Gow - Hypervelocity Impact Crater

Alternate Names Gow Lake (Thomas and Innes, 1977).
Local Language
Coordinates 56° 27' 24" N; 104° 28' 60" W
Notes
  1. NE Saskatchewan, ~90 km W of Deep Bay, Reindeer Lake.
  2. NE Saskatchewan, ~90 km W of Deep Bay, Reindeer Lake.
Country Canada
Region Saskatchewan
Date Confirmed 1977
Notes
  1. Confirmed by planar deformation structures in quartz within breccias, as well as impact melts desrcibed by their "felted matrices" (Thomas and Innes, 1977).
  2. Confirmed by planar deformation structures in quartz within breccias, as well as impact melts desrcibed by their "felted matrices" (Thomas and Innes, 1977).
Buried? No
Drilled? No
Target Type Crystalline
Notes
  1. Precambrian, granite, quartzofeldspathic gneiss.
  2. Precambrian, granite, quartzofeldspathic gneiss.
Sub-Type Gneiss, Granite
Apparent Crater Diameter (km) 4 km
Age (Ma) 196.8 ± 9.9
Notes :
  1. Combining 40Ar/39Ar step heating with in situ UV laser, impact melt rock samples were dated to be 196.8 ± 9.9 Ma (Pickersgill et al., 2019). Additional age constraints: (Bottomley et al.,1990) performed an 40Ar/39Ar study on the melt rocks and suggested an age <250 Ma. On the basis of the level of erosion and a comparison with the Deep Bay crater, (Thomas and Innes, 1977) estimate a minimum age of 100 Ma.

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

Advanced Data Fields

Notes

Erosion
5
  1. (Osinski et al., 2012) report an almost complete sequence of crater-fill rocks on central island. Extensive glacial erosion has left the crater floor exposed and has removed the rim rocks and most of the crater-fill products (Ogilvie et al., 1984).
  2. (Osinski et al., 2012) report an almost complete sequence of crater-fill rocks on central island. Extensive glacial erosion has left the crater floor exposed and has removed the rim rocks and most of the crater-fill products (Ogilvie et al., 1984).
Final Rim Diameter
Unknown
Apparent Rim Diameter
4 km
  1. (Thomas and Innes, 1977).
  2. (Thomas and Innes, 1977).
Rim Reliability Index
2
  1. Transects the local structural grain and takes the form of a conspicuous circular lake with a central island. A central uplift is reported but the dimensions are not clear (Thomas and Innes, 1977). The central island of the lake is 1x2 km (Osinski et al., 2012) and it may be the remnant of the central uplift (Thomas and Innes, 1977).
  2. Transects the local structural grain and takes the form of a conspicuous circular lake with a central island. A central uplift is reported but the dimensions are not clear (Thomas and Innes, 1977). The central island of the lake is 1x2 km (Osinski et al., 2012) and it may be the remnant of the central uplift (Thomas and Innes, 1977).
Crater Morphology
Transitional
Central Uplift Diameter
km
Central Uplift Height
Unknown
Uplift Reliability Index
Structural Uplift
Unknown
Thickness of Seds
Target Age
Precambrian
Marine
No
Impactor Type
Other Shock Metamorphism
Ballen quartz
  1. Ballen quartz (Fig 9.3b) (Grieve, 2006).
  2. Ballen quartz (Fig 9.3b) (Grieve, 2006).
Shatter Cones
No
  1. No shatter cones reported.
  2. No shatter cones reported.
Planar Fractures
No
Planar Deformation Features
Yes
  1. PDF in quartz grains (Thomas and Innes, 1971) (Thomas et al., 1977). PDFs in quartz and feldspar (Fig. 9.3c) (Grieve, 2006).
  2. PDF in quartz grains (Thomas and Innes, 1971) (Thomas et al., 1977). PDFs in quartz and feldspar (Fig. 9.3c) (Grieve, 2006).
Diaplectic Glass
No
Coesite
No
Stisovite
No
Crater Fill
LB, MB, M
  1. Pink and green impact melt rocks (clast-rich and clast-poor), along with melt-bearing breccias (as lenses) and lithic breccias in uplift (Osinski et al., 2012) (Pickersgill et al., 2015). Most breccias are clastic, but some have glass with shocked quartz (PDFs present) (Thomas and Innes, 1977). Shocked plagioclase as well, possibly (Pickersgill et al., 2015) (Pickersgill et al., 2017).
  2. Pink and green impact melt rocks (clast-rich and clast-poor), along with melt-bearing breccias (as lenses) and lithic breccias in uplift (Osinski et al., 2012) (Pickersgill et al., 2015). Most breccias are clastic, but some have glass with shocked quartz (PDFs present) (Thomas and Innes, 1977). Shocked plagioclase as well, possibly (Pickersgill et al., 2015) (Pickersgill et al., 2017).
Proximal Ejecta
Distal Ejecta
Dykes
Volume of Melt
Depth of Melting

References

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M D Thomas, M J S Innes (1977) The Gow Lake impact structure, northern Saskatchewan, Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre 14(8), p. 1788-1795, National Research Council of Canada, Ottawa, ON, url, doi:http://dx.doi.org/10.1139/e77-152

A E Pickersgill, D F Mark, M R Lee, G R Osinski (2019) A refined age for the Gow Lake impact structure, 50th Lunar and Planetary Science Conference, p. Abstract 2375, Lunar and Planetary Science Conference, Houston, TX