Hostname: page-component-78c5997874-v9fdk Total loading time: 0 Render date: 2024-11-19T13:08:37.146Z Has data issue: false hasContentIssue false
  • English
  • Français

40Ar–39Ar biotite and hornblende geochronology from the Oskarshamn area, SE Sweden: discerning multiple Proterozoic tectonothermal events

Published online by Cambridge University Press:  16 June 2008

PIA SÖDERLUND ,
LAURENCE M. PAGE  and
ULF SÖDERLUND
PIA SÖDERLUND*
Affiliation:
Department of Geology, GeoBiosphere Science Centre, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
LAURENCE M. PAGE
Affiliation:
Department of Geology, GeoBiosphere Science Centre, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
ULF SÖDERLUND
Affiliation:
Department of Geology, GeoBiosphere Science Centre, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
*
*Author for correspondence: e-mail: pia.soderlund@geol.lu.se
Get access Rights & Permissions [Opens in a new window]

Abstract

Twelve 40Ar–39Ar biotite and four hornblende age determinations have been carried out to constrain the cooling history of the Proterozoic bedrock near Oskarshamn, SE Sweden, an area identified as a possible site for long-term nuclear waste storage. The bedrock hosts c. 1.80 Ga granites and diorites of the Transscandinavian Igneous Belt and two 1.45–1.44 Ga granite intrusions, the Götemar and Uthammar plutons. Biotite was selected from three surface samples, representing both the older rocks and the younger granites, and from three cored boreholes at nine different depth levels. Hornblende was extracted from samples at the top and bottom of one borehole and at two sub-surface levels of another borehole. Three age groups were distinguished: ≥1.62 Ga, 1.51–1.47 Ga and 1.43–1.42 Ga. In the first group, two hornblende analyses yielded ages of 1799±4 Ma and 1773±13 Ma, which indicate initial fast cooling after emplacement of 1.80 Ga rocks of the Transscandinavian Igneous Belt. Two biotite ages of 1618±7 Ma and 1621±3 Ma are interpreted to date final cooling, through 300 °C, after the youngest suite (1.68–1.67 Ga) of the Transscandinavian Igneous Belt in south-central Sweden. Seven biotite ages, in the range 1.51–1.47 Ga, are enigmatic to interpret but largely coincide in age with the end of widespread rapakivi magmatism in Fennoscandia and the initiation of the Danopolonian event. The 1.43–1.42 Ga biotite and hornblende ages reflect cooling after thermal heating from the 1.45–1.44 Ga Götemar and Uthammar plutons. Later events thermally affected the bedrock in the Oskarshamn area as indicated by a poorly defined biotite age of 928±6 Ma and other disturbed 40Ar–39Ar ages of samples bordering a complex deformation zone.

Keywords

40Ar–39Ar geochronologyMesoproterozoictectonothermal evolutionFennoscandia
Type
Original Article
Information
Geological Magazine , Volume 145 , Issue 6 , November 2008 , pp. 790 - 799
Copyright
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Åhäll, K.-I. 2001. Åldersbestämning av svårdaterade bergarter i sydöstra Sverige. Svensk kärnbränslehantering AB, R-01–60.Google Scholar
Åhäll, K.-I., Connelly, J. N. & Brewer, T. S. 2000. Episodic rapakivi magmatism due to distal orogenesis?: Correlation of 1.69–1.50 Ga orogenic and inboard, ‘anorogenic’ events in the Baltic Shield. Geology 28, 823–6.Google Scholar
Alviola, R., Johanson, B. S., Rämö, O. T. & Vaasjoki, M. 1999. The Proterozoic Ahvenisto rapakivi granite-massive-type anorthosite complex, south-eastern Finland; petrography and U–Pb chronology. Precambrian Research 95, 89–107.CrossRefGoogle Scholar
Amelin, Y. V., Larin, A. M. & Tucker, R. D. 1997. Chronology of multiphase emplacement of the Salmi rapakivi granite–anorthosite complex, Baltic Shield: implications for magmatic evolution. Contributions to Mineralogy and Petrology 127, 343–68.Google Scholar
Andersson, U. B., Neymark, L. A. & Billström, K. 2002. Petrogenesis of Mesoproterozoic (Subjotnian) rapakivi complexes of central Sweden: Implications from U–Pb zircon ages, Nd, Sr and Pb isotopes. Transactions of the Royal Society of Edinburgh: Earth Sciences 92, 201–28.CrossRefGoogle Scholar
Andersson, U. B., Rutanen, H., Johansson, Å., Mansfeld, J. & Rimša, A. 2007. Characterization of the Paleoproterozoic Mantle beneath the Fennoscandian Shield: Geochemistry and Isotope Geology (Nd, Sr) of ~1.8 Ga Mafic Plutonic Rocks from the Transscandinavian Igneous Belt in Southeast Sweden. International Geology Review 49, 587–625.Google Scholar
Beunk, F. F. & Page, L. M. 2001. Structural evolution of the accretional continental margin of the Paleoproterozoic Svecofennian orogen in southern Sweden. Tectonophysics 339, 67–92.CrossRefGoogle Scholar
Bogdanova, S., Bingen, B., Gorbatschev, R., Kheraskova, T. N., Kozlov, V. I., Puchkov, V. N. & Volozh, Yu. A. 2008. The East European Craton (Baltica) before and during the assembly of Rodinia. Precambrian Research 160, 23–45.Google Scholar
Bogdanova, S. V., Page, L. M., Skridlaite, G. & Taran, L. N. 2001. Proterozoic tectonothermal history in the western part of the East European Craton: 40Ar/39Ar geochronological constraints. Tectonophysics 339, 39–66.Google Scholar
Brander, L. & Söderlund, U. 2008. Mesoproterozoic (1.47–1.44 Ga) orogenic magmatism in Fennoscandia; Baddeleyite U–Pb dating of a suite of massif-type anorthosite in S Sweden. International Journal of Earth Sciences, doi 10.1007/s00531-007-0281-0, 18pp.Google Scholar
Čečys, A. & Benn, K. 2007. Emplacement and deformation of the ca. 1.45 Ga Karlshamn granitoid pluton, southeastern Sweden, during ENE-WSW Danopolonian shortening. International Journal of Earth Sciences 96, 397–414.Google Scholar
Čečys, A., Bogdanova, S., Janson, C., Bibikova, E. & Kornfält, K.-A. 2002. The Stenshuvud and Tåghusa granitoids: new representatives of Mesoproterozoic magmatism in southern Sweden. GFF 124, 149–62.Google Scholar
Claesson, S. & Kresten, P. 1997. The anorogenic Noran intrusion – a Mesoproterozoic rapakivi massif in south-central Sweden. GFF 119, 115–22.CrossRefGoogle Scholar
Dalrymple, G. B. & Lanphere, M. A. 1971. 40Ar/39Ar technique of K–Ar dating: a comparison with the conventional technique. Earth and Planetary Science Letters 12, 300–8.CrossRefGoogle Scholar
Dörr, W., Zdzislaw, B., Marheine, D., Schastok, J., Valverde-Vaquero, P. & Wiszniewska, J. 2002. U–Pb and Ar–Ar geochronology of anorogenic granite magmatism of the Mazury complex, NE Poland. Precambrian Research 119, 101–20.CrossRefGoogle Scholar
Drake, H., Page, L. & Tullborg, E.-L. 2007. Oskarshamn site investigation. 40Ar/39Ar dating of fracture minerals. Svensk kärnbränslehantering AB, P-07-27.Google Scholar
Hellström, F. A., Johansson, Å. & Larson, S.-Å. 2004. Age and emplacement of late Sveconorwegian monzogabbroic dykes, SW Sweden. Precambrian Research 128, 39–55.CrossRefGoogle Scholar
Högdahl, K., Andersson, U. B. & Eklund, O. 2004. The Transscandinavian Igneous Belt (TIB) in Sweden: a review of its character and evolution. Geological Survey of Finland, Special Paper 37, 125 pp.Google Scholar
Hultgren, P., Stanfors, R., Wahlgren, C.-H., Carlsten, S. & Mattsson, H. 2004. Oskarshamn site investigation. Geological single-hole interpretation of KSH03A, KSH03B, KLX02, HAV09 and HAV10. Revised June 2006. Svensk kärnbränslehantering AB, P-04-231.Google Scholar
Mansfeld, J. 1996. Geological, geochemical and geochronological evidence for a new Palaeoproterozoic terrane in southwestern Sweden. Precambrian Research 77, 91–103.CrossRefGoogle Scholar
Mansfeld, J., Beunk, F. F. & Barling, J. 2005. 1.83–1.82 Ga formation of a juvenile volcanic arc – implications from U–Pb and Sm–Nd analyses of the Oskarshamn–Jönköping Belt, southeastern Sweden. GFF 127, 149–57.Google Scholar
Page, L. M., Beunk, F., Bogdanova, S. & Wijbrans, J. 1999. 40Ar/39Ar geochronological constraints on the tectonothermal history of the western part of the East European Craton in the southern Peri-Baltic region. Journal of Conference Abstracts 4 (1), 131.Google Scholar
Page, L., Hermansson, T., Söderlund, P. & Stephens, M. B. 2007. Forsmark site investigation. 40Ar/39Ar and (U–Th)/He geochronology Phase II. Svensk Kärnbränslehantering AB, P-06–211.Google Scholar
Persson, A. I. 1999. Absolute (U–Pb) and relative age determinations of intrusive rocks in the Ragunda rapakivi complex, central Sweden. Precambrian Research 95, 109–27.Google Scholar
Persson, P.-O. & Wikman, H. 1997. U–Pb zircon ages of two volcanic rocks from the Växjö region, Småland, south central Sweden. Geological Survey of Sweden C830, 50–6.Google Scholar
Puura, V. & Flodén, T. 1999. Rapakivi-granite-anorthosite magmatism – a way of thinning and stabilisation of the Svecofennian crust, Baltic Sea Basin. Tectonophysics 305, 75–92.Google Scholar
Rämö, O. T., Huhma, H. & Kirs, J. 1996. Radiogenic isotopes of the Estonian and Latvian rapakivi granite suites: new data from the concealed Precambrian of the East European Craton. Precambrian Research 79, 209–26.CrossRefGoogle Scholar
Renne, P. R., Swisher, C. C., Deino, A. L., Karner, D. B., Owena, T. L. & DePaolo, D. J. 1998. Intercalibration of standards, absolute ages and uncertainties in 40Ar/39Ar dating. Chemical Geology 145, 117–52.Google Scholar
Skridlaite, G., Wiszniewska, J. & Duchesne, J.-C. 2003. Ferro-potassic A-type granites and related rocks in NE Poland and S Lithuania: west of the East European Craton. Precambrian Research 124, 305–26.CrossRefGoogle Scholar
Söderlund, U., Isachsen, C., Bylund, G., Heaman, L., Patchett, P. J., Vervoort, J. D. & Andersson, U. B. 2005. U–Pb baddeleyite ages and Hf, Nd isotope chemistry constraining repeated mafic magmatism in the Fennoscandian Shield from 1.6 to 0.9 Ga. Contributions to Mineralogy and Petrology 150, 174–94.CrossRefGoogle Scholar
Söderlund, U. & Rodhe, A. 1998. Constraints on syn-intrusive ca. 1.8 Ga conglomerate deposits associated with the Småland-Värmland Belt, SE Sweden; Pb–Pb zircon evaporation dating of the Malmbäck conglomerate. GFF 120, 69–74.CrossRefGoogle Scholar
Suominen, V. 1991. The chronostratigraphy of southwestern Finland with special reference to Postjotnian and Subjotnian diabases. Geological Survey of Finland Bulletin 356, 106 pp.Google Scholar
Wahlgren, C.-H., Ahl, M., Sandahl, K.-A., Berglund, J., Petersson, J., Ekström, M. & Persson, P.-O. 2004. Oskarshamn site investigation. Bedrock mapping 2003 – Simpevarp subarea. Svensk Kärnbränslehantering AB, P-04-102.Google Scholar
Wahlgren, C.-H. Bergman, T., Ahl, M. & Ekström, M. 2006a. Oskarshamn site investigation. Modal and geochemical analyses of drill core samples 2006 and updated bedrock map of the Laxemar subarea. Classification of rock types in KLX08, KLX10, KLX11A, KLX12A, KLX18A and KLX20A. Svensk Kärnbränslehantering AB, StB P-06-279.Google Scholar
Wahlgren, C.-H., Hermanson, J., Forssberg, O., Curtis, P., Triumf, C.-A., Drake, H. & Tullborg, E.-L. 2006b. Oskarshamn site investigation. Geological description of rock domains and deformation zones in the Simpevarp and Laxemar subareas. Preliminary site description Laxemar subarea – version 1.2. Svensk Kärnbränslehantering AB, R-05-69.Google Scholar
Welin, E. & Lundqvist, T. 1984. Isotopic investigations of the Nordingrå rapakivi massif, north-central Sweden. Geologiska Föreningens i Stockholm Förhandlingar 106, 41–9.CrossRefGoogle Scholar
Wijbrans, J. R., Pringle, M. S., Koppers, A. A. P. & Scheevers, R. 1995. Argon geochronology of small samples using the Vulkaan argon laserprobe. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen 98, 185–218.Google Scholar
Wikman, H. 1993. U–Pb ages of Småland granites and a Småland volcanite from the Växjö region, southern Sweden. Geological Survey of Sweden C823, 65–72.Google Scholar
Wikman, H. & Kornfält, K.-A. 1995. Updating of a lithological model of the bedrock of the Äspö area. Svensk Kärnbränslehantering AB, PR 25-95-04.Google Scholar
Wikström, A. 1993. U–Pb dating of the Stormandebo rhyolite in the Västervik area, southeastern Sweden. Geological Survey of Sweden C823, 73–6.Google Scholar
Supplementary material: File

Soderlund Supplementary Material

Appendix.doc

Download Soderlund Supplementary Material(File)
File 746 KB