Pub Date : 2023-04-01DOI: 10.1016/j.pgeola.2023.02.002
Riadh Aouissi , Sihem Salmi-Laouar
In the northern Aurès Range near Batna, Algeria, the Cenomanian Smail Marls Formation consists of fossiliferous deposits rich in diverse benthic macrofauna, mostly dominated by bivalves, among them the carditid Maghrebella forgemoli (Coquand, 1862). Almost exclusively Cenomanian, the abundance zone of Maghrebella forgemoli is in the higher levels of Lower Cenomanian, extending from the Sharpeiceras schlueteri zone to the Mantelliceras dixoni zone and corresponds to a limited circalittoral interval with relatively low energy, soft substrata, and relatively cold temperatures. The distribution of Maghrebella forgemoli in Mountains of Batna evidences bathymetric variation controlled by the tectonic activity affecting the ante-Triassic and the Upper Cretaceous substrata and generating a system of tilted blocks, at the beginning of the uppermost Albian-Cenomanian and Turonian, in the eastern Atlasic domain that extends to central Tunisia.
{"title":"The heterodont bivalve Maghrebella forgemoli (Coquand, 1862) from Cenomanian of Batna, northeastern Algeria: Palaeobiogeography, biostratigraphy and palaeoenvironment","authors":"Riadh Aouissi , Sihem Salmi-Laouar","doi":"10.1016/j.pgeola.2023.02.002","DOIUrl":"https://doi.org/10.1016/j.pgeola.2023.02.002","url":null,"abstract":"<div><p><span><span>In the northern Aurès Range near Batna, Algeria, the Cenomanian Smail Marls Formation consists of fossiliferous deposits rich in diverse benthic </span>macrofauna, mostly dominated by bivalves, among them the carditid </span><em>Maghrebella forgemoli</em> (Coquand, 1862). Almost exclusively Cenomanian, the abundance zone of <em>Maghrebella forgemoli</em> is in the higher levels of Lower Cenomanian, extending from the <em>Sharpeiceras schlueteri</em> zone to the <em>Mantelliceras dixoni</em> zone and corresponds to a limited circalittoral interval with relatively low energy, soft substrata, and relatively cold temperatures. The distribution of <em>Maghrebella forgemoli</em><span> in Mountains of Batna evidences bathymetric variation controlled by the tectonic activity affecting the ante-Triassic and the Upper Cretaceous<span> substrata and generating a system of tilted blocks, at the beginning of the uppermost Albian-Cenomanian and Turonian, in the eastern Atlasic domain that extends to central Tunisia.</span></span></p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49875191","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}
Pub Date : 2023-04-01DOI: 10.1016/j.pgeola.2023.01.004
James Tayler , Christopher J. Duffin , Claudia Hildebrandt , Adam Parker , Michael J. Benton
The Rhaetian (latest Triassic) succession of Doniford Bay, North Somerset has been noted as a site of fossils for over 200 years, and yet has never been described in detail despite its importance for palaeontology, for knowledge of a classic Triassic-to-Jurassic transition sequence, for structural geology, and as a venue for field trips. There are two bone beds, which differ substantially in sedimentary and palaeontological characteristics. Fossils include the usual teeth, denticles, and scales of small hybodont sharks, bony fishes, and marine reptiles. The lower (basal) bone bed is in many ways like those from other localities around Bristol and in South Wales, whereas the upper bone bed shows rich organic matter and an absence of calcite, suggesting a deeper location of deposition. Further, the lower bone bed contains abundant abraded silica grains, suggesting transport of sediment and bone debris from a beach or river. The two bone beds differ in faunal composition, and the upper bone bed lacks the locally derived clasts, larger silica grains, and calcite seen in the lower bone bed. Bones and teeth are equally abraded in both bone beds, confirming long-distance transport of fish and reptile fossils and that the upper bone bed cannot be interpreted as having derived from the lower.
{"title":"Geology and microvertebrate faunas of the Rhaetian Westbury Formation of Doniford Bay, Somerset","authors":"James Tayler , Christopher J. Duffin , Claudia Hildebrandt , Adam Parker , Michael J. Benton","doi":"10.1016/j.pgeola.2023.01.004","DOIUrl":"https://doi.org/10.1016/j.pgeola.2023.01.004","url":null,"abstract":"<div><p>The Rhaetian (latest Triassic) succession of Doniford Bay, North Somerset has been noted as a site of fossils for over 200 years, and yet has never been described in detail despite its importance for palaeontology, for knowledge of a classic Triassic-to-Jurassic transition sequence, for structural geology, and as a venue for field trips. There are two bone beds, which differ substantially in sedimentary and palaeontological characteristics. Fossils include the usual teeth, denticles, and scales of small hybodont sharks, bony fishes, and marine reptiles. The lower (basal) bone bed is in many ways like those from other localities around Bristol and in South Wales, whereas the upper bone bed shows rich organic matter and an absence of calcite, suggesting a deeper location of deposition. Further, the lower bone bed contains abundant abraded silica grains, suggesting transport of sediment and bone debris from a beach or river. The two bone beds differ in faunal composition, and the upper bone bed lacks the locally derived clasts, larger silica grains, and calcite seen in the lower bone bed. Bones and teeth are equally abraded in both bone beds, confirming long-distance transport of fish and reptile fossils and that the upper bone bed cannot be interpreted as having derived from the lower.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49838256","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}
Pub Date : 2023-04-01DOI: 10.1016/j.pgeola.2023.02.003
Richard Birch , Lucy M.E. McCobb
Historical published works on the fossil fauna of the Llanberis Slates Formation in Gwynedd, North Wales, concentrated on the endemic trilobite Pseudatops viola (Woodward, 1888), and placed the formation towards the top of Stage 3 (Series 2) of the Cambrian chronostratigraphy.
The impression given was that the fauna is not particularly diverse and fossils are rare. However, recent collecting has produced a comprehensive fauna of sponges, hyolithids and diverse arthropods including over 250 trilobite specimens from two localities of the uppermost Green Slate horizon. Among them are examples of the endemic trilobite Pseudatops viola, sufficiently well preserved to enable a reappraisal of its status. The most abundant trilobite is a form of Strenuella (cf. strenua), but the collection includes previously unrecorded eodiscoid trilobites and specimens representing unrecorded and potentially new taxa. These additions result in the most comprehensive lower Cambrian trilobite assemblage yet described from Wales, and place it in the lower part of Stage 4, Series 2 in standard global terms.
{"title":"The oldest trilobites in Cambria: Early Cambrian trilobite faunas from the Llanberis Slates Formation, Gwynedd, North Wales","authors":"Richard Birch , Lucy M.E. McCobb","doi":"10.1016/j.pgeola.2023.02.003","DOIUrl":"https://doi.org/10.1016/j.pgeola.2023.02.003","url":null,"abstract":"<div><p><span>Historical published works on the fossil<span> fauna of the Llanberis Slates Formation in Gwynedd, North Wales, concentrated on the endemic trilobite </span></span><em>Pseudatops viola</em> (<span>Woodward, 1888</span><span>), and placed the formation towards the top of Stage 3 (Series 2) of the Cambrian chronostratigraphy.</span></p><p>The impression given was that the fauna is not particularly diverse and fossils are rare. However, recent collecting has produced a comprehensive fauna of sponges, hyolithids and diverse arthropods including over 250 trilobite specimens from two localities of the uppermost Green Slate horizon. Among them are examples of the endemic trilobite <em>Pseudatops viola</em>, sufficiently well preserved to enable a reappraisal of its status. The most abundant trilobite is a form of <em>Strenuella</em> (<em>cf. strenua</em>), but the collection includes previously unrecorded eodiscoid trilobites and specimens representing unrecorded and potentially new taxa. These additions result in the most comprehensive lower Cambrian trilobite assemblage yet described from Wales, and place it in the lower part of Stage 4, Series 2 in standard global terms.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49838255","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}
Pub Date : 2023-04-01DOI: 10.1016/j.pgeola.2023.01.002
Paul A. Carling , Teng Su , Lyubov Meshkova
The Lune Gorge and the uplands of the southern Shap Fells represent a key area in developing an understanding of the dynamics of the Late Devensian glaciation (Dimlington Stadial) of northern England. Here ice masses emanating from southern Scotland, the Lake District and the Howgill Fells interacted in the area of the upper Lune valley. Glacial landforms are recorded and tills noted. The dispersal pattern of Shap granite (Sg) erratics is mapped as these clasts are an important tracer of regional ice movements and local ice dynamics. This new information is synthesised with existing literature to provide an understanding of ice dynamics in an area of complex ice flow history. In particular, the ice flow interactions over an area of the western Pennines and the southern Shap Fells have been defined.
Early Dimlington ice flow in the vicinity of the upper Lune valley was easterly. Later a northerly shift in the position of a regionally significant west–east aligned ice divide led to topographic steering of southerly basal ice flows, resulting in the development of a western ice stream (Mint Sg plume) and an eastern ice stream (Lune Sg plume); both flowing south around the massif of the southern Shap Fells. At that time, southerly flow of basal ice over the highest ridges of the Grayrigg massif in the southern Shap Fells was relatively weak. Whereas the western stream extended into the Lancashire lowlands, the eastern ice stream was impeded in the Lune Gorge by ice emanating from Borrowdale which forced northern ice to the eastern side of the Lune Gorge where it was blocked by western flowing Howgill ice; the latter extending as far as just east of Kendal.
During the late Dimlington, the ice masses over the Mint valley and the southern Shap Fells largely thinned and retreated to the north and west, with a surge in northerly ice movement within the upper Lune valley that did not override the western Pennines. Local ice dynamics are well-illustrated in the western margin of the Pennines (Crosby Ravensworth Fell Gaythorne Plain), where the disposition of erratics reflects local late west-to-east weak down-wasting ice flow and the presence of subglacial meltwater drainage channels. However, ice ultimately decayed in situ on Crosby Ravensworth Fell Gaythorne Plain. Similarly, after complex variable easterly and southerly ice flow during the early Dimlington, there was weak northerly ice flow in the later phase over Birkbeck Fells Common before ice thinned and retreated from Grayrigg Forest. An extensive ice stream, fed by ice emanating from an ice dispersal centre in the eastern Lake District, occupied the large trough of Borrowdale that transverses the southern Shap Fells, but its extension and recession dynamics remain enigmatic.
“Glacial Theory …, in its application to the transport of blocks across Stainmoor, involves such obvious mechanical absurdities that
{"title":"Distribution of Devensian glacial erratics and related evidence elucidate complex ice flow changes across a former ice divide: Northern England","authors":"Paul A. Carling , Teng Su , Lyubov Meshkova","doi":"10.1016/j.pgeola.2023.01.002","DOIUrl":"https://doi.org/10.1016/j.pgeola.2023.01.002","url":null,"abstract":"<div><p>The Lune Gorge and the uplands of the southern Shap Fells represent a key area in developing an understanding of the dynamics of the Late Devensian<span> glaciation (Dimlington Stadial) of northern England. Here ice masses emanating from southern Scotland, the Lake District and the Howgill Fells interacted in the area of the upper Lune valley. Glacial landforms are recorded and tills noted. The dispersal pattern of Shap granite (Sg) erratics is mapped as these clasts are an important tracer of regional ice movements and local ice dynamics. This new information is synthesised with existing literature to provide an understanding of ice dynamics in an area of complex ice flow history. In particular, the ice flow interactions over an area of the western Pennines and the southern Shap Fells have been defined.</span></p><p>Early Dimlington ice flow in the vicinity of the upper Lune valley was easterly. Later a northerly shift in the position of a regionally significant west–east aligned ice divide led to topographic steering of southerly basal ice flows, resulting in the development of a western ice stream (Mint Sg plume) and an eastern ice stream (Lune Sg plume); both flowing south around the massif of the southern Shap Fells. At that time, southerly flow of basal ice over the highest ridges of the Grayrigg massif in the southern Shap Fells was relatively weak. Whereas the western stream extended into the Lancashire lowlands, the eastern ice stream was impeded in the Lune Gorge by ice emanating from Borrowdale which forced northern ice to the eastern side of the Lune Gorge where it was blocked by western flowing Howgill ice; the latter extending as far as just east of Kendal.</p><p>During the late Dimlington, the ice masses over the Mint valley and the southern Shap Fells largely thinned and retreated to the north and west, with a surge in northerly ice movement within the upper Lune valley that did not override the western Pennines. Local ice dynamics are well-illustrated in the western margin of the Pennines (Crosby Ravensworth Fell <img><span> Gaythorne Plain), where the disposition of erratics reflects local late west-to-east weak down-wasting ice flow and the presence of subglacial meltwater drainage channels. However, ice ultimately decayed </span><em>in situ</em> on Crosby Ravensworth Fell <img> Gaythorne Plain. Similarly, after complex variable easterly and southerly ice flow during the early Dimlington, there was weak northerly ice flow in the later phase over Birkbeck Fells Common before ice thinned and retreated from Grayrigg Forest. An extensive ice stream, fed by ice emanating from an ice dispersal centre in the eastern Lake District, occupied the large trough of Borrowdale that transverses the southern Shap Fells, but its extension and recession dynamics remain enigmatic.</p><p>“<em>Glacial Theory</em> …, <em>in its application to the transport of blocks across Stainmoor</em>, <em>involves such obvious mechanical absurdities that","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49838257","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}
Pub Date : 2023-02-01DOI: 10.1016/j.pgeola.2022.09.002
Bryan Lovell
Over the last 30 years, a growing body of research has shown that first-order control of the elevation of Earth's surface is exercised by thermal anomalies in the upper asthenosphere. One line of research is to test models and observations of mantle behaviour against the sedimentary record. A second line of research is to use the sedimentary record to further understanding of mantle behaviour. Here this second line of research is adopted: a particular hypothesis of mantle behaviour is tested against the Quaternary sedimentary record of the Thames valley, England. Schoonman et al. (2017) have proposed that a warm finger of mantle material extending from the Icelandic plume underlies southern England at the present day. That warm finger would represent the distal end of the influence of the Icelandic plume in this area, and would have advanced broadly from west to east, causing a progressive tilt of the surface of the Thames valley towards the east. The warm-finger hypothesis is supported by the evidence reviewed here. That evidence consists of two main sets of observations, both sets established beyond reasonable doubt by many researchers over many years. First, there is the progressive increase in elevation westward from the present-day coast of the North Sea of the 2.5–2 Ma shallow-marine Red and Norwich Crags. Second, there is the subsequent Quaternary record of progressive eastward tilting of the Thames valley shown in the river terraces.
{"title":"Is the tilt of the Thames valley towards the east caused by a distal lobe of the Icelandic mantle plume?","authors":"Bryan Lovell","doi":"10.1016/j.pgeola.2022.09.002","DOIUrl":"https://doi.org/10.1016/j.pgeola.2022.09.002","url":null,"abstract":"<div><p><span><span>Over the last 30 years, a growing body of research has shown that first-order control of the elevation of Earth's surface is exercised by thermal anomalies in the upper </span>asthenosphere<span>. One line of research is to test models and observations of mantle behaviour against the sedimentary record. A second line of research is to use the sedimentary record to further understanding of mantle behaviour. Here this second line of research is adopted: a particular hypothesis of mantle behaviour is tested against the Quaternary sedimentary record of the Thames valley, England. Schoonman et al. (2017) have proposed that a warm finger of mantle material extending from the Icelandic plume underlies southern England at the present day. That warm finger would represent the distal end of the influence of the Icelandic plume in this area, and would have advanced broadly from west to east, causing a progressive tilt of the surface of the Thames valley towards the east. The warm-finger hypothesis is supported by the evidence reviewed here. That evidence consists of two main sets of observations, both sets established beyond reasonable doubt by many researchers over many years. First, there is the progressive increase in elevation westward from the present-day coast of the North Sea of the 2.5–2 Ma shallow-marine Red and Norwich Crags. Second, there is the subsequent Quaternary record of progressive eastward tilting of the Thames valley shown in the </span></span>river terraces.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49836499","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}
Pub Date : 2023-02-01DOI: 10.1016/j.pgeola.2023.02.001
Andrew J. Jeram , Michael J. Simms , Stephen P. Hesselbo , Robert Raine
A continuous succession of marine and marginal-marine sediments of Rhaetian (Late Triassic) and Hettangian (Early Jurassic) age is present in the Larne Basin in Northern Ireland. These strata cover a period in Earth's history that included the emplacement of the Central Atlantic Magmatic Province (CAMP), the End Triassic Mass extinction (ETE), the Triassic–Jurassic Boundary (TJB), and major perturbations in the global carbon cycle. The Waterloo Bay section in the Larne Basin offers a well exposed sedimentary succession that spans this interval, and it has previously been proposed as a candidate GSSP for the base of the Jurassic System. A high-resolution δ13Corg and organic carbon record for this locality is presented here, with these new data tied to previous stratigraphic descriptions, ammonite biostratigraphy, atmospheric carbon dioxide concentration (pCO2) estimates, and nearby borehole sections that do not suffer from the thermal alteration that has affected the Waterloo Bay section. Several new exposures, unaffected by thermal metamorphism, are described that could provide future palynological and micropalaentological studies across this important boundary interval. Correlation is established between the well-studied sections in north Somerset and the likely position of the TJB in the Larne Basin, and records of soft sediment deformation, synsedimentary fault movement, relative sea-level change and their likely causes are discussed.
{"title":"Carbon isotopes, ammonites and earthquakes: Key Triassic-Jurassic boundary events in the coastal sections of south-east County Antrim, Northern Ireland, UK","authors":"Andrew J. Jeram , Michael J. Simms , Stephen P. Hesselbo , Robert Raine","doi":"10.1016/j.pgeola.2023.02.001","DOIUrl":"https://doi.org/10.1016/j.pgeola.2023.02.001","url":null,"abstract":"<div><p>A continuous succession of marine and marginal-marine sediments of Rhaetian (Late Triassic) and Hettangian (Early Jurassic) age is present in the Larne Basin in Northern Ireland. These strata cover a period in Earth's history that included the emplacement of the Central Atlantic Magmatic Province (CAMP), the End Triassic Mass extinction (ETE), the Triassic–Jurassic Boundary (TJB), and major perturbations in the global carbon cycle. The Waterloo Bay section in the Larne Basin offers a well exposed sedimentary succession that spans this interval, and it has previously been proposed as a candidate GSSP for the base of the Jurassic System. A high-resolution δ<sup>13</sup>C<sub>org</sub> and organic carbon record for this locality is presented here, with these new data tied to previous stratigraphic descriptions, ammonite biostratigraphy, atmospheric carbon dioxide concentration (<em>p</em>CO<sub>2</sub>) estimates, and nearby borehole sections that do not suffer from the thermal alteration that has affected the Waterloo Bay section. Several new exposures, unaffected by thermal metamorphism, are described that could provide future palynological and micropalaentological studies across this important boundary interval. Correlation is established between the well-studied sections in north Somerset and the likely position of the TJB in the Larne Basin, and records of soft sediment deformation, synsedimentary fault movement, relative sea-level change and their likely causes are discussed.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49873575","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}
Pub Date : 2023-02-01DOI: 10.1016/j.pgeola.2022.12.001
Andy S. Gale
New material of pterasterid asteroids from the UK chalk is described on the basis of ossicles recovered from washed residues. A new species, Pteraster lyddenensis sp. nov., is erected for oral and adambulacral ossicles and a primary radial ossicle from the Cenomanian Grey Chalk Subgroup of Dover (Kent), and the first UK record of Pteraster kutscheri Gale, 2022 is described from the upper Campanian Chalk of Norwich (Norfolk); both taxa belong to extant groups of Pteraster. Pteraster lyddenensis sp. nov. is the oldest known representative of the genus. The benthic invertebrate fauna of the Cretaceous chalk facies includes a number of extant genera which at the present day dwell in the deep sea. However, their presence was probably due to the low-productivity oceanic palaeoenvironment of the Chalk Sea, simulating deep-ocean conditions, rather than its depth.
{"title":"A new “slime star” (Echinodermata, Asteroidea, Velatida) from the Upper Cretaceous Chalk of the United Kingdom","authors":"Andy S. Gale","doi":"10.1016/j.pgeola.2022.12.001","DOIUrl":"https://doi.org/10.1016/j.pgeola.2022.12.001","url":null,"abstract":"<div><p>New material of pterasterid asteroids from the UK chalk is described on the basis of ossicles recovered from washed residues. A new species, <em>Pteraster lyddenensis</em><span> sp. nov., is erected for oral and adambulacral ossicles and a primary radial ossicle from the Cenomanian Grey Chalk Subgroup of Dover (Kent), and the first UK record of </span><em>Pteraster kutscheri</em><span> Gale, 2022 is described from the upper Campanian Chalk of Norwich (Norfolk); both taxa belong to extant groups of </span><em>Pteraster</em>. <em>Pteraster lyddenensis</em><span> sp. nov. is the oldest known representative of the genus. The benthic invertebrate fauna of the Cretaceous chalk facies includes a number of extant genera which at the present day dwell in the deep sea. However, their presence was probably due to the low-productivity oceanic palaeoenvironment of the Chalk Sea, simulating deep-ocean conditions, rather than its depth.</span></p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49836497","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}
Pub Date : 2023-02-01DOI: 10.1016/j.pgeola.2022.10.001
W.J. Barclay, S. Hay, M.J.P. Payne, M. Jenkins, P. Olver
A disused Victorian gravel pit [SO 7450 5956] 1 km west of Martley, Worcestershire formerly exposed an inlier of Neoproterozoic meta-igneous rocks and early Palaeozoic quartz arenite. The pit is back-filled, but trenching at the site between 2010 and 2014 re-exposed the rocks of the inlier and the surrounding Silurian and Carboniferous cover rocks. The site lies on the East Malvern Fault (EMF) and the work has proved the relationships between the meta-igneous rocks, quartz arenite and cover rocks, and revealed a complex of thrust faults in the footwall of the EMF. The thrusts are interpreted as footwall shortcuts and provide evidence of the Variscan inversion and compressive events resolved along this fault line (the Malvern Lineament) which has a prolonged and complex history of activation and reactivation. The structures at Martley provide a model in microcosm for other Variscan compressional structures along the Malvern Lineament.
{"title":"New data on the stratigraphy, structure and petrology of the Precambrian/Cambrian inlier at Martley, Worcestershire","authors":"W.J. Barclay, S. Hay, M.J.P. Payne, M. Jenkins, P. Olver","doi":"10.1016/j.pgeola.2022.10.001","DOIUrl":"https://doi.org/10.1016/j.pgeola.2022.10.001","url":null,"abstract":"<div><p><span>A disused Victorian gravel pit<span><span> [SO 7450 5956] 1 km west of Martley, Worcestershire formerly exposed an inlier of Neoproterozoic meta-igneous rocks and early </span>Palaeozoic quartz </span></span>arenite<span><span><span>. The pit is back-filled, but trenching at the site between 2010 and 2014 re-exposed the rocks of the inlier and the surrounding Silurian and Carboniferous cover rocks. The site lies on the East Malvern Fault (EMF) and the work has proved the relationships between the meta-igneous rocks, quartz arenite and cover rocks, and revealed a complex of </span>thrust faults in the footwall of the EMF. The thrusts are interpreted as footwall shortcuts and provide evidence of the </span>Variscan inversion and compressive events resolved along this fault line (the Malvern Lineament) which has a prolonged and complex history of activation and reactivation. The structures at Martley provide a model in microcosm for other Variscan compressional structures along the Malvern Lineament.</span></p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49820608","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}
Pub Date : 2023-02-01DOI: 10.1016/j.pgeola.2022.12.002
Richard Waller
{"title":"","authors":"Richard Waller","doi":"10.1016/j.pgeola.2022.12.002","DOIUrl":"https://doi.org/10.1016/j.pgeola.2022.12.002","url":null,"abstract":"","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49873574","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}
Pub Date : 2023-02-01DOI: 10.1016/j.pgeola.2022.08.002
R.M.L. Wignall , M. Dempster , R. Roberts , H.C. Townley
Geosite condition monitoring makes an assessment or value judgement about the current condition of a geosite compared to a defined desired baseline state. Such work has been undertaken in the UK for over 20 years. The original framework for monitoring nationally and internationally important geosites, first implemented in 1999, has been trialled independently in each of the four UK conservation agencies (Natural England, Northern Ireland Environment Agency, NatureScot, Natural Resources Wales and their predecessor bodies). Different adaptations and insights to geosite condition monitoring have been made depending on devolved circumstances, but the ability to report results on a UK basis, using some shared common standards, has been retained. This paper assesses the geosite monitoring programme in the UK, identifies the commonalities and differences in approach across the four UK countries and compares the results produced. As a long-running and widely tested national geosite condition monitoring programme, the lessons learned from the UK may be applicable to any geosite monitoring programme globally.
{"title":"Geosite condition monitoring in the UK 1999–2019","authors":"R.M.L. Wignall , M. Dempster , R. Roberts , H.C. Townley","doi":"10.1016/j.pgeola.2022.08.002","DOIUrl":"https://doi.org/10.1016/j.pgeola.2022.08.002","url":null,"abstract":"<div><p>Geosite<span> condition monitoring makes an assessment or value judgement about the current condition of a geosite compared to a defined desired baseline state. Such work has been undertaken in the UK for over 20 years. The original framework for monitoring nationally and internationally important geosites, first implemented in 1999, has been trialled independently in each of the four UK conservation agencies (Natural England, Northern Ireland Environment Agency, NatureScot, Natural Resources Wales and their predecessor bodies). Different adaptations and insights to geosite condition monitoring have been made depending on devolved circumstances, but the ability to report results on a UK basis, using some shared common standards, has been retained. This paper assesses the geosite monitoring programme in the UK, identifies the commonalities and differences in approach across the four UK countries and compares the results produced. As a long-running and widely tested national geosite condition monitoring programme, the lessons learned from the UK may be applicable to any geosite monitoring programme globally.</span></p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":null,"pages":null},"PeriodicalIF":1.2,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49836500","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}