The Neugrund Marine Impact Structure (Gulf of Finland, Estonia)

  • Sten Suuroja
  • Kalle Suuroja
Part of the Impact Studies book series (IMPACTSTUD)


The Early Cambrian (approximately 535 Ma) Neugrund marine impact structure is located on the southern side of the entrance to the Gulf of Finland, immediately eastward of Osmussaar Island, Estonia. The origin of the structure was noted already in 1995–1998, but data obtained during the expeditions of 2000 and 2001 have shed new light on its morphology. The impact structure is about 20 km in diameter and spatially delimited by a ring fault between dislocated rocks and mostly intact target rocks. The structure has a central depression (crater deep or crater proper) 5.5 km in diameter, surrounded by a 50–100 m high and anomalously wide (2.5–3 km) 3-ridge shaped rim wall. The crater deep is filled with post-impact Early Cambrian and Early Ordovician siliciclastic rocks and covered with Middle and Late Ordovician calcareous rocks. The slight (some metres) uplift of limestone beds in the centre of the crater suggests that a central uplift also exists. The Ordovician erosion-resistant limestone forms a circular Central Plateau (Neugrund Bank) above the crater proper about 4.5 km in diameter. The plateau is surrounded by a 200–500 m wide and 20–70 m deep canyon (Ring Canyon). A 3–5 km wide circular depression where the crystalline target rocks are dislocated lies outside the rim wall. Sedimentary target rocks are eroded in the northern part of the structure. Outside the ring fault (outer boundary of the structure), sedimentary target rocks are dislocated within about 10 km, obviously due to the Neugrund impact. The 1–2 m thick ejecta layer consists of sandstones with abundant shock-metamorphosed quartz grains with well-developed planar deformation features (PDFs). Erratics consisting of Neugrund Breccia, derived by glacial action from the exposed parts of the impact structure, spread in an area of more than 10 000 km2.


Drill Hole Impact Crater Impact Structure Impact Centre Seismic Reflection Profile 
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  1. Abels A, Zumsprekel H, Bischoff L (2000) Basic remote sensing signatures of large, deeply eroded impact structures. Gilmour I, Koeberl C (eds) Impacts and the Early Earth. Lecture Notes in Earth Sciences 91, Springer Heidelberg, pp 309–326Google Scholar
  2. French BM (1998) Traces of Catastrophe. A handbook of Shock-Metamorphic Effects in Terrestrial Meteorite Impact Structures. LPI Contribution No 954, Lunar and Planetary Institute, Houston, 120 ppGoogle Scholar
  3. Dence MR (1973) Dimensional analysis of impact structures. Meteoritics 8: 343–344Google Scholar
  4. Deutsch A, Schärer U (1994) Dating terrestrial impact events. Meteoritics 29: 301–322CrossRefGoogle Scholar
  5. Dypvik H, Gudlaugsson ST, Attrep M Jr, Ferrell RE, Krinsley DH, Mørk A, Faleide JIGoogle Scholar
  6. Nagy J (1996) Mjølnir structure: An impact crater in the Barents Sea. Geology 24: 779–782CrossRefGoogle Scholar
  7. Gibson RL, Reimold WU (2000) Deeply exhumed impact structures: The case of the Vredefort Structure, South Africa. Gilmour I, Koeberl C (eds) Impacts and the early earth. Lecture Notes in Earth Sciences 91, Springer, Heidelberg, pp 249–277Google Scholar
  8. Grieve RAF (1987) Terrestrial impact structures. Annual Reviews of Earth and Planetary Sciences 15: 245–270CrossRefGoogle Scholar
  9. Grieve RAF, Langenhorst F, Stöffler D (1996) Shock metamorphism in nature and experiment: II. Significance in geoscience. Meteoritics and Planetary Science 31: 6–35Google Scholar
  10. Kenkmann T, Ivanov BA, Stöffler D (2000) Identification of ancient impact structures: Low-angle faults and related geological features of crater basements. In: Gilmour I, Koeberl C (eds) Impacts and the Early Earth. Lecture Notes in Earth Sciences 91, Springer, Heidelberg, pp 279–307CrossRefGoogle Scholar
  11. Koeberl C, Anderson RA (1996) Manson and company: Impact structures in the United States. In: Koeberl C, Anderson RR (eds) Manson Impact Structure, Iowa: Anatomy of an Impact Crater. Geological Society of America, Special Paper 302: 1–30Google Scholar
  12. Lilljequist R (2000) The Gallejaur structure, Northern Sweden. In: Gilmour I, Koeberl C (eds) Impacts and the Early Earth. Lecture Notes in Earth Sciences, Springer Verlag, Berlin-Heidelberg 91, pp 363–387Google Scholar
  13. Lindström M, Sturkell EFF, Törnberg R, Ormö J (1996) The marine impact crater at Lockne, central Sweden. GFF 118: 193–206CrossRefGoogle Scholar
  14. Malkov B, Kiipli T, Rennel G, Tammik P, Dulin E (1986) The regional geological-geophysical investigation of the Baltic Sea shelf area Estonian SSR at a scale of 1: 200 000. Report of Investigations (in Russian). Geological Survey of Estonian SSR, Tallinn, 199 ppGoogle Scholar
  15. Melosh HJ (1989) Impact Cratering. A Geologic Process. Oxford University Press, Oxford 245 ppGoogle Scholar
  16. Melosh HJ, Ivanov BA (1999) Impact crater collapse. Annual Reviews of Earth and Planetary Sciences 27: 385–425CrossRefGoogle Scholar
  17. O´Keefe JD, Ahrens TJ (1977) Meteorite impact ejecta: Dependence of mass and energy lost on planetary escape velosity. Science 198: 1249–1251Google Scholar
  18. O’Keefe JD, Ahrens TJ (1999) Complex craters: relationship of stratigraphy and rings to impact conditions. Journal of Geophysical Research 104 (E 11): 27091–27104CrossRefGoogle Scholar
  19. Ormö J, Lindström M (2000) When a cosmic impact strikes the sea bed. Geological Magazine 137: 67–80CrossRefGoogle Scholar
  20. Peil T (1999) Settlement history and cultural landscapes on Osmussaar. Estonia Maritima 4: 5–38Google Scholar
  21. Pike R (1985) Some morphologic systematic of complex impact structures. Meteoritics 20: 49–68CrossRefGoogle Scholar
  22. Pesonen L (1996) The impact cratering record of Fennoscandia. Earth, Moon and Planets 72: 377–393CrossRefGoogle Scholar
  23. Pesonen L, Henkel H (eds) (1992) Terrestrial impact craters and craterform structures, with a special focus on Fennoscandia. Tectonophysics 216: 1–234Google Scholar
  24. Poag CW (1997) Structural outer rim of Chesapeake Bay impact crater: Seismic and and bore hole evidence. Meteoritics and Planetary Science 31: 218–226CrossRefGoogle Scholar
  25. Puura V, Suuroja K (1992) Ordovician impact crater at Kärdla, Hiiumaa Island, Estonia. Tectonophysics 216: 143–156Google Scholar
  26. Stöffler D, Grieve RAF (1996) Classification and nomeclature of impact metamorphic rocks: a proposal to the IUGS Subcommission on the Systematics of Metamorphic Rocks [abs.]. Lunar and Planetary Science 25: 1347–1348Google Scholar
  27. Stöffler D, Langenhorst F (1994) Shock metamorphism of quartz in nature and experiment: I. Basic observation and theory. Meteoritics 29: 155–181Google Scholar
  28. Suuroja K (2001) Kärdla Meteorite Crater. Geological Survey of Estonia, Tallinn, 38 pp Suuroja K, Saadre T (1995) Gneiss-breccia erratic boulders from Northwestern Estonia asGoogle Scholar
  29. witnesses of an unknown impact structure (in Estonian). Bulletin of Geological Survey of Estonia 5/1: 26–28Google Scholar
  30. Suuroja K, Suuroja S (2000) Neugrund Structure–the newly discovered submarine early Cambrian impact crater. In: Gilmour I, Koeberl C (eds) Impacts and the Early Earth. Lecture Notes in Earth Sciences, 91, Springer Verlag, Berlin-Heidelberg, pp 389–416CrossRefGoogle Scholar
  31. Suuroja K, Koppelmaa H, Kivisilla J, Niin M (1987) The deep geological mapping of the Nõva-Haapsalu area at a scale of 1:200 000. Three maps with explanatory note (in Russian). Geological Survey of Estonian SSR, Tallinn, 220 ppGoogle Scholar
  32. Suuroja K, Kadastik E, Ploom K (1998) Geological mapping of Northwestern Estonia at a scale of 1:50 000 (in Estonian with English summary). Three maps with explanatory note (in Estonian with English summary). Geological Survey of Estonia, Tallinn, 210 ppGoogle Scholar
  33. Suuroja K, Suuroja S, Talpas A (1999) The marine geological investigations of the Neugrund structure area. Three maps with explanatory note (in Estonian). Geological Survey of Estonia, Tallinn, 180 ppGoogle Scholar
  34. Suuroja K, Suuroja S, All T, Floden (2001a) Kärdla (Hiiumaa Island, Estonia)–the buried and well-preserved Ordovician marine impact structure. Deep Sea Research, Part II 982: 101–124Google Scholar
  35. Suuroja S, All T, Plado J, Suuroja K (2001b) Geology and magnetic signatures of the Neugrund impact structure, Estonia. In: Plado J, Pesonen L (eds) Impacts in Precambrian Shields, Impact Studies vol. 2, Springer Verlag, Heidelberg, pp 277–294Google Scholar
  36. Suuroja K, Kirsimäe K, Ainsaar L, Kohv M, Mahaney WC, Suuroja S (2002) The Osmussaar Breccia in Northwestern Estonia–Evidence of a 475 Ma Earthquake or an Impact? In: Koeberl C, Martinez-Ruiz F (eds) Impact Markers in the Stratigraphic Records, Impact Studies 3, Springer Verlag, Heidelberg, pp 333–347Google Scholar
  37. Talpas A, Väling P, Kask J, Mardla A, Sakson M (1993) The geological mapping of the shelf area of the Baltic Sea at a scale of 1:200 000. Report of Investigations (in Russian). Geological Survey of Estonia, Tallinn, 152 ppGoogle Scholar
  38. Torsvik TH, Smethurst MA, Van der Voo R, Trench N, Halvorsen E (1992) Baltica. A synopsis of Vendian-Permian palaeomagnetic data and their palaeotectonic implications. Earth-Science Reviews 33: 133–152Google Scholar
  39. Tsikalas F, Gudlaugsson ST, Faleide JI (1998) The anatomy of a buried complex structure: The Mjølnir Structure, Barents Sea. Journal of Geophysical Research 103: 30469–30483Google Scholar
  40. Tucker RD, McKerrow WS (1995) Early Paleozoic chronology: a review in light of new U-Pb zircon ages from Newfoundland and Britain. Canadian Journal of Earth Sciences 32: 368–379CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2004

Authors and Affiliations

  • Sten Suuroja
    • 1
    • 2
  • Kalle Suuroja
    • 1
  1. 1.Geological Survey of EstoniaTallinnEstonia
  2. 2.Department of MiningTallinn Technical UniversityTallinnEstonia

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