{"title":"Redox changes in the deep shelf of the East Baltic Basin in the Aeronian and early Telychian (early Silurian)","authors":"E. Kiipli","doi":"10.3176/geol.2004.2.02","DOIUrl":"https://doi.org/10.3176/geol.2004.2.02","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122677506","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":"ОЦЕНКА УСТОЙЧИВОСТИ ГОРНОГО МАССИВА РАКВЕРЕСКОГО МЕСТОРОЖДЕНИЯ ФОСФОРИТОВ ПОДАННЫМ СКВАЖИННОЙ ГЕОФИЗИКИ","authors":"A. Shogenova","doi":"10.3176/geol.1991.3.04","DOIUrl":"https://doi.org/10.3176/geol.1991.3.04","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"405 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123070645","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":"FRACTURE SYSTEMS IN DEVONIAN SANDSTONES, SOUTH ESTONIA","authors":"A. Kleesment, E. Pirrus","doi":"10.3176/geol.2000.4.03","DOIUrl":"https://doi.org/10.3176/geol.2000.4.03","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131151161","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":"The earliest known Trypanites borings in the shells of articulate brachiopods from the Arenig (Ordovician) of Baltica","authors":"O. Vinn","doi":"10.3176/geol.2004.4.03","DOIUrl":"https://doi.org/10.3176/geol.2004.4.03","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131426608","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}
The spread of broad-leaved trees ( Ulmus, Tilia, Quercus, Fraxinus, Carpinus, and Fagus) is reviewed on the basis of 46 radiocarbon dated pollen diagrams from lake and mire sediments from Estonia. Ulmus immigrated into Estonia in the second half of the Pre-Boreal, expanded between 9000 and 7800 BP, and reached its maximum values 7900-4200 BP. The immigration of Tilia began between 8800 and 6200 BP; it expanded at 8200-5200 BP, and culminated between 7200 and 4000 BP. Quercus was the next tree to arrive in Estonia, about 7900-7500 BP. Oak spread between 6800 and 4000 BP, with a maximum intermittent between 4200 and 3100 BP. Fraxinus was first recorded about 6500 BP from East Estonia. Carpinus is a late immigrant which reached Estonia in the Sub-Boreal. Comparison of the immigration and expansion of elm, lime, and oak manifests their different response to climate, with elm forest being most broadly distributed between 9000 and 7000 BP, lime between 7000 and 4000 BP (forming then up to 30% of the total forest area), and oak between 4000 and 3500 BP. Elm showed a very rapid colonization from the south; the immigration of lime was more time-transgressive and took place from the south and east. Oak immigrated from the southwest and, in contrast to elm, spread very slowly. The broad-leaved forest reached its maximum density in the second half of the Atlantic and at the beginning of the Sub-Boreal. A gradual retreat of thermophilous trees started with the elm decline at about 5500- 5000 BP, which was quite asynchronous, being caused by the combination of climate deterioration, anthropogenic forest clearances, and fungal diseases.
{"title":"SPREAD OF BROAD-LEAVED TREES IN ESTONIA","authors":"L. Saarse, S. Veski","doi":"10.3176/geol.2001.1.05","DOIUrl":"https://doi.org/10.3176/geol.2001.1.05","url":null,"abstract":"The spread of broad-leaved trees ( Ulmus, Tilia, Quercus, Fraxinus, Carpinus, and Fagus) is reviewed on the basis of 46 radiocarbon dated pollen diagrams from lake and mire sediments from Estonia. Ulmus immigrated into Estonia in the second half of the Pre-Boreal, expanded between 9000 and 7800 BP, and reached its maximum values 7900-4200 BP. The immigration of Tilia began between 8800 and 6200 BP; it expanded at 8200-5200 BP, and culminated between 7200 and 4000 BP. Quercus was the next tree to arrive in Estonia, about 7900-7500 BP. Oak spread between 6800 and 4000 BP, with a maximum intermittent between 4200 and 3100 BP. Fraxinus was first recorded about 6500 BP from East Estonia. Carpinus is a late immigrant which reached Estonia in the Sub-Boreal. Comparison of the immigration and expansion of elm, lime, and oak manifests their different response to climate, with elm forest being most broadly distributed between 9000 and 7000 BP, lime between 7000 and 4000 BP (forming then up to 30% of the total forest area), and oak between 4000 and 3500 BP. Elm showed a very rapid colonization from the south; the immigration of lime was more time-transgressive and took place from the south and east. Oak immigrated from the southwest and, in contrast to elm, spread very slowly. The broad-leaved forest reached its maximum density in the second half of the Atlantic and at the beginning of the Sub-Boreal. A gradual retreat of thermophilous trees started with the elm decline at about 5500- 5000 BP, which was quite asynchronous, being caused by the combination of climate deterioration, anthropogenic forest clearances, and fungal diseases.","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"85 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134162859","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}
. Stratigraphical units of the Juuru and Raikküla regional stages (lower to middle Llandovery) are described and correlated in the Põltsamaa, Heimtali, and Ikla drill cores. A new unit, the Heinaste Member, is established at the base of the Saarde Formation. The Distomodus kentuckyensis , Aspelundia expansa , and A. fluegeli conodont biozones, as well as the Ancyrochitina laevaensis , Belonechitina postrobusta , Euconochitina electa , Ancyrochitina convexa , Conochitina alargada , and C. malleus chitinozoan biozones are recognized, the last two zones in both groups for the first time in Estonian sections. Biostratigraphical correlation by means of chitinozoans and conodonts proves synchroneity of extensive strata of micritic limestones recurring three times in the sequence of the Raikküla Stage. The pure, micritic limestones, almost barren of benthic shelly fossils, alternate with more argillaceous, nodular, biomicritic limestones (skeletal packstones and wacke-stones) in the Nurmekund Formation, and with marlstones or argillaceous limestones in the Saarde Formation. Alternation of micritic deposits, very poor in benthic fauna, with argillaceous, biomicritic deposits rich in shelly fauna, suggests that such cyclicity was not directly controlled by changes in water depth, but more likely by cyclic changes in certain biogeochemical conditions. Alternation of arid and humid climate states supposedly induced lime mud accumulation cycles: during humid periods terrigenous input and freshwater runoff from the adjacent continent produced more argillaceous sediments, whereas during the arid periods terrigenous input decreased but salinity increased, causing accumulation of pure lime muds. Cyclic accumulation of lime muds in low-latitude shallow seas was characteristic of the supposed latest Ordovician–earliest Silurian ice-house period.
{"title":"Correlation of lower–middle Llandovery sections in central and southern Estonia and sedimentation cycles of lime muds","authors":"H. Nestor, R. Einasto, P. Männik, V. Nestor","doi":"10.3176/geol.2003.1.01","DOIUrl":"https://doi.org/10.3176/geol.2003.1.01","url":null,"abstract":". Stratigraphical units of the Juuru and Raikküla regional stages (lower to middle Llandovery) are described and correlated in the Põltsamaa, Heimtali, and Ikla drill cores. A new unit, the Heinaste Member, is established at the base of the Saarde Formation. The Distomodus kentuckyensis , Aspelundia expansa , and A. fluegeli conodont biozones, as well as the Ancyrochitina laevaensis , Belonechitina postrobusta , Euconochitina electa , Ancyrochitina convexa , Conochitina alargada , and C. malleus chitinozoan biozones are recognized, the last two zones in both groups for the first time in Estonian sections. Biostratigraphical correlation by means of chitinozoans and conodonts proves synchroneity of extensive strata of micritic limestones recurring three times in the sequence of the Raikküla Stage. The pure, micritic limestones, almost barren of benthic shelly fossils, alternate with more argillaceous, nodular, biomicritic limestones (skeletal packstones and wacke-stones) in the Nurmekund Formation, and with marlstones or argillaceous limestones in the Saarde Formation. Alternation of micritic deposits, very poor in benthic fauna, with argillaceous, biomicritic deposits rich in shelly fauna, suggests that such cyclicity was not directly controlled by changes in water depth, but more likely by cyclic changes in certain biogeochemical conditions. Alternation of arid and humid climate states supposedly induced lime mud accumulation cycles: during humid periods terrigenous input and freshwater runoff from the adjacent continent produced more argillaceous sediments, whereas during the arid periods terrigenous input decreased but salinity increased, causing accumulation of pure lime muds. Cyclic accumulation of lime muds in low-latitude shallow seas was characteristic of the supposed latest Ordovician–earliest Silurian ice-house period.","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133828220","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":"REFLECTION OF WENLOCK OCEANIC EPISODES AND EVENTS ON THE CHITINOZOAN SUCCESSION OF ESTONIA","authors":"V. Nestor","doi":"10.3176/geol.1997.3.02","DOIUrl":"https://doi.org/10.3176/geol.1997.3.02","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133844877","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":"LOWER SILURIAN STRATIGRAPHY OF THE TIMAN-NORTHERN URAL REGION AND EUSTATIC FLUCTUATION","authors":"S. Melnikov, V. Zhemchugova","doi":"10.3176/geol.2000.2.02","DOIUrl":"https://doi.org/10.3176/geol.2000.2.02","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"500 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134089666","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}
. Four lateral chitinozoan biofacies, mainly defined by the distribution of Cyathochitina species, are recognized from the uppermost lower Llandovery strata (Coronograptus cyphus age) in 18 eastern Baltic sections. Cyathochitina kuckersiana (Eisenack, 1934) seems to have preferred shallow-water near-shore conditions and С. сайх (Eisenack, 1931) deeper parts of the shelf, whereas C. campanulaeformis (Eisenack, 1931) is more widespread. Representatives of the genus Cyathochitina appear to be absent in most of the near-shore environment. However, these chitinozoan biofacies are probably of only regional significance and occur where calcareous muds (which formed calcilutites) were deposited.
{"title":"CHITINOZOAN BIOFACIES OF LATE EARLY LLANDOVERY (CORONOGRAPTUS CYPHUS) AGE IN THE EAST BALTIC","authors":"V. Nestor","doi":"10.3176/geol.1998.4.01","DOIUrl":"https://doi.org/10.3176/geol.1998.4.01","url":null,"abstract":". Four lateral chitinozoan biofacies, mainly defined by the distribution of Cyathochitina species, are recognized from the uppermost lower Llandovery strata (Coronograptus cyphus age) in 18 eastern Baltic sections. Cyathochitina kuckersiana (Eisenack, 1934) seems to have preferred shallow-water near-shore conditions and С. сайх (Eisenack, 1931) deeper parts of the shelf, whereas C. campanulaeformis (Eisenack, 1931) is more widespread. Representatives of the genus Cyathochitina appear to be absent in most of the near-shore environment. However, these chitinozoan biofacies are probably of only regional significance and occur where calcareous muds (which formed calcilutites) were deposited.","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"172 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114015383","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}
Changes in ostracode diversity and mineralogical composition of insoluble residue were studied to document environmental and biological events in the Volkhov succession of North Estonia. The most prominent bioevents occur in the basal and middle parts of the stage. The higher quartz1K-feldspar ratio in silt fraction of insoluble residue of the early Volkhov carbonates is interpreted as indicative of extensive reworking and redeposition of Cambrian-earliest Ordovician terrigenous formations. The data are discussed in the context of different models of sea level changes.
{"title":"VOLKHOV STAGE IN NORTH ESTONIA AND SEA LEVEL CHANGES","authors":"L. Ainsaar","doi":"10.3176/geol.1998.3.02","DOIUrl":"https://doi.org/10.3176/geol.1998.3.02","url":null,"abstract":"Changes in ostracode diversity and mineralogical composition of insoluble residue were studied to document environmental and biological events in the Volkhov succession of North Estonia. The most prominent bioevents occur in the basal and middle parts of the stage. The higher quartz1K-feldspar ratio in silt fraction of insoluble residue of the early Volkhov carbonates is interpreted as indicative of extensive reworking and redeposition of Cambrian-earliest Ordovician terrigenous formations. The data are discussed in the context of different models of sea level changes.","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"217 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115572283","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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