A Paleogeographic Reconstruction of Impact Craters April 19, 2008 Catherine Juranek Dr. David M. Best

Earth’s Geology 4.6 billion years old Plate tectonic movement –Arizona has moved through 65° latitude in past 500 million years [20°S to 45°N] 174 extraterrestrial impacts Photo courtesy of: Dr. Ron Blakey, NAU

South America & Africa 19 impacts Density: 1/614K mi 2 8 impacts Density: 1/861K mi 2 Photos courtesy of: The Planetary and Space Science Centre University of New Brunswick Fredericton, New Brunswick, Canada

Asia & Australia Photos courtesy of: The Planetary and Space Science Centre University of New Brunswick Fredericton, New Brunswick, Canada 27 impacts Density: 1/635K mi 2 26 impacts Density: 1/114K mi 2

North America & Europe 57 impacts Density: 1/167K mi 2 Photos courtesy of: The Planetary and Space Science Centre University of New Brunswick Fredericton, New Brunswick, Canada 37 impacts Density: 1/108K mi 2

Paleomapping Software PointTracker –Plots current impact positions in terms of paleolocations in past geologic time PlateTracker –Moves plates back in geologic time to focus PointTracker locations ARCGIS –Mapping tool

Results No correlation

Results Youngest/oldest correlation

Results 26 of 31 youngest are the smallest

Results Unprocessed data points –33 craters < 10 million years old –13 craters > 600 million years old

Results Correlation: Younger – north Older - south

Conclusions 26 of 30 youngest craters are the smallest –Ancient Earth atmospheric effect –Size of extraterrestrial bodies over time –Erosion of older smaller craters

Conclusions Correlation between latitude and age Division at 310 million years 62% older craters in southern latitudes and 85% younger craters in northern latitudes Possible explanation: shift of land masses Does not explain latitudinal differences in South America and Africa South America and Africa

Challenges No record of oceanic impacts No record of oceanic impacts Software restrictions –Posit processing limited to my only –Posits myo rounded to nearest 10 my –Posits myo rounded to nearest 20 my Graphing and mapping options

What’s in the Future? Further Analysis Comparison with terrestrial/marine boundaries Spatial analysis of impacts Using nearest neighbor statistics Determine random vs clustered patterns

Africa and South America – The FIT Photos courtesy of: The Planetary and Space Science Centre University of New Brunswick Fredericton, New Brunswick, Canada

What’s in the Future? Possible Connections Theory of antipodal focusing Astronomical implications Evidence of asteroid storms Asteroids impacts as further proof of plate tectonics

Questions ??????????