Theses and Dissertations
Issuing Body
Mississippi State University
Advisor
Skarke, Adam
Committee Member
Kirkland, Brenda L.
Committee Member
Rodgers, John C.
Committee Member
Gabitov, Rinat I.
Committee Member
Dash, Padmanava
Date of Degree
4-30-2021
Original embargo terms
Visible to MSU only for 1 year
Document Type
Dissertation - Open Access
Major
Earth and Atmospheric Sciences
Degree Name
Doctor of Philosophy
Degree Name
Doctor of Philosophy (Ph.D)
College
College of Arts and Sciences
College
College of Arts and Sciences
Department
Department of Geosciences
Department
Department of Geosciences
Abstract
The colloquially named leopard rock of the Holder and Laborcita formations (Late Pennsylvanian-Early Permian) is an algal/foraminiferal boundstone that occurs within a cyclic, interfingered, carbonate siliciclastic system in the Sacramento Mountains of southeastern New Mexico) and often accompanies phylloid algal mounds. This project is the first to fully characterize and evaluate the evidence that leopard rock is microbial in origin and assess the potential influence of methane seeps and deltaic organics on its genesis. Characterization of the algal-foraminiferal boundstone revealed a highly variable expression in outcrop based on geolocated photo imagery, hand samples, optical microscopy, and scanning electron microscopy (SEM) data. Leopard rock is interpreted as microbial in origin based upon all features observed in aggregate, particularly upward-oriented concentric gradational laminae and striking clusters of segmented curvilinear cylinders (~1000 nm long). Leopard rock is best described as thrombolytic. A comprehensive categorization into thrombolite types was conducted and field and analytical data were used in creating a geospatial data base. The data was evaluated spatially in ArcMap for co-occurrence, trends, and possible associations within, and between, categorizations and formations. Distribution and associations of dome (1-3 m), small coniform (< 1 m), and planar outcrop structures and thrombolite types reflect a hierarchy of complexity and prevalence that would be expected from a microbial system. An extensive multi-scale feature comparison of potential modern analogues from Australia, the Bahamas, and Canada, in conjunction with contiguous paleo-analogues, support the interpretation of a highly adaptable complex microbial ecosystem. Results were also consistent within the global chemical, biologic, and physical context at the time of deposition. Evidence for methane seep contribution support the plausibility of supplemental microbial energy sources based on modern examples and limited paleo-analogues. Stratigraphic position and a paucity of data do not support a significant role for deltaic bathymetry or organic influx in leopard rock genesis. The results of this study provide robust evidence that leopard rock is a multi-faceted complex microbial thrombolite that displays a continuum of expression not represented by one all-encompassing term and illustrates the value of multi-parameter analyses augmented across time and space using analogues and geospatial software.
Recommended Citation
Tischler, Keith Louris, "The role of microbes and organic matter in the genesis of complex carbonate facies and lithologies referred to as leopard rock, Sacramento Mountains, New Mexico" (2021). Theses and Dissertations. 5154.
https://scholarsjunction.msstate.edu/td/5154