I am pleased to learn that James Forbes’ notes from Jameson's lecture course survive at the University of St Andrews and thank John Gordon for bringing their existence to general notice. Cunningham (1990) provides a good summary and the timing of Forbes’ attendance is particularly useful. As a student in the 1827–28 session, …
{"title":"Reply to Discussion on ‘Robert Jameson's transition from Neptunism to Plutonism as reflected in his lectures at Edinburgh University, 1820–33’: Scottish Journal of Geology, 56, 85–99, https://doi.org/10.1144/sjg2019-031","authors":"P. Stone","doi":"10.1144/sjg2020-021","DOIUrl":"https://doi.org/10.1144/sjg2020-021","url":null,"abstract":"I am pleased to learn that James Forbes’ notes from Jameson's lecture course survive at the University of St Andrews and thank John Gordon for bringing their existence to general notice. Cunningham (1990) provides a good summary and the timing of Forbes’ attendance is particularly useful. As a student in the 1827–28 session, …","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2020-021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44573554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Articulated cheiracanthid acanthodians are relatively rare above the Dickosteus thrieplandi biostratigraphic zone in the Orcadian Basin, with Cheiracanthus peachi den Blaauwen, Newman & Burrow the only species identified to date. Here we describe two other taxa Fallodentus davidsoni nov. gen. et sp. and Markacanthus costulatus Valiukevičius from the Mey Flagstone Formation. F. davidsoni occurs at the base of the formation, in the Osteolepis panderi biostratigraphic zone, and is readily identified by its robust fin spines which have a wide longitudinal ridge on each side below the groove separating the leading edge from the side of the spine. The taxon is most similar to Homalacanthus concinnus (Whiteaves) from the younger (Frasnian) Escuminac Formation in Quebec, Canada. The unique specimen of Markacanthus costulatus is from the top of the Mey Flagstone Formation. This taxon was previously only known from isolated scales from the upper Narva and Aruküla Regional Stages of the east Baltic region. The dorsoventral preservation of the head region in the F. davidsoni specimens reveals clearly the position of the ceratohyal cartilages in a cheiracanthid, as well as showing for the first time that there is a basihyal cartilage anterior to the ceratohyals.
{"title":"Two newly identified cheiracanthid acanthodians from the Mey Flagstone Formation (Givetian, Middle Devonian) of the Orcadian Basin, Scotland","authors":"M. Newman, J. D. Den Blaauwen, C. Burrow","doi":"10.1144/sjg2020-009","DOIUrl":"https://doi.org/10.1144/sjg2020-009","url":null,"abstract":"Articulated cheiracanthid acanthodians are relatively rare above the Dickosteus thrieplandi biostratigraphic zone in the Orcadian Basin, with Cheiracanthus peachi den Blaauwen, Newman & Burrow the only species identified to date. Here we describe two other taxa Fallodentus davidsoni nov. gen. et sp. and Markacanthus costulatus Valiukevičius from the Mey Flagstone Formation. F. davidsoni occurs at the base of the formation, in the Osteolepis panderi biostratigraphic zone, and is readily identified by its robust fin spines which have a wide longitudinal ridge on each side below the groove separating the leading edge from the side of the spine. The taxon is most similar to Homalacanthus concinnus (Whiteaves) from the younger (Frasnian) Escuminac Formation in Quebec, Canada. The unique specimen of Markacanthus costulatus is from the top of the Mey Flagstone Formation. This taxon was previously only known from isolated scales from the upper Narva and Aruküla Regional Stages of the east Baltic region. The dorsoventral preservation of the head region in the F. davidsoni specimens reveals clearly the position of the ceratohyal cartilages in a cheiracanthid, as well as showing for the first time that there is a basihyal cartilage anterior to the ceratohyals.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2020-009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44521157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The well-known late Mississippian/early Carboniferous locality of East Kirkton in Scotland has the earliest described fauna of terrestrial tetrapods. Seven species are now known, represented by articulated skeletons of moderate-sized animals with snout-vent length of up to 200 mm, and each is unique to East Kirkton. Here we describe the skull bones of a much larger tetrapod that closely resembles those of embolomeres from the Pennsylvanian. Although the new material is too incomplete to be named as a new species, it enhances the taxonomic diversity of the East Kirkton tetrapod fauna, predates the embolomeres from other sites in Scotland and extends the range of the group earlier into the Mississippian.
{"title":"A new large embolomere from East Kirkton","authors":"J. Clack, T. Smithson","doi":"10.1144/sjg2020-008","DOIUrl":"https://doi.org/10.1144/sjg2020-008","url":null,"abstract":"The well-known late Mississippian/early Carboniferous locality of East Kirkton in Scotland has the earliest described fauna of terrestrial tetrapods. Seven species are now known, represented by articulated skeletons of moderate-sized animals with snout-vent length of up to 200 mm, and each is unique to East Kirkton. Here we describe the skull bones of a much larger tetrapod that closely resembles those of embolomeres from the Pennsylvanian. Although the new material is too incomplete to be named as a new species, it enhances the taxonomic diversity of the East Kirkton tetrapod fauna, predates the embolomeres from other sites in Scotland and extends the range of the group earlier into the Mississippian.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"56 1","pages":"153 - 158"},"PeriodicalIF":0.7,"publicationDate":"2020-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2020-008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42864092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sandstones of the Middle–Upper Jurassic Brora Arenaceous Formation of the Inner Moray Firth, NE Scotland have hitherto been interpreted as representing coastal, tidally-influenced bars. The formation is exposed close to the northern basin-bounding Helmsdale Fault, and the middle member of the formation, the Clynelish Quarry Sandstone, consists of thick, mainly structureless sandstone beds with wavy, commonly amalgamated boundaries. It also includes sandstone bodies with sigmoidal clinothems, erosional surfaces and backset beds. Rich marine faunas dominated by bivalves and ammonites occur at a few levels, whereas trace fossils are rare or absent. The Clynelish Quarry Sandstone is here reinterpreted as reflecting deposition by hyperpycnal sandy density flows in flood-generated marine, subaqueous, delta-scale clinoforms and lobes in front of local mountain streams. The reinterpretation of these sandstones implies the presence of a tectonically controlled, relatively steep basin margin along the line of the Helmsdale Fault. The Brora Arenaceous Formation thus dates the onset of Jurassic rifting in the Inner Moray Firth to the latest Callovian rather than the late Oxfordian as previously interpreted from seismic data.
{"title":"Flood-generated hyperpycnal delta front sands of the Brora Arenaceous Formation (upper Callovian–middle Oxfordian) of the Inner Moray Firth, Scotland, record the onset of rifting","authors":"F. Surlyk, Rikke Bruhn","doi":"10.1144/sjg2020-004","DOIUrl":"https://doi.org/10.1144/sjg2020-004","url":null,"abstract":"Sandstones of the Middle–Upper Jurassic Brora Arenaceous Formation of the Inner Moray Firth, NE Scotland have hitherto been interpreted as representing coastal, tidally-influenced bars. The formation is exposed close to the northern basin-bounding Helmsdale Fault, and the middle member of the formation, the Clynelish Quarry Sandstone, consists of thick, mainly structureless sandstone beds with wavy, commonly amalgamated boundaries. It also includes sandstone bodies with sigmoidal clinothems, erosional surfaces and backset beds. Rich marine faunas dominated by bivalves and ammonites occur at a few levels, whereas trace fossils are rare or absent. The Clynelish Quarry Sandstone is here reinterpreted as reflecting deposition by hyperpycnal sandy density flows in flood-generated marine, subaqueous, delta-scale clinoforms and lobes in front of local mountain streams. The reinterpretation of these sandstones implies the presence of a tectonically controlled, relatively steep basin margin along the line of the Helmsdale Fault. The Brora Arenaceous Formation thus dates the onset of Jurassic rifting in the Inner Moray Firth to the latest Callovian rather than the late Oxfordian as previously interpreted from seismic data.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"56 1","pages":"159 - 174"},"PeriodicalIF":0.7,"publicationDate":"2020-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2020-004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64034106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Louis P. Howell, B. Besly, Surika Sooriyathasan, S. Egan, G. Leslie
Local seismic and borehole-based mapping of the Carboniferous Pennine Coal Measures and Warwickshire Group successions in the Canonbie Coalfield (SW Scotland) provides evidence of repeated episodes of positive inversion, syn-depositional folding and unconformities. A Duckmantian (Westphalian B) episode of NE–SW transpression is recognized, based on onlapping seismic reflector geometries against NE-trending positive inversion structures and contemporaneous NNE-trending syn-depositional growth folding. The basin history thus revealed at Canonbie is at variance with generally accepted models in neighbouring northern England that imply subsidence was due to post-rift thermal subsidence during late Carboniferous times. A late Westphalian–Stephanian unconformity recognized within the Warwickshire Group succession signifies NW–SE, c. 10% local basin shortening during a time of major shortening in the late Carboniferous Variscan foreland, contradicting suggestions that maximum Variscan shortening had negligible impact on Carboniferous basins in northern Britain. Local inversion structures appear to have strongly influenced local late Westphalian–Stephanian depocentres. In this respect, the Variscan foreland at Canonbie may have resembled a ‘broken’ foreland system. Variations in crustal rheology, fault strength and orientation, and mid-crustal detachments are suggested to have played important roles in determining strain localization and the nature of Westphalian–Stephanian depocentres in the Canonbie Coalfield.
{"title":"Seismic and borehole-based mapping of the late Carboniferous succession in the Canonbie Coalfield, SW Scotland: evidence for a ‘broken’ Variscan foreland?","authors":"Louis P. Howell, B. Besly, Surika Sooriyathasan, S. Egan, G. Leslie","doi":"10.1144/sjg2020-007","DOIUrl":"https://doi.org/10.1144/sjg2020-007","url":null,"abstract":"Local seismic and borehole-based mapping of the Carboniferous Pennine Coal Measures and Warwickshire Group successions in the Canonbie Coalfield (SW Scotland) provides evidence of repeated episodes of positive inversion, syn-depositional folding and unconformities. A Duckmantian (Westphalian B) episode of NE–SW transpression is recognized, based on onlapping seismic reflector geometries against NE-trending positive inversion structures and contemporaneous NNE-trending syn-depositional growth folding. The basin history thus revealed at Canonbie is at variance with generally accepted models in neighbouring northern England that imply subsidence was due to post-rift thermal subsidence during late Carboniferous times. A late Westphalian–Stephanian unconformity recognized within the Warwickshire Group succession signifies NW–SE, c. 10% local basin shortening during a time of major shortening in the late Carboniferous Variscan foreland, contradicting suggestions that maximum Variscan shortening had negligible impact on Carboniferous basins in northern Britain. Local inversion structures appear to have strongly influenced local late Westphalian–Stephanian depocentres. In this respect, the Variscan foreland at Canonbie may have resembled a ‘broken’ foreland system. Variations in crustal rheology, fault strength and orientation, and mid-crustal detachments are suggested to have played important roles in determining strain localization and the nature of Westphalian–Stephanian depocentres in the Canonbie Coalfield.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"57 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2020-007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41446707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vertebrate fossils are extremely rare below the Achanarras fish beds and equivalent strata in northern Scotland. Here we describe the cheiracanthid acanthodians from the lowest Middle Devonian of this region, comprising partial articulated specimens and squamation patches of two species Cheiracanthus flabellicostatus and C. brevicostatus. Both species were previously only known as isolated scales from the eastern Baltic and Russia. The stratigraphic range of the two species in Scotland extends up into the Achanarras equivalent fish beds in the Moray Firth.
{"title":"Cheiracanthid acanthodians from the lower fossil fish-bearing horizons (Eifelian, Middle Devonian) of the Orcadian Basin, Scotland","authors":"C. Burrow, M. Newman, J. D. Den Blaauwen","doi":"10.1144/sjg2020-006","DOIUrl":"https://doi.org/10.1144/sjg2020-006","url":null,"abstract":"Vertebrate fossils are extremely rare below the Achanarras fish beds and equivalent strata in northern Scotland. Here we describe the cheiracanthid acanthodians from the lowest Middle Devonian of this region, comprising partial articulated specimens and squamation patches of two species Cheiracanthus flabellicostatus and C. brevicostatus. Both species were previously only known as isolated scales from the eastern Baltic and Russia. The stratigraphic range of the two species in Scotland extends up into the Achanarras equivalent fish beds in the Moray Firth.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2020-006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46363666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paucity of ammonite recovery from North Sea wells has meant that offshore correlations are largely dependent upon microfossil assemblages. While rare, ammonites have been found in a few boreholes during the course of oil exploration activities. The occurrence of ammonites in ten wells in the UK sector of the Viking Graben and the Moray Firth rift arms provides a new basis by which to demonstrate that there was a distinct separation between Arctic and sub-Mediterranean species that lasted from Bajocian to Early Callovian times. Five wells contain ‘Boreal Bathonian' ammonites from the Arctic Realm. Arctocephalites from the Boreal Arcticus Zone (uppermost Bajocian) correlates basinal partly anoxic mudstones in the Beryl Embayment (9/13b) with both bioturbated siltstones in the southern Viking Graben (9/10b), and calcareous mudstones in the East Shetland Basin (211/21). Upper Bajocian Pompeckji Zone Cranocephalites and younger Arcticoceras from Lower to Middle Bathonian Greenlandicus, Ishmae and Cranocephaloide zones are confined to 211/21 demonstrating that the marine transgression began earlier and lasted longer. A Cadoceras from well 3/3-8 dates to the Lower Callovian Koenigi and Calloviense zones during which renewed extensional faulting re-established ammonite migration routes between the Boreal and sub-Mediterranean realms. A Middle Oxfordian (Densiplicatum Zone) Perisphinctes from well 22/5b-8 confirms an episode of northward migration from the sub-Mediterranean into the Boreal Realm. Upper Oxfordian (Regulare to Rosenkantzi zones) Amoeboceras in wells 211/21-1 and 9/13b-19 are close to Upper Bajocian/Lower Bathonian faunas, suggesting an absence of Upper Bathonian to Middle Oxfordian strata as a result of rift-related footwall uplift and erosion. In four wells from Block 15/21 (-4, -11, -12A and -25) Lower Kimmeridgian ammonites have been documented, including Rasenia, Amoebites, Aulacostephanoides and Zenostephanoides, from the Baylei (?), Cymodoce, Mutabilis and Eudoxus zones, the latter (confirmed at well 13/28b-8) dating a widespread regional marine flooding surface in the Inner Moray Firth. Supplementary material: The detailed measurements of dimensions of the ammonites described are available at: https://doi.org/10.6084/m9.figshare.c.5087313
{"title":"Ammonite occurrences in North Sea cores: implications for Jurassic Arctic–Mediterranean marine seaway connectivity","authors":"N. Morton, V. Mitta, J. Underhill","doi":"10.1144/sjg2019-030","DOIUrl":"https://doi.org/10.1144/sjg2019-030","url":null,"abstract":"The paucity of ammonite recovery from North Sea wells has meant that offshore correlations are largely dependent upon microfossil assemblages. While rare, ammonites have been found in a few boreholes during the course of oil exploration activities. The occurrence of ammonites in ten wells in the UK sector of the Viking Graben and the Moray Firth rift arms provides a new basis by which to demonstrate that there was a distinct separation between Arctic and sub-Mediterranean species that lasted from Bajocian to Early Callovian times. Five wells contain ‘Boreal Bathonian' ammonites from the Arctic Realm. Arctocephalites from the Boreal Arcticus Zone (uppermost Bajocian) correlates basinal partly anoxic mudstones in the Beryl Embayment (9/13b) with both bioturbated siltstones in the southern Viking Graben (9/10b), and calcareous mudstones in the East Shetland Basin (211/21). Upper Bajocian Pompeckji Zone Cranocephalites and younger Arcticoceras from Lower to Middle Bathonian Greenlandicus, Ishmae and Cranocephaloide zones are confined to 211/21 demonstrating that the marine transgression began earlier and lasted longer. A Cadoceras from well 3/3-8 dates to the Lower Callovian Koenigi and Calloviense zones during which renewed extensional faulting re-established ammonite migration routes between the Boreal and sub-Mediterranean realms. A Middle Oxfordian (Densiplicatum Zone) Perisphinctes from well 22/5b-8 confirms an episode of northward migration from the sub-Mediterranean into the Boreal Realm. Upper Oxfordian (Regulare to Rosenkantzi zones) Amoeboceras in wells 211/21-1 and 9/13b-19 are close to Upper Bajocian/Lower Bathonian faunas, suggesting an absence of Upper Bathonian to Middle Oxfordian strata as a result of rift-related footwall uplift and erosion. In four wells from Block 15/21 (-4, -11, -12A and -25) Lower Kimmeridgian ammonites have been documented, including Rasenia, Amoebites, Aulacostephanoides and Zenostephanoides, from the Baylei (?), Cymodoce, Mutabilis and Eudoxus zones, the latter (confirmed at well 13/28b-8) dating a widespread regional marine flooding surface in the Inner Moray Firth. Supplementary material: The detailed measurements of dimensions of the ammonites described are available at: https://doi.org/10.6084/m9.figshare.c.5087313","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"56 1","pages":"175 - 195"},"PeriodicalIF":0.7,"publicationDate":"2020-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2019-030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45813131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Hecke orbit conjecture plays an important role in understanding the geometric structure of Shimura varieties. First postulated by Chai and Oort in 1995, the Hecke orbit conjecture predicts that prime-to-p Hecke correspondences on mod p reductions of Shimura varieties characterize the foliation structure formed by Oort's central leaves. In other words, every prime-to-p Hecke orbit is Zariski dense in the central leaf containing it. Roughly speaking, a central leaf is the locus in a Shimura variety consisting of all points whose corresponding Barsotti-Tate groups belong to a fixed geometric isomorphism class. On the other hand, the prime-to-p Hecke orbit of a closed point x is the (countable) set consisting of all points y such that there is a prime-to-p quasi-isogeny from x to y. In 2005, Chai and Yu proved the Hecke orbit conjecture for Hilbert modular varieties, followed by a proof for Siegel modular varieties by Chai and Oort in the same year. The major purpose of the present work is to generalize the method of Chai and Oort to Shimura varieties of PEL type. We show that the Hecke orbit conjecture holds for points in certain irreducible components of Newton strata under our assumptions.
{"title":"On The Hecke Orbit Conjecture for PEL Type Shimura Varieties","authors":"L. Xiao","doi":"10.7907/SJG9-0688.","DOIUrl":"https://doi.org/10.7907/SJG9-0688.","url":null,"abstract":"The Hecke orbit conjecture plays an important role in understanding the geometric structure of Shimura varieties. First postulated by Chai and Oort in 1995, the Hecke orbit conjecture predicts that prime-to-p Hecke correspondences on mod p reductions of Shimura varieties characterize the foliation structure formed by Oort's central leaves. In other words, every prime-to-p Hecke orbit is Zariski dense in the central leaf containing it. Roughly speaking, a central leaf is the locus in a Shimura variety consisting of all points whose corresponding Barsotti-Tate groups belong to a fixed geometric isomorphism class. On the other hand, the prime-to-p Hecke orbit of a closed point x is the (countable) set consisting of all points y such that there is a prime-to-p quasi-isogeny from x to y. In 2005, Chai and Yu proved the Hecke orbit conjecture for Hilbert modular varieties, followed by a proof for Siegel modular varieties by Chai and Oort in the same year. The major purpose of the present work is to generalize the method of Chai and Oort to Shimura varieties of PEL type. We show that the Hecke orbit conjecture holds for points in certain irreducible components of Newton strata under our assumptions.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42893953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Serena Tarlati, S. Benetti, S. L. Callard, C. Ó. Cofaigh, P. Dunlop, A. Georgiopoulou, R. Edwards, K. V. Van Landeghem, M. Saher, R. Chiverrell, D. Fabel, S. Moreton, S. Morgan, C. Clark
During the last glacial maximum, the British–Irish Ice Sheet (BIIS) extended to the shelf edge in the Malin Sea between Ireland and Scotland, delivering sediments to the Donegal Barra Fan (DBF). Analysis of well-preserved, glacially derived sediment in the DBF provides new insights on the character of the BIIS final deglaciation and palaeoenvironmental conditions at the Younger Dryas. Chaotic/laminated muds, ice-rafted debris (IRD)-rich layers and laminated sand–mud couplets are interpreted as respectively mass transport deposits, plumites and turbidites of BIIS-transported sediments. Peaks in IRD, constrained by radiocarbon dating to after 18 cal ka BP, indicate discrete intervals of iceberg calving during the last stages of deglaciation. Glacially derived sedimentation on the slope occurred until c. 16.9 cal ka BP. This is interpreted as the last time the ice sheet was present on to the shelf, allowing glacial meltwater to reach the fan. Bioturbated and foraminifera-rich muds above glaciomarine sediments are interpreted as interglacial hemipelagites and contourites, with the presence of Zoophycos suggesting restoration of bottom currents at the transition between stadial and interstadial conditions. During the Younger Dryas, Neogloboquadrina pachyderma sinistral abundances and an isolated peak in IRD indicate the temporary restoration of cold conditions and the presence of icebergs in the region. Thematic collection: This article is part of the Early Career Research collection available at: https://www.lyellcollection.org/cc/SJG-early-career-research
在最后一次冰期高峰期间，英国-爱尔兰冰盖(BIIS)延伸到爱尔兰和苏格兰之间的马林海大陆架边缘，向多尼戈尔巴拉扇(DBF)输送沉积物。对DBF中保存完好的冰川衍生沉积物的分析为BIIS最终消冰的特征和新仙女木时期的古环境条件提供了新的见解。混沌/层状泥、冰筏碎屑(IRD)富层和层状砂泥联层分别被解释为biis输运沉积物的块体输运沉积、plumites和浊积岩。IRD的峰值受放射性碳测年限制在18 cal ka BP之后，表明在冰川消融的最后阶段，冰山崩解的间隔是离散的。斜坡上的冰川沉积一直持续到约16.9 calka BP。这被解释为最后一次冰原出现在冰架上，允许冰川融水到达风扇。冰川海洋沉积物上的生物扰动和富含有孔虫的泥浆被解释为间冰期半浮游岩和等高岩，植生藻的存在表明在静止和间冰期条件之间的过渡期间底流的恢复。在新仙女木期，厚皮虫sinstral的丰度和IRD的一个孤立高峰表明该地区暂时恢复了寒冷条件和冰山的存在。主题收集:本文是早期职业研究收集的一部分:https://www.lyellcollection.org/cc/SJG-early-career-research
{"title":"Final deglaciation of the Malin Sea through meltwater release and calving events","authors":"Serena Tarlati, S. Benetti, S. L. Callard, C. Ó. Cofaigh, P. Dunlop, A. Georgiopoulou, R. Edwards, K. V. Van Landeghem, M. Saher, R. Chiverrell, D. Fabel, S. Moreton, S. Morgan, C. Clark","doi":"10.1144/sjg2019-010","DOIUrl":"https://doi.org/10.1144/sjg2019-010","url":null,"abstract":"During the last glacial maximum, the British–Irish Ice Sheet (BIIS) extended to the shelf edge in the Malin Sea between Ireland and Scotland, delivering sediments to the Donegal Barra Fan (DBF). Analysis of well-preserved, glacially derived sediment in the DBF provides new insights on the character of the BIIS final deglaciation and palaeoenvironmental conditions at the Younger Dryas. Chaotic/laminated muds, ice-rafted debris (IRD)-rich layers and laminated sand–mud couplets are interpreted as respectively mass transport deposits, plumites and turbidites of BIIS-transported sediments. Peaks in IRD, constrained by radiocarbon dating to after 18 cal ka BP, indicate discrete intervals of iceberg calving during the last stages of deglaciation. Glacially derived sedimentation on the slope occurred until c. 16.9 cal ka BP. This is interpreted as the last time the ice sheet was present on to the shelf, allowing glacial meltwater to reach the fan. Bioturbated and foraminifera-rich muds above glaciomarine sediments are interpreted as interglacial hemipelagites and contourites, with the presence of Zoophycos suggesting restoration of bottom currents at the transition between stadial and interstadial conditions. During the Younger Dryas, Neogloboquadrina pachyderma sinistral abundances and an isolated peak in IRD indicate the temporary restoration of cold conditions and the presence of icebergs in the region. Thematic collection: This article is part of the Early Career Research collection available at: https://www.lyellcollection.org/cc/SJG-early-career-research","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"56 1","pages":"117 - 133"},"PeriodicalIF":0.7,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2019-010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45741248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As part of the Glasgow Geothermal Energy Research Field Site (GGERFS) project, intended as a test site for mine-water geothermal heat, the GGC-01 borehole was drilled in the Dalmarnock area in the east of the city of Glasgow, starting in November 2018. It was logged in January 2019 to provide a record of subsurface temperature to 197 m depth, in this urban area with a long history of coal mining and industrial development. This borehole temperature record is significantly perturbed away from its natural state, in part because of the ‘permeabilizing’ effect of past nearby coal mining and in part due to surface warming as a result of the combination of anthropogenic climate change and creation of a subsurface urban heat island by local urban development. Our numerical modelling indicates the total surface warming effect as 2.7°C, partitioned as 2.0°C of global warming since the Industrial Revolution and 0.7°C of local UHI development. We cannot resolve the precise combination of local factors that influence the surface warming because uncertainty in the subsurface thermal properties trades against uncertainty in the history of surface warming. However, the background upward heat flow through the shallow subsurface is estimated as only c. 28–33 mW m−2, depending on choice of other model parameters, well below the c. 80 mW m−2 expected in the Glasgow area. We infer that the ‘missing’ geothermal heat flux is entrained by horizontal flow at depth beyond the reach of the shallow GGC-01 borehole. Although the shallow subsurface in the study area is warmer than it would have been before the Industrial Revolution, at greater depths – between c. 90 and >300 m – it is colder, due to the effect of reduced background heat flow. In future the GGERFS project might utilize water from depths of c. 90 m, but the temperature of the groundwater at these depths is maintained largely by the past effect of surface warming, due to climate change and urban development; it is thus a resource that might be ‘mined’ but not sustainably replenished and, being the result of surface warming rather than upward heat flow, arguably should not count as ‘geothermal’ heat in the first place. Our analysis thus indicates that the GGERFS site is a poor choice as a test site for mine-water geothermal heat. Supplementary material: A summary history of coal mining in the study area is available at: https://doi.org/10.6084/m9.figshare.c.4911495.v2
{"title":"Borehole temperature log from the Glasgow Geothermal Energy Research Field Site: a record of past changes to ground surface temperature caused by urban development","authors":"S. Watson, R. Westaway","doi":"10.1144/sjg2019-033","DOIUrl":"https://doi.org/10.1144/sjg2019-033","url":null,"abstract":"As part of the Glasgow Geothermal Energy Research Field Site (GGERFS) project, intended as a test site for mine-water geothermal heat, the GGC-01 borehole was drilled in the Dalmarnock area in the east of the city of Glasgow, starting in November 2018. It was logged in January 2019 to provide a record of subsurface temperature to 197 m depth, in this urban area with a long history of coal mining and industrial development. This borehole temperature record is significantly perturbed away from its natural state, in part because of the ‘permeabilizing’ effect of past nearby coal mining and in part due to surface warming as a result of the combination of anthropogenic climate change and creation of a subsurface urban heat island by local urban development. Our numerical modelling indicates the total surface warming effect as 2.7°C, partitioned as 2.0°C of global warming since the Industrial Revolution and 0.7°C of local UHI development. We cannot resolve the precise combination of local factors that influence the surface warming because uncertainty in the subsurface thermal properties trades against uncertainty in the history of surface warming. However, the background upward heat flow through the shallow subsurface is estimated as only c. 28–33 mW m−2, depending on choice of other model parameters, well below the c. 80 mW m−2 expected in the Glasgow area. We infer that the ‘missing’ geothermal heat flux is entrained by horizontal flow at depth beyond the reach of the shallow GGC-01 borehole. Although the shallow subsurface in the study area is warmer than it would have been before the Industrial Revolution, at greater depths – between c. 90 and >300 m – it is colder, due to the effect of reduced background heat flow. In future the GGERFS project might utilize water from depths of c. 90 m, but the temperature of the groundwater at these depths is maintained largely by the past effect of surface warming, due to climate change and urban development; it is thus a resource that might be ‘mined’ but not sustainably replenished and, being the result of surface warming rather than upward heat flow, arguably should not count as ‘geothermal’ heat in the first place. Our analysis thus indicates that the GGERFS site is a poor choice as a test site for mine-water geothermal heat. Supplementary material: A summary history of coal mining in the study area is available at: https://doi.org/10.6084/m9.figshare.c.4911495.v2","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"56 1","pages":"134 - 152"},"PeriodicalIF":0.7,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42860612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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