Pub Date : 2022-03-23DOI: 10.37570/bgsd-2022-70-03
T. Waight, Mikael Stokholm, B. Heredia, T. Thomsen
A granitic sample from the Danish island of Christiansø in the Ertholmene island group north of Bornholm is described petrographically and geochemically, and dated using U-Pb in zircon and titanite. Zircon systematics in the sample are complicated by abundant Pb loss and a large population of zircons interpreted as being inherited. Removal of highly disturbed zircons, imprecise analyses, and assumed inherited zircons yield an upper intercept date of 1500 ± 18 Ma (MSWD = 13, n = 58). Removal of zircons with high common Pb from this population yields an identical result of 1500 ± 22 Ma (MSWD = 8, n = 34). Zircons that are ≤3% discordant give a weighted average 206Pb/238U age of 1458 ± 12 Ma (MSWD = 3.0, n = 18), and a weighted average 207Pb/206Pb age of 1495 ± 14 Ma (MSWD = 4.7, n = 19). Titanites from the sample yield a lower intercept age of 1448 ± 15 Ma (MSWD = 6.8, n = 45). The sample contains a significant number of inherited grains indicative of ages around 1.7–1.8 Ga. The relatively large MSWDs for these age determinations indicate geological complexity, likely reflecting Pb loss, and the possible presence of inherited zircons which suffered major Pb loss during incorporation in the granitic magma. The zircon and titanite dates agree reasonably well with previous age determinations on felsic lithologies from the Bornholm mainland, as well as from the Blekinge Province of southern Sweden. Petrographically and geochemically, the Christiansø granite is indistinguishable from, and can be correlated with, the A-type granites and gneisses which occur on Bornholm. The high abundance of disturbed and inherited zircons (c. 1.7–1.8 Ga) may indicate that the granite was intruded into and assimilated a nearby region of unexposed Transscandinavian Igneous Belt rocks. The somewhat altered nature of the rock, and overall disturbance of U-Pb zircon systematics, suggest alteration associated with fluid-flow along nearby faults defining the northern margin of the Sorgenfrei–Tornquist Zone.
{"title":"U-Pb zircon and titanite age of the Christiansø granite, Ertholmene, Denmark, and correlation with other Bornholm granitoids","authors":"T. Waight, Mikael Stokholm, B. Heredia, T. Thomsen","doi":"10.37570/bgsd-2022-70-03","DOIUrl":"https://doi.org/10.37570/bgsd-2022-70-03","url":null,"abstract":"A granitic sample from the Danish island of Christiansø in the Ertholmene island group north of Bornholm is described petrographically and geochemically, and dated using U-Pb in zircon and titanite. Zircon systematics in the sample are complicated by abundant Pb loss and a large population of zircons interpreted as being inherited. Removal of highly disturbed zircons, imprecise analyses, and assumed inherited zircons yield an upper intercept date of 1500 ± 18 Ma (MSWD = 13, n = 58). Removal of zircons with high common Pb from this population yields an identical result of 1500 ± 22 Ma (MSWD = 8, n = 34). Zircons that are ≤3% discordant give a weighted average 206Pb/238U age of 1458 ± 12 Ma (MSWD = 3.0, n = 18), and a weighted average 207Pb/206Pb age of 1495 ± 14 Ma (MSWD = 4.7, n = 19). Titanites from the sample yield a lower intercept age of 1448 ± 15 Ma (MSWD = 6.8, n = 45). The sample contains a significant number of inherited grains indicative of ages around 1.7–1.8 Ga. The relatively large MSWDs for these age determinations indicate geological complexity, likely reflecting Pb loss, and the possible presence of inherited zircons which suffered major Pb loss during incorporation in the granitic magma. The zircon and titanite dates agree reasonably well with previous age determinations on felsic lithologies from the Bornholm mainland, as well as from the Blekinge Province of southern Sweden. Petrographically and geochemically, the Christiansø granite is indistinguishable from, and can be correlated with, the A-type granites and gneisses which occur on Bornholm. The high abundance of disturbed and inherited zircons (c. 1.7–1.8 Ga) may indicate that the granite was intruded into and assimilated a nearby region of unexposed Transscandinavian Igneous Belt rocks. The somewhat altered nature of the rock, and overall disturbance of U-Pb zircon systematics, suggest alteration associated with fluid-flow along nearby faults defining the northern margin of the Sorgenfrei–Tornquist Zone.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49535799","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 : 2022-03-03DOI: 10.37570/bgsd-2022-70-02
Iban Goñi, G. Cuny
Nine shark teeth were collected at Arnager in the south-western part of the island of Bornholm (Baltic Sea, Denmark). They all come from the basal conglomerate of the Coniacian (Upper Cretaceous) Arnager Limestone Formation and belong to the genus Ptychodus Agassiz, 1834. Three different species are dentified: P. altior, P. latissimus and P. mammillaris, which were hitherto unknown in Denmark.
{"title":"New record of the genus Ptychodus Agassiz, 1834, (Chondrichthyes, Elasmobranchii) from the Upper Cretaceous of Bornholm (Denmark)","authors":"Iban Goñi, G. Cuny","doi":"10.37570/bgsd-2022-70-02","DOIUrl":"https://doi.org/10.37570/bgsd-2022-70-02","url":null,"abstract":"Nine shark teeth were collected at Arnager in the south-western part of the island of Bornholm (Baltic Sea, Denmark). They all come from the basal conglomerate of the Coniacian (Upper Cretaceous) Arnager Limestone Formation and belong to the genus Ptychodus Agassiz, 1834. Three different species are dentified: P. altior, P. latissimus and P. mammillaris, which were hitherto unknown in Denmark.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47732447","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 : 2022-01-30DOI: 10.37570/bgsd-2022-70-01
Thomas Holm, L. L. Delsett, P. Alsen
Vertebral centra are some of the most common fossils from ichthyosaurs and thus valuable for understanding these marine reptiles. This study sets out to provide further information on the dimensional ratios of centra and how these might be used to obtain more information about an assemblage of Late Jurassic disarticulated centra found at Kingofjeldet on Kuhn Ø in North-East Greenland in 2017. The centra are used to test whether vertebral ratios (H:W and H:L) can be used to assign disarticulated and possibly weathered centra to a region in the vertebral column. In order to evaluate this, the ratios of the centra from Greenland were compared with those of five articulated and well-known ophthalmosaurid specimens, as well as classical traits based on morphology. Assigning the correct position in the vertebral column from ratios is, however, not straightforward. Firstly, comparing different ichthyosaur taxa gives different possible positions for the disarticulated centra. Secondly, centra from different vertebral regions commonly display similar ratios. Thirdly, ratios are sensitive to alteration by taphonomic processes. The ratios of the centra hints towards an ichthyosaur with a more regionalised vertebral column being present in the Late Jurassic sea of North-East Greenland. Further studies are needed to improve our understanding of the significance of the degree of regionalisation of the vertebral column among ichthyosaurs.
{"title":"Vertebral size ratios and the ichthyosaurian vertebral column – a case study based on Late Jurassic fossils from North-East Greenland","authors":"Thomas Holm, L. L. Delsett, P. Alsen","doi":"10.37570/bgsd-2022-70-01","DOIUrl":"https://doi.org/10.37570/bgsd-2022-70-01","url":null,"abstract":"Vertebral centra are some of the most common fossils from ichthyosaurs and thus valuable for understanding these marine reptiles. This study sets out to provide further information on the dimensional ratios of centra and how these might be used to obtain more information about an assemblage of Late Jurassic disarticulated centra found at Kingofjeldet on Kuhn Ø in North-East Greenland in 2017. The centra are used to test whether vertebral ratios (H:W and H:L) can be used to assign disarticulated and possibly weathered centra to a region in the vertebral column. In order to evaluate this, the ratios of the centra from Greenland were compared with those of five articulated and well-known ophthalmosaurid specimens, as well as classical traits based on morphology. Assigning the correct position in the vertebral column from ratios is, however, not straightforward. Firstly, comparing different ichthyosaur taxa gives different possible positions for the disarticulated centra. Secondly, centra from different vertebral regions commonly display similar ratios. Thirdly, ratios are sensitive to alteration by taphonomic processes. The ratios of the centra hints towards an ichthyosaur with a more regionalised vertebral column being present in the Late Jurassic sea of North-East Greenland. Further studies are needed to improve our understanding of the significance of the degree of regionalisation of the vertebral column among ichthyosaurs.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2022-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44015988","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 : 2021-12-18DOI: 10.37570/bgsd-2021-69-09
Kai Ingemann Schnetler, Mogens Stentoft Nielsen
The predominantly Cretaceous gastropod genus Vanikoropsis Meek, 1876 is represented in the Paleocene of Denmark and West Greenland by four species, of which three are established herein as new, viz. Vanikoropsis mortenseni n. sp., Vanikoropsis (s.l.) jakobseni n. sp. and Vanikoropsis (s.l.) bashforthi n. sp. The Danish species was found in a boulder of Kerteminde Marl (Selandian, middle Paleocene) from Gundstrup, while the species from West Greenland were found in the localities Sonja Lens and Qaarsutjægerdal on the Nuussuaq peninsula (late Danian, early Paleocene). The Danish species extends the stratigraphic range of the genus into the middle Paleocene and supports the affinities of the Kerteminde Marl fauna to the Paleocene fauna of West Greenland.
{"title":"On the genus Vanikoropsis Meek, 1876 (Gastropoda, Caenogastropoda) from the Paleocene of Denmark and West Greenland with descriptions of three new species","authors":"Kai Ingemann Schnetler, Mogens Stentoft Nielsen","doi":"10.37570/bgsd-2021-69-09","DOIUrl":"https://doi.org/10.37570/bgsd-2021-69-09","url":null,"abstract":"The predominantly Cretaceous gastropod genus Vanikoropsis Meek, 1876 is represented in the Paleocene of Denmark and West Greenland by four species, of which three are established herein as new, viz. Vanikoropsis mortenseni n. sp., Vanikoropsis (s.l.) jakobseni n. sp. and Vanikoropsis (s.l.) bashforthi n. sp. The Danish species was found in a boulder of Kerteminde Marl (Selandian, middle Paleocene) from Gundstrup, while the species from West Greenland were found in the localities Sonja Lens and Qaarsutjægerdal on the Nuussuaq peninsula (late Danian, early Paleocene). The Danish species extends the stratigraphic range of the genus into the middle\u0000Paleocene and supports the affinities of the Kerteminde Marl fauna to the Paleocene fauna of West Greenland.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44143172","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 : 2021-12-18DOI: 10.37570/bgsd-2021-69-10
A. Rosenkrantz, F. Surlyk, K. Anderskouv, P. Frykman, L. Stemmerik, N. Thibault
A 460 m long profile of the Cretaceous–Paleogene (K–T) boundary strata at Stevns Klint was measured by the late Professor A. Rosenkrantz probably in 1944. The measured profile was inherited by Finn Surlyk around 1974 together with other original boundary data. This material was dug up in a long-forgotten drawer in connection with detailed field work by the co-authors on the boundary succession in the late spring and summer of 2021. The profile illustrates the stratigraphy, geometry and palaeotopography of the boundary strata in unprecedented detail. The part of the cliff illustrated in the profile is today partly covered by beach ridges composed of flint rubble but is situated below the finest section of the lower Danian bryozoan mounds exposed at Stevns Klint. This coastal section is situated immediately adjacent to a large limestone quarry and was planned to be quarried away around 1937, but was saved by A. Rosenkrantz who demonstrated its great scientific and educational value to the authorities.
{"title":"The K–T boundary strata north of Korsnæb, Stevns Klint, Denmark – evolution and geometry revealed in a long, horizontal profile","authors":"A. Rosenkrantz, F. Surlyk, K. Anderskouv, P. Frykman, L. Stemmerik, N. Thibault","doi":"10.37570/bgsd-2021-69-10","DOIUrl":"https://doi.org/10.37570/bgsd-2021-69-10","url":null,"abstract":"A 460 m long profile of the Cretaceous–Paleogene (K–T) boundary strata at Stevns Klint was measured by the late Professor A. Rosenkrantz probably in 1944. The measured profile was inherited by Finn Surlyk around 1974 together with other original boundary data. This material was dug up in a long-forgotten drawer in connection\u0000with detailed field work by the co-authors on the boundary succession in the late spring and summer of 2021. The profile illustrates the stratigraphy, geometry and palaeotopography of the boundary strata in unprecedented detail. The part of the cliff illustrated in the profile is today partly covered by beach ridges composed of flint rubble but is situated below the finest section of the lower Danian bryozoan mounds exposed at Stevns Klint. This coastal section is situated immediately adjacent to a large limestone quarry and was planned to be quarried away around 1937, but was saved by A. Rosenkrantz who demonstrated its great scientific and educational value to the authorities.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42946834","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 : 2021-10-07DOI: 10.37570/bgsd-2021-69-08
A. T. Nielsen, L. Andersen
The Furongian (upper Cambrian) trilobite-agnostoid fauna from the Alum Shale Formation of Bornholm, Denmark, is reviewed and revised. The study is based on the museum material stored at the Natural History Museum of Denmark, including the material originally monographed by C. Poulsen (1923) [Bornholms Olenuslag og deres fauna. Danmarks Geologiske Undersøgelse II. Række, Vol. 40, 83 pp]. A total of 8502 specimens, mostly disarticulated sclerites, have been registered. The taxonomy of all species is updated and the best preserved specimens are illustrated. A total of 39 olenid and 5 agnostoid taxa (incl. the Miaolingian Agnostus pisiformis) are recorded including one new species, Ctenopyge magna n. sp. Two specimens of Ctenopyge, treated in open nomenclature as Ctenopyge sp. 1 and sp. 2, may also rep-resent new species. 14 taxa have not been previously reported from Bornholm, viz. Ctenopyge ahlbergi, Ctenopyge tumidoides, Eurycare brevicauda, Leptoplastus abnormis, Leptoplastus crassicornis, Olenus transversus, Parabolina lobata praecurrens, Peltura acu-tidens, Peltura minor, Peltura westergaardi, Protopeltura planicauda, Protopeltura praecursor, Pseudagnostus leptoplastorum? and Sphaerophthalmus drytonensis. Ctenopyge pecten and Ctenopyge affinis are also new to Bornholm as the material formerly described under these names represent Ctenopyge tenuis and C. magna n. sp., respectively. Lotagnostus americanus, Ctenopyge fletcheri, Sphaerophthalmus alatus and Triangulopyge humilis were described under different names by C. Poulsen (1923). Peltura westergaardi and Ctenopyge tenuis are elevated from subspecies to species rank. A redescription of Leptoplastus bornholmensis is presented; the species is transferred to Eurycare. The identification of isolated skeletal parts of L. abnormis and Leptoplastus ovatus and Sphaerophthalmus flagellifer and S. drytonensis are remarked on. The presence of three agnostoid and 14 trilobite zones is confirmed by fossils and all six Furongian superzones are developed on Bornholm. At least the Leptoplastus paucisegmentatus and Leptoplastus raphidophorus zones seem to be absent. Other undocumented zones may be unfossiliferous, not exposed or truly absent. Three different trilobite assemblages (potential subzones) are discerned in the Peltura acu-tidens–Ctenopyge tumida Zone; Ctenopyge tumidoides and Sphaerophthalmus angustus range into the basal part of this zone. All exposures of the Furongian Alum Shale Formation along the Læså and Øleå streams on southern Bornholm are briefly described including GPS coordinates.
对丹麦Bornholm Alum Shale组的芙蓉阶（上寒武纪）三叶虫agnostoid动物群进行了评述和订正。这项研究基于丹麦自然历史博物馆保存的博物馆材料，包括C.Poulsen（1923）最初专著的材料[Bornholms Olenuslag og deres africas.Danmarks Geologiske Undersøgelse II.Række，第40卷，83页]。共登记了8502个标本，其中大部分是关节缺失的巩膜炎。更新了所有物种的分类学，并举例说明了保存最完好的标本。共记录了39个olenid和5个agnostoid分类群（包括苗岭无尾类），其中包括一个新种，大型Ctenopyge n.sp.。Ctenoproge的两个标本，在开放命名法中被处理为Ctenopig sp.1和sp.2，也可能代表新物种。Bornholm以前没有报道过14个分类群，即Ctenopyge ahlbergi、Ctenopig tumidoides、Eurycare brevicauda、Leptoplactus abnormalis、Leptoplastus crassicornis、Olenus transversus、Parabolina lobata praecurrens、Peltura acu tidens、Peltur minor、Peltura-westergardi、Protopetura planicauda、Protopeltra praecursor、Pseudagnostus leptoplastorum？和drytonensis Sphaerophthamus。Ctenopyge pecten和Ctenoproge affinis对Bornholm来说也是新的，因为以前以这些名称描述的材料分别代表了Ctenopig tenuis和C.magna n.sp。C.Poulsen（1923）以不同的名称描述了美洲Lotanostus americanus、fletcheri Ctenopyge、有翼鞘翅目鞘翅目和humilis Triangulopyge。Peltura westergaardi和Ctenopyge tenuis从亚种提升到物种等级。对bornholmensis钩虫进行了重新描述；该物种被转移到Eurycare。本文评述了L.abnoris和Leptoplactus ovatus、Sphaerophthamus鞭毛虫和S.drytonensis的骨骼分离部位的鉴定，化石证实了三个类银带和14个三叶虫带的存在，6个芙蓉超带均在Bornholm上发育。至少少节钩端虫和广场钩端虫区似乎不存在。其他未记录的区域可能没有化石，没有暴露或真正不存在。在Peltura acu tidens-Ctenopyge tumida带中发现了三种不同的三叶虫组合（潜在的亚带）；锥尾蝶和狭口蝶分布在该区域的基底部分。包括GPS坐标在内，简要描述了沿Bornholm南部Læså和Öleå河的芙蓉安明矾页岩组的所有暴露。
{"title":"Furongian (upper Cambrian) trilobites and agnostoids from the Alum Shale Formation of Bornholm, Denmark: revised taxonomy and biostratigraphy","authors":"A. T. Nielsen, L. Andersen","doi":"10.37570/bgsd-2021-69-08","DOIUrl":"https://doi.org/10.37570/bgsd-2021-69-08","url":null,"abstract":"The Furongian (upper Cambrian) trilobite-agnostoid fauna from the Alum Shale Formation of Bornholm, Denmark, is reviewed and revised. The study is based on the museum material stored at the Natural History Museum of Denmark, including the material originally monographed by C. Poulsen (1923) [Bornholms Olenuslag og deres fauna. Danmarks Geologiske Undersøgelse II. Række, Vol. 40, 83 pp]. A total of 8502 specimens, mostly disarticulated sclerites, have been registered. The taxonomy of all species is updated and the best preserved specimens are illustrated. A total of 39 olenid and 5 agnostoid taxa (incl. the Miaolingian Agnostus pisiformis) are recorded including one new species, Ctenopyge magna n. sp. Two specimens of Ctenopyge, treated in open nomenclature as Ctenopyge sp. 1 and sp. 2, may also rep-resent new species. 14 taxa have not been previously reported from Bornholm, viz. Ctenopyge ahlbergi, Ctenopyge tumidoides, Eurycare brevicauda, Leptoplastus abnormis, Leptoplastus crassicornis, Olenus transversus, Parabolina lobata praecurrens, Peltura acu-tidens, Peltura minor, Peltura westergaardi, Protopeltura planicauda, Protopeltura praecursor, Pseudagnostus leptoplastorum? and Sphaerophthalmus drytonensis. Ctenopyge pecten and Ctenopyge affinis are also new to Bornholm as the material formerly described under these names represent Ctenopyge tenuis and C. magna n. sp., respectively. Lotagnostus americanus, Ctenopyge fletcheri, Sphaerophthalmus alatus and Triangulopyge humilis were described under different names by C. Poulsen (1923). Peltura westergaardi and Ctenopyge tenuis are elevated from subspecies to species rank. A redescription of Leptoplastus bornholmensis is presented; the species is transferred to Eurycare. The identification of isolated skeletal parts of L. abnormis and Leptoplastus ovatus and Sphaerophthalmus flagellifer and S. drytonensis are remarked on. \u0000The presence of three agnostoid and 14 trilobite zones is confirmed by fossils and all six Furongian superzones are developed on Bornholm. At least the Leptoplastus paucisegmentatus and Leptoplastus raphidophorus zones seem to be absent. Other undocumented zones may be unfossiliferous, not exposed or truly absent. Three different trilobite assemblages (potential subzones) are discerned in the Peltura acu-tidens–Ctenopyge tumida Zone; Ctenopyge tumidoides and Sphaerophthalmus angustus range into the basal part of this zone. All exposures of the Furongian Alum Shale Formation along the Læså and Øleå streams on southern Bornholm are briefly described including GPS coordinates.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46424849","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 : 2021-09-29DOI: 10.37570/bgsd-2021-69-07
J. Hvid, F. V. van Buchem, F. Andreasen, E. Sheldon, I. Fabricius
The Faxe limestone quarry in eastern Denmark exposes Danian (Lower Paleocene) cool-water carbonate deposits. They constitute remnants of an apparent build-up that covers about 12 km2 today. The Danian deposits at Faxe are conspicuous due to their pronounced thickness of coral limestone relative to the regional carbonate system. In the Faxe quarry, scleractinian corals are uniquely exposed in up to 30 m high mounds. The rapid accumulation of scleractinians combined with induration of the mounds may locally have protected the limestone from Quaternary glacial erosion and created a Danian thickness anomaly at Faxe. The position of Faxe above a local fault-bounded basement high and the extent of coral limestone has been better defined by new mapping. A mapped lithostratigraphic surface in the quarry reveals the large-scale organisation of nested bryozoan mounds on three elongated ridges striking NW–SE. The main scleractinian coral mounds are located above this horizon. Data for reservoir characterisation, mainly of the bryozoan mounds, were collected as photographs of the outcrop, petrophysical and petrographical data from cored boreholes, and as ground-penetrating radar sections. Old boreholes and measured sections were used to reconstruct the build-up, and new nannofossil data allow a discussion of stratigraphy and accumulation rate. The petrophysical data show that common mound-building bryozoan packstone has higher permeability and lower capillary entry pressure than chalk, whereas less commonly occurring grain-dominated packstone and grainstone deposits from local higher-energy sites of the mound complex were found to have reduced amounts of coccolith mud, significantly higher permeability and a higher degree of lithification. Based on biostratigraphic age constraints, correlation of flint – limestone couplets and recog-nised hierarchical patterns, we develop a cyclostratigraphy for the middle Danian and suggest that cyclicity in lithology and petrophysical characteristics of bryozoan limestone are controlled by precession and eccentricity of the orbit of the Earth.
{"title":"Stratigraphy and petrophysical characteristics of Lower Paleocene cool-water carbonates, Faxe quarry, Denmark","authors":"J. Hvid, F. V. van Buchem, F. Andreasen, E. Sheldon, I. Fabricius","doi":"10.37570/bgsd-2021-69-07","DOIUrl":"https://doi.org/10.37570/bgsd-2021-69-07","url":null,"abstract":"The Faxe limestone quarry in eastern Denmark exposes Danian (Lower Paleocene) cool-water carbonate deposits. They constitute remnants of an apparent build-up that covers about 12 km2 today. The Danian deposits at Faxe are conspicuous due to their pronounced thickness of coral limestone relative to the regional carbonate system. In the Faxe quarry, scleractinian corals are uniquely exposed in up to 30 m high mounds. The rapid accumulation of scleractinians combined with induration of the mounds may locally have protected the limestone from Quaternary glacial erosion and created a Danian thickness anomaly at Faxe. The position of Faxe above a local fault-bounded basement high and the extent of coral limestone has been better defined by new mapping. A mapped lithostratigraphic surface in the quarry reveals the large-scale organisation of nested bryozoan mounds on three elongated ridges striking NW–SE. The main scleractinian coral mounds are located above this horizon. Data for reservoir characterisation, mainly of the bryozoan mounds, were collected as photographs of the outcrop, petrophysical and petrographical data from cored boreholes, and as ground-penetrating radar sections. Old boreholes and measured sections were used to reconstruct the build-up, and new nannofossil data allow a discussion of stratigraphy and accumulation rate. The petrophysical data show that common mound-building bryozoan packstone has higher permeability and lower capillary entry pressure than chalk, whereas less commonly occurring grain-dominated packstone and grainstone deposits from local higher-energy sites of the mound complex were found to have reduced amounts of coccolith mud, significantly higher permeability and a higher degree of lithification. Based on biostratigraphic age constraints, correlation of flint – limestone couplets and recog-nised hierarchical patterns, we develop a cyclostratigraphy for the middle Danian and suggest that cyclicity in lithology and petrophysical characteristics of bryozoan limestone are controlled by precession and eccentricity of the orbit of the Earth.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49189837","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 : 2021-06-25DOI: 10.37570/bgsd-2021-69-06
F. Surlyk, E. Håkansson, P. Agger
The eminent palaeontologist and Greenland explorer Claus Heinberg was born in 1945 and died in 2021 after prolonged illness. His scientific production was focused on two remarkably different subjects: the bivalve fauna of the Cretaceous–Palaeogene (K–T) boundary beds and the Mesozoic geology and stratigraphy of eastern North Greenland. He was employed at Roskilde University during most of his career until he retired in 2012. He was part of a cross disciplinary collaborative environment, comprising biologists, geographers, geologists, sociologists, civil engineers and architects. He was a highly engaged social debater of a wide spectrum of societal subjects throughout his life. He was a fine person, a good colleague and friend.
{"title":"Claus Heinberg (1945–2021) – Trace fossils, Greenland expeditions and bivalves of the K–T boundary strata","authors":"F. Surlyk, E. Håkansson, P. Agger","doi":"10.37570/bgsd-2021-69-06","DOIUrl":"https://doi.org/10.37570/bgsd-2021-69-06","url":null,"abstract":"The eminent palaeontologist and Greenland explorer Claus Heinberg was born in 1945 and died in 2021 after prolonged illness. His scientific production was focused on two remarkably different subjects: the bivalve fauna of the Cretaceous–Palaeogene (K–T) boundary beds and the Mesozoic geology and stratigraphy of eastern North Greenland. He was employed at Roskilde University during most of his career until he retired in 2012. He was part of a cross disciplinary collaborative environment, comprising biologists, geographers, geologists, sociologists, civil engineers and architects. He was a highly engaged social debater of a wide spectrum of societal subjects throughout his life. He was a fine person, a good colleague and friend.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43334582","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 : 2021-06-21DOI: 10.37570/bgsd-2021-69-05
J. Milán, Mateus Octávio, M. Mau, A. Rudra, H. Sanei, L. Clemmensen
A large, well-preserved vertebrate coprolite was found in a lacustrine sediment in the Malmros Klint Formation of the Late Triassic Fleming Fjord Group in the Jameson Land Basin, central East Greenland. The size and internal and external morphology of the coprolite is consistent with that of crocodilian coprolites and one end of the coprolite exhibits evidence of post-egestion trampling. As the associated vertebrate fauna of the Fleming Fjord Group contains abundant remains of pseudosuchian phytosaurs, the coprolite is interpreted as being from a large phytosaur.
{"title":"A possible phytosaurian (Archosauria, Pseudosuchia) coprolite from the Late Trias-sic Fleming Fjord Group of Jameson Land, central East Greenland","authors":"J. Milán, Mateus Octávio, M. Mau, A. Rudra, H. Sanei, L. Clemmensen","doi":"10.37570/bgsd-2021-69-05","DOIUrl":"https://doi.org/10.37570/bgsd-2021-69-05","url":null,"abstract":"A large, well-preserved vertebrate coprolite was found in a lacustrine sediment in the Malmros Klint Formation of the Late Triassic Fleming Fjord Group in the Jameson Land Basin, central East Greenland. The size and internal and external morphology of the coprolite is consistent with that of crocodilian coprolites and one end of the coprolite exhibits evidence of post-egestion trampling. As the associated vertebrate fauna of the Fleming Fjord Group contains abundant remains of pseudosuchian phytosaurs, the coprolite is interpreted as being from a large phytosaur.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45682595","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 : 2021-05-31DOI: 10.37570/BGSD-2021-69-03
Tom J. Giltaij, J. Milán, J. Jagt, A. Schulp
Two mosasaur tooth crowns collected from the Maastrichtian chalk sequences of Stevns Klint and Møns Klint are here assigned to Prognathodon, a mosasaur genus hitherto unknown from Denmark. Together with previous records of the mosasaurs Plioplatecarpus, Mosasaurus and Carinodens, these new finds of Prognathodon document the coexistence of four mosasaurid genera in the Danish chalk and underscore similarities to coeval assemblages from the Maastrichtian type area in the Netherlands and Belgium.
{"title":"Prognathodon (Squamata, Mosasauridae) from the Maastrichtian chalk of Denmark","authors":"Tom J. Giltaij, J. Milán, J. Jagt, A. Schulp","doi":"10.37570/BGSD-2021-69-03","DOIUrl":"https://doi.org/10.37570/BGSD-2021-69-03","url":null,"abstract":"Two mosasaur tooth crowns collected from the Maastrichtian chalk sequences of Stevns Klint and Møns Klint are here assigned to Prognathodon, a mosasaur genus hitherto unknown from Denmark. Together with previous records of the mosasaurs Plioplatecarpus, Mosasaurus and Carinodens, these new finds of Prognathodon document the coexistence of four mosasaurid genera in the Danish chalk and underscore similarities to coeval assemblages from the Maastrichtian type area in the Netherlands and Belgium.","PeriodicalId":55310,"journal":{"name":"Bulletin of the Geological Society of Denmark","volume":"69 1","pages":"53-58"},"PeriodicalIF":1.2,"publicationDate":"2021-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42679066","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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