About 64,000 years ago, during the Late Pleistocene, an iron meteorite impacted western Texas about 9 to 10 miles southwest of the town of Odessa (Ector County). The resulting impact crater is about 160-170 meters in diameter.  The present crater floor is only a few meters below the level of the surrounding plain.  The original impact crater was about 30 meters deep.  It has since been filled with fine- to coarse-grained siliciclastic and lithic sediments.  It is currently a dry depression, but a small lake occupied the site in the past.


Large and small fragments of the impactor have been collected from the Odessa Crater area for decades.  The meteorite is an 4.55 billion year old octahedrite originating from the asteroid belt between Mars and Jupiter.  It is dominated by the minerals kamacite and taenite (both are Fe-Ni alloys).


Odessa Impact Crater (looking north) - low oblique aerial photo from the 1950s.


Odessa Impact Crater - schematic cross-section.  The basal crater-filling unit is a very fine-grained "rock flour", formed by impact pulverizing of target rocks.  Above that is an impact breccia unit and many layers of fine- to coarse-grained siliciclastic and lithic sediment fill.


Odessa Meteorite - a nice 32-kilogram individual with well formed regmaglypts (the surficial depressions).  This rock is composed principally of the iron-nickel alloy minerals kamacite and taenite.


Odessa Impact Crater (looking southwest) - the small ridge in the distance is uplifted rim rocks along the crater edge.


Odessa Impact Crater (looking NW)


Odessa Impact Crater (panoramic view) - north is toward the building; the trail at left is looking to the southwest.  Photo provided by Mary Ellen St. John.

The rim rocks at Odessa Impact Crater have been uplifted and upturned (see cross section on previous page).  These rocks are Lower Cretaceous oncolitic limestones of the Fredericksburg Group.  The oncolites range in shape from subspherical to irregular.


Odessa Impact Crater rim rocks - oncolitic limestones from the Lower Cretaceous Fredericksburg Group.


Odessa Impact Crater rim rock - oncolitic limestone from the Lower Cretaceous Fredericksburg Group.


Odessa Impact Crater rim rock - oncolitic limestone from the Lower Cretaceous Fredericksburg Group.



The impact breccia deposits at this site are referred as the Odessa Breccia.  The rocks consist of a mixture of large and small, angular fragments formed by shattering and pulverizing of target bedrock by the meteorite.


Odessa Breccia (large brownish clast at left is 3.5 cm across at its widest)


Odessa Breccia (field of view: 28.6 cm across)


Odessa Breccia



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