Doctoral Dissertations

Keywords and Phrases

38th parallel; impact clustering; Orange Basin; Ordovician Meteor Event; palynology; terrestrial impact


"The unique alignment of the Decaturville, Crooked Creek, and Weaubleau geological structures in central Missouri, three of nine known such structures along the 38th parallel in Illinois, Missouri, and Kansas, has puzzled geoscientists for decades. Research using palynology (palynomorphs and particulate organic matter) and radiometric dating of impact spherules were used to constrain age and a relationship between these enigmatic structures and infer their paleoenvironmental conditions. Novel melting damages, unique to impact, were documented in the palynomorphs in all the three structures. Early Ordovician acritarchs with melted processes correlate with 40Ar-39Ar stepwise heating age of impact spherules from the Crooked Creek structure. This age is coeval with a large clustering event that was responsible for other craters in North America and globally during the Ordovician. The presence of melted acritarchs and palynological material of mixed ages and environments reflect the effects of meteorite impact on the sedimentary environments and stratigraphy.

Another study utilized the palynomorph, palynofacies and foraminiferal contents of 43 samples from four wells in the Orange Basin located offshore western South Africa. The aim was to constrain paleoenvironmental conditions and evaluate the hydrocarbon potential of an understudied area of this offshore frontier basin. Key biostratigraphic and palynofacies information provided evidence for a Cenomanian age for the studied interval, inner to middle shelf settings, and an arid hinterland at the time of deposition of the studied interval. This case study also suggested that the sediments were characterized primarily by gas-prone type III kerogen and some oil-prone type II kerogen"--Abstract, p. iv


Oboh-Ikuenobe, Francisca E.

Committee Member(s)

Warny, Sophie
Gertsch, Leslie
Yang, Wan
Obrist-Farner, Jonathan


Geosciences and Geological and Petroleum Engineering

Degree Name

Ph. D. in Geology and Geophysics


Missouri University of Science and Technology

Publication Date

Spring 2023


xii, 111 pages

Note about bibliography

Includes_bibliographical_references_(pages 16, 43 and 86)


© 2023 Marissa Kay Spencer, All Rights Reserved

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 12263

Electronic OCLC #