Coragyps

Patrick wrote: Whattaya mean, "non-coeval?" They're ALL coeval, evo-boy!

edited to ask nicely: Patrick, can you point me to your piece on evaporites in West Texas? I'm sure it was on here, but I don't remember when...I found a somewhat similar argument, though, in a 1950's book on the geology of the Guadalupe Mts. area - 7000 feet of alternating limestone and sandstone in 1/4 inch thick laminations.

[ June 28, 2002: Message edited by: Coragyps ]</p>

Allkholollick

Thanks, Patrick those articles are great.

I was out in West Texas last summer. We went on the Permian Reef trail up to the top of the Capitan Reef. It wasn't as bad of a hike as expected.

We had a guide along from the Park. Great guy but I forgot to include his name in my field notebook. It was the middle of Field Camp and I was getting a bit lazy.

ps418

Ah, you mean the Ochoan series evaporites of Texas and New Mexico, which includes the Castile and Saludo formations. The Ochoan series evaporites immediately overly the Capitan limestones, have a thickness up to 1300m, a lateral subsurface extent of 150,000km2 (virtually the entire Delaware basin), and a volume of about 65,000km3 (Blatt and Tracy, Petrology, p. 329). The Castile is characterized by millimeter-scale couplets of calcium carbonate and anhydrite, about 260,000 of them. Individual cycles and groups of couplets can be correlated over dozens of miles across the Delaware Basin (Anderson, 1982. A long geoclimatic record from the Permian: Journal of Geophysical Research 87, pp. 7285-7294).

Above the Castile, the Salado Formation consists of about 600 meters worth of bedded halite and other salts. These salts show a concentric arrangement, as would be expected from a dessicated basin. Blatt and Tracy (Petrology, 1996, p. 330) write:

The distribution of sedimentary rock types in the Deleware Basin shows a crude concentric zonation, characteristic of a dessicating basin. Along the outer fringe are either fine-grained clastics or carbonate rocks, depending on the location of nearby land areas. Within this outer fringe are gypsum and/or anhydrite, followed by halite, and finally by the more soluable salts in the center of the dessicated area - salts such as polyhalite, langbeinite, carnallite, and sylvite.

Peter Scholle has a great webpage on the Permian of west Texas: <a href="http://geoinfo.nmt.edu/staff/scholle/guadalupe.html" target="_blank">Virtual Geologic Field Trip to the Permian Reef Complex, Guadalupe and Delaware Mountains, New Mexico-West Texas</a>

Patrick

[ June 28, 2002: Message edited by: ps418 ]</p>

Dr.GH

Howdy Patrick,

Your job description reminds me of when I was a private investigator. I bet you will be happier in geology.

I just changed jobs: I quit the museum and signed up with an environmental consulting firm. We'll see how it goes.

Coragyps

Patrick: Thanks! Scholle's site is fantastic - I think I feel a road trip coming on about Februrary, when it's cool enough to go outside down there.