Origin of limestone-marl cycles in the Fort Worth and Denton formations (upper Albian), north central Texas
- Univ. of Texas, Arlington, TX (United States). Dept. of Geology
The Fort Worth and Denton formations (Lower Cretaceous, Washita Group) exhibit classic limestone-marl alternations similar to those of the Western Interior Seaway, Britain and southern France. Outcrops of the two formations in north-central Texas record deposition in shallow marine environments along the margin of the East Texas Basin. Limestone-marl couplets vary in thickness from several centimeters to greater than one meter and are often laterally traceable for more than 50 kilometers along strike. Bed thicknesses and their temporal duration fall within the realm of Milankovitch periodicities. Key outcrops were measured and samples taken for lab analysis of petrographic features and faunal content and variability. These analyses provide no compelling evidence in favor of either diagenesis or eustatic cyclicity as being the cause of cycles in the Fort Worth and Denton. The lateral continuity and constant thickness of the couplets are not indicative of tectonic control. Variations in biologic surface productivity and in terrigenous fine-clastic input (dilution) were the primary factors responsible for producing the couplets. Both productivity and dilution cycles may be controlled by orbital (Milankovitch-band) parameters, modified by oceanic and atmospheric circulation patterns. Regional paleogeography and paleoclimate modeling suggest that ocean circulation patterns within the Gulf of Mexico along with prevalent monsoonal conditions may have modified the orbitally-driven limestone-marl cycles in the Forth Worth and Denton formations.
- OSTI ID:
- 5933495
- Report Number(s):
- CONF-9303212--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 25:1; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
CARBONATE ROCKS
CRETACEOUS PERIOD
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
LIMESTONE
MESOZOIC ERA
NORTH AMERICA
PALEOCLIMATOLOGY
PALEONTOLOGY
PETROGRAPHY
ROCKS
SEDIMENTARY ROCKS
STRATIFICATION
STRATIGRAPHY
TEXAS
USA