Thesis
A Paleozoic accretion history: igneous and detrital zircon signatures of the Kulutingwak and Danish River formations in the Yelverton Inlet-Phillips Inlet region, Ellesmere Island, Nunavut, Canada
University of Iowa
Master of Science (MS), University of Iowa
Summer 2021
DOI: 10.25820/etd.006995
Abstract
Juxtaposition of the composite Pearya terrane with the northern Laurentian margin at Ellesmere Island, Nunavut, Canada is an understudied tectonic event that has significant ramifications for the tectonic histories of other crustal fragments in the circum-Arctic region during the Paleozoic. Two end member models for accretion currently exist: 1) translation and emplacement along a sinistral margin-parallel strike-slip system, or 2) orthogonal collision with the Laurentian margin. Current hypotheses regarding this accretionary event rely upon interpretation of the Kulutingwak formation, an Ordovician sedimentary package often identified as a subduction-related sequence, and the Danish River formation, a laterally continuous unit often cited as a post-accretionary overlap assemblage.
Geologic relationships present in the Yelverton Inlet-Phillips Inlet region offer a unique opportunity to understand this accretion event, where the Ordovician Kulutingwak formation separates the crystalline basement of the Pearya terrane from the Silurian Danish River formation. Seventeen igneous and detrital zircon samples were collected from this area for U-Pb and Lu-Hf analysis in order to better characterize the Paleozoic sedimentary packages which underpin current tectonic models. Detrital zircon age distributions from the Kulutingwak formation demonstrate a transition from signatures indicative of the Laurentian margin to those diagnostic of the Pearya terrane in the Late Ordovician. Detrital zircon signatures in the Danish River formation record a dynamic tectonic setting in the Silurian where distinct facies belts with variable provenance signals are preserved. Both units are disturbed by late translation along major northeast-southwest striking structures and included in structural assemblages, exposing the need for additional quantitative data in this complex tectonic system.
Details
- Title: Subtitle
- A Paleozoic accretion history: igneous and detrital zircon signatures of the Kulutingwak and Danish River formations in the Yelverton Inlet-Phillips Inlet region, Ellesmere Island, Nunavut, Canada
- Creators
- Megan M. Koch
- Contributors
- William C McClelland (Advisor)Jane A Gilotti (Committee Member)Karolina Kosminska (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Geoscience
- Date degree season
- Summer 2021
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.006995
- Number of pages
- vii, 129 pages
- Copyright
- Copyright 2021 Megan M. Koch
- Grants
- Grant note
- Additional funding was provided by a research-based grant from the University of Iowa Graduate and Professional Student Government, a Graduate Stanley Grant for International Research from University of Iowa International Programs, and the Earth and Environmental Sciences Department at the University of Iowa (Max and Lorraine Littlefield Fund).
- Language
- English
- Date submitted
- 06/25/2021
- Description illustrations
- illustrations, graphs, tables
- Description bibliographic
- Includes bibliographical references (pages 27-34).
- Public Abstract (ETD)
- The Pearya terrane of Ellesmere Island, Nunavut, Canada is an exotic crustal fragment that is currently hypothesized to have accreted to the North American margin sometime in the Paleozoic period of Earth history, approximately 450 million years ago. Due to a scarcity of data, the style and timing of this accretionary event are not well constrained, but two endmember models have emerged: 1) translation along margin-parallel strike slip faults, or 2) head-on collision with the North American margin. Both of the existing tectonic models rely upon interpretation of the Kulutingwak and Danish River formations of north-central Ellesmere Island. The Kulutingwak formation is a sedimentary package of rocks including marbles, siliciclastic sediments, volcanic flows, and serpentinites, which have previously been interpreted as related to subduction processes. The Danish River formation is a siliciclastic sedimentary formation which has been interpreted to either be involved in a subduction-related setting, or to overlap the post-collisional boundary between the Pearya terrane and North America. These rocks are best exposed in the Yelverton Inlet-Phillips Inlet region, where the Pearya terrane is in structural contact with the Kulutingwak formation, which is in turn in structural contact with the Danish River formation. In order to better understand the derivation and timing of deposition for these units, U-Pb radiometric dates and Lu-Hf geochemical analyses of igneous and detrital zircon were collected from seventeen samples in this area. These data demonstrate that the Kulutingwak formation is sourced by the North American margin until the Late Ordovician approximately 450 million years ago, when the approach of the Pearya terrane is recorded. These data also show that the Danish River formation has a complex history where many areas with different source components are preserved. Interpretation of the detrital zircon data obtained in this study is complicated by continued tectonic activity after the deposition of the Danish River formation, resulting in structural assemblages that contain blocks of Paleozoic sedimentary packages and reveals the need for future work in this multiphase tectonic system.
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984454542402771
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