RASC Regular Meeting
June 8, 2015
Steen River Impact Structure

Impact Crater in Mars Credit: NASA/JPL-Caltech/Univ. of Arizona

Impact Crater on Mars
Credit: NASA/JPL-Caltech/Univ. of Arizona

RASC Regular Meeting
TELUS World of Science
Note: Location Change! This meeting will occur in the IMAX Theatre.

FREE and open to the public.

7:00 PM Pre-meeting mix and mingle.
7:30 PM Guest Speaker

Dr. Erin Walton
MacEwan University
Steen River Impact Structure

Impact cratering is now recognized as a widespread geologic process that has modified all planetary objects with a solid surface. Meteorite impact structures, the holes made when an asteroid or comet collides with a larger solid object at or near cosmic velocity, are one of the most common geological landforms on all the rocky terrestrial planets (except Earth and to a lesser extent Venus), asteroids, dwarf planets, and many of the rocky moons and icy moons of Saturn and Jupiter. In this talk Dr. Erin Walton will give a general overview of the impact cratering process using the Steen River Impact Structure (SRIS) as an example.

20150608 ALH84001

ALH84001 Martian meteorite
Credit: Open University

The SRIS is a 25-km diameter buried complex crater formed when a km-size asteroid travel hit NW Alberta approximately 95 million years ago. The SRIS is one of the largest known impact structures in the Western Canada Sedimentary Basin and is a producer and host of oil and gas reservoirs. Despite the importance of this well-preserved impact crater, few research publications exist and those that do focussed on characterizing unique shock metamorphic effects such planar deformation features in quartz. These studies, undertaken in the 1960s and early 70’s helped to show that the SRIS formed by meteor impact and not volcanism.  Despite the documentation of diagnostic shock effects in minerals uncertainty as to the origin of the SRIS structure by volcanic or meteoritic origin remains, primarily within the industrial sector. A portion of this uncertainty lies in the inability of previous studies to isolate high-pressure, high-temperature minerals such as coesite and stishovite at the crater. This may also reflect the lack of recognition of impact cratering as a ubiquitous geologic process outside the planetary science community.  Several novel high-pressure mineral transformations including SiO2 polymorphs will be described, as well as unusual melt-bearing breccias within the crater fill deposits.

Presenter’s Biography
Dr. Erin Walton is an assistant professor of earth and planetary sciences in the Department of Physical Sciences at MacEwan University and an adjunct professor in the University of Alberta’s Department of Earth & Atmospheric Sciences. She received her Bachelor of Science degree with honours in Geology from the University of New Brunswick and finished a PhD at the same institution in planetary sciences with Dr. John Spray. Her PhD research focused on shock metamorphism of Martian meteorites. In 2005 she moved to the University of Alberta to pursue postdoctoral work under the supervision of Dr. Chris Herd. Erin’s current research focuses on the high-pressure high-temperature mineralogy of quench-crystallized melts in meteorites and in terrestrial impact structures using advanced analytical techniques such as transmission electron microscopy and Raman spectroscopy.