The Benavides Impact Structure

A large, multiple airburst, geo-ablative impact structure.

The semi circular ring of  The Benavides Impact Structure is 17 miles wide. Just across the border from Terlingua, Texas, and Big Bend National Park, USA.

The maps show this area to be volcanic due to the melt formations. But don’t you believe it. There is no volcanic vent here. This violence did not come from below. The 17 mile ring, as well as the smaller, overlapping, 8 mile wide impressions are all perfect circles incised into the surface from above.  The mega-breccias and airburst melt outside the structure were blown there by a great force of heat and pressure which scoured everything from inside the circles and cut into the surface like a giant cookie cutter. And the heat inside the circles was enough to re-weld the fractures in the rock.

We see the sequence of these explosions in the layering of the ejecta that was blown to the northwest. The arrowhead shaped splash on northwest side, came first as a result of the 17 mile wide larger explosion. The mountains of mega-breccias on the southeast side of the ring was formed at the same time as the arrowhead splash of melt. The ring itself was incised into the ground when the downward momentum of the exploding fragment was coupled with the detonation shock wave of the blast, concentrating the force of the blast at the edge of the detonation shock wave.

The shorter of the two ejecta blankets on the northwest side of the structure are the ejecta of the smaller 8 mile wide blast that followed 2 or 3 seconds after the larger blast.

Here we begin to see some of the clear evidence of the predominant southeast to northwest direction of the impact firestorm in the directional nature of the breccias, and other blast effected materials of this structure.

Outside of the southeast edge of the structure, the ejecta was thrown into the super-sonic impact wind coming from the southeast so they piled up outside the compression wave of the explosion in a mountain of mega breccias.

The breccias are heaped 800 to 1000 ft high.

The pristine condition of the materials is startling. On the opposite side, outside of the northwest edge of the  structure are repeated blankets of ejecta, and airburst melt were thrown down wind 10 miles, or more.



The emplacement motions of this ejecta blanket are perfectly clear, and legible.

The melted material did not come out of the ground. There is no vent, magma chamber, or any volcanic system whatsoever. The blankets of melt, and ejecta, consist of the original surface terrain, flash melted from above, and quickly blown away, from its points of origin.

As for the age? That remains to be determined. But, as you can see for yourself, since the moment of their emplacement, these splashes of ejecta, and impact melt, have not undergone any significant weathering at all. What ever else they are, those pristine ejecta curtains are not old at all.

These are stereoscopic images. Click on them for an enlarged view. To see the 3D effect simply focus on the center line, and cross your eyes a little, until a 3D image seems to appear in the middle.

Looking down to the southeast from about 45 km up.

The inter-fingering patterns of movement, and flow in the edges of these blankets of melt are consistent with sudden emplacement like impact melt ejected from a crater.

Looking west, down the valley formed by the ring, we see the mega-breccias on the up-wind side of the structure.

If you want conclusive evidence of an extra terrestrial origin for this violence look no further. Only impact events make mega-breccias.

And only giant impact events make mountains of them.

Published on December 28, 2009 at 4:14 pm  Comments (2)  

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  1. soy geografo y trabajo para la confederacion hidrográfica del segura en murcia españa y creo que he encontrado la capa oscura en varios puntos de las terrazas fluviales del rio segura que pertenecen al tardiglacial momento en el que se produjeros los impactos en norteamérica hace 12900 años poseen restos de cenizas y otras sustancias pónganse en contacto conmigo tal vez este evento tambien afecto a la peninsula ibérica.

  2. McDowell, F. W., 2010, Geologic Map of Manuel Benavides area, Chihuahua, Mexico. Map and Chart no. 99. Geological Society of America, Boulder, Colorado.

    This map and text cover an area of eastern Chihuahua state adjacent to the Rio Grande and the Big Bend of Texas. The area contains an 1100-m-thick volcanic section very similar in lithology and age (by Ar-Ar dating) to that exposed in both Big Bend National and State Parks. This includes, from older to younger, a heterogeneous sequence very much like to the Chisos Formation, a thick locally derived rhyolitic flow complex comparable to the Tule Mountain trachyandesite, distal thin ignimbrites similar in age to the Mitchell Mesa ash-flow tuff (the largest unit in the Trans-Pecos volcanic field), and a caldera source for both the 31 Ma San Carlos tuff and the 28 Ma Santana tuff. The caldera is an unusual trap-door type with a hinge zone on the southwest and two separate collapse and eruption margins around the north and east. Its outer diameter is approximately 25 km, which is unusually large for the tuffs that erupted from it, suggestive of a shallow collapse. Inflation or tumescence prior to the eruptions modified a preexisting Laramide fold by bowing it outward toward the north and east; a 31.5 Ma granitoid was intruded into the fold axis, resulting in the formation of skarn deposits in the surrounding limestones of the fold.

    Most uniformitarian geologists agree that terrestrial volcanism is the only possible source of enough heat, and pressure to melt rocks on the Earth. And most of them don’t believe in impact events. I disagree with both of those assumptions.

    But you can’t have a ‘vent’ without a magma chamber to vent from. And there is no seismic, ground penetrating radar, aeromagnetic, or any other data that describes a magma chamber under the Benavides structure. There is also no convincing explanation in the literature for the crazy mantle physics required for a 25 kilometer diameter, perfectly circular, “hinged trap door" vent.

    And, at 60 bucks for a copy of the map, I’m not buying any.

    That is not a volcano. Impact melt is commonly mistaken for volcanic tuff. And those are blankets of impact melt blown to the northwest, and mountains of mega-breccias on the southeast. Volcanoes don’t make mountains of megabreccias. The proof will be in the isotope mix. We should expect to find significant siderophile, or Platinum group, element enrichment there.

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