C. Young, Christophe Hendrickx, T. Challands, D. Foffa, D. Ross, I. Butler, S. Brusatte
The Middle Jurassic is a largely mysterious interval in dinosaur evolution, as few fossils of this age are known worldwide. In recent years, the Isle of Skye has yielded a substantial record of trackways, and a more limited inventory of body fossils, that indicate a diverse fauna of Middle Jurassic dinosaurs living in and around lagoons and deltas. Comparatively little is known about the predators in these faunas (particularly theropod dinosaurs), as their fossils are among the rarest discoveries. We here report two new isolated theropod teeth, from the Valtos Sandstone Formation and Lealt Shale Formation of Skye, which we visualized and measured using high-resolution x-ray computed microtomographic scanning (µCT) and identified via statistical and phylogenetic analyses of a large comparative dental dataset. We argue that these teeth most likely represent at least two theropod species – one small-bodied and the other large-bodied – which likely belonged to one or several clades of basal avetheropods (ceratosaurs, megalosauroids, or allosauroids). These groups, which were diversifying during the Middle Jurassic and would become dominant in the Late Jurassic, filled various niches in the food chain of Skye, probably both on land and in the lagoons. Supplementary material: Character lists, datasets, and measurements are available at https://doi.org/10.6084/m9.figshare.c.4452533
{"title":"New theropod dinosaur teeth from the Middle Jurassic of the Isle of Skye, Scotland","authors":"C. Young, Christophe Hendrickx, T. Challands, D. Foffa, D. Ross, I. Butler, S. Brusatte","doi":"10.1144/sjg2018-020","DOIUrl":"https://doi.org/10.1144/sjg2018-020","url":null,"abstract":"The Middle Jurassic is a largely mysterious interval in dinosaur evolution, as few fossils of this age are known worldwide. In recent years, the Isle of Skye has yielded a substantial record of trackways, and a more limited inventory of body fossils, that indicate a diverse fauna of Middle Jurassic dinosaurs living in and around lagoons and deltas. Comparatively little is known about the predators in these faunas (particularly theropod dinosaurs), as their fossils are among the rarest discoveries. We here report two new isolated theropod teeth, from the Valtos Sandstone Formation and Lealt Shale Formation of Skye, which we visualized and measured using high-resolution x-ray computed microtomographic scanning (µCT) and identified via statistical and phylogenetic analyses of a large comparative dental dataset. We argue that these teeth most likely represent at least two theropod species – one small-bodied and the other large-bodied – which likely belonged to one or several clades of basal avetheropods (ceratosaurs, megalosauroids, or allosauroids). These groups, which were diversifying during the Middle Jurassic and would become dominant in the Late Jurassic, filled various niches in the food chain of Skye, probably both on land and in the lagoons. Supplementary material: Character lists, datasets, and measurements are available at https://doi.org/10.6084/m9.figshare.c.4452533","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"55 1","pages":"19 - 7"},"PeriodicalIF":0.7,"publicationDate":"2019-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2018-020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47365207","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}
Two errors have been identified in this paper. The correct text is noted below. page 104 2nd col line 18: ‘3.664 + 105 cal ka BP’ should be ‘3.664 + 0.105 cal ka BP’. page 111 2nd col line 2: ‘late Holocene’ should be corrected to ‘early Holocene
本文中发现了两个错误。正确的文本如下所示。第1042页第18行：“3.664+105 cal ka BP”应为“3.664+0.105 cal ka BP’。第1112页第2行：“全新世晚期”应更正为“全新世早期”
{"title":"Erratum for ‘Lateglacial to Holocene palaeoenvironmental change in the Muck Deep, offshore western Scotland’ Scottish Journal of Geology, 54, 99-114","authors":"R. Arosio, J. Howe","doi":"10.1144/SJG2018-025","DOIUrl":"https://doi.org/10.1144/SJG2018-025","url":null,"abstract":"Two errors have been identified in this paper. The correct text is noted below.\u0000\u0000page 104\u0000\u00002nd col line 18: ‘3.664 + 105 cal ka BP’ should be ‘3.664 + 0.105 cal ka BP’.\u0000\u0000page 111\u0000\u00002nd col line 2: ‘late Holocene’ should be corrected to ‘early Holocene","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"55 1","pages":"71 - 71"},"PeriodicalIF":0.7,"publicationDate":"2019-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/SJG2018-025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42660121","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 Orkney granite complex dominates the outcropping basement on Orkney, Scotland. It comprises a grey and a pink variably foliated granite, and structurally younger pegmatites and aplites. Based on geochemical characteristics the granites are assigned to the Scottish high Ba–Sr granites. The granites are deformed by synmagmatic extensional east–west-trending mylonite zones. These are locally overprinted by similarly oriented extensional phyllonites and, in one case, by similarly oriented extensional faults. The grey and the pink granites are dated by zircon U–Pb CA-ID-TIMS to 431.93 ± 0.46 and 430.26 ± 0.92 Ma, respectively. An aplite cutting mylonitic granite and cut by phyllonite is dated to 428.50 ± 0.31 Ma. We interpret the shear zones to record north–south extension during emplacement and cooling of the granites, likely at a shallow crustal depth (4–12 km). The extension is best explained by a subsidiary pull-apart structure related to displacement on the Great Glen Fault. In this case, the Orkney granite complex dates transcurrent faulting to 432–429 Ma, coeval with the 431–429 Ma Moine Thrust. This indicates that strain partitioning and high Ba–Sr magmatism across the Scottish Highlands was an immediate response to attempted subduction of Avalonia beneath Laurentia during the Scandian collision. Supplementary material: Geochronological and geochemical data (Tables 1 and 2) as spreadsheets are available at https://doi.org/10.6084/m9.figshare.c.4304387
{"title":"Timing of strain partitioning and magmatism in the Scottish Scandian collision, evidence from the high Ba–Sr Orkney granite complex","authors":"A. Lundmark, L. Augland, Audun Dalene Bjerga","doi":"10.1144/sjg2018-001","DOIUrl":"https://doi.org/10.1144/sjg2018-001","url":null,"abstract":"The Orkney granite complex dominates the outcropping basement on Orkney, Scotland. It comprises a grey and a pink variably foliated granite, and structurally younger pegmatites and aplites. Based on geochemical characteristics the granites are assigned to the Scottish high Ba–Sr granites. The granites are deformed by synmagmatic extensional east–west-trending mylonite zones. These are locally overprinted by similarly oriented extensional phyllonites and, in one case, by similarly oriented extensional faults. The grey and the pink granites are dated by zircon U–Pb CA-ID-TIMS to 431.93 ± 0.46 and 430.26 ± 0.92 Ma, respectively. An aplite cutting mylonitic granite and cut by phyllonite is dated to 428.50 ± 0.31 Ma. We interpret the shear zones to record north–south extension during emplacement and cooling of the granites, likely at a shallow crustal depth (4–12 km). The extension is best explained by a subsidiary pull-apart structure related to displacement on the Great Glen Fault. In this case, the Orkney granite complex dates transcurrent faulting to 432–429 Ma, coeval with the 431–429 Ma Moine Thrust. This indicates that strain partitioning and high Ba–Sr magmatism across the Scottish Highlands was an immediate response to attempted subduction of Avalonia beneath Laurentia during the Scandian collision. Supplementary material: Geochronological and geochemical data (Tables 1 and 2) as spreadsheets are available at https://doi.org/10.6084/m9.figshare.c.4304387","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"55 1","pages":"21 - 34"},"PeriodicalIF":0.7,"publicationDate":"2018-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2018-001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45931162","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}
Small round holes, Oichnus Bromley, are a locally common feature of crinoid pluricolumnals in the Mississippian of the British Isles. Numerous examples have been found from mudrocks in the Brigantian (Mississippian) Blackhall Limestone, Lower Limestone Formation, at Trearne Quarry, near Beith, north Ayrshire, all assigned to Oichnus simplex Bromley. These trace fossils are typically associated with growth deformities of the pluricolumnals, which are commonly swollen and more rarely grew a lip around the pit. Oichnus simplex is commonly centred on a columnal latus and adjacent sutures between columnals are deflected towards it. More rarely, pits are centred on the sutures between columnals. The O. simplex borings are interpreted as domiciles developed in live crinoids by an indeterminate, unmineralized invertebrate. The pluricolumnals are similar and are presumed to be derived from a single species, perhaps the poteriocrinine cladid Ureocrinus bockshii (Geinitz), the only nominal crinoid recorded from this site.
{"title":"Site selection of small round holes in crinoid pluricolumnals, Trearne Quarry SSSI (Mississippian, Lower Carboniferous), north Ayrshire, UK","authors":"S. Donovan, Gary Hoare","doi":"10.1144/sjg2018-010","DOIUrl":"https://doi.org/10.1144/sjg2018-010","url":null,"abstract":"Small round holes, Oichnus Bromley, are a locally common feature of crinoid pluricolumnals in the Mississippian of the British Isles. Numerous examples have been found from mudrocks in the Brigantian (Mississippian) Blackhall Limestone, Lower Limestone Formation, at Trearne Quarry, near Beith, north Ayrshire, all assigned to Oichnus simplex Bromley. These trace fossils are typically associated with growth deformities of the pluricolumnals, which are commonly swollen and more rarely grew a lip around the pit. Oichnus simplex is commonly centred on a columnal latus and adjacent sutures between columnals are deflected towards it. More rarely, pits are centred on the sutures between columnals. The O. simplex borings are interpreted as domiciles developed in live crinoids by an indeterminate, unmineralized invertebrate. The pluricolumnals are similar and are presumed to be derived from a single species, perhaps the poteriocrinine cladid Ureocrinus bockshii (Geinitz), the only nominal crinoid recorded from this site.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"55 1","pages":"1 - 5"},"PeriodicalIF":0.7,"publicationDate":"2018-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2018-010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48093441","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 Ballantrae Complex, SW Scotland, is an ophiolitic assemblage of mostly Early and early Middle Ordovician age (Tremadoc–Arenig in terms of the British Ordovician Series). Its varied components were generated and assembled in the Iapetus Ocean, then obducted on to the Laurentian continental margin by the earliest Llanvirn. The timing of obduction is constrained by biostratigraphic and radiometric data. It was most probably a polyphase process initiated at about the beginning of the Arenig, at around 478 Ma. However, parts of the Complex are significantly younger, with some recent evidence taken to suggest an earliest Llanvirn age of about 464 Ma for the emplacement of some of the volcanic and pelagic sedimentary rocks. The oldest strata in the succession that now unconformably overlies the Ballantrae Complex were deposited at about 463 Ma. Hence there may have been as little as one million years available for the final stages of the Complex's tectonic assembly, obduction, uplift, erosion and downfaulting. Obduction of the Complex has been invoked as a factor in the initiation of the Grampian Orogeny and, whilst there is a broad correlation in timing, the detail from Ballantrae militates against a causal relationship.
{"title":"On the age of the Ballantrae Complex, SW Scotland","authors":"P. Stone, A. Rushton","doi":"10.1144/sjg2017-012","DOIUrl":"https://doi.org/10.1144/sjg2017-012","url":null,"abstract":"The Ballantrae Complex, SW Scotland, is an ophiolitic assemblage of mostly Early and early Middle Ordovician age (Tremadoc–Arenig in terms of the British Ordovician Series). Its varied components were generated and assembled in the Iapetus Ocean, then obducted on to the Laurentian continental margin by the earliest Llanvirn. The timing of obduction is constrained by biostratigraphic and radiometric data. It was most probably a polyphase process initiated at about the beginning of the Arenig, at around 478 Ma. However, parts of the Complex are significantly younger, with some recent evidence taken to suggest an earliest Llanvirn age of about 464 Ma for the emplacement of some of the volcanic and pelagic sedimentary rocks. The oldest strata in the succession that now unconformably overlies the Ballantrae Complex were deposited at about 463 Ma. Hence there may have been as little as one million years available for the final stages of the Complex's tectonic assembly, obduction, uplift, erosion and downfaulting. Obduction of the Complex has been invoked as a factor in the initiation of the Grampian Orogeny and, whilst there is a broad correlation in timing, the detail from Ballantrae militates against a causal relationship.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"54 1","pages":"77 - 86"},"PeriodicalIF":0.7,"publicationDate":"2018-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2017-012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42598495","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}
Over recent years the authors have been co-authors on a number of papers re-describing acanthodian species from classic localities in the Devonian strata of Scotland and Canada. In a number of works the noting of syntypes of particular species has been mentioned, but the authors have neglected to designate a lectotype for some of these species. In this article we remedy this oversight.
{"title":"Allocation of Devonian acanthodian lectotypes","authors":"M. Newman, C. Burrow","doi":"10.1144/sjg2018-008","DOIUrl":"https://doi.org/10.1144/sjg2018-008","url":null,"abstract":"Over recent years the authors have been co-authors on a number of papers re-describing acanthodian species from classic localities in the Devonian strata of Scotland and Canada. In a number of works the noting of syntypes of particular species has been mentioned, but the authors have neglected to designate a lectotype for some of these species. In this article we remedy this oversight.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"54 1","pages":"115 - 115"},"PeriodicalIF":0.7,"publicationDate":"2018-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2018-008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64033645","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 Lonfearn Member, Lealt Shale Formation, is a distinctive unit within the Great Estuarine Group in the Middle Jurassic of the Inner Hebrides, Scotland. Its dominant lithology of fine-grained, partly laminated mudstone marks it out as a time of minimum input of coarse clastic material into the Hebridean Basin, when consistent facies extended over some 90 km between north Skye and the Isle of Eigg. Interbedded with the mudstones are thin (decimetre) shelly and partly ferruginous and oolitic limestones, the combination giving a unique facies association in the British Bathonian. The predominantly low-salinity biota is dominated by the bivalve Neomiodon, ostracods and spinicaudatans. Episodes of inferred higher salinity aid in correlating sections from the type locality in North Trotternish, Skye to other localities, principally Strathaird in south Skye and the Isle of Eigg. We describe the principal outcrops of the Lonfearn Member and the remarkable facies continuity within the Great Estuarine Group indicating tectonic quiescence within the basin and hinterland at this time. Supplementary material: The detailed measured stratigraphical logs discussed in this paper are available at https://doi.org/10.6084/m9.figshare.c.4093991
{"title":"The Lonfearn Member, Lealt Shale Formation, (Middle Jurassic) of the Inner Hebrides, Scotland","authors":"J. D. Hudson, M. Wakefield","doi":"10.1144/sjg2017-015","DOIUrl":"https://doi.org/10.1144/sjg2017-015","url":null,"abstract":"The Lonfearn Member, Lealt Shale Formation, is a distinctive unit within the Great Estuarine Group in the Middle Jurassic of the Inner Hebrides, Scotland. Its dominant lithology of fine-grained, partly laminated mudstone marks it out as a time of minimum input of coarse clastic material into the Hebridean Basin, when consistent facies extended over some 90 km between north Skye and the Isle of Eigg. Interbedded with the mudstones are thin (decimetre) shelly and partly ferruginous and oolitic limestones, the combination giving a unique facies association in the British Bathonian. The predominantly low-salinity biota is dominated by the bivalve Neomiodon, ostracods and spinicaudatans. Episodes of inferred higher salinity aid in correlating sections from the type locality in North Trotternish, Skye to other localities, principally Strathaird in south Skye and the Isle of Eigg. We describe the principal outcrops of the Lonfearn Member and the remarkable facies continuity within the Great Estuarine Group indicating tectonic quiescence within the basin and hinterland at this time. Supplementary material: The detailed measured stratigraphical logs discussed in this paper are available at https://doi.org/10.6084/m9.figshare.c.4093991","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"54 1","pages":"87 - 97"},"PeriodicalIF":0.7,"publicationDate":"2018-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41742688","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 Givetian (Middle Devonian) antiarch Asterolepis thule was first described in 1932 and its stratigraphical horizon was poorly understood as were all the Devonian deposits in the SE of Shetland (South East Shetland Group). Since that time a greater understanding of the age of these deposits has been made. This, coupled with the greater clarity of the biostratigraphy of the Devonian of Scotland and its correlation with the Baltic Devonian, has allowed the species to be placed in a biostratigraphical zonation. The species is confined to Sumburgh Head and so appears endemic. Other species are also endemic and there are some relict fauna in the South East Shetland Group. This suggests that the South East Shetland Group fauna originated mostly in isolation to the main depositional areas of the Givetian in Scotland and elsewhere, although some species are more cosmopolitan.
{"title":"A redescription of the endemic antiarch placoderm Asterolepis thule from the Middle Devonian (Givetian) of Shetland and its biostratigraphical horizon","authors":"M. Newman, J. D. Den Blaauwen","doi":"10.1144/sjg2018-005","DOIUrl":"https://doi.org/10.1144/sjg2018-005","url":null,"abstract":"The Givetian (Middle Devonian) antiarch Asterolepis thule was first described in 1932 and its stratigraphical horizon was poorly understood as were all the Devonian deposits in the SE of Shetland (South East Shetland Group). Since that time a greater understanding of the age of these deposits has been made. This, coupled with the greater clarity of the biostratigraphy of the Devonian of Scotland and its correlation with the Baltic Devonian, has allowed the species to be placed in a biostratigraphical zonation. The species is confined to Sumburgh Head and so appears endemic. Other species are also endemic and there are some relict fauna in the South East Shetland Group. This suggests that the South East Shetland Group fauna originated mostly in isolation to the main depositional areas of the Givetian in Scotland and elsewhere, although some species are more cosmopolitan.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"54 1","pages":"69 - 75"},"PeriodicalIF":0.7,"publicationDate":"2018-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2018-005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47268831","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}
Shelf basins (‘glacial incisions’) can preserve a detailed record of palaeoclimatic changes due to their low-energy environment. The ‘Muck Deep’, a complex of glacially-overdeepened troughs on the Inner Hebrides shelf constitutes an example of such an environment. Five sediment cores from the Muck Deep have been analysed and related to geomorphological evidence and subsurface seismic facies. The cores show an integrated sequence of sedimentary and faunal variations from the retreat of ice (c. 17 ka) to the present day. Glacimarine sandy muds with ice-rafted debris are dated to about 11.9 cal ka BP, supporting glacial occupancy in western Scotland until the latest stages of GS-1. The transition from a paraglacial to a more stable landscape is indicated by an erosional boundary in one of the cores dated between 11.3 and 11.6 cal ka BP. Sandy sediments in a core from 200 m water depth show two upward-fining cycles and a mid-core erosional unconformity, interpreted as bottom-current deposits. Such structures do not occur in the western Muck Deep, indicating different bottom current velocities through time. A regional signal of increasing current energy at the end of the Holocene marine transgression is interpreted as the onset of modern oceanographic conditions. Supplementary material: Extra figures and table content is available at https://doi.org/10.6084/m9.figshare.c.4093997
陆架盆地（“冰川切口”）由于其低能量环境，可以保存古气候变化的详细记录。“Muck Deep”是内赫布里底群岛大陆架上一个由冰川覆盖过度的槽组成的综合体，就是这种环境的一个例子。对Muck Deep的五个沉积物岩心进行了分析，并将其与地貌证据和地下地震相联系起来。岩心显示了一个完整的沉积和动物群变化序列，这些变化源于冰的消退（约17 ka）直到今天。含冰椽碎屑的灰岩砂质泥岩的年代约为11.9年 cal ka BP，支持苏格兰西部冰川的占用，直到GS-1的最新阶段。从副冰川到更稳定景观的过渡由11.3年至11.6年期间的一个岩芯中的侵蚀边界指示 cal ka BP。200岩芯中的砂质沉积物 m水深显示两个向上变细旋回和一个中芯侵蚀不整合，解释为底流沉积。这种结构没有出现在西部Muck Deep，表明随着时间的推移，底部洋流速度不同。全新世海侵结束时洋流能量增加的区域信号被解释为现代海洋学条件的开始。补充材料：额外的数字和表格内容可在https://doi.org/10.6084/m9.figshare.c.4093997
{"title":"Lateglacial to Holocene palaeoenvironmental change in the Muck Deep, offshore western Scotland","authors":"R. Arosio, J. Howe","doi":"10.1144/sjg2017-014","DOIUrl":"https://doi.org/10.1144/sjg2017-014","url":null,"abstract":"Shelf basins (‘glacial incisions’) can preserve a detailed record of palaeoclimatic changes due to their low-energy environment. The ‘Muck Deep’, a complex of glacially-overdeepened troughs on the Inner Hebrides shelf constitutes an example of such an environment. Five sediment cores from the Muck Deep have been analysed and related to geomorphological evidence and subsurface seismic facies. The cores show an integrated sequence of sedimentary and faunal variations from the retreat of ice (c. 17 ka) to the present day. Glacimarine sandy muds with ice-rafted debris are dated to about 11.9 cal ka BP, supporting glacial occupancy in western Scotland until the latest stages of GS-1. The transition from a paraglacial to a more stable landscape is indicated by an erosional boundary in one of the cores dated between 11.3 and 11.6 cal ka BP. Sandy sediments in a core from 200 m water depth show two upward-fining cycles and a mid-core erosional unconformity, interpreted as bottom-current deposits. Such structures do not occur in the western Muck Deep, indicating different bottom current velocities through time. A regional signal of increasing current energy at the end of the Holocene marine transgression is interpreted as the onset of modern oceanographic conditions. Supplementary material: Extra figures and table content is available at https://doi.org/10.6084/m9.figshare.c.4093997","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"54 1","pages":"114 - 99"},"PeriodicalIF":0.7,"publicationDate":"2018-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2017-014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48440494","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}
Upper Devonian strata occur in the Central and Northern North Sea and crop out in coastal exposures in northeastern Scotland. The strata comprise continental sandstones and intercalated conglomerates, siltstones and mudstones. The offshore Upper Devonian unit (Buchan Formation) has been proven as a locally important hydrocarbon reservoir; however, the limited core coverage in the North Sea means that the architecture of the Buchan Formation is poorly understood. This study looks at two localities in Caithness and Orkney with excellent Upper Devonian exposures, which are chronologically equivalent to the Buchan Formation. The main aims are to describe the facies present and to investigate the mineralogical compositions and porosity variations using petrographic analyses. The results indicate that the studied outcrops were formed by braided fluvial and aeolian dune deposition. The aeolian sandstones have higher compositional/textural maturity and porosity than the fluvial sandstones. The main control on porosity is facies variation that results in differences in sedimentary structures, grain size and abundance of rock fragments. With similar palaeoclimate, depositional environments, lithologies and petrographies, these outcrops can be considered excellent analogues for the Buchan Formation reservoirs in the North Sea.
{"title":"Facies and petrographic assessment of Upper Devonian outcrops, Dunnet Head and Orkney, northern Scotland","authors":"Longxun Tang, S. Jones, J. Gluyas","doi":"10.1144/sjg2017-017","DOIUrl":"https://doi.org/10.1144/sjg2017-017","url":null,"abstract":"Upper Devonian strata occur in the Central and Northern North Sea and crop out in coastal exposures in northeastern Scotland. The strata comprise continental sandstones and intercalated conglomerates, siltstones and mudstones. The offshore Upper Devonian unit (Buchan Formation) has been proven as a locally important hydrocarbon reservoir; however, the limited core coverage in the North Sea means that the architecture of the Buchan Formation is poorly understood. This study looks at two localities in Caithness and Orkney with excellent Upper Devonian exposures, which are chronologically equivalent to the Buchan Formation. The main aims are to describe the facies present and to investigate the mineralogical compositions and porosity variations using petrographic analyses. The results indicate that the studied outcrops were formed by braided fluvial and aeolian dune deposition. The aeolian sandstones have higher compositional/textural maturity and porosity than the fluvial sandstones. The main control on porosity is facies variation that results in differences in sedimentary structures, grain size and abundance of rock fragments. With similar palaeoclimate, depositional environments, lithologies and petrographies, these outcrops can be considered excellent analogues for the Buchan Formation reservoirs in the North Sea.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":"54 1","pages":"51 - 61"},"PeriodicalIF":0.7,"publicationDate":"2018-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2017-017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42059091","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：