Pub Date : 2017-01-01DOI: 10.37570/bgsd-2017-65-06
T. Waight, S. Serre, Sebastian H. Næsby, T. Thomsen
The ongoing search for the oldest rock on the Danish island of Bornholm: new U-Pb zircon ages for a quartz-rich xenolith and country rock from the Svaneke Granite. by pp. Previous geochronological studies on the Danish island of Bornholm have not identified any rocks older than c. 1.46 Ga. New LA-ICP-MS U-Pb zircon ages are presented for a xenolith within, and the country rock gneiss adjacent to, the Svaneke Granite on Bornholm. The xenolith is fine-grained and quartz-rich and was likely derived from either a quartz-rich sedimentary protolith or a hydrother-mally altered felsic volcanic rock. The relatively fine-grained felsic nature of the country rock gneiss and the presence of large zoned feldspars that may represent phenocrysts suggest its protolith may have been a felsic volcanic or shallow intrusive rock. A skarn-like inclusion from a nearby locality likely represents an originally carbonate sediment and is consistent with supracrustal rocks being present at least locally. Zircon data from the xenolith define an upper intercept age of 1483 ± 12 Ma (2 σ , MSWD = 2.5) with a poorly defined lower intercept age of 474 ± 250 Ma, and a weighted average 207 Pb/ 206 Pb age of 1477.9 ± 4.6 Ma; both these ages are older than the host Svaneke Granite (weighted average 207 Pb/ 206 Pb age of 1465.0 ± 4.8 Ma). Zircons from the gneiss define an upper intercept age of 1477.7 ± 6.8 Ma when anchored at 0 Ma, and a weighted average 207 Pb/ 206 Pb age of 1475.4 ± 6.6 Ma which overlaps statistically with the Svaneke Granite age. These ages are currently the oldest ages determined for in situ rocks on Bornholm. Evidence for substantially older basement lithologies (e.g. 1.8 Ga as observed in southern Sweden) remains absent. The zircons display clear oscillatory zoning, have Th/U typical of magmatic zircons and in some cases preserve inherited cores, all of which suggest that the ages are robust and do not represent resetting due to incorporation within or intrusion by the Svaneke Granite. Inherited zircons are not common; they have ages ( c . 1.6–1.8 Ga) that are similar to those observed in other felsic basement lithologies on Bornholm. These new results suggest that prior to intrusion of the Svaneke Granite, the upper crust on Bornholm was dominated, at least locally, by lithologies similar in composition to the currently exposed felsic basement. The protoliths to the two samples investigated here must have been buried to mid-crustal depths over a relatively short time period ( c . 10 Ma) prior to intrusion of the Svaneke Granite. This suggests a dynamic tectonic environment and is consistent with evidence for broadly simultaneous magmatism and deformation in basement rocks at 1.46 Ga in southern Scandinavia and burial and metamorphism of sediments in southern Skåne.
{"title":"The ongoing search for the oldest rock on the Danish island of Bornholm: new U-Pb zircon ages for a quartz-rich xenolith and country rock from the Svaneke Granite","authors":"T. Waight, S. Serre, Sebastian H. Næsby, T. Thomsen","doi":"10.37570/bgsd-2017-65-06","DOIUrl":"https://doi.org/10.37570/bgsd-2017-65-06","url":null,"abstract":"The ongoing search for the oldest rock on the Danish island of Bornholm: new U-Pb zircon ages for a quartz-rich xenolith and country rock from the Svaneke Granite. by pp. Previous geochronological studies on the Danish island of Bornholm have not identified any rocks older than c. 1.46 Ga. New LA-ICP-MS U-Pb zircon ages are presented for a xenolith within, and the country rock gneiss adjacent to, the Svaneke Granite on Bornholm. The xenolith is fine-grained and quartz-rich and was likely derived from either a quartz-rich sedimentary protolith or a hydrother-mally altered felsic volcanic rock. The relatively fine-grained felsic nature of the country rock gneiss and the presence of large zoned feldspars that may represent phenocrysts suggest its protolith may have been a felsic volcanic or shallow intrusive rock. A skarn-like inclusion from a nearby locality likely represents an originally carbonate sediment and is consistent with supracrustal rocks being present at least locally. Zircon data from the xenolith define an upper intercept age of 1483 ± 12 Ma (2 σ , MSWD = 2.5) with a poorly defined lower intercept age of 474 ± 250 Ma, and a weighted average 207 Pb/ 206 Pb age of 1477.9 ± 4.6 Ma; both these ages are older than the host Svaneke Granite (weighted average 207 Pb/ 206 Pb age of 1465.0 ± 4.8 Ma). Zircons from the gneiss define an upper intercept age of 1477.7 ± 6.8 Ma when anchored at 0 Ma, and a weighted average 207 Pb/ 206 Pb age of 1475.4 ± 6.6 Ma which overlaps statistically with the Svaneke Granite age. These ages are currently the oldest ages determined for in situ rocks on Bornholm. Evidence for substantially older basement lithologies (e.g. 1.8 Ga as observed in southern Sweden) remains absent. The zircons display clear oscillatory zoning, have Th/U typical of magmatic zircons and in some cases preserve inherited cores, all of which suggest that the ages are robust and do not represent resetting due to incorporation within or intrusion by the Svaneke Granite. Inherited zircons are not common; they have ages ( c . 1.6–1.8 Ga) that are similar to those observed in other felsic basement lithologies on Bornholm. These new results suggest that prior to intrusion of the Svaneke Granite, the upper crust on Bornholm was dominated, at least locally, by lithologies similar in composition to the currently exposed felsic basement. The protoliths to the two samples investigated here must have been buried to mid-crustal depths over a relatively short time period ( c . 10 Ma) prior to intrusion of the Svaneke Granite. This suggests a dynamic tectonic environment and is consistent with evidence for broadly simultaneous magmatism and deformation in basement rocks at 1.46 Ga in southern Scandinavia and burial and metamorphism of sediments in southern Skåne.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"65 1","pages":"75-86"},"PeriodicalIF":1.2,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889969","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 : 2015-01-01DOI: 10.37570/bgsd-2015-63-06
Thomas Weidner, G. Geyer, J. R. Ebbestad, Volker Seckendorff von
Reinvestigation of glacial erratic boulders from Jutland, Denmark, and from northern Germany,has revealed a moderately diverse fauna with the trilobites Holmiella? sp., Epichalnipsus anartanus,Epic ...
{"title":"Glacial erratic boulders from Jutland, Denmark, feature an uppermost lower Cambrian fauna of the Lingulid Sandstone Member of Västergötland, Sweden","authors":"Thomas Weidner, G. Geyer, J. R. Ebbestad, Volker Seckendorff von","doi":"10.37570/bgsd-2015-63-06","DOIUrl":"https://doi.org/10.37570/bgsd-2015-63-06","url":null,"abstract":"Reinvestigation of glacial erratic boulders from Jutland, Denmark, and from northern Germany,has revealed a moderately diverse fauna with the trilobites Holmiella? sp., Epichalnipsus anartanus,Epic ...","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"63 1","pages":"59-86"},"PeriodicalIF":1.2,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69890411","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 : 2013-08-23DOI: 10.37570/BGSD-2013-61-02
Sebastian Pauly, J. Mutterlose, P. Alsen
{"title":"Depositional environments of Lower Cretaceous (Ryazanian– Barremian) sediments from Wollaston Forland and Kuhn Ø, North-East Greenland","authors":"Sebastian Pauly, J. Mutterlose, P. Alsen","doi":"10.37570/BGSD-2013-61-02","DOIUrl":"https://doi.org/10.37570/BGSD-2013-61-02","url":null,"abstract":"","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"61 1","pages":"19-36"},"PeriodicalIF":1.2,"publicationDate":"2013-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889851","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 : 2011-09-02DOI: 10.37570/BGSD-2011-59-04
L. Clemmensen, M. Bendixen, L. Nielsen, S. Jensen, Louise Schrøder
Flakket is a cuspate marine foreland on the north coast of Anholt in the Kattegat sea. it is composed of a number of gravel-rich beach ridges typically covered by aeolian sand and intervening swales and wetlands including a relatively large lagoon. the most recent evolution of the coastline of this marine foreland between may 2006 and september 2010 is documented in this paper. Flakket is under erosion on its northwestern side, which has retreated up to 40 m during the observation period. the shoreline of the northeastern side of the beach-ridge plain moved up to 70 m in a seaward direction during the same period.
{"title":"Coastal evolution of a cuspate foreland (Flakket, Anholt, Denmark) between 2006 and 2010.","authors":"L. Clemmensen, M. Bendixen, L. Nielsen, S. Jensen, Louise Schrøder","doi":"10.37570/BGSD-2011-59-04","DOIUrl":"https://doi.org/10.37570/BGSD-2011-59-04","url":null,"abstract":"Flakket is a cuspate marine foreland on the north coast of Anholt in the Kattegat sea. it is composed of a number of gravel-rich beach ridges typically covered by aeolian sand and intervening swales and wetlands including a relatively large lagoon. the most recent evolution of the coastline of this marine foreland between may 2006 and september 2010 is documented in this paper. Flakket is under erosion on its northwestern side, which has retreated up to 40 m during the observation period. the shoreline of the northeastern side of the beach-ridge plain moved up to 70 m in a seaward direction during the same period.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"40 1","pages":"37-44"},"PeriodicalIF":1.2,"publicationDate":"2011-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889724","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 : 2005-12-31DOI: 10.37570/bgsd-2005-52-19
F. Schmid, E. Håkansson, F. Surlyk
Our friend and colleague Walter Kegel Christensen died prematurely at the age of 60 years, at the peak of his career. This commemorative volume gathers the tributes from a wide range of his scientific friends and colleagues.
{"title":"Walter Kegel Christensen\u000025 May 1942 – 18 October 2002","authors":"F. Schmid, E. Håkansson, F. Surlyk","doi":"10.37570/bgsd-2005-52-19","DOIUrl":"https://doi.org/10.37570/bgsd-2005-52-19","url":null,"abstract":"Our friend and colleague Walter Kegel Christensen died prematurely at the age of 60 years, at the peak of his career. This commemorative volume gathers the tributes from a wide range of his scientific friends and colleagues.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2005-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889902","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 : 2003-12-31DOI: 10.37570/bgsd-2003-50-16
Finn Surlyk
Docent, universitetslektor lie. scient. Walter Kegel Christensen ved Geologisk Museum, K0benhavns Universitet, afgik ved d0den 18. oktober 2002 efter kart tids sygdom.
{"title":"Walter Kegel Christensen \u000025. maj 1942 - 18. oktober 2002","authors":"Finn Surlyk","doi":"10.37570/bgsd-2003-50-16","DOIUrl":"https://doi.org/10.37570/bgsd-2003-50-16","url":null,"abstract":"Docent, universitetslektor lie. scient. Walter Kegel Christensen ved Geologisk Museum, K0benhavns Universitet, afgik ved d0den 18. oktober 2002 efter kart tids sygdom.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2003-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889828","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 : 2003-04-30DOI: 10.37570/bgsd-2003-50-18
Ø. Hammer
A database recording published fossil occurrences in the Ordovician of Baltoscandia has been constructed and made available on the Internet (http:/ /asaphus.uio.no). The database presently contains 10340 entries, each recording the first and last appearances of a single species at a single locality, together with other stratigraphical, taxonomic and geographical information. The data are taken from 141 publications, most of them from 1980 or later but also included are some older key references. The database will be continuously maintained, revised and expanded. In addition to serving as a reference for researchers working on the Ordovician of Baltoscandia, the database has been used to produce biodiversity curves for different fossil groups. These curves reflect the global increase in biodiversity through the Ordovician, but also show interesting local fluctuations.
{"title":"A database of fossil occurrences in the Ordovician of Baltoscandia","authors":"Ø. Hammer","doi":"10.37570/bgsd-2003-50-18","DOIUrl":"https://doi.org/10.37570/bgsd-2003-50-18","url":null,"abstract":"A database recording published fossil occurrences in the Ordovician of Baltoscandia has been constructed and made available on the Internet (http:/ /asaphus.uio.no). The database presently contains 10340 entries, each recording the first and last appearances of a single species at a single locality, together with other stratigraphical, taxonomic and geographical information. The data are taken from 141 publications, most of them from 1980 or later but also included are some older key references. The database will be continuously maintained, revised and expanded. In addition to serving as a reference for researchers working on the Ordovician of Baltoscandia, the database has been used to produce biodiversity curves for different fossil groups. These curves reflect the global increase in biodiversity through the Ordovician, but also show interesting local fluctuations.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2003-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889888","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 : 2002-12-31DOI: 10.37570/bgsd-2001-48-14
F. Surlyk, E. Håkansson
{"title":"The Oscar Volume","authors":"F. Surlyk, E. Håkansson","doi":"10.37570/bgsd-2001-48-14","DOIUrl":"https://doi.org/10.37570/bgsd-2001-48-14","url":null,"abstract":"","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2002-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889503","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 : 2002-06-26DOI: 10.37570/bgsd-2003-49-15
W. Christensen
Book review
书评
{"title":"The Upper Cretaceous rocks and fossil faunas of Britain","authors":"W. Christensen","doi":"10.37570/bgsd-2003-49-15","DOIUrl":"https://doi.org/10.37570/bgsd-2003-49-15","url":null,"abstract":"Book review","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"61 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2002-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889643","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 : 2002-06-26DOI: 10.37570/bgsd-2003-49-16
O. V. Vejbæk
Book review
书评
{"title":"Tectonic atlas of Northwest Germany and the German North Sea sector","authors":"O. V. Vejbæk","doi":"10.37570/bgsd-2003-49-16","DOIUrl":"https://doi.org/10.37570/bgsd-2003-49-16","url":null,"abstract":"Book review","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2002-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69889696","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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