Mundy Breccia and Castner Limestone, undivided (TXpCAmc;0)

State	Texas
Name	Mundy Breccia and Castner Limestone, undivided
Geologic age	preCambrian (Proterozoic)
Lithologic constituents	Major Sedimentary > Carbonate > Limestone (Bed)Castner Limestone includes hornfels, conglomerate, dolomite, and diabase and is mostly light gray, green, and blue limestone, fine to coarse grained, lt. gray chert lenses, thin bedded, irreg. bedded in upper one-third; metamorphic minerals such as serpentine, tremolite, and garnet abdt in green ls. beds. Minor Metamorphic > Granoblastic > Hornfels (Hornfels)hornfels present in the upper third of the Castner Limestone, thus is ranked a minor part of the whole map unit (Mundy Breccia and Castner Limestone, undivided). Hornfels very fine grained, dark gray, in many thin beds, laminated and contains a few beds of conglomerate. Incidental Sedimentary > Carbonate > Dolostone (Bed)Dolomite in the basal exposed beds of the Castner Limestone in the Franklin Mtns. The dolomite is white to light gray, one bed contains algal structures Tectonite > CataclasiteThe Mundy Breccia randomly oriented, black basalt boulders, angular to slightly rounded, in matrix of dark gray mudstone. thickness about 90 ft, as much as 250 ft maximum.
Comments	Mundy Breccia, randomly oriented, black basalt boulders, angular to slightly rounded, in matrix of dark-gray mudstone; thickness 250 feet maximum. Castner Limestone, limestone, hornfels, conglomerate, dolomite, and diabase. Mostly limestone, fine to coarse grained, light-gray chert lenses, thin bedded, irregularly bedded in upper one-third, light gray, green, blue; metamorphic minerals such as serpentine, tremolite, and garnet abundant in green limestone beds. In upper third, hornfels, very fine grained, numerous thin beds, dark gray, laminated and a few beds of conglomerate. Dolomite in basal part of exposure, white to light gray, one bed contains algal structures. Diabase, dark greenish gray, thin-to-thick sills near base and middle, constitutes about one-third of outcrop. Thickness of formation 1.100+ feet, base not exposed.
References	Bureau of Economic Geology, 1968, Van Horn-El Paso Sheet, Geologic Atlas of Texas: Bureau of Economic Geology, The University of Texas at Austin, scale 1:250,000. Harbour,R.L., 1960, American Association of Petroleum Geologists Bulletin v. 44, no. 11, p. 1788-1790. Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.
NGMDB product	NGMDB product page for 68390
Counties	El Paso

State

Name

Mundy Breccia and Castner Limestone, undivided

Geologic age

preCambrian (Proterozoic)

Lithologic constituents

Major

Sedimentary > Carbonate > Limestone (Bed)Castner Limestone includes hornfels, conglomerate, dolomite, and diabase and is mostly light gray, green, and blue limestone, fine to coarse grained, lt. gray chert lenses, thin bedded, irreg. bedded in upper one-third; metamorphic minerals such as serpentine, tremolite, and garnet abdt in green ls. beds.

Minor

Metamorphic > Granoblastic > Hornfels (Hornfels)hornfels present in the upper third of the Castner Limestone, thus is ranked a minor part of the whole map unit (Mundy Breccia and Castner Limestone, undivided). Hornfels very fine grained, dark gray, in many thin beds, laminated and contains a few beds of conglomerate.

Incidental

Sedimentary > Carbonate > Dolostone (Bed)Dolomite in the basal exposed beds of the Castner Limestone in the Franklin Mtns. The dolomite is white to light gray, one bed contains algal structures

Tectonite > CataclasiteThe Mundy Breccia randomly oriented, black basalt boulders, angular to slightly rounded, in matrix of dark gray mudstone. thickness about 90 ft, as much as 250 ft maximum.

Comments

Mundy Breccia, randomly oriented, black basalt boulders, angular to slightly rounded, in matrix of dark-gray mudstone; thickness 250 feet maximum. Castner Limestone, limestone, hornfels, conglomerate, dolomite, and diabase. Mostly limestone, fine to coarse grained, light-gray chert lenses, thin bedded, irregularly bedded in upper one-third, light gray, green, blue; metamorphic minerals such as serpentine, tremolite, and garnet abundant in green limestone beds. In upper third, hornfels, very fine grained, numerous thin beds, dark gray, laminated and a few beds of conglomerate. Dolomite in basal part of exposure, white to light gray, one bed contains algal structures. Diabase, dark greenish gray, thin-to-thick sills near base and middle, constitutes about one-third of outcrop. Thickness of formation 1.100+ feet, base not exposed.

References

Bureau of Economic Geology, 1968, Van Horn-El Paso Sheet, Geologic Atlas of Texas: Bureau of Economic Geology, The University of Texas at Austin, scale 1:250,000.

Harbour,R.L., 1960, American Association of Petroleum Geologists Bulletin v. 44, no. 11, p. 1788-1790.

Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.

NGMDB product

NGMDB product page for 68390

Counties

El Paso