Online guide to the continental Cretaceous-Tertiary boundary in the Raton basin, Colorado and New Mexico
Figure 3. Diagrammatic block diagrams depicting paleoenvironments of Upper Cretaceous and Paleocene rocks of the Raton basin: A. The offshore environments of Pierre Shale; the contemporaneous delta front and barrier environments of the Trinidad Sandstone; and the fluvio-deltaic plain of the Vermejo Formation. Diagram shows oxbow lakes, crevasse splays, and coal-forming swamps related to meandering streams of the lower delta plain. B. The floodplain and fine-grained meanderbelt environments on the alluvial plain that developed during the Late Cretaceous after deposition of the basal conglomerate of the lower coal zone of the Raton Formation. Coal-forming swamps and oxbow lakes characterized the floodplain. C. The depositional environments on the alluvial plain of the lower coal zone of the Raton Formation at the end of the Cretaceous Period. The K-T boundary fallout material was deposited on a surface such as that shown here. The letters show representative depositional sites: B, Berwind site (floodplain sequence, dominated by crevasse splays from nearby stream channel); M, Madrid site (channel-floodplain-crevasse splay sequence); S, Starkville sites (floodplain sequence developed on abandoned channel sequence); Y, York Canyon (floodplain-crevasse splay sequence); R, Raton site (floodplain, marginal to major backswamp); SU, Sugarite site (dominated by an extensive swamp). D. The braided stream and coarse meanderbelt environments of the Paleocene barren series of the Raton Formation. After Pillmore and Flores, 1987.
U.S. Department of the Interior, U.S. Geological SurveyThis page is http://esp.cr.usgs.gov/info/kt/fig3.html
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