Relative sea level changes in the Late Cretaceous (Cenomanian and Turonian stages) as reflected in the Tuscaloosa Group in the subsurface of southwest Alabama
- Univ. of Alabama, Tuscaloosa, AL (United States) Geological Survey of Alabama, Tuscaloosa, AL (United States)
In the subsurface of southwest Alabama, the Upper Cretaceous Tuscaloosa Group includes approximately 1,000 feet of nonmarine, marginal marine, and marine terrigenous clastic rocks. Three unconformity-bounded depositional sequences reflecting relative changes in sea level and coastal onlap during the Late Cretaceous (Cenomanian and Turonian) are recognized for these strata. These depositional sequences are herein designated the UZAGC (Upper Zuni A Gulf Coast)-2.3, UZAGC-2.4, and UZAGC-2.5 sequences and probably correspond to the UZA-2.3, UZA-2.4, and UZA-2.5 global sequences of Haq and others. Undifferentiated Lower Cretaceous terrigenous clastic deposits underlie the UZAGC-2.3 sequence, which consists of a basal type 2 unconformity, shelf margin deposits (marginal marine sandstones), transgressive and condensed section deposits (marine shelf sandstones and claystones) and progradational regressive highstand deposits (marine shelf to strandplain sandstones and claystones). This sequence reflects relative sea level rise in the early Cenomanian and sea level fall in the middle Cenomanian. The overlying UZAGC-02.4 depositional sequence consists of a basal type 1 unconformity, lowstand deposits (aggradational coastal barrier sandstones), transgressive and condensed section deposits (marine shelf sandstones and claystones) and progradational regressive highstand deposits (strandplain to lagoonal sandstones and claystones). This sequence indicates that relative sea level rose in the middle Cenomanian and then fell during the Late Cenomanian. The UZAGC-2.5 sequence consists of a basal type 2 unconformity, transgressive deposits (marine shelf sandstones), condensed section deposits (marine shelf claystones), and progradational regressive highstand deposits (marginal marine sandstones and claystones). This sequence reflects a major sea level rise beginning in the late Cenomanian and continuing into the Turonian, followed by sea level fall in the Turonian.
- OSTI ID:
- 5973582
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
Sedimentary architecture of marginal and shallow marine depositional systems tracts in upper Cretaceous series of San Juan basin
Mesozoic stratigraphy of northwestern Australian and northern Himalayan margins