S. Archer, R. Steel, D. Mellere, Stuart Blackwood, B. Cullen
The Hebridean Province of NW Scotland provides insight into the interaction between tectonics and shallow-marine and tidal strait depositional environments in the Sea of the Hebrides and Inner Hebrides basins. The study tests the influence of syn-depositional block tilting on gross thickness, sand to mud ratio and the distribution of shallow-marine facies in the resulting succession. New Middle Jurassic palaeogeographical maps and stratigraphic correlations are presented that integrate both outcrop and well data and illustrate the evolution of the deltaic sedimentary system in a broad, semi-regional context. Results show that distance from the sediment entry point and the syn-rift tectonic geomorphology were the critical controls on gross thickness, sand to mud ratios and facies types. The impact of relative sea-level change is hard to detect in locations proximal to the Scottish hinterland, where sediment supply was large relative to accommodation (Ss > Ac), but becomes more influential in distal locations where eustasy and tectonic subsidence convolved to increase the influence of accommodation over sediment supply (Ac > Ss). Supplementary material: An outcrop to well log correlation exercise is available at https://doi.org/10.6084/m9.figshare.c.4397858
{"title":"Response of Middle Jurassic shallow-marine environments to syn-depositional block tilting: Isles of Skye and Raasay, NW Scotland","authors":"S. Archer, R. Steel, D. Mellere, Stuart Blackwood, B. Cullen","doi":"10.1144/sjg2018-014","DOIUrl":"https://doi.org/10.1144/sjg2018-014","url":null,"abstract":"The Hebridean Province of NW Scotland provides insight into the interaction between tectonics and shallow-marine and tidal strait depositional environments in the Sea of the Hebrides and Inner Hebrides basins. The study tests the influence of syn-depositional block tilting on gross thickness, sand to mud ratio and the distribution of shallow-marine facies in the resulting succession. New Middle Jurassic palaeogeographical maps and stratigraphic correlations are presented that integrate both outcrop and well data and illustrate the evolution of the deltaic sedimentary system in a broad, semi-regional context. Results show that distance from the sediment entry point and the syn-rift tectonic geomorphology were the critical controls on gross thickness, sand to mud ratios and facies types. The impact of relative sea-level change is hard to detect in locations proximal to the Scottish hinterland, where sediment supply was large relative to accommodation (Ss > Ac), but becomes more influential in distal locations where eustasy and tectonic subsidence convolved to increase the influence of accommodation over sediment supply (Ac > Ss). Supplementary material: An outcrop to well log correlation exercise is available at https://doi.org/10.6084/m9.figshare.c.4397858","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2019-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2018-014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42442622","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}
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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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 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":null,"pages":null},"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}
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":null,"pages":null},"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}
Three closely associated arthropleurid trackways, Diplichnites cuithensis, from the Lower Carboniferous of Fife, Scotland, exhibit signs of interaction between track-makers. An extra file of footprints is found on the downslope side of two trackways (A and C), the upslope side of another (B). These additional files of footprints suggest that either: each trackway resulted from two arthropleurids of different sizes walking in tandem, matching their footprints exactly on one side for some distance; or that one arthropleurid was partially mounted on the back of another producing the three parallel files. It is here argued that the latter is correct and that this represents evidence of mating behaviour in arthropleurids.
{"title":"Mating trackways of a fossil giant millipede","authors":"M. Whyte","doi":"10.1144/sjg2017-013","DOIUrl":"https://doi.org/10.1144/sjg2017-013","url":null,"abstract":"Three closely associated arthropleurid trackways, Diplichnites cuithensis, from the Lower Carboniferous of Fife, Scotland, exhibit signs of interaction between track-makers. An extra file of footprints is found on the downslope side of two trackways (A and C), the upslope side of another (B). These additional files of footprints suggest that either: each trackway resulted from two arthropleurids of different sizes walking in tandem, matching their footprints exactly on one side for some distance; or that one arthropleurid was partially mounted on the back of another producing the three parallel files. It is here argued that the latter is correct and that this represents evidence of mating behaviour in arthropleurids.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2018-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg2017-013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44567327","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}
A coccosteid nuchal bone from the Middle Devonian Tamme Cliffs locality in Estonia is described as Dickosteus cf. threiplandi, D. threiplandi being a common species in the Middle Devonian of the Orcadian Basin, Scotland. A number of other bones from Tamme Cliffs are also placed in this genus. It is already known that the coccosteids Coccosteus cuspidatus and probably Millerosteus minor are present in both areas. A final coccosteid genus Watsonosteus has been shown previously to also be present in both areas. We can confirm that the sequence of coccosteid genera is the same in both the Orcadian Basin and Estonia and is, from the lowest horizon, Coccosteus–Dickosteus–Millerosteus–Watsonosteus. The coccosteids in Estonia are also associated with other Scottish faunal elements (including co-specific species), such as other placoderms, acanthodians and sarcopterygians. This implies a very close connection between the two areas in the Middle Devonian. Some of the acanthodian species of the Orcadian Basin are also present in Belarus and Severnaya Zemlya, suggesting that other Orcadian Basin forms, including coccosteids may be present at these localities and perhaps elsewhere on the Old Red Sandstone continent. Further investigation may allow a continent-wide correlation at species level across the whole continent.
{"title":"Middle Devonian coccosteid (Arthrodira, Placodermi) biostratigraphy of Scotland and Estonia","authors":"M. Newman, J. D. Den Blaauwen, Tormi Tuuling","doi":"10.1144/sjg-2016-012","DOIUrl":"https://doi.org/10.1144/sjg-2016-012","url":null,"abstract":"A coccosteid nuchal bone from the Middle Devonian Tamme Cliffs locality in Estonia is described as Dickosteus cf. threiplandi, D. threiplandi being a common species in the Middle Devonian of the Orcadian Basin, Scotland. A number of other bones from Tamme Cliffs are also placed in this genus. It is already known that the coccosteids Coccosteus cuspidatus and probably Millerosteus minor are present in both areas. A final coccosteid genus Watsonosteus has been shown previously to also be present in both areas. We can confirm that the sequence of coccosteid genera is the same in both the Orcadian Basin and Estonia and is, from the lowest horizon, Coccosteus–Dickosteus–Millerosteus–Watsonosteus. The coccosteids in Estonia are also associated with other Scottish faunal elements (including co-specific species), such as other placoderms, acanthodians and sarcopterygians. This implies a very close connection between the two areas in the Middle Devonian. Some of the acanthodian species of the Orcadian Basin are also present in Belarus and Severnaya Zemlya, suggesting that other Orcadian Basin forms, including coccosteids may be present at these localities and perhaps elsewhere on the Old Red Sandstone continent. Further investigation may allow a continent-wide correlation at species level across the whole continent.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1144/sjg-2016-012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45106311","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 only official maps to show a boundary between the Middle Devonian Stromness and Rousay Flagstones on Orkney are those published by the Geological Survey in 1932 and 1935. Since then, the difficulties of defining and locating this boundary have challenged many workers in the Orcadian Lake Basin. In 2015, the introduction of biozones by Uisdean Michie, based on fossil fish, and the recent discovery in Westray of the zone fossils Osteolepis panderi and Thursius pholidotus in a prominent fish bed across the island, has permitted the boundary for the base of the Rousay Formation to be determined in that part of Orkney. It is suggested that other characteristics of the fish bed of this rhythmic cycle of sediments, together with those in adjacent cycles, may be used as a marker for further correlation and mapping across the basin.
{"title":"Demarcation of the boundary between Middle Devonian Upper Stromness Flagstone and Rousay Flagstone formations in Westray, Orkney","authors":"D. Leather","doi":"10.1144/sjg2017-007","DOIUrl":"https://doi.org/10.1144/sjg2017-007","url":null,"abstract":"The only official maps to show a boundary between the Middle Devonian Stromness and Rousay Flagstones on Orkney are those published by the Geological Survey in 1932 and 1935. Since then, the difficulties of defining and locating this boundary have challenged many workers in the Orcadian Lake Basin. In 2015, the introduction of biozones by Uisdean Michie, based on fossil fish, and the recent discovery in Westray of the zone fossils Osteolepis panderi and Thursius pholidotus in a prominent fish bed across the island, has permitted the boundary for the base of the Rousay Formation to be determined in that part of Orkney. It is suggested that other characteristics of the fish bed of this rhythmic cycle of sediments, together with those in adjacent cycles, may be used as a marker for further correlation and mapping across the basin.","PeriodicalId":49556,"journal":{"name":"Scottish Journal of Geology","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2017-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45761886","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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