Physics – Geophysics
Scientific paper
Jan 2012
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012jgre..11701007c&link_type=abstract
Journal of Geophysical Research, Volume 117, Issue E1, CiteID E01007
Physics
Geophysics
Exploration Geophysics: Magnetic And Electrical Methods (5109), Geomagnetism And Paleomagnetism: Magnetic Anomalies: Modeling And Interpretation, Geomagnetism And Paleomagnetism: Remagnetization, Atmospheric Processes: Lightning, Planetary Sciences: Solid Surface Planets: Impact Phenomena, Cratering (6022, 8136)
Scientific paper
The Vredefort impact crater in South Africa is one of the oldest and largest craters on Earth, making it a unique analog for planetary basins. Intense and randomly oriented remanent magnetization observed in surface samples at Vredefort has been attributed to impact-generated magnetic fields. This possibility has major implications for extraterrestrial paleomagnetism since impact-generated fields have been proposed as a key alternative to the dynamo hypothesis for magnetization on the Moon and asteroids. Furthermore, the presence of single-domain magnetite found along shock-generated planar deformation features in Vredefort granites has been widely attributed to the 2.02 Ga impact event. An alternative hypothesis is that the unusual magnetization and/or rock magnetic properties of Vredefort rocks are the products of recent lightning strikes. Lightning and impact-generated fields can be distinguished by measuring samples collected from below the present surface. Here we present a paleomagnetic and rock magnetic study of samples from two 10 m deep vertical boreholes. We show that the magnetization at depth is consistent with a thermoremanent magnetization acquired in the local geomagnetic field following the impact, while random, intense magnetization and some of the unusual rock magnetic properties observed in surface rocks are superficial phenomena produced by lightning. Because Vredefort is the only terrestrial crater that has been proposed to contain records of impact-generated fields, this removes a key piece of evidence in support of the hypothesis that paleomagnetism of the Moon and other extraterrestrial bodies is the product of impacts rather than past core dynamos.
Carporzen Laurent
Gilder Stuart A.
Hart Rodger J.
Pommier Anne
Weiss Benjamin P.
No associations
LandOfFree
Lightning remagnetization of the Vredefort impact crater: No evidence for impact-generated magnetic fields does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Lightning remagnetization of the Vredefort impact crater: No evidence for impact-generated magnetic fields, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lightning remagnetization of the Vredefort impact crater: No evidence for impact-generated magnetic fields will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-912491