Evolution of playa basins on the Texas High Plains--Evidence from playa-basin fills

Conference · Mon Feb 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5976811

Hovorka, S D ^[1]

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1. Univ. of Texas, Austin, TX (United States). Bureau of Economic Geology

Heterogeneous sediments in playa basins document the evolution of shallow depressions on the Texas High Plains surface through the late Quaternary. The suite of sediments encountered in playa-lake basins differs from the typical lithologies of the Blackwater Draw Formation in upland areas. The upland Blackwater Draw Formation has red-brown clayey silt containing root casts, well-developed soil fabrics, and abundant pedogenic carbonate nodules. Cores drilled in playa basins encountered a repetitive suite of gray clay, well-sorted fine to medium sand, and laminated sand and silt associated with clay drapes and beds of pedogenic calcite pebbles. The gray clay was deposited in ephemeral lakes similar to modern playa lakes. Small clams and drab colors extending downward from these deposits demonstrate ponding. Soil fabrics, soil slickensides, deep clay-filled cracks, and root tubules within the clayey beds indicate desiccation and exposure of the lake floor. Well-sorted sand layers represent episodic migration of sand sheets across the playa. Laminated sand and silt beds are interpreted as delta deposits that formed at the mouths of draws. Minimal soil formation indicates relatively rapid deposition during delta progradation. The suite of playa sediments interfingers with upland Blackwater Draw facies, documenting the temporal equivalence of playa and upland deposition and expansion and contraction of the lake within the playa basin. Complex patterns of oxidation, reduction, and precipitation and dissolution of calcite document the interaction between ground water and sediments.

• OSTI ID: 5976811
• Report Number(s): CONF-9303212--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:1
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CENOZOIC ERA
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
LITHOLOGY
NORTH AMERICA
PALEONTOLOGY
PETROLOGY
QUATERNARY PERIOD
SEDIMENTARY BASINS
STRATIGRAPHY
TEXAS
USA