Masters Theses

Chao Liu

Keywords and Phrases

Buckle folds; Finite Element Modeling; Karst collapase; Periclines; Roubidoux; Transpression zone

Abstract

"The Ordovician Rubidoux Formation of the Ozark Plateau, Missouri is typically identified as mechanically competent sub-horizontal beds of medium grained sandstone. North of Licking, MO, the Rubidoux Formation was deformed into a series of dome-and-basin shaped buckle folds, exposed in road cuts over a distance of ~10 km. Such folds are highly unusual within the Ozark Plateau and their origin remains controversial. Three major hypotheses have been proposed based on field observations and stereographic analysis. Given the pervasive distribution of karst collapse throughout Missouri, one hypothesis to explain these folds is that the Roubidoux Formation sagged into collapsed caverns. A second hypothesis is that these folds are the result of compression induced in a possible transpression zone between two left-lateral strike-slip faults. A combination of the two processes is also possible.

Field measurements of 37 fold structures including more than 300 recordings of bedding attitudes and stereographic projections confirm that these Roubidoux folds are periclinal folds. They elongate along N59E to S59W, with the maximum shortening occurring along N60W to S60E. The uniformity of the fold orientations over this large distance is inconsistent with an origin by sag folding related to karst collapse. While the orientation of the shortening direction is inconsistent with the general trend of midcontinent deformation structures, two possible left-lateral strike-slip faults mapped to the north and south of the folding zone may have locally reoriented the stress field. This is supported by a simple 2D finite element model indicating that transpressional deformation in a restraining jog results in localized shortening direction consistent with the distribution field data.

It is concluded that a regional tectonic event induced localized buckle folding whereby local karst effects may have contributed in forming the initial perturbation"--Abstract, page iii.

Advisor(s)

Hogan, John Patrick

Committee Member(s)

Eckert, Andreas
Yang, Wan

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

M.S. in Geology and Geophysics

Sponsor(s)

Geological Society of America Research
Missouri University of Science and Technology

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2016

Pagination

ix, 60 pages

Note about bibliography

Includes bibliographical references (pages 55-59).

Geographic Coverage

Missouri

Rights

© 2016 Chao Liu

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Folds (Geology) -- Missouri -- AnalysisGeology, Structural -- MissouriSandstone -- MissouriFinite element method

Thesis Number

T 11038

Electronic OCLC #

974715844

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Thesis Location

 
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