Upper Cretaceous (Maastrichtian) paleosols in Trans-Pecos Texas

Abstract

Research Article| February 01, 1989 Upper Cretaceous (Maastrichtian) paleosols in Trans-Pecos Texas THOMAS M. LEHMAN THOMAS M. LEHMAN 1Department of Geosciences, Texas Tech University, Lubbock, Texas 79409 Search for other works by this author on: GSW Google Scholar Author and Article Information THOMAS M. LEHMAN 1Department of Geosciences, Texas Tech University, Lubbock, Texas 79409 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 (2): 188–203. https://doi.org/10.1130/0016-7606(1989)101<0188:UCMPIT>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 MailTo Tools Icon Tools Get Permissions Search Site Citation THOMAS M. LEHMAN; Upper Cretaceous (Maastrichtian) paleosols in Trans-Pecos Texas. GSA Bulletin 1989;; 101 (2): 188–203. doi: https://doi.org/10.1130/0016-7606(1989)101<0188:UCMPIT>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 Fluvial flood-plain deposits of the upper Aguja, Javelina, and El Picacho Formations in Brewster and Presidio Counties of West Texas record multiple episodes of soil formation during Late Cretaceous (Maastrichtian) time. These well-differentiated alluvial paleosols are characterized by pale gray leached (albic) A horizons and purple or red, clay-and iron oxide-enriched (cambic, argillic) B horizons. These characteristics indicate that podzolization and lessivage were important pedogenic processes and suggest that these paleosols are comparable to some modern AI-fisols. Texturally diverse accumulations of calcite nodules, coalesced masses of nodules, rhizocretions, and thin discontinuous hard-pans indicate that calichification also occurred. The extreme development of the petrocalcic horizons, partial silicification, association with sulfate minerals, and high position within the soil profiles indicate that calichification was in many cases not con-temporaneous with iron and clay illuviation. The compound paleosols thus formed indicate that the Maastrichtian climate in this region may have fluctuated between regimes of humid and semiarid character, each at least several thousand years in duration. This inferred long-term climatic cyclicity may correspond to climatically induced sedimentation cycles observed in the marine realm that are ascribed to Milankovitch cycles. Fossil wood suggests that the flood-plain paleosols supported coniferous forests, whereas adjacent stream courses were lined by angiosperm woodlands. 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.