Author ORCID Identifier

https://orcid.org/0000-0002-8608-2363

Date Available

7-3-2023

Year of Publication

2023

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Arts and Sciences

Department/School/Program

Earth and Environmental Sciences (Geology)

Advisor

Dr. Frank R. Ettensohn

Abstract

Divided between Norway and Russia, the Barents Sea shelf (BSS) is an ~1.4 million km2 Arctic province, containing significant hydrocarbon accumulations. However, much of the area is frontier, and geologic data are often restricted or unavailable. One strategy to mitigate lack of geologic data is the use of analogues from well-known, mature basins. Even though there have been attempts to use analogues to study the geology of the BSS, such use is limited. Moreover, no analogue, to my knowledge, has been capable of addressing the regional tectonostratigraphic development of the shelf as a whole.

In this research, the Appalachian system of basins and platforms and its included flexural stratigraphic sequences are defined as a tectonostratigraphic analogue, aiding the interpretation of BSS tectonostratigraphic evolution. Although temporally and paleogeographically different, both the Appalachian and BSS areas reflect collisional regimes, characterized by early subduction-related orogenies that concluded with a final collisional event. In the Appalachian foreland basin and adjacent intracratonic areas, each orogeny was defined by one or more, unconformity-bound, flexural stratigraphic sequences, called “tectophase” sequences.

The BSS tectonostratigraphic succession exhibits several unconformity-bound stratigraphic sequences that are comparable to tectophase sequences from the Appalachian area. These BSS sequences begin with black shales and end with molasse-like wedges of clastic sediments, which suggest flexural responses to orogeny. Much of this succession was deposited across structural elements that were likely reactivated by far-field responses to periods of Uralian–Pai–Khoi–Novaya Zemlya (Late Permian to Middle Jurassic) tectonism, involving the collision of Siberia-Kazakhstania with northern Baltican parts of Pangea. This widespread structural reactivation is discussed herein by applying the backstripping method for analysis of structural mechanisms, based on sediment thicknesses across various BSS structural elements. As in the Appalachian area, BSS structural reactivation occurred in various ways and times during ongoing Uralian–Pai–Khoi–Novaya Zemlya tectonism. In this context, the only part of the BSS collisional succession with sufficient lithologic data for regional studies is the Upper Triassic–Lower Jurassic (Carnian–Hettangian) stratigraphic succession. This succession includes erosional surfaces, as well as open-marine, marginal-marine and fluvio-deltaic deposits, and the varying nature and thicknesses of these sediments across the several BSS structural elements suggest far-field reactivation by the coeval Novaya Zemlya Orogeny.

The Appalachian tectophase cycle is herein used to define pulses (tectophases) of deformational loading and possible sedimentary responses to foreland-basin and forebulge development. Although many BSS models suggest that tectonism in the area did not begin until the Late Triassic–Early Jurassic transition, sedimentary responses similar to those in the Appalachian tectophase model suggest that tectonism may have begun as early as Late Triassic (Norian) time. Even though many questions remain, the use of analogues external to the BSS, has not been a widespread practice. However, mature collisional settings like the Appalachian and BSS areas typically exhibit similar large-scale processes, meaning that analogues from one may provide new sources of information about the other.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2023.374

Funding Information

This study was supported by the Norwegian Petroleum Directorate (contract no.: 2190) from 2020 to 2023.

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