{"title":"THE KÄRDLA, TVÄREN, AND LOCKNE CRATERS – POSSIBLE EVIDENCES OF AN ORDOVICIAN ASTEROID SWARM","authors":"T. Flodén, M. Lindström, V. Puura, K. Suuroja","doi":"10.3176/geol.1992.2.01","DOIUrl":"https://doi.org/10.3176/geol.1992.2.01","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"1 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":"132786531","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 Estonian Devonian sediments consist of carbonate, siliciclastic, and mixed carbonatesiliciclastic deposits that have undergone extensive dolomitization. Chemical analysis of 165 samples and XRD mineralogical analysis of 10 samples from 8 drill cores were carried out and combined with previous results, obtained particularly on the heavy and clay fraction residues of 131 samples. The carbonate residues include illite, illite-smectite, and chlorite, with accessory biotite, muscovite, pyrite, goethite, hematite, siderite, sphalerite, and magnetite. The residues of siliciclastic rocks consist of quartz, K-feldspar, illite, montmorrilonite-chlorite and chlorite, with accessory biotite, muscovite, leucoxene, ilmenite, pyrite, hematite, goethite, and siderite. The iron content of rocks is related to the detrital input during primary sedimentation or diagenetic products formed during cementation, dolomitization, and authigenic mineral growth. Iron minerals underwent chemical alteration during diagenesis and are partly corroded and dissolved. Fe(III) minerals, responsible for red coloration of rocks, became dominant due to oxidation, low water table, and arid climate, which prevailed during diagenesis. The red coloration of siliciclastic rocks is due to hematite coatings of quartz grains. It may be primary in origin, but also diagenetic due to alterations of magnetite to hematite and dispersed distribution of Fe-oxides in dolomite cement. The red coloration of carbonate rocks (dolostones and marlstones) may have an early diagenetic origin prior to dolomitization, with possible redistribution of colour at later diagenetic stages. The variable origin of iron minerals (primary, early, middle, and late diagenetic) is distinguishable by thin-section petrography, and can be also supported by chemical and mineralogical data. The average Fe2O3total/Al2O3 ratio in the studied carbonates is higher than in siliciclastics, being in accordance with the distribution of these elements in the Earths crust. In contrast to the Earths crust data, the average TiO2/Al2O3 and K2O/Al2O3 ratios are higher in Devonian siliciclastics. This could be explained by alteration of clay during late diagenesis.
{"title":"Diagenetic influences on iron-bearing minerals in Devonian carbonate and siliciclastic rocks of Estonia","authors":"A. Kleesment, A. Shogenova","doi":"10.3176/geol.2006.4.02","DOIUrl":"https://doi.org/10.3176/geol.2006.4.02","url":null,"abstract":"The Estonian Devonian sediments consist of carbonate, siliciclastic, and mixed carbonatesiliciclastic deposits that have undergone extensive dolomitization. Chemical analysis of 165 samples and XRD mineralogical analysis of 10 samples from 8 drill cores were carried out and combined with previous results, obtained particularly on the heavy and clay fraction residues of 131 samples. The carbonate residues include illite, illite-smectite, and chlorite, with accessory biotite, muscovite, pyrite, goethite, hematite, siderite, sphalerite, and magnetite. The residues of siliciclastic rocks consist of quartz, K-feldspar, illite, montmorrilonite-chlorite and chlorite, with accessory biotite, muscovite, leucoxene, ilmenite, pyrite, hematite, goethite, and siderite. The iron content of rocks is related to the detrital input during primary sedimentation or diagenetic products formed during cementation, dolomitization, and authigenic mineral growth. Iron minerals underwent chemical alteration during diagenesis and are partly corroded and dissolved. Fe(III) minerals, responsible for red coloration of rocks, became dominant due to oxidation, low water table, and arid climate, which prevailed during diagenesis. The red coloration of siliciclastic rocks is due to hematite coatings of quartz grains. It may be primary in origin, but also diagenetic due to alterations of magnetite to hematite and dispersed distribution of Fe-oxides in dolomite cement. The red coloration of carbonate rocks (dolostones and marlstones) may have an early diagenetic origin prior to dolomitization, with possible redistribution of colour at later diagenetic stages. The variable origin of iron minerals (primary, early, middle, and late diagenetic) is distinguishable by thin-section petrography, and can be also supported by chemical and mineralogical data. The average Fe2O3total/Al2O3 ratio in the studied carbonates is higher than in siliciclastics, being in accordance with the distribution of these elements in the Earths crust. In contrast to the Earths crust data, the average TiO2/Al2O3 and K2O/Al2O3 ratios are higher in Devonian siliciclastics. This could be explained by alteration of clay during late diagenesis.","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"4 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":"131258254","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":"LATE-GLACIAL STRATIGRAPHY IN ESTONIA","authors":"R. Pirrus, A. Raukas","doi":"10.3176/geol.1996.1.04","DOIUrl":"https://doi.org/10.3176/geol.1996.1.04","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"74 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":"133021727","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 RATIO OF DEPRESSION AND MOUND VOLUMES - A PROMISING CRITERION FOR THE IDENTIFICATION OF SMALL METEORITE CRATERS","authors":"E. Pirrus","doi":"10.3176/geol.1995.3.05","DOIUrl":"https://doi.org/10.3176/geol.1995.3.05","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"1 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":"132102534","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":"Ralf Männil 24. X 1924 - 27. IX 1990","authors":"D. Kaljo, H. Nestor, V. Puura","doi":"10.3176/geol.1991.1.06","DOIUrl":"https://doi.org/10.3176/geol.1991.1.06","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":"127852667","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":"MAAVARARESSURSSIDE KLASSIFIKATSIOONIDEST","authors":"A. Teedumäe","doi":"10.3176/geol.1996.1.05","DOIUrl":"https://doi.org/10.3176/geol.1996.1.05","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"77 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":"131409137","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}
. Llandovery and Wenlock altered volcanic ash layers, metabentonites, of Estonia were investigatedusing X-raydiffractometry and X-ray fluorescence methods. Large-scale compositional variations, ranging from almost pure K-feldspar, illite-smectite or kaolinite to differentmixtures of these minerals, K,O contents from 3.6 to 15.3%, and A1,05 from 18 to 31%, show great differences from source pyroclastic material. There is a distinct relationship between the metabentonite composition and Silurian shelf sea facies. The presence of kaolinite in deep shelffacies proves low pH (below 7.4) conditions near the sea floor. On the shallow shelf area K-feldspar (low sanidine) formed; accordingly, sea water was more alkaline (pH 7.8-8.2), like in present-day sea.
{"title":"METABENTONITE COMPOSITION RELATED TO SEDIMENTARY FACIES IN THE LOWER SILURIAN OF ESTONIA","authors":"T. Kiipli, Enli Kiipli, T. Kallaste","doi":"10.3176/geol.1997.2.03","DOIUrl":"https://doi.org/10.3176/geol.1997.2.03","url":null,"abstract":". Llandovery and Wenlock altered volcanic ash layers, metabentonites, of Estonia were investigatedusing X-raydiffractometry and X-ray fluorescence methods. Large-scale compositional variations, ranging from almost pure K-feldspar, illite-smectite or kaolinite to differentmixtures of these minerals, K,O contents from 3.6 to 15.3%, and A1,05 from 18 to 31%, show great differences from source pyroclastic material. There is a distinct relationship between the metabentonite composition and Silurian shelf sea facies. The presence of kaolinite in deep shelffacies proves low pH (below 7.4) conditions near the sea floor. On the shallow shelf area K-feldspar (low sanidine) formed; accordingly, sea water was more alkaline (pH 7.8-8.2), like in present-day sea.","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"223 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":"124208342","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}
L. Bityukova, V. Puura, T. Saarde, A. Shogenova, K. Suuroja
{"title":"GEOCHEMISTRY OF MAJOR ELEMENTS IN MIDDLE ORDOVICIAN CARBONATE ROCKS - COMPARATIVE ANALYSIS OF ALTERATION ZONES, NORTH ESTONIA","authors":"L. Bityukova, V. Puura, T. Saarde, A. Shogenova, K. Suuroja","doi":"10.3176/geol.1996.2.03","DOIUrl":"https://doi.org/10.3176/geol.1996.2.03","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"162 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":"114365648","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":"MINERALOGICAL ANALYSIS APPLIED IN PROVENANCE STUDIES OF ESTONIAN NEOLITHIC POTTERY","authors":"T. Aruväli, V. Kalm, A. Kriiska","doi":"10.3176/geol.1997.1.02","DOIUrl":"https://doi.org/10.3176/geol.1997.1.02","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"193 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":"114748329","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}
I. Korchagin, T. Mikheeva, M. Orlova, M. Yakymchuk, Y. Yakymchuk
{"title":"Gravity and magnetic modelling of anomalous sources of complex configuration","authors":"I. Korchagin, T. Mikheeva, M. Orlova, M. Yakymchuk, Y. Yakymchuk","doi":"10.3176/geol.2002.1.04","DOIUrl":"https://doi.org/10.3176/geol.2002.1.04","url":null,"abstract":"","PeriodicalId":237994,"journal":{"name":"Proceedings of the Estonian Academy of Sciences. Geology","volume":"36 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":"115108032","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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