Charity Shoal Crater, an Exhumed Middle Ordovician Impact Crater

Charity Shoal Crater, an Exhumed Middle Ordovician Impact Crater

Holcombe, T. L., S. Youngblut, and N. Slowey, 2013,
Geological structure of Charity Shoal crater, Lake
Ontario, revealed by multi beam bathymetry. Geo-Marine
Letters. col. 33, no. 4, pp 245-252
http://link.springer.com/article/10.1007%2Fs00367-013-0322-6
http://adsabs.harvard.edu/abs/2013GML....33..245H

They argue that the Charity Shoal Crater in Lake
Ontario formed as the result of an extraterrestrial
impact event in a shallow marine environment during
the Middle Ordovician. After the impact, it was
eventually buried by post-impact marine
sedimentation, which covered it with fossiliferous
marine carbonate strata. Much later, they argue,
it was exhumed by Pleistocene glacial erosion.

Other publications are:

Holcombe, T. L., J. S. Warren, D. F. Reid, W. T.
Virden, and D. L. Divins, 2001, Small Rimmed Depression
in Lake Ontario: An Impact Crater? Journal of Great
Lakes Research. vol. 27, no. 4, pp. 510-517
PDF file at http://www.glerl.noaa.gov/pubs/fulltext/2001/20010012.pdf
abstract at https://www.sciencedirect.com/science/journal/03801330/27/4

Phillip, S. A., 2013, High-resolution lake-based
magnetic mapping and modelling of basement structures,
with examples from Küçükçekmece Lagoon, Turkey and
Charity Shoal, Lake Ontario. unpublished MS thesis,
School of Geography and Earth Sciences, McMaster
University, Hamilton, Ontario. 113 pp.
https://macsphere.mcmaster.ca/handle/11375/13532

Bathymetric map of Charity Crater area.

Great Lakes Data Rescue Project - Lake Ontario Bathymetry
https://www.ngdc.noaa.gov/mgg/greatlakes/lakeontario_cdrom/html/area12.htm
https://www.ngdc.noaa.gov/mgg/greatlakes/lakeontario_cdrom/images/a12_lg.jpg

Yours,

Paul H.

Meteoritic trigger for Global Mass Wasting During the Middle Ordovician Disputed

The association of widespread mass wasting along 
Middle Ordovician continental margins with a period
of high meteorite influx is disputed in a recent paper
in Gondwana Research. The paper is:

Meinhold, G., A. Arslan, O. Lehnert, and G. M. Stampfli,
2011, Global mass wasting during the Middle Ordovician: 
Meteoritic trigger or plate-tectonic environment?
Gondwana Research. vol. 19, no. 2, pp. 535-541.
http://dx.doi.org/10.1016/j.gr.2010.07.001
http://www.casp.cam.ac.uk/publications/publication-20100603
http://www.casp.cam.ac.uk/people/guido-meinhold

Yours,

Paul H.