[meteorite-list] Impact Crater in New Mexico – Part 1 Lea County

From: Paul H. <oxytropidoceras_at_meteoritecentral.com>
Date: Wed, 5 Jan 2011 9:35:22 -0600
Message-ID: <20110105103522.RAY9X.562034.imail_at_eastrmwml46>

About an area in Lea County, New Mexico, Abe wrote:

?I plan to go on another meteorite hunting trip to New Mexico
soon before the Tucson show. Would you guys think that this
is an impact crater? 32?21'54.39" N 103?23'47.50" W. I
remember reading about it on a site but it appears that there
are just too many craters in the area to all be impact craters.
If they aren?t impact craters what would be the possibility
they are ancient ponds for wildlife? I would imagine that as
West Texas and New Mexico dried up, any remaining wet
ground would become extremely populated with wild life
and over centuries these locations would become deep ponds.?

These are playa lakes. They are neither impact craters nor
related any type of impact processes. Some of these playa
lakes have been in existence throughout the Pleistocene.
However, there is one known exception to how playa lakes
typically form, it is the playa lake that occupied the Odessa
impact crater.

About playa Lakes, Holliday et al. (1996) states

?These lithostratigraphic and chronostratigraphic
relationships show that some basins have a prolonged
history as depressions, persisting in more or less the
same location as the High Plains surface aggraded by
eolian addition (Blackwater Draw Formation) throughout
the Pleistocene. Sizes of the basins varied through time as
they were encroached upon by the Blackwater Draw
Formation, enlarged by fluvial, lake margin, and eolian
erosion, were filled and reexposed, or were buried.
Some basins are newly formed on the High Plains
surface and have no apparent predecessors.?

About the origin of playa basins, Gustavson et al. (1995a) wrote

?The initial formation of playa basins involved many
processes but most likely started with collection of runoff
in small, irregular topographic depressions on the High
Plains. Initial depressions may have resulted from surface
drainage, dissolution of the Caprock calcrete, subsidence
caused by salt dissolution, differential compaction, animal
wallows, or blowouts where vegetation was missing.
Ponded runoff killed vegetation or inhibited plant growth
and allowed deflation to remove some of the surface
sediment when the pond dried out. As the initial small
basin expanded, fluvial erosion and lacustrine sedimentation
became more important. centripetal drainage enlarged the
basin by eroding the basin margin and carrying sediment
to the basin floor. Periodic flooding continued to keep the
center of the playa basin relatively clear of vegetation.
Wind deflated dry sediment from the playa center.
Deflation may have been accelerated after large herds of
bison pulverized dried surface soils and carried small
amounts of sediment out of the basin on their hooves.
Sediments deflated from these basins were carried
downwind.?

Some Publications About Playa Lakes

Gustavson, T. C., V. T. Holliday, and S, D. Hovorka, 1995a
Development of Playa Basins, Southern High Plains, Texas
and New Mexico. In Proceedings of the Playa Basin
Symposium, edited by L.V. Urban and A.W. Wyatt, pp. 5-14.
Texas Tech University, Water Resources Center, Lubbock.

Gustavson, T. C., V. T. Holliday, and S. D. Hovorka, 1995b
Origin and Development of Playa Basins, Sources of
Recharge to the Ogallala Aquifer, Southern High Plains,
Texas and New Mexico. The University of Texas at Austin,
Bureau of Economic Geology Report of Investigation 229.

Holliday, V. T., T. C. Gustavson, and S. D. Hovorka, 1996,
Stratigraphy and Geochronology of Playa Fills on the
Southern High Plains. Geological Society of America
Bulletin. vol. 108, no. 8, pp. 953-965.
Abstract at http://gsabulletin.gsapubs.org/content/108/8/953.short
PDF file at http://www.argonaut.arizona.edu/articles/holliday_etal1996.pdf
and http://www.argonaut.arizona.edu/holliday.htm

Hovorka, S.D., 1997, Quaternary evolution of ephemeral playa
lakes on the Southern High Plains of Texas, USA: cyclic
variation in lake level recorded in sediments. Journal of
Paleolimnology. vol. 17, pp. 131?146.
http://www.springerlink.com/content/u20316917821568q/

Osterkamp, W. R. and W. W. Wood, 1987, Playa-lake basins
on the Southern High Plains of Texas and New Mexico:
Part I. Hydrologic, geomorphic, and geologic evidence for
their development. Geological Society of America Bulletin.
vol. 99, no.2, pp. 215-223.
http://bulletin.geoscienceworld.org/cgi/content/abstract/99/2/215

Wood, W. W., and W. R. Osterkamp, 1987, Playa-lake basins
on the Southern High Plains of Texas and New Mexico: Part II.
A hydrologic model and mass-balance arguments for their
development. Geological Society of America Bulletin.
vol. 99, no.2, pp. 224-230.
http://bulletin.geoscienceworld.org/cgi/content/abstract/99/2/224

Playa lakes are an extremely important to local wildlife as
the primary wetlands in this part of the southern High Plains
as discussed in:

Haukosa, D. A., and L. M. Smith, 1994, The importance of
playa wetlands to biodiversity of the Southern High Plains.
Landscape and Urban Planning. vol. 28, pp. 83-98.
http://dx.doi.org/10.1016/0169-2046(94)90046-9

Smith, L. M., 2003, Playas of the Great Plains. University of
Texas Press, Austin, Texas. 275 pp. ISBN: 978-0-292-70177-9
http://www.utexas.edu/utpress/books/smipla.html
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1781&context=greatplainsresearch

Yours,

Paul H.
Received on Wed 05 Jan 2011 10:35:22 AM PST