Abstract During more than a century since its original identification, the Gowganda Formation in Ontario (Canada) has gradually been reinterpreted from representing mainly subglacial tillites to secondary gravity flow and glaciomarine deposits. The main pieces of geological evidence advanced in favour of glaciation in recent articles are outsized clasts that have been interpreted as dropstones and patches of diamictites in a single small-sized area at Cobalt which is still interpreted as displaying subglacial basal tillites. The present research considers field evidence in the Gowganda Formation in the light of more recent work on gravity flows linked to tectonics. Detailed studies have demonstrated that the clasts which are interpreted to be dropstones rarely penetrate laminae and are commonly draped by sediments the appearance of which is similar to lonestones in gravity flows. The “subglacial area” at Cobalt displays evidence of tectonics and gravity flows, which can be traced from the underlying bedrock, and then further in the overlying sequence of diamictites and rhythmites. The sum of geological features displays appearances at odds with a primary glaciogenic origin, and there is no unequivocal evidence present of glaciation. The data indicate deposition by non-glaciogenic gravity flows, including cohesive debris flows for the more compact units, probably triggered by tectonic displacements.
{"title":"Field evidence suggests that the Palaeoproterozoic Gowganda Formation in Canada is non-glacial in origin","authors":"Mats O. Molén","doi":"10.2478/logos-2021-0009","DOIUrl":"https://doi.org/10.2478/logos-2021-0009","url":null,"abstract":"Abstract During more than a century since its original identification, the Gowganda Formation in Ontario (Canada) has gradually been reinterpreted from representing mainly subglacial tillites to secondary gravity flow and glaciomarine deposits. The main pieces of geological evidence advanced in favour of glaciation in recent articles are outsized clasts that have been interpreted as dropstones and patches of diamictites in a single small-sized area at Cobalt which is still interpreted as displaying subglacial basal tillites. The present research considers field evidence in the Gowganda Formation in the light of more recent work on gravity flows linked to tectonics. Detailed studies have demonstrated that the clasts which are interpreted to be dropstones rarely penetrate laminae and are commonly draped by sediments the appearance of which is similar to lonestones in gravity flows. The “subglacial area” at Cobalt displays evidence of tectonics and gravity flows, which can be traced from the underlying bedrock, and then further in the overlying sequence of diamictites and rhythmites. The sum of geological features displays appearances at odds with a primary glaciogenic origin, and there is no unequivocal evidence present of glaciation. The data indicate deposition by non-glaciogenic gravity flows, including cohesive debris flows for the more compact units, probably triggered by tectonic displacements.","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"73 - 91"},"PeriodicalIF":1.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46921888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Asghar Roozpeykar, I. M. Moghaddam, Mehdi Yaazdi, B. Yousefi
Abstract The foraminiferal contents of the lower–middle Miocene succession exposed in three sections in north Nur Abad on the northwestern side of the High Zagros Thrust Belt were studied. Assemblages of larger foraminifera from these sections can be referred to Zone SBZ 25 (and the Miogypsina globulus and Miogypsina intermedia subzones), which correlates with the Burdigalian Stage. For the first time, planktonic foraminifera documented from the Nur Abad area document Lang-hian deposits in the High Zagros, the upper 20 metres of the upper Sayl Cheshmeh section being characterised by the occurrence of planktonic foraminifera such as Globigerina concinna (Reuss), Globigerina diplostoma (Reuss), Globigerinoides obliquus (Bolli), Orbulina bilobata (d’Orbigny) and O.universa (d’Orbigny). This association characterises the Orbulina suturalis Interval Zone.
{"title":"Burdigalian-Langhian foraminifera of the northwest High Zagros Thrust Belt, southwest Iran","authors":"Asghar Roozpeykar, I. M. Moghaddam, Mehdi Yaazdi, B. Yousefi","doi":"10.2478/logos-2021-0012","DOIUrl":"https://doi.org/10.2478/logos-2021-0012","url":null,"abstract":"Abstract The foraminiferal contents of the lower–middle Miocene succession exposed in three sections in north Nur Abad on the northwestern side of the High Zagros Thrust Belt were studied. Assemblages of larger foraminifera from these sections can be referred to Zone SBZ 25 (and the Miogypsina globulus and Miogypsina intermedia subzones), which correlates with the Burdigalian Stage. For the first time, planktonic foraminifera documented from the Nur Abad area document Lang-hian deposits in the High Zagros, the upper 20 metres of the upper Sayl Cheshmeh section being characterised by the occurrence of planktonic foraminifera such as Globigerina concinna (Reuss), Globigerina diplostoma (Reuss), Globigerinoides obliquus (Bolli), Orbulina bilobata (d’Orbigny) and O.universa (d’Orbigny). This association characterises the Orbulina suturalis Interval Zone.","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"115 - 126"},"PeriodicalIF":1.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46778586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Book reviews: Geological records of tsunamis and other extreme waves, by M. Engel, J. Pilarczyk, S.M. May, D. Brill & E. Garrett (Eds.), 2020. Elsevier Inc., Amsterdam. 848 pages. Paperback: price €156,19, ISBN 9780128156865; e-Book: price €156,19, ISBN 9780128156872","authors":"K. Stattegger","doi":"10.2478/logos-2021-0006","DOIUrl":"https://doi.org/10.2478/logos-2021-0006","url":null,"abstract":"","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"67 - 68"},"PeriodicalIF":1.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41845115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Book reviews: Earth materials. Introduction to mineralogy and petrology (Second edition), by Cornelis Klein and Anthony R. Philpotts, 2017. Cambridge University Press, Cambridge, UK. 616 pages. Paperback: price £44.99 ISBN: 9781316608852.","authors":"A. Duczmal-Czernikiewicz","doi":"10.2478/logos-2021-0008","DOIUrl":"https://doi.org/10.2478/logos-2021-0008","url":null,"abstract":"","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"71 - 72"},"PeriodicalIF":1.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45706545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bizhan Yousefi Yegane, A.J. van Loon Tom, S. A. Fard, M. Farahpour, Safoora Yasbolaghi Sharahi
Abstract A transgression of the Tethys Ocean occurred in east central Iran, like in other areas of the Tethys Ocean, around the Yakhtashian/Bolorian (regional chronostratigraphical units corresponding with the Artinskian/Kungurian of the Early Permian) transition. This led to the development of a carbonate platform that is represented in the Shirgesht area on the northern part of the Tabas Block by the Bagh-e-Vang Formation, which constitutes the only known sedimentary unit from the late Early Permian in Iran. Field data and thin-section analysis indicate deposition on a carbonate ramp with barriers separating a lagoonal area with intertidal mud flats from the open-marine environment. The overall transgressive development is indicated by the presence of open-marine sediments on top of the barrier and lagoonal sediments.
{"title":"Depositional environment of the Bagh-e-Vang Formation – the only occurrence of upper Lower Permian in Iran","authors":"Bizhan Yousefi Yegane, A.J. van Loon Tom, S. A. Fard, M. Farahpour, Safoora Yasbolaghi Sharahi","doi":"10.2478/logos-2021-0001","DOIUrl":"https://doi.org/10.2478/logos-2021-0001","url":null,"abstract":"Abstract A transgression of the Tethys Ocean occurred in east central Iran, like in other areas of the Tethys Ocean, around the Yakhtashian/Bolorian (regional chronostratigraphical units corresponding with the Artinskian/Kungurian of the Early Permian) transition. This led to the development of a carbonate platform that is represented in the Shirgesht area on the northern part of the Tabas Block by the Bagh-e-Vang Formation, which constitutes the only known sedimentary unit from the late Early Permian in Iran. Field data and thin-section analysis indicate deposition on a carbonate ramp with barriers separating a lagoonal area with intertidal mud flats from the open-marine environment. The overall transgressive development is indicated by the presence of open-marine sediments on top of the barrier and lagoonal sediments.","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"1 - 14"},"PeriodicalIF":1.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45279574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Book reviews: Forecasting and planning for volcanic hazards, risks, and disasters, by Paolo Papale (Ed.), 2020. Elsevier, London, 708 pages. Paperback: price $150.00, ISBN 9780128180822.","authors":"C. Scarpati","doi":"10.2478/logos-2021-0007","DOIUrl":"https://doi.org/10.2478/logos-2021-0007","url":null,"abstract":"","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"69 - 70"},"PeriodicalIF":1.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46850529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Analyses of sedimentology, ichnology and depositional environments of Langhian–Tortonian siliciclastic deposits in the southern Tebessa Basin (eastern Algeria) have revealed a tidally dominated deltaic setting with a high concentration of vertical burrows. From south to north, two depositional environments are here distinguished in the Tebessa Basin: a subaerial lower delta plain in the Oum Ali region with the trace fossils Ophiomorpha and Skolithos linearis, and a proximal delta front with numerous Skolithos, situated in the Hjer Essefra area. The occurrence of Skolithos pipe rock in this Miocene subtidal domain is unusual. Pipe rocks have been commonly reported from shallow and well-oxygenated environments, especially from Cambrian strata; their number decreased significantly during the Ordovician, coupled with an increase in biodiversity. Here different deltaic subenvironments and tidal signals that are exceptionally well preserved in outcrops are analysed and interpreted. Different ichnotaxa are briefly described, and the uncommon density and size of Skolithos pipe-rock in these Miocene strata are discussed.
{"title":"Tidally dominated Miocene deltaic deposits and pipe rocks in the Tebessa Basin, eastern Algeria: sedimentological and ichnological characteristics","authors":"Samia Mazrou, M. Mahboubi","doi":"10.2478/logos-2021-0002","DOIUrl":"https://doi.org/10.2478/logos-2021-0002","url":null,"abstract":"Abstract Analyses of sedimentology, ichnology and depositional environments of Langhian–Tortonian siliciclastic deposits in the southern Tebessa Basin (eastern Algeria) have revealed a tidally dominated deltaic setting with a high concentration of vertical burrows. From south to north, two depositional environments are here distinguished in the Tebessa Basin: a subaerial lower delta plain in the Oum Ali region with the trace fossils Ophiomorpha and Skolithos linearis, and a proximal delta front with numerous Skolithos, situated in the Hjer Essefra area. The occurrence of Skolithos pipe rock in this Miocene subtidal domain is unusual. Pipe rocks have been commonly reported from shallow and well-oxygenated environments, especially from Cambrian strata; their number decreased significantly during the Ordovician, coupled with an increase in biodiversity. Here different deltaic subenvironments and tidal signals that are exceptionally well preserved in outcrops are analysed and interpreted. Different ichnotaxa are briefly described, and the uncommon density and size of Skolithos pipe-rock in these Miocene strata are discussed.","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"15 - 34"},"PeriodicalIF":1.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47755374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the hydraulic conditions for their formation, development and sedimentary records are different. The present review discusses the results of previously published studies of fan deltas (Gilbert-type deltas) and subaqueous fans of lacustrine and glaciolacustrine environments. The depositional mechanisms of deltas and subaqueous fans, textural and structural features of the lithofacies associations and their typical lithofacies are presented. The characteristics of subaqueous fans, which are still relatively poorly understood and are often overlooked in sedimentological interpretations of lacustrine sedimentary successions, receive particular attention. The palaeoenvironmental and lithological differences between deltas and sub-aqueous fans are highlighted.
{"title":"Lacustrine deltas and subaqueous fans: almost the same, but different – a review","authors":"B. Gruszka, T. Zieliński","doi":"10.2478/logos-2021-0004","DOIUrl":"https://doi.org/10.2478/logos-2021-0004","url":null,"abstract":"Abstract Although deltas and subaqueous fans are both formed in the same near-shore zones of basins, the hydraulic conditions for their formation, development and sedimentary records are different. The present review discusses the results of previously published studies of fan deltas (Gilbert-type deltas) and subaqueous fans of lacustrine and glaciolacustrine environments. The depositional mechanisms of deltas and subaqueous fans, textural and structural features of the lithofacies associations and their typical lithofacies are presented. The characteristics of subaqueous fans, which are still relatively poorly understood and are often overlooked in sedimentological interpretations of lacustrine sedimentary successions, receive particular attention. The palaeoenvironmental and lithological differences between deltas and sub-aqueous fans are highlighted.","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"43 - 55"},"PeriodicalIF":1.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42362480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Colour is a common physical property in exposures of unique geological objects, but is only marginally addressed in geoheritage literature. We here present our point of view on how this feature can be treated in geoheritage studies, with the general aim at setting up a broad discussion. Three functions of colour in geoheritage are outlined, namely geological interpretation (e.g., compositional and genetic peculiarities of sedimentary rocks), higher visibility due to colour contrast and aesthetic attractiveness to geotourists. Assessment of colour at geosites is challenging, especially because of uncertain colour nomenclatures. We propose to focus on colour identification, calculation of the number of colours, qualitative evaluation of colour contrast and comparison of colours of a given geological object to its landscape context. Geoheritage colours may have different meanings to geosite visitors, and colour-emotion associations revealed by national and international studies are important to trace these meanings.
{"title":"The power of colour in geoheritage studies and marketing: some tentative reflections","authors":"D. Ruban, A. Mikhailenko, N. Yashalova","doi":"10.2478/logos-2021-0005","DOIUrl":"https://doi.org/10.2478/logos-2021-0005","url":null,"abstract":"Abstract Colour is a common physical property in exposures of unique geological objects, but is only marginally addressed in geoheritage literature. We here present our point of view on how this feature can be treated in geoheritage studies, with the general aim at setting up a broad discussion. Three functions of colour in geoheritage are outlined, namely geological interpretation (e.g., compositional and genetic peculiarities of sedimentary rocks), higher visibility due to colour contrast and aesthetic attractiveness to geotourists. Assessment of colour at geosites is challenging, especially because of uncertain colour nomenclatures. We propose to focus on colour identification, calculation of the number of colours, qualitative evaluation of colour contrast and comparison of colours of a given geological object to its landscape context. Geoheritage colours may have different meanings to geosite visitors, and colour-emotion associations revealed by national and international studies are important to trace these meanings.","PeriodicalId":44833,"journal":{"name":"Geologos","volume":"27 1","pages":"57 - 65"},"PeriodicalIF":1.0,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45743040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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