Advanced Geophysical Operations and Services Inc. (AGCOS)

Results of AMT survey at Patomsky crater case study


Courtesy of Courtesy of Advanced Geophysical Operations and Services Inc. (AGCOS)

The Patomsky crater is located in east part of the Irkutsk region (Russia). This geological object has anomaly appearance and is discordant placed relative to hosting geological structure. The crater has been discovered in 1949 during routine geological survey of the territory by geologist V.V. Kolpakov. The drastic investigations of Patomsky crater by modern technology have begun since 2006. The first electroprospecting investigations by AMT method have been carried out in 2008 by «Irkutsk Electroprospecting Enterprise».

By now there is no agreement about crater origin. Two possible versions are considered: impact and endogenous, but neither of them have proper confirmation. The new attempt to shed the light on origin of this wonderful geological object has been making in august of 2010 by joint geological and geophysical expedition. The field АМТ crew includes 2 geophysicists (expert in EM methods) from Saint Petersburg Mining University.

The Patomsky crater is the ring structure of central type with piled up cone. The cone size is 160x130 m. The age of the crater talus is very young (200 -500 years) and the crater breaks metamorphic sediments of Proterozoic ages. The crater is located at the synclinal flexure wing which long axis is oriented in northwest direction. Numerous faults of northwest direction are found in the area of investigation. The spatial or genetic connections of the crater location with structural features have not been established.

The geological and geophysical model constructed on the base of previous investigations is shown. The hosting rocks for Patomsky structure are metamorphic and folded terrigenous and carbonate layers of early Proterozoic age, which have high resistivity (1 000 – 100 000 Ohm-m). Also several conductive thin layers (with less than 150 m thickness) represented by coaly shale and coaly sandstone are observed. Resistivity of this layers could as low as 1-10 Ohm-m. So hosting medium could be approximated as 2-D structure with strike -45 degree.

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