Fig. 1. Geological map of the Skjoldungen region, South-East Greenland, showing locations of samples (blue circles) selected for zircon U-Pb geochronology and zircon Hf isotope analysis. We report new zircon U-Pb and Hf isotopic data from the Skjoldungen region between c. 62°30 ́ and 63°40 ́N in SouthEast Greenland. The work was carried out under the SouthEast Greenland Mineral Endowment Task (SEGMENT); a joint project between the Geological Survey of Denmark and Greenland (GEUS) and the Ministry of Mineral Resources (MMR) in Greenland to assess the mineral endowment and update the geological knowledge of the region using modern petrological, geochemical and geochronological tools. This paper presents new zircon U-Pb and Hf isotopic data from a range of different Archaean rocks in the Skjoldungen region, which greatly improve the understanding of the history of crustal growth.
{"title":"New zircon U-Pb and Hf isotopic constraints on the crustal evolution of the Skjoldungen region, South-East Greenland","authors":"T. Kokfelt, T. Næraa, K. Thrane, L. Bagas","doi":"10.34194/geusb.v35.4927","DOIUrl":"https://doi.org/10.34194/geusb.v35.4927","url":null,"abstract":"Fig. 1. Geological map of the Skjoldungen region, South-East Greenland, showing locations of samples (blue circles) selected for zircon U-Pb geochronology and zircon Hf isotope analysis. We report new zircon U-Pb and Hf isotopic data from the Skjoldungen region between c. 62°30 ́ and 63°40 ́N in SouthEast Greenland. The work was carried out under the SouthEast Greenland Mineral Endowment Task (SEGMENT); a joint project between the Geological Survey of Denmark and Greenland (GEUS) and the Ministry of Mineral Resources (MMR) in Greenland to assess the mineral endowment and update the geological knowledge of the region using modern petrological, geochemical and geochronological tools. This paper presents new zircon U-Pb and Hf isotopic data from a range of different Archaean rocks in the Skjoldungen region, which greatly improve the understanding of the history of crustal growth.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"68 1","pages":"55-58"},"PeriodicalIF":0.0,"publicationDate":"2016-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84109033","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}
Thick successions of marine Middle Jurassic deposits rich in ammonites occur in the Jameson Land Basin in central East Greenland. The fauna of the so-called Cranocephalites beds of this basin, comprising the Borealis–Pompeckji Standard Zones, was until now largely represented by a single collection. This was made by T.M. Harris during a 1927 excursion up the valley of Ugleelv to Katedralen, the type area of Cranocephalites pompeckji, which is the oldest named species of this genus. Revisits to this area in 1994 and 1996 by JHC resulted in a large bed-by-bed collection of Cranocephalites. The number of faunal horizons that could be distinguished grew from the nine previously recognised to thirty-four today. The zonal stratigraphy of the Cranocephalites beds encompasses the Borealis, Indistinctus and Pompeckji Standard Zones. The Pompeckji Zone is subdivided into four new subzones, reflecting four successive basic morphologies of Cranocephalites that should be recognisable more widely and are thus useful for subzonal correlations. The detailed zonation that serves as the secondary standard zonation for the Boreal Province in the Middle Jurassic is thus highly improved. The biostratigraphic resolution obtained here is near the achievable limits. It allows a high-resolution study of the evolution of the ammonites which on this timescale appears to be continuous. Three new species are described: Cranocephalites carolae sp. nov., Cranocephalites intermissus sp. nov. and Cranocephalites episcopalis sp. nov. An additional new species, Cranocephalites tvaerdalensis sp. nov., is described in the appendix by P. Alsen based on collections from Tvaerdal on Geographical Society O, North-East Greenland. This species is also recorded in Jameson Land.
{"title":"The ammonites of the Middle Jurassic Cranocephalites beds of East Greenland","authors":"J. Callomon, P. Alsen, F. Surlyk","doi":"10.34194/geusb.v34.4488","DOIUrl":"https://doi.org/10.34194/geusb.v34.4488","url":null,"abstract":"Thick successions of marine Middle Jurassic deposits rich in ammonites occur in the Jameson Land Basin in central East Greenland. The fauna of the so-called Cranocephalites beds of this basin, comprising the Borealis–Pompeckji Standard Zones, was until now largely represented by a single collection. This was made by T.M. Harris during a 1927 excursion up the valley of Ugleelv to Katedralen, the type area of Cranocephalites pompeckji, which is the oldest named species of this genus. Revisits to this area in 1994 and 1996 by JHC resulted in a large bed-by-bed collection of Cranocephalites. The number of faunal horizons that could be distinguished grew from the nine previously recognised to thirty-four today. The zonal stratigraphy of the Cranocephalites beds encompasses the Borealis, Indistinctus and Pompeckji Standard Zones. The Pompeckji Zone is subdivided into four new subzones, reflecting four successive basic morphologies of Cranocephalites that should be recognisable more widely and are thus useful for subzonal correlations. The detailed zonation that serves as the secondary standard zonation for the Boreal Province in the Middle Jurassic is thus highly improved. The biostratigraphic resolution obtained here is near the achievable limits. It allows a high-resolution study of the evolution of the ammonites which on this timescale appears to be continuous. Three new species are described: Cranocephalites carolae sp. nov., Cranocephalites intermissus sp. nov. and Cranocephalites episcopalis sp. nov. An additional new species, Cranocephalites tvaerdalensis sp. nov., is described in the appendix by P. Alsen based on collections from Tvaerdal on Geographical Society O, North-East Greenland. This species is also recorded in Jameson Land.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"56 1","pages":"1-86"},"PeriodicalIF":0.0,"publicationDate":"2015-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89849958","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}
A 558 m long, complete section of the Lower Palaeozoic succession preserved onshore southern Bornholm has been compiled from fi ve fully cored scientifi c wells, carried out between 2005 and 2012. Th e scientifi c programme included coring and geophysical logging of the fi ve scientifi c wells that yielded a total of c. 750 m of partially overlapping cores as well as re-logging of water wells and acquisition of shallow seismic data. Th e last well drilled, the Sommerodde-1, cored the youngest preserved Silurian strata on Bornholm including strata not exposed in outcrops. Th e well penetrated 168.1 m of Silurian shales, 42.7 m of Upper Ordovician shales and 27.9 m of Alum Shale before it terminated at a depth of 250.3 m in the Lower Cambrian Norretorp Member of the Læså Formation. Th e Sommerodde-1 well documents that the Lower Silurian Cyrtograptus shale is at least 91.7 m thick and that the Rastrites shale is 76.4 m thick. Th e complete Lower Cambrian succession has previously been covered by the 316.0 m deep Borggård-1 well that terminated in basement rocks (Nielsen et al. 2006).
在2005年至2012年期间，研究人员从5口完整的科学井中收集了一条558米长的下古生代连续剖面，该剖面保存在Bornholm南部陆上。科学方案包括5口科学井的取心和地球物理测井，这些井共获得了750米部分重叠的岩心，以及水井的重新测井和浅层地震数据的获取。最后一口井，Sommerodde-1，钻取了Bornholm上保存最年轻的志留纪地层，包括未露头的地层。井深分别为志留系168.1 m、上奥陶统42.7 m和明质页岩27.9 m，井深250.3 m止于下寒武统l′s段北段。Sommerodde-1井记录下志留统cytorgraptus页岩厚度至少为91.7 m, Rastrites页岩厚度为76.4 m。之前，316.0 m深的borgg rd-1井已经覆盖了完整的下寒武统序列，该井的末端是基底岩石(Nielsen et al. 2006)。
{"title":"The Lower Palaeozoic now fully cored and logged on Bornholm, Denmark","authors":"N. Schovsbo, A. T. Nielsen, K. Klitten","doi":"10.34194/GEUSB.V33.4477","DOIUrl":"https://doi.org/10.34194/GEUSB.V33.4477","url":null,"abstract":"A 558 m long, complete section of the Lower Palaeozoic succession preserved onshore southern Bornholm has been compiled from fi ve fully cored scientifi c wells, carried out between 2005 and 2012. Th e scientifi c programme included coring and geophysical logging of the fi ve scientifi c wells that yielded a total of c. 750 m of partially overlapping cores as well as re-logging of water wells and acquisition of shallow seismic data. Th e last well drilled, the Sommerodde-1, cored the youngest preserved Silurian strata on Bornholm including strata not exposed in outcrops. Th e well penetrated 168.1 m of Silurian shales, 42.7 m of Upper Ordovician shales and 27.9 m of Alum Shale before it terminated at a depth of 250.3 m in the Lower Cambrian Norretorp Member of the Læså Formation. Th e Sommerodde-1 well documents that the Lower Silurian Cyrtograptus shale is at least 91.7 m thick and that the Rastrites shale is 76.4 m thick. Th e complete Lower Cambrian succession has previously been covered by the 316.0 m deep Borggård-1 well that terminated in basement rocks (Nielsen et al. 2006).","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"43 1","pages":"9-12"},"PeriodicalIF":0.0,"publicationDate":"2015-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79004190","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}
Th e Geological Survey of Denmark and Greenland (GEUS) operates a network of seismic stations in Denmark primarily to detect earthquakes. But from time to time other sources than earthquakes generate seismic signals that are detected at the stations. Here we show that both meteoroids and thunder have generated seismic signals with high signal-to-noise ratios at some of GEUS’ seismic stations (Fig. 1). Th e purpose of the seismic stations is to provide data for the earthquake database of the Kingdom of Denmark, hosted and maintained by GEUS. In order to avoid that the earthquake database is contaminated by other events not related to tectonism, these events are given special markers when possible.
{"title":"Acoustic events on a small seismological network – shock waves from thunder and fireballs","authors":"P. Voss, T. Dahl-Jensen, T. Larsen","doi":"10.34194/geusb.v33.4481","DOIUrl":"https://doi.org/10.34194/geusb.v33.4481","url":null,"abstract":"Th e Geological Survey of Denmark and Greenland (GEUS) operates a network of seismic stations in Denmark primarily to detect earthquakes. But from time to time other sources than earthquakes generate seismic signals that are detected at the stations. Here we show that both meteoroids and thunder have generated seismic signals with high signal-to-noise ratios at some of GEUS’ seismic stations (Fig. 1). Th e purpose of the seismic stations is to provide data for the earthquake database of the Kingdom of Denmark, hosted and maintained by GEUS. In order to avoid that the earthquake database is contaminated by other events not related to tectonism, these events are given special markers when possible.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"12 1","pages":"25-28"},"PeriodicalIF":0.0,"publicationDate":"2015-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81982072","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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