Hydrocarbon weathering color age dating
(2) Dark-greenish sand containing 20 to 80 percent of coarse glauconite grains and weathering to lighter shades of green; generally fossiliferous where strongly glauconitic; contains hard irregular concretionary beds cemented with calcite and subordinate beds of dark blue-gray argillaceous massive fine-grained sand. Nacatoch sand (southwestern Arkansas, northwestern Louisiana); Nacatoch sand of Navarro group (northeastern Texas).
From point west of Washington, Hempstead County, Arkansas, east to Dobyville, Clark County, the Nacatoch is divisible into three gradational lithologic units (descending): (1) Unconsolidated gray fine-grained quartz sand which weathers yellowish and reddish.
consists mainly of gray massive more or less calcareous marine sand, subordinate parts of which are indurated to hard calcareous concretionary masses of various sizes as much as several feet in longest dimension. Narrow belt of outcrop lies immediately to east of, and parallel to, that of Neylandville marl and has been traced southward through Texas as far as northern Falls County, where it passes under transgressing Corsicana marl. Units were traced on surface from Little River in Hempstead County to Arkadelphia in Clark County. [Corsicana Marl, which overlies the Nacatoch on the Dallas Sheet to the north, is not mapped or discussed on this map sheet.]Source: Publication; supplemental information from GNU records (USGS DDS-6; Denver GNULEX).
demagnetized) data indicates the Upper Cretaceous Nacatoch Sand in the Arkla basin in southwest AR possesses a remanent magnetization of reversed magnetic polarity. Quartz sand, fine-grained, poorly sorted, friable, silty, glauconitic, local lenses of silty clay, compact, light gray to greenish gray; thin calcareous sandstone beds in upper and lower parts. Lies above Neylandville Formation and below Corsicana Marl.
[Available online, with subscription, from AAPG archives: or Paleomagnetic (a.f. (project director), 1987, Geologic atlas of Texas, Dallas sheet [revision of 1972 ed.]: University of Texas-Austin, Bureau of Economic Geology Geologic Atlas of Texas, 1 sheet, [10 p., revised 1988], scale 0,000, Gayle Scott memorial edition Nacatoch Sand. [Mapped in Hunt, Kaufman, Navarro, and Rockwall Cos., eastern TX.]Source: Publication.
G., 1960, Stratigraphy and Ostracoda of the Exogyra costata zone in southwestern Arkansas: Dissertation Abstracts, v. Discussion of stratigraphy and Ostracoda of EMOGYRA COSTATA zone which embraces Saratoga, Nacatoch, and Arkadelphia formations of southwestern Arkansas. 404-434, and references therein.)Source: US geologic names lexicon (USGS Bull. Lies above Neylandville Formation and below Kemp Clay. Mapped in Falls, Limestone, Milam, and Navarro Cos., eastern TX.
4367-4368., Louisiana State University, Ph D dissert., 158 p., 1959 Nacatoch sand of Navarro group. Thickness up to 180 feet, feathers out southward near Rosebud.
Search for hydrocarbon weathering color age dating:
Thickness 150 to 400 feet; in vicinity of Arkadelphia not much over 150 feet.