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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Sequence stratigraphy and the development of a clinoformal carbonate ramp on an abandoned delta system: Mississippian Fort Payne--Salem Interval, Kentucky

Khetani, Amy B. 01 November 2008 (has links)
Middle Mississippian ramp carbonates in Kentucky (Fort Payne to Salem interval) form a large scale depositional supersequence (0 to 500 feet thick, approximately 8 m. y. duration). It formed on and in front of the abandoned Early Mississippian Borden deltaic marine paleoshelf, which had up to 100 m of relief above the adjacent starved basin. Major facies consist of marine quartz sandstone and shale; peritidal carbonates; high-energy ramp margin, crinoidal-bryozoan grainstones; deeper ramp mounds, skeletal grainstone/packstone sheets and channel-fills interlayered with shale or calcisiltite; and slope deposits of siliceous calcisiltite. Regional slopes on the paleoshelf edge and ramp margin are 0.5 to 2.5 mIkm (less than 0.25 degrees), although clinoforms of 2 to 10 degrees occur locally associated with mounds and depositional lobes. The supersequence LST is dominated by mounds interlayered with green shaly, deeper ramp facies. The mounded units are located in a fairway that is normal to the Borden margin but parallel to the Appalachian Grainger deltaic shelf. No TST is evident, except for a glauconite horizon capping the Borden paleoshelf. The supersequence HST consists of at least eight third-order sequences (each approximately 1 m.y. duration), the older ones downlapping onto the shelf 20 to 30 m deep, the younger ones downlapping into the deeper basin (over 150 m water depth). Sequences show marked toplap with the upper sequence boundary. The third-order sequences locally have lowstand sands, some of which may be associated with a paleodrainage system off the Borden paleo shelf. They lack recognizable TSTs, but have well-developed prograding HST units of nearshore shale and peritidal dolomite, skeletal packstone/grainstone banks, and siliceous calcisiltite slope facies. The supersequence correlates with a global sea level cycle in the lower Visean terminating in a major sea-level fall. The highly clinofonned toplapping supersequence reflects this long term, sea-level fall which prevented space from being created on the old delta top. The third-order sequences, although mappable between the sections, are not easily correlated with global third order cycles. / Master of Science

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