Montagnais - Hypervelocity Impact Crater

Alternate Names N/A
Coordinates 42° 52' 60" N; 64° 13' 0" W
Notes
  1. 200 km SE of Halifax, near the outer edge of the Scotian Shelf, in 113 m of water.
Country Canada
Region Nova Scotia
Date Confirmed 1987
Notes
  1. Confirmed by planar lamallae in quartz and feldspar, maskelynite and lechatelierite, and anomalous iridium concentration (Jansa and Pe-Piper, 1987).
Buried? Yes
Notes
  1. The crater is well preserved, covered by 540 m of Tertiary and Quaternary marine sediments (Jansa and Pe-Piper, 1987) (Jansa et al., 1989).
Drilled? Yes
Notes
  1. A single oil exploration well (Montagnais I-94) penetrated the central uplift (Jansa and Pe-Piper, 1987; Jansa et al., 1989) down to a depth of 1,646 m.
Target Type Sedimentary
Notes
  1. Cambro-Ordovician metasedimentary rocks (Meguma group) are found in the central uplift and are believed to be the basement rocks of this area (Jansa and Pe-Piper, 1987) (Jansa et al., 1989).
Sub-Type Metasedimentary
Apparent Crater Diameter (km) 45 km
Age (Ma) 51.1 ± 1.6
Notes :
  1. 51.1 ± 1.6 Ma determined by 40Ar/39Ar of impact melt rock (recalculated by Schmieder and Kring, 2020); the pre-recalulated age was 50.5 ± 1.6 Ma (Bottomley and York, 1988). Additional age constraints: K-Ar whole rock analyses of the impact melt rock gives ages of 49.9 ± 2.1 Ma and 55.8 ± 0.9 Ma (Jansa and Pe-Piper, 1987).

Method :
  1. 40Ar/39Ar
Impactor Type Unknown

Advanced Data Fields

Notes

Local Language
N/A
Erosion
2
  1. The complex erosion around the crater periphery may be the result of the back flow of sea water as tsunami-type waves were generated as a consequence of water - column disturbances by shock waves (Jansa and Pe-Piper, 1987) (Jansa et al., 1989).
Final Rim Diameter
Unknown
Apparent Rim Diameter
45 km
  1. Annular trough of down-dropped basement extends out from the central uplift to a diameter of 45 km (Jansa and Pe-Piper, 1987) (Jansa et al., 1989) (Pilkington et al., 1995).
Rim Reliability Index
1
  1. Seismic profiles reveal a circular structure, at least 45 km in diameter, with a central uplift 11.5 km wide. This uplift is surrounded by one or more concentric depressions (Jansa and Pe-Piper, 1987) (Jansa et al., 1989).
Crater Morphology
Complex
Central Uplift Diameter
11.5 km
Central Uplift Height
Unknown
Uplift Reliability Index
4
Structural Uplift
Unknown
Thickness of Seds
Unknown
Target Age
Palaeozoic
Marine
No
Impactor Type
Unknown
Other Shock Metamorphism
No
Shatter Cones
No
  1. Buried impact structure.
Planar Fractures
No
Planar Deformation Features
Yes
  1. Well cuttings from the basement show PDF in quartz and feldspar near the top of the sequence (Jansa and Pe-Piper, 1987).
Diaplectic Glass
Yes
  1. The upper parts of both melt zones is a mixture of variably melted clasts of graywacke, which show partial melting and the presence of diaplectic glass..." (Jansa and Pe-Piper, 1987).
Coesite
No
Stisovite
No
Crater Fill
LB, MB, M
  1. Lithic breccias, melt-bearing breccias and melt rocks are reported by (Jansa et al., 1989). Two zones of melt rocks (71 and 35 m thick).
Proximal Ejecta
Unknown
Distal Ejecta
Unknown
Dykes
Unknown
Volume of Melt
Unknown
Depth of Melting
Unknown

References

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L Jansa, B Robertson, G Pe-Piper (1986) Montagnais: The first discovery of a submarine impact structure, LPI Contribution 600, p. G-4, Lunar and Planetary Institute, Houston, TX, url

R Bishop (1987) Montagnais Impact Structure, Journal of the Royal Astronomical Society of Canada 81, p. 10

S C Solomon, L Meinke (1988) Longevity of impact-induced faults as preferred sites for later tectonic activity: A further terrestrial test, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference 19, Part 3, p. 1105-1106, Lunar and Planetary Science Conference, Houston, TX, url

Richard J Bottomley, D York (1988) Refining the impact time scale, Eos, Transactions, American Geophysical Union 69(44), p. 1290, American Geophysical Union, Washington, DC, url

O R Friedenreich (1988) Montagnais submarine meteorite impact structure, offshore Nova Scotia, Canada, AAPG Bulletin 72(2), p. 187, American Association of Petroleum Geologists, Tulsa, OK, url

Richard J Bottomley, D York (1988) Age measurement of the submarine Montagnais impact crater, Geophysical Research Letters 15(12), p. 1409-1412, American Geophysical Union, Washington, DC, url, doi:http://dx.doi.org/10.1029/GL015i012p01409

B P Glass (1988) Montagnais impact crater: Possible source of the North American tektite strewn field, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference 19, Part 1, p. 391-392, Lunar and Planetary Science Conference, Houston, TX, url

O Stecher, H H Ngo, D A Papanastassiou, G J Wasserburg, L F Jansa (1989) Rb-Sr and Sm-Nd signatures from the Montagnais and Popigai impact craters, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference 20, Part 3, p. 1048-1049, Lunar and Planetary Science Conference, Houston, TX, url

A Edwards (1989) Geophysical investigation of a potential meteorite impact site, offshore Nova Scotia, Canada, SEG Abstracts 59, Vol. 1, p. 535-537, Society of Exploration Geophysicists, International Meeting and Exposition, Tulsa, OK, url

L F Jansa, G Pe-Piper, P B Robertson, O R Friedenreich (1989) Montagnais; a submarine impact structure on the Scotian Shelf, Eastern Canada, Geological Society of America Bulletin 101(4), p. 450-463, Geological Society of America (GSA), Boulder, CO, url, doi:http://dx.doi.org/10.1130/0016-7606(1989)101<0450:MASISO>2.3.CO;2

L F Jansa, M-P Aubry, F M Gradstein (1990) Comets and extinctions; cause and effect?, Special Paper - Geological Society of America 247, p. 223-232, Geological Society of America (GSA), Boulder, CO, url, doi:http://dx.doi.org/10.1130/SPE247-p223

M-P Aubry, F M Gradstein, L F Jansa (1990) The late early Eocene Montagnais bolide: No impact on biotic diversity, Micropaleontology 36(2), p. 164-172, url

L F Jansa (1993) Cometary impacts into ocean: Their recognition and the threshold constraint for biological extinctions, Palaeogeography, Palaeoclimatology, Palaeoecology 104(1-4), p. 271-286, doi:10.1016/0031-0182(93)90137-8

M Pilkington, L F Jansa, R A F Grieve (1994) Geophysical studies of the Montagnais impact crater, Abstracts of Papers Submitted to the Lunar and Planetary Science Conference 25, Part 3, p. 1085-1086, Lunar and Planetary Science Conference, Houston, TX, url

M Pilkington, L F Jansa, R A F Grieve (1995) Geophysical studies of the Montagnais impact crater, Canada, Meteoritics 30(4), p. 446-450

C W Poag (1997) Breccia by the bowlful; the clastic fill of submarine impact craters, Abstracts with Programs - Geological Society of America 29(6), p. 79, Geological Society of America (GSA), Boulder, CO, url

C W Poag, J B Plescia, P C Molzer (2002) Ancient impact structures on modern continental shelves: The Chesapeake Bay, Montagnais, and Toms Canyon craters, Atlantic margin of North America, Deep-Sea Research Part II: Topical Studies in Oceanography 49(6), p. 1081-1102, doi:10.1016/S0967-0645(01)00144-8

H Dypvik, L F Jansa (2003) Sedimentary signatures and processes during marine bolide impacts: A review, Sedimentary Geology 161(3-4), p. 309-337, url, doi:10.1016/S0037-0738(03)00135-0

M E Deptuck, D C Campbell (2012) Widespread erosion and mass failure from the ~51 Ma Montagnais marine bolide impact off southwestern Nova Scotia, Canada, Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre 49(12), p. 1567-1594, National Research Council of Canada, Ottawa, ON, url, doi:http://dx.doi.org/10.1139/e2012-075

Enrico Flamini, A Coletta, M L Battagliere, M Virelli (2019) Montagnais, Canada, Encyclopedic Atlas of Terrestrial Impact Craters, p. 565-566, Springer, Cham, url, doi:https://doi.org/10.1007/978-3-030-05451-9_157