Date of Award
Summer 6-10-2025
Document Type
Thesis (Ph.D.)
Department or Program
Earth Sciences
First Advisor
Dr. Justin Strauss
Abstract
The study of the Neoproterozoic sedimentary record is often challenged by the limited temporal constraints and inherent ambiguity commonly associated with the geological record. An improved understanding of the profound changes in this dynamic period in Earth’s history requires robust treatments of uncertainties as well as detailed and comprehensive approaches to interpreting the sedimentary archive. For my doctoral dissertation, I employ quantitative basin analysis techniques along with integrated sedimentological and stratigraphic analyses to advance our understanding of the two critical Neoproterozoic extensional basins.
For the first chapter of my dissertation, I developed a novel Bayesian age-depth modeling program, SubsidenceChron.jl, designed for extensional sedimentary basins. This program incorporates and propagates uncertainties in various model inputs, notably the lithology-dependent parameters and age constraints, under a Bayesian framework. This statistically robust tool was then applied to the Tonian Akademikerbreen Group in Svalbard, Norway. With the addition of two new radiometric dates, I constructed an age model with appropriate uncertainties for this succession and provided age predictions that confirmed previously hypothesized chemostratigraphic correlations.
My doctoral research then pivots to the Neoproterozoic strata of the southern Great Basin, western Laurentia. For the second chapter, I performed integrated sedimentological and stratigraphic analyses on the less-studied late Ediacaran Reed Dolomite in the White-Inyo Mountains and Esmeralda County region. Specifically, I constrained the platform geometry while proposing a new regional correlation framework. This study also provided the first radiometric age constraint for Precambrian strata in this region (i.e., a maximum depositional age of 542.60 ± 0.30 Ma for the Hines Tongue) and revealed new biostratigraphically-significant fossil occurrences (Cloudinid).
Finally, the updated SubsidenceChron.jl was employed to re-examine the Neoproterozoic to early Paleozoic subsidence history of the southwestern Laurentian margin. The analysis supports protracted and polyphase extension, and predicts an earliest Cambrian timing for transition from active rifting to thermal subsidence, while highlighting the critical role of uncertainty treatment. Overall, my doctoral research bridges gaps in our understanding of key Neoproterozoic basins and provides a foundational quantitative tool for future subsidence analyses.
Recommended Citation
Zhang, Tianran, "Reconstructing Neoproterozoic rift basins in Laurentia through sedimentology, stratigraphy and subsidence analyses" (2025). Dartmouth College Ph.D Dissertations. 417.
https://digitalcommons.dartmouth.edu/dissertations/417
Included in
Geology Commons, Other Earth Sciences Commons, Sedimentology Commons, Stratigraphy Commons
