Mid-Cretaceous alluvial-plain incision related to eustasy, southeastern Colorado Plateau

Research Article| April 01, 1989 Mid-Cretaceous alluvial-plain incision related to eustasy, southeastern Colorado Plateau W. M. AUBREY W. M. AUBREY 1U.S. Geological Survey, M.S. 939, Box 25046, Federal Center, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar Author and Article Information W. M. AUBREY 1U.S. Geological Survey, M.S. 939, Box 25046, Federal Center, Denver, Colorado 80225 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1989) 101 (4): 443–449. https://doi.org/10.1130/0016-7606(1989)101<0443:MCAPIR>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation W. M. AUBREY; Mid-Cretaceous alluvial-plain incision related to eustasy, southeastern Colorado Plateau. GSA Bulletin 1989;; 101 (4): 443–449. doi: https://doi.org/10.1130/0016-7606(1989)101<0443:MCAPIR>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Eustatic effects on the deposition of ancient coastal and marine rocks are well known, but eustasy also can affect depositional patterns and processes well inland from the sea and play an important role in the development of nonmarine unconformities.In the southeastern part of the Colorado Plateau, fluvial rocks of the lowermost Cenomanian (lowermost Upper Cretaceous) Encinal Canyon Member at the base of the Dakota Sandstone fill paleovalleys incised into underlying formations. In most of region, the Encinal Canyon disconformably overlies fluvial rocks of the Aptian to middle Albian (upper Lower Cretaceous) Burro Canyon Formation. Along the southern margin of the plateau, the Encinal Canyon overlies progressively older Mesozoic and Paleozoic formations toward the south.In the latter part of the Early Cretaceous, an epicontinental sea lay about 240 km east of the southeastern Colorado Plateau and was base level for streams in the plateau region. Near the end of the Early Cretaceous, sea level fell, base level was lowered, and streams incised valleys into alluvial deposits of the Burro Canyon Formation and into older formations. The resulting incised paleodrainage surface was preserved as the sub-Dakota unconformity when the succeeding sea-level rise, in earliest Late Cretaceous time, caused Dakota streams to aggrade and backfill the paleovalleys with alluvial sediments of the Encinal Canyon Member. Unconformities in continental rocks have rarely been attributed to sea-level changes. The example of sub-Dakota unconformity, however, suggests that eustatic lowering of sea level can result in erosion far inland from the sea and play an important role in the formation of unconformities in continental strata. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.