Ancient Meteor Hits Near Santa Fe, New Mexico

In my wanderings on-line, I recently stumbled upon a website created by retired petroleum geologist, Thornton (Tim) McElvain.  http://www.impactstructure.net/

Tim writes, "With this website I will present evidence to support my hypothesis that there was an enormous Mid-Tertiary Impact Event in the Southern Rocky Mountains and Colorado Plateau." The Mid-Tertiary was 25-40 million years ago.

Tim's website makes for some interesting reading. "After I retired from the oil business I decided to map the geology surrounding our home near Pecos,  NM. The geology and the structure in that area completely confused me until serendipitously my wife and I visited Rochechouart, France...."

He continues, "While we were there I found a museum dedicated to the Rochechouart Impact Structure, which also had a map of walks illustrating various elements of the structure. During our stay as I visited the museum and walked the countryside a light went off in my head, I all of a sudden understood what was confusing me at home. Further investigation convinced me that our home lay within the central uplift of a morphological complex impact crater approximately 9 miles in diameter."

"I am proposing several new impact structures along with known impact structures, and evidence of shock metamorphism (see Wikipedia for an explanation) in areas that I cannot associate with a specific impact structure within the Southern Rocky Mountains and Colorado Plateau."

"My hypothesis speculates that all the impact structures, proposed impact structures, and evidence of shock metamorphism is coeval and is the result of the impact of an asteroid or comet composed of loosely packed bolides ranging in size from dust to very large bolides capable of creating an impact crater fifty or more kilometers in diameter."

One of these objects reportedly impacted about 10 kilometers east of the Historic Santa Fe Plaza.  In a peer reviewed article in Earth and Planetary Science Letters in 2008, Fackelman et al report their evidence for the impact near Santa Fe, NM. The impact site borders NM route 475 from approximately the location of Ten Thousand Waves, a wonderful bath and massage business, as far up NM 475 as Hyde Park. The authors, including Tim, reported on the discovery of shatter cones along NM 475 as well as microscopic changes to quartz crystals that are only created by large impacts.  

In the article summary the authors declare: "Paleoproterozoic crystalline rocks exposed over an area > 5 km², located ˜ 8 km northeast of Santa Fe, New Mexico, USA, give robust evidence of a previously unrecognized terrestrial impact structure. Herein, we provisionally name this the “Santa Fe impact structure”.

As a retired scientist, I am always looking for interesting things to do. This looked interesting so I decided to look for the shatter cones reported by Tim McElvain. My problem was I had never seen a shatter cone but I had a copy of the paper and Tim's website. I also knew they were spotted on some road cuts on the way up to New Mexico's Hyde Park on NM 475.  So, I began my search for shatter cones along NM 475 on March 22, 2011.

Above. I got lucky and found one of the shatter cones located by the authors of the research articles. Notice the direction of the cone; up and toward the peak where the stone is broken off.

See blue arrow in picture below.

 The shattered rock comes in two halves but the half that would have covered the surface of the shatter cone shown above is long gone. Probably removed by the crew that cleared the route for the road.  

Earth and Planetary Science Letters Vol 270:290-299; 2008
http://www.astrobio.net/exclusive/3579/the-impact-that-shattered-santa-fe

Paleoproterozoic - 1.6 to 2.5 billion years ago