GEOLEX

Summary of Citation: Datil

Publication:
Winchester, D.E., 1920, Geology of Alamosa Creek Valley, Socorro
   County, New Mexico, with special reference to the occurrence
   of oil and gas, IN Contributions to economic geology, 1920;
   Part 2, Mineral fuels: U.S. Geological Survey Bulletin, 716-A,
   p. 1-15

Usage in Publication:
Datil formation*

Modifications:	Geologic Province:	Dominant Lithology:
Named	Orogrande basin	Tuff Rhyolite Sandstone Conglomerate Andesite

Summary:
Unconformably overlying Cretaceous Chamiso formation (new) and underlying Quaternary gravels is a formation forming rugged mountain topography, consisting of a series of well-indurated tuffs, rhyolites, andesites, cross-bedded sandstones, and conglomerates here named Datil formation for Datil Mountains of west-central NM. At most places beds of this formation are practically horizontal; none of the members are persistent, cross bedding and steep depositional angles being common. No fossils found. No type locality designated. At section measured at north end Bear Mountains, Socorro Co, NM, Orogrande basin, is 1,824.5 ft thick and consists of (ascending): white conglomerate with well-rounded pebbles of granite, obsidian, feldspar, and quartz; reddish-gray conglomerate; red clay; red sandstone; dark conglomeratic tuff with angular fragments of igneous rock; friable sandstone containing earthy material; red compact tuff with glassy inclusions and phenocrysts of feldspar, biotite, and iron ore; gray, porous tuff; agglomerate with igneous pebbles; light-purple vesicular andesite; light-colored vitreous rhyolite; conglomeratic tuff with fragments of as much as 18-in; argillaceous sandstone; sandstone and conglomerate in alternating beds; conglomerate with 1-ft pebbles; sandstone; reddish friable conglomerate and sandstone; and quartz rhyolite. Age probably late Tertiary; more definite correlation not possible. Geologic map.

Summary of Citation: Datil

Publication:
Wilpolt, R.H., MacAlpin, A.J., Bates, R.L. and Vorbe, George,
   1946, Geologic map and stratigraphic sections of Paleozoic
   rocks of Joyita Hills, Los Pinos Mountains, and northern
   Chupadera Mesa, Valencia, Torrance, and Socorro Counties,
   New Mexico: U.S. Geological Survey Oil and Gas Investigations
   Map, OM-61, 1 sheet, scale 1:63,360

Usage in Publication:
Datil formation*

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Orogrande basin

Summary:
Stratigraphically restricted to the upper 1,140 ft of Winchell's (1920) measured section north of Bear Mountain, Socorro Co, NM in the Orogrande basin. The lower 694 ft of Winchell's section is assigned to the newly named Baca formation of Eocene age. Mapped (geologic map) in the Joyita Hills, Socorro Co. Estimated to be 2,000 ft thick. Restricted Datil consists of dominantly purple, some red and gray, latite, rhyolite, andesite flows, agglomerate, tuff, conglomerate, and sandstone. Rests on eroded edges of Sandia formation, Madera limestone, and Abo formation. Is older than Santa Fe formation which is assigned to the Pliocene. Assigned a Miocene? age, though the age of the Baca is in doubt and could be Eocene or younger.

Summary of Citation: Datil

Publication:
Elston, W.E., 1968, Terminology and distribution of ash-flows
   of the Mogollon-Silver City-Lordsburg region, New Mexico, IN
   Titley, S.R., ed., Southern Arizona guidebook III: Arizona
   Geological Society Guidebook, p. 231-240

Usage in Publication:
Datil Formation

Modifications:	Geologic Province:	Dominant Lithology:
Overview	Basin-and-Range province

Summary:
Most of the ash-flows are considered part of the Datil Formation. Name refers to the Datil Mountains, Socorro Co, NM but the type section 1,824 ft thick is located 30 mi east in the Bear Mountains. Type has been modified three times. Term was used for rhyolites and quartz latites characterized by thick ash-flow cooling units that separated older andesite from younger basalt. Previously believed that all rhyolitic rocks were contemporaneous, probably Miocene. Is unconformably above Laramide rocks. Is cut by basin-and-range faults. No fossils found. Used for rocks bracketed from 38 to 29 m.y. or Oligocene and that represent three cycles of eruptions. Use in restricted sense for rocks of 38-29 m.y. Use in broad sense includes younger, undated rocks.

Summary of Citation: Datil

Publication:
Lopez, D.A. and Bornhorst, T.J., 1979, Geologic map of the Datil
   area, Catron County, New Mexico: U.S. Geological Survey
   Miscellaneous Investigations Series Map, I-1098, 1 sheet,
   scale

Usage in Publication:
Datil Group

Modifications:	Geologic Province:	Dominant Lithology:
Not used

Summary:
Terms Datil Group and Datil Formation are ambiguous and need revision. Term Datil not used in report on Basin-and-Range province, NM.

Summary of Citation: Datil

Publication:
Osburn, G.R. and Chapin, C.E., 1983, Nomenclature for Cenozoic
   rocks of northeast Mogollon-Datil volcanic field, New Mexico:
   New Mexico Bureau of Mines and Mineral Resources Stratigraphic
   Chart, no. 1

Usage in Publication:
Datil Group

Modifications:	Geologic Province:	Dominant Lithology:
Revised Overview	Orogrande basin Basin-and-Range province

Summary:
Present throughout northeast Mogollon-Datil volcanic field, Catron and Socorro Cos, Basin-and-Range province and Orogrande basin. Term has been applied to several combinations of rocks. Efforts to not use or to abandon term have not worked. Term is so deeply entrenched that it is impossible to abandon it. Therefore, term "redefined" [revised] and applied to rocks above Baca Formation and below Hells Mesa Tuff. Represents the early volcaniclastic apron of the northeast Mogollon-Datil volcanic field. Datil rocks range from andesite to low-silica rhyolite in composition and generally lack phenocrystic quartz. Includes Spears Formation, Datil Well, Rock House Canyon, and Blue Canyon Tuffs, as well as several unnamed units. Assigned to Oligocene. Is about 39-33 m.y. from units within group, and from age obtained from overlying Hells Mesa. Source unknown.

Summary of Citation: Datil

Publication:
Ratte, J.C., 1989, Geologic map of the Bull Basin quadrangle,
   Catron County, New Mexico: U.S. Geological Survey Geologic
   Quadrangle Map, GQ-1651, 1 sheet, scale 1:24,000, Supersedes
   U.S. Geological Survey Open-File Report OF-86-194.

Usage in Publication:
Datil Group*

Modifications:	Geologic Province:	Dominant Lithology:
Revised	Basin-and-Range province

Summary:
Includes all rocks beneath the erosional unconformity at the base of the Oligocene Davis Canyon Tuff in this quad, Catron Co, NM in the Basin-and-Range province. Datil divided into (ascending): 1) tuff of Bishop Peak?; 2) unnamed tuffs, one of which is equivalent to the Hells Mesa Tuff; and 3) Pueblo Creek Formation (newly named), all of Oligocene age. Tuff of Bishop Peak? tongues into the "volcaniclastic rocks" map unit, the basal unit of the Pueblo Creek. The unnamed tuffs numbered t1 to t4 are discontinuous and are interlayered with the "alluvial facies" and "volcaniclastic rocks" map units of the Pueblo Creek.

Summary of Citation: Datil

Publication:
Ratte, J.C., McIntosh, W.C. and Houser, B.B., 1991, Geologic
   map of the Horse Mountain West quadrangle, Catron County,
   New Mexico: U.S. Geological Survey Geologic Quadrangle Map,
   GQ-1685, 1 sheet, scale 1:24,000, Supersedes U.S. Geological
   Survey Open-File Report OF-89-210.

Usage in Publication:
Datil Group*

Modifications:	Geologic Province:	Dominant Lithology:
Isotopic dating Paleomagnetics Revised	Basin-and-Range province

Summary:
Consists of several outflow sheets of rhyolitic ash-flow tuffs and minor other volcanic rocks interlayered with volcaniclastic sedimentary rocks of the Spears Formation (Osburn and Chapin, 1983). Is revised to specifically include the Kneeling Nun Tuff, which was not specifically included in the Datil by Osburn and Chapin (1983). Mapped volcanic units of the Datil in the Horse Mountain West quadrangle, Catron Co, NM, in the eastern part of the Basin-and-Range province include (descending): pumice breccia of Old Horse Springs (about 33 Ma; reversed polarity); Blue Canyon Tuff (33.75 Ma; reversed polarity); Rock House Canyon Tuff (34.81 Ma; reversed polarity); tuff of Lebya Well (reversed polarity); Kneeling Nun Tuff (35.28 Ma; reversed polarity); tuff of Farr Ranch (35.50 Ma; normal polarity); Datil Well Tuff (35.41 Ma; normal polarity); and basaltic flow of Alamocito Canyon. Isotopic ages (40Ar/39Ar), natural remanent magnetism, and chemical analyses data are presented in tables. Age is Oligocene.