Show simple item record

dc.contributor.advisorRankey, Eugene C
dc.contributor.authorLowery, Jennifer Giselle
dc.date.accessioned2017-08-13T21:45:57Z
dc.date.available2017-08-13T21:45:57Z
dc.date.issued2016-05-31
dc.date.submitted2016
dc.identifier.otherhttp://dissertations.umi.com/ku:14770
dc.identifier.urihttp://hdl.handle.net/1808/24819
dc.description.abstractAbstract Whereas Holocene carbonate accumulations of isolated platforms and rimmed shelves are well-understood, modern carbonate ramps have not been as extensively studied. Yet, many ancient successions consist of fine-grained sediment deposited on low-energy carbonates ramps. To better understand the sedimentologic variability and accumulations of low-energy ramp systems, this project tests the hypothesis that sediment size, sorting and type, and organic matter abundance varies among geomorphic elements on the Holocene ramp system on the northwestern Yucatan shelf, Mexico. Understanding how sediment and organic matter abundance vary in ramp carbonates is important for constructing actualistic depositional models for depositional heterogeneity within their ancient analogs, some of which include prolific hydrocarbon reservoirs. These results illustrate trends in geomorphology, sedimentology, and organic matter on shoreface-beach ridge-lagoon systems on a low-energy carbonate ramp. In terms of physical oceanographic processes, regional data suggest that currents generated by the day-to-day easterly trade winds, and larger waves caused by winter cold fronts, have the net effect of transporting sediment and upwelled waters southward along the northwestern Yucatan Peninsula. Offshore regions include shore-parallel belts of Halimeda-rich muddy gravel and skeletal (mainly molluscan) muddy sand to gravel. Longshore sediment transport along the coast forms barrier island spits made up of molluscan coquina beach ridges, which have prograded southward and westward in a repeated pattern. The barrier islands at Celestun and Isla Arena in turn act as barriers to the offshore wind and wave energy, creating semi-restricted, low-energy lagoons in their lee. These lagoons contain finer sediment (including abundant mud, 20%) and a higher abundance of organic matter (up to 15%). A landward supratidal marsh (the “Petenes”) includes dominantly fine-grained carbonate sediment. In addition to physical processes, chemical oceanographic factors likely influence the sediment of the area. The presence of upwelled waters containing elevated nutrient levels (5 mg/m3, eutrophic to hypertrophic) and cooler water (~17-18°C) shape the assemblage of sediment producers present in the study area. Molluscs are the main sediment contributors in the region, along with Halimeda offshore. Barnacles, foraminifera, sponges, bryozoans, and serpulid worm tubes constitute the remainder of carbonate sediment producers. Corals are markedly absent, as are peloids and ooids. Unexpectedly, as the northwestern Yucatan occurs in a tropical ocean, abundant biosiliceous organisms such as diatoms and sponge spicules, as well as some dinoflagellates and coccolithophores, contribute to sediment throughout the offshore and lagoon. This diverse biosilicious assemblage further implicates the influence of nutrients and cool waters on the sediment producers in the area. The results of this study illustrate physical (energy level, SST) and chemical (upwelled waters) oceanographic influences on the geomorphology and sedimentology of a Holocene ramp system. The insights motivate a conceptual model for the nature and controls on sedimentologic and geomorphic heterogeneity in ancient nearshore, low-energy ramp systems, including some ancient reservoir analogs.
dc.format.extent60 pages
dc.language.isoen
dc.publisherUniversity of Kansas
dc.rightsCopyright held by the author.
dc.subjectGeology
dc.subjectSedimentary geology
dc.subjectGeomorphology
dc.subjectCarbonate
dc.subjectHeterozoan
dc.subjectHolocene
dc.subjectSedimentology
dc.subjectUpwelling
dc.subjectYucatan
dc.titleControls on Geomorphology and Sedimentology of Shoreface-Beach Ridge-Lagoon Systems on a Low-Energy Carbonate Ramp: Holocene, Northwestern Yucatan Shelf, Mexico
dc.typeThesis
dc.contributor.cmtememberFranseen, Evan K
dc.contributor.cmtememberOlcott-Marshall, Alison
dc.contributor.cmtememberGarza-Perez, Rodrigo
dc.thesis.degreeDisciplineGeology
dc.thesis.degreeLevelM.S.
dc.identifier.orcid
dc.rights.accessrightsopenAccess


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record