates of surprise, because ","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"30 1","pages":"59 - 60"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45637771","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 Cuilcagh Dyke in Co. Fermanagh forms part of the NW—SE trending Donegal—Kingscourt dyke swarm. Dykes in this swarm, along with others in the Irish Tertiary Igneous Province, are associated with negative magnetic anomalies. Segments of the Cuilcagh Dyke have these negative magnetic anomalies but some parts have been found to be associated with positive magnetic anomalies. Susceptibility measurements also show significant variations along the dyke. Palaeomagnetic investigations suggest that parts of the dyke formed during a period of reverse polarity, similar to the rest of the Irish Tertiary Igneous Province, and parts formed during normal polarity conditions. The Cuilcagh Dyke is unique in Ireland in that it is the only known dyke to possess both normal (positive) and reverse (negative) polarity magnetic characteristics.
{"title":"MAGNETIC CHARACTERISTICS OF THE CUILCAGH DYKE, CO. FERMANAGH, NORTHERN IRELAND","authors":"P. Gibson, P. Lyle, N. Thomas","doi":"10.3318/IJES.2009.27.1","DOIUrl":"https://doi.org/10.3318/IJES.2009.27.1","url":null,"abstract":"Abstract:The Cuilcagh Dyke in Co. Fermanagh forms part of the NW—SE trending Donegal—Kingscourt dyke swarm. Dykes in this swarm, along with others in the Irish Tertiary Igneous Province, are associated with negative magnetic anomalies. Segments of the Cuilcagh Dyke have these negative magnetic anomalies but some parts have been found to be associated with positive magnetic anomalies. Susceptibility measurements also show significant variations along the dyke. Palaeomagnetic investigations suggest that parts of the dyke formed during a period of reverse polarity, similar to the rest of the Irish Tertiary Igneous Province, and parts formed during normal polarity conditions. The Cuilcagh Dyke is unique in Ireland in that it is the only known dyke to possess both normal (positive) and reverse (negative) polarity magnetic characteristics.","PeriodicalId":35911,"journal":{"name":"Irish Journal of Earth Sciences","volume":"27 1","pages":"1 - 9"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43714977","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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