Tectonic and eustatic controls of facies architecture of upper Cretaceous Dakota sandstone, San Juan basin, New Mexico
- Geological Survey, Denver, CO (USA)
Two type-1 sea level falls occurred during deposition of the lower part of the Dakota Sandstone in the eastern part of the San Juan basin, the first during the late Albian (latest Early Cretaceous) and the second during the middle Cenomanian (earliest Late Cretaceous). Type 1 falls generally occur faster than subsidence on continental margins and thus result in stream incision. Subsidence rates, however, were more rapid during the middle Cenomanian in the San Juan basin area than on passive continental margins and were probably great enough to partially override the effects of the second fall. Incised valleys at the base of the Dakota are filled with fluvial deposits of the lowest Cenomanian Encinal Canyon member of the Dakota Sandstone; these deposits are separated from the overlying marine shales of the Oak Canyon Member of the Dakota by a ravinement surface. The Oak Canyon grades upward into prograding shore-face deposits of the Cubero sandstone member of the Dakota. The upper part of the Oak Canyon and lower part of the Cubero contain the middle Cenomanian Thatcher fossil interval. Regional correlations and age relations suggest that basal Dakota valleys resulted from the late Albian fall. Magnitude of this fall and depth of incision are nearly equal, suggesting that the coeval subsidence rate was relatively slow. Thickness of the middle Cenomanian section indicates that sedimentation and subsidence rates were probably high enough to nullify the effects of falling sea level. Consequently, rather than incision, progradation and deposition of the Cubero sandstone resulted.
- OSTI ID:
- 5461514
- Report Number(s):
- CONF-8910195--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Vol. 73:9; ISSN AABUD; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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