Ames crater

File:Ames crater LC08 CU 015012 20211031 20211113 02.jpg

Ames Crater is {{convert|10|mi|km}} in diameter and the age is estimated to be 470 ± 30 million years (Ordovician). The crater is not exposed at the surface.{{cite Earth Impact DB |name=Ames |accessdate=2017-10-14}}

It may be one of several Middle Ordovician meteors that fell roughly simultaneously 469 million years ago, part of a proposed Ordovician meteor event, including the Decorah crater in Iowa, the Slate Islands crater in Lake Superior, and the Rock Elm crater in Wisconsin.{{cite news|last=Vastag|first=Brian|title=Crater found in Iowa points to asteroid break-up 470 million years ago|url=https://www.washingtonpost.com/national/health-science/crater-found-in-iowa-points-to-asteroid-break-up-470-million-years-ago/2013/02/18/545131f8-76d5-11e2-aa12-e6cf1d31106b_story.html?wprss=rss_national|accessdate=19 February 2013|newspaper=The Washington Post|date=18 February 2013}}

The crater's origin has been postulated as meteorite impact, volcanic activity, dissolution collapse and other causes. Geomorphology, rock textures, mineralogies and stratigraphic arguments have been used to support impact origin.[http://geophysics.ou.edu/solid_earth/notes/solar_system/Ames3.htm Ahern, Judson L. "The Potential of Potential Fields for Detecting Buried Impact Structures: Earth and Mars."] {{webarchive |url=https://web.archive.org/web/20100710050906/http://geophysics.ou.edu/solid_earth/notes/solar_system/Ames3.htm |date=July 10, 2010 }} Retrieved May 1, 2014.

When the meteor struck, this part of the Earth was covered by a shallow sea. The object, traveling at an estimated speed of {{convert|70000|mph|abbr=on}}, created a crater in the Earth's crust. This created enormous pressures below the point of impact, which made the remnant of the meteorite recoil slightly, creating an uplift. The sea returned and over eons, deposited layers of sediment. Other geological movements tilted the formation slightly. The sea eventually disappeared, leaving the crater buried in the earth, invisible from the surface. It was discovered by Rex Olson in 1991 as he was studying a map generated using data from seismic tests. Olson, an exploration manager for Continental Resources, saw a seismic pattern that resembled a hoof print, or "a cow track in the mud". Showing the map to Harold Hamm, owner and chief executive officer (CEO) of the company, he pointed out what appeared to be an anomaly or "glitch" in the data. The two agreed that the anomaly resembled an astrobleme, a term meaning "star wound."[http://newsok.com/unusual-feature-lies-under-ames/article/3458591 Zizzo, David. News OK. "Unusual feature lies under Ames."] May 4, 2010. Retrieved May 16, 2014.

An unknown number of concealed impact sites have been discovered. Some have produced uranium, gold or diamonds. Prior to 1991, geologists were skeptical that worthwhile quantities of oil and gas could be found at such a site.

The Ames Crater is covered by about {{convert|9000|ft|m}} of sediment, so it is not visible from the surface. It was discovered only in 1991. Prior to its discovery, many geologists believed that impact craters were unlikely to contain petroleum. Wells had been drilled near the crater site since the 1960s, but none had been drilled within the crater. However, Continental Resources drilled deep into the crater. The well struck oil at a {{convert|10000|feet|m}} depth that initially produced about {{convert|200|oilbbl/d}}.

The crater penetrated the Arbuckle Dolomite which resulted in vast amounts of oil and gas becoming accessible in the fractured rock. There were even rumors that the impact might have created diamonds. But no evidence of that was found. Iridium was also not found although it is used to identify astroblemes elsewhere.

At least 60 wells have been drilled in Ames Crater since 1991.[http://www.enidnews.com/localnews/x518673449/Ames-Astrobleme-Museum-records-meteor-crater-history Barron, Robert. Enid News. "Ames Astrobleme Museum."] July 29, 2007. Retrieved May 15, 2014. About 30 of the original wells were still producing in 2007. According to an article published by the American Oil & Gas Historical Society (AOGHS), Ames had produced over {{convert|17.4|e6oilbbl}} of oil and {{convert|79.5|e9ft3}} of natural gas, making it the largest of the six producing astroblemes in the United States.{{efn|Presumably the production data are valid for 2007}}

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• [https://web.archive.org/web/20100710050906/http://geophysics.ou.edu/solid_earth/notes/solar_system/Ames3.htm Judson L. Ahern, Univ. of Okla.: Imaging the Ames Impact Structure] - good general interest article
• [https://web.archive.org/web/20100710050906/http://geophysics.ou.edu/solid_earth/notes/solar_system/Ames3.htm Ahern, Judson L. "The Potential of Potential Fields for Detecting Buried Impact Structures: Earth and Mars."]
• [http://www.ogj.com/articles/print/volume-96/issue-19/in-this-issue/general-interest/north-american-impact-structures-hold-giant-field-potential.html Denofrio, Richard R. "North American impact structures hold giant field potential."] Oil & Gas Journal. May 11, 1998. Retrieved May 17, 2014. Good discussion of why hydrocarbons are found in some meteoric impact structures and not in others.
• [https://web.archive.org/web/20121203122640/http://ottawa.rasc.ca/articles/odale_chuck/earth_craters/slate_islands/index.html Aerial Exploration of the Slate Islands Structure]
• [https://web.archive.org/web/20140528005417/http://cpsx.uwo.ca/wp-content/uploads/2011/05/BGInfoCraters-Osinski_2008_Meteorite_impact_structures_Geology_Today.pdf Osinski, Gordon R. "Meteorite impact structures: the good and the bad." Geology Today.] Vol 24, No. 1. January–February 2008. Retrieved May 26, 2014.

{{Impact cratering on Earth}}

Category:Impact craters of the United States

Category:Ordovician impact craters

Category:Landforms of Oklahoma

Category:Landforms of Major County, Oklahoma