Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada

Degree: Master of Science Abstract: The Wombat pipe (64.918° N, 110.447° W) is a diamondiferous kimberlite in the Lac de Gras kimberlite field of Northwest Territories, Canada. Two drill cores, CH93-29 and 00-05, intersect the Wombat crater facies and include 195 m of well preserved, undisturbed lak...

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Bibliographic Details
Main Author: Buryak, Serhiy D.
Other Authors: Reyes, Alberto (Earth and Atmospheric Sciences)
Format: Thesis
Language:English
Published: University of Alberta. Department of Earth and Atmospheric Sciences. 2020
Subjects:
geo
Online Access:https://era.library.ualberta.ca/items/09f7d682-55e3-429d-91af-b20f276b6f6b
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spelling fttriple:oai:gotriple.eu:10670/1.cz2n73 2023-05-15T17:46:47+02:00 Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada Buryak, Serhiy D. Reyes, Alberto (Earth and Atmospheric Sciences) 2020-01-23 https://era.library.ualberta.ca/items/09f7d682-55e3-429d-91af-b20f276b6f6b en eng University of Alberta. Department of Earth and Atmospheric Sciences. 10670/1.cz2n73 https://era.library.ualberta.ca/items/09f7d682-55e3-429d-91af-b20f276b6f6b undefined ERA : Education and Research Archive geo anthro-bio Thesis https://vocabularies.coar-repositories.org/resource_types/c_46ec/ 2020 fttriple 2023-01-22T17:28:40Z Degree: Master of Science Abstract: The Wombat pipe (64.918° N, 110.447° W) is a diamondiferous kimberlite in the Lac de Gras kimberlite field of Northwest Territories, Canada. Two drill cores, CH93-29 and 00-05, intersect the Wombat crater facies and include 195 m of well preserved, undisturbed lake sediment fill. Bulk sediment elemental analysis, C isotope composition, and Rock-Eval pyrolysis together with inferences from microfossils, are used to characterize conditions of sedimentation and paleoenvironmental variability in the maar lake. Bulk sediment C/N, hydrogen index (HI), and d13C indicate material derived from C3 land plants dominates the sedimentary organic matter, with a possible minor algal contribution. The d13C values range from -25.3 ‰ to -30.2 ‰ and C/N ratios vary between 14.6 and 38.4, recording the shifts in the proportions of land-derived material and algal organic matter as climate conditions fluctuated. Eighteen samples analyzed by Rock-Eval pyrolysis all plot in the Type III kerogen field for HI vs. Tmax, with average Tmax values ~425 °C indicative of the low thermal maturity of organic matter. Total organic carbon (TOC) averages 3.6 wt% and average total carbonate content is 14.1 wt%, indicating bottom water anoxia and substantial carbonate input from weathering of overlying carbonate cover rocks, respectively. Together with well-preserved freshwater microfossils (e.g. diatoms, chrysophytes, synurophytes), the results indicate deposition in a non-marine setting, likely during a period of regression of the Western Interior Seaway. The age of the Wombat maar lake sediments is determined using MC-LA-ICP-MS U-Pb zircon geochronology from two distal rhyolitic tephra beds found in the core 00-05, yielding a date of 82.36 ± 0.44 Ma (n = 18/34, MSWD = 1.51). This minimum age suggests that Wombat kimberlite pipe emplacement occurred during the Late Cretaceous, with sedimentation in the maar beginning shortly thereafter. The major and trace element geochemical analysis of the tephra glasses allows ... Thesis Northwest Territories Subarctic Unknown Canada Lac de Gras ENVELOPE(-110.501,-110.501,64.500,64.500) Northwest Territories
institution Open Polar
collection Unknown
op_collection_id fttriple
language English
topic geo
anthro-bio
spellingShingle geo
anthro-bio
Buryak, Serhiy D.
Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada
topic_facet geo
anthro-bio
description Degree: Master of Science Abstract: The Wombat pipe (64.918° N, 110.447° W) is a diamondiferous kimberlite in the Lac de Gras kimberlite field of Northwest Territories, Canada. Two drill cores, CH93-29 and 00-05, intersect the Wombat crater facies and include 195 m of well preserved, undisturbed lake sediment fill. Bulk sediment elemental analysis, C isotope composition, and Rock-Eval pyrolysis together with inferences from microfossils, are used to characterize conditions of sedimentation and paleoenvironmental variability in the maar lake. Bulk sediment C/N, hydrogen index (HI), and d13C indicate material derived from C3 land plants dominates the sedimentary organic matter, with a possible minor algal contribution. The d13C values range from -25.3 ‰ to -30.2 ‰ and C/N ratios vary between 14.6 and 38.4, recording the shifts in the proportions of land-derived material and algal organic matter as climate conditions fluctuated. Eighteen samples analyzed by Rock-Eval pyrolysis all plot in the Type III kerogen field for HI vs. Tmax, with average Tmax values ~425 °C indicative of the low thermal maturity of organic matter. Total organic carbon (TOC) averages 3.6 wt% and average total carbonate content is 14.1 wt%, indicating bottom water anoxia and substantial carbonate input from weathering of overlying carbonate cover rocks, respectively. Together with well-preserved freshwater microfossils (e.g. diatoms, chrysophytes, synurophytes), the results indicate deposition in a non-marine setting, likely during a period of regression of the Western Interior Seaway. The age of the Wombat maar lake sediments is determined using MC-LA-ICP-MS U-Pb zircon geochronology from two distal rhyolitic tephra beds found in the core 00-05, yielding a date of 82.36 ± 0.44 Ma (n = 18/34, MSWD = 1.51). This minimum age suggests that Wombat kimberlite pipe emplacement occurred during the Late Cretaceous, with sedimentation in the maar beginning shortly thereafter. The major and trace element geochemical analysis of the tephra glasses allows ...
author2 Reyes, Alberto (Earth and Atmospheric Sciences)
format Thesis
author Buryak, Serhiy D.
author_facet Buryak, Serhiy D.
author_sort Buryak, Serhiy D.
title Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada
title_short Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada
title_full Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada
title_fullStr Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada
title_full_unstemmed Geochronology and bulk sediment geochemistry of the Late Cretaceous maar lake sedimentary fill of the Wombat kimberlite pipe, subarctic Canada
title_sort geochronology and bulk sediment geochemistry of the late cretaceous maar lake sedimentary fill of the wombat kimberlite pipe, subarctic canada
publisher University of Alberta. Department of Earth and Atmospheric Sciences.
publishDate 2020
url https://era.library.ualberta.ca/items/09f7d682-55e3-429d-91af-b20f276b6f6b
long_lat ENVELOPE(-110.501,-110.501,64.500,64.500)
geographic Canada
Lac de Gras
Northwest Territories
geographic_facet Canada
Lac de Gras
Northwest Territories
genre Northwest Territories
Subarctic
genre_facet Northwest Territories
Subarctic
op_source ERA : Education and Research Archive
op_relation 10670/1.cz2n73
https://era.library.ualberta.ca/items/09f7d682-55e3-429d-91af-b20f276b6f6b
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