Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils
The Re-Os radiogenic isotope system has over the past three decades been successfully applied to organic-rich sedimentary rocks and oils as a geochronometer and geochemical tracer. The Re-Os geochronometer has provided a direct way of constraining the depositional age of organic-rich sediments as we...
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ftvictoriauwfig:oai:figshare.com:article/17151119 2023-05-15T17:38:00+02:00 Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils Enock Rotich 2020-01-01T00:00:00Z https://doi.org/10.26686/wgtn.17151119.v1 https://figshare.com/articles/thesis/Rhenium-osmium_geochronology_and_isotopic_systematics_in_New_Zealand_source_rocks_and_oils/17151119 unknown doi:10.26686/wgtn.17151119.v1 https://figshare.com/articles/thesis/Rhenium-osmium_geochronology_and_isotopic_systematics_in_New_Zealand_source_rocks_and_oils/17151119 Author Retains Copyright Isotope Geochemistry Geochronology Petroleum and Coal Geology Rhenium Osmium Source rocks Oils Isotopes Taranaki Basin East Coast Basin Coals School: School of Geography Environment and Earth Sciences 040203 Isotope Geochemistry 040309 Petroleum and Coal Geology 040303 Geochronology 850103 Oil and Gas Exploration Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy Text Thesis 2020 ftvictoriauwfig https://doi.org/10.26686/wgtn.17151119.v1 2021-12-16T00:03:58Z The Re-Os radiogenic isotope system has over the past three decades been successfully applied to organic-rich sedimentary rocks and oils as a geochronometer and geochemical tracer. The Re-Os geochronometer has provided a direct way of constraining the depositional age of organic-rich sediments as well as the timing of oil generation events. Osmium isotopic compositions have further been utilised in understanding past climatic, oceanographic and geological events recorded in sediments, and in correlating oils to their source. Thus far, however, Re-Os studies of organic-rich sediments have mainly focused on marine black shales where Re and Os are primarily sourced from seawater. The work presented in this thesis seeks to investigate factors controlling Re-Os systematics and potential for geochronology in a range of fluvio-deltaic coaly rocks and terrestrial organic matter-dominated marine sediments, and associated oils from New Zealand’s Taranaki and East Coast basins. The Re-Os data presented here yield the first radiometric age for the late Paleocene Waipawa Formation (57.5 ± 3.5 Ma), a marine sedimentary unit that was formed by episodic input of large amounts of terrestrial woody plant matter resulting in high average sedimentation rates of up to ~10.6 cm/ky. This age is consistent with available biostratigraphic age determinations. The formation possesses Re (38.9 ± 17.6 ppb) and Os (526 ± 75.8 ppt) concentrations similar to those found in typical marine sediments containing amorphous organic matter deposited under much lower sedimentation rates. This indicates that organic matter type and sedimentation rate may not play a significant role in sequestration of these elements in organic-rich sediments. Unlike the Waipawa Formation, coals and coaly mudstones with varying degrees of marine influence (purely terrestrial to strongly marine-influenced) from the Rakopi, North Cape, Farewell and Mangahewa formations record low average Re (0.37 ± 0.25 ppb) and Os (24.5 ± 11.9 ppt) concentrations. These concentrations ... Thesis North Cape Open Access Victoria University of Wellington / Te Herenga Waka New Zealand North Cape ENVELOPE(165.700,165.700,-70.650,-70.650) |
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Open Access Victoria University of Wellington / Te Herenga Waka |
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ftvictoriauwfig |
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unknown |
topic |
Isotope Geochemistry Geochronology Petroleum and Coal Geology Rhenium Osmium Source rocks Oils Isotopes Taranaki Basin East Coast Basin Coals School: School of Geography Environment and Earth Sciences 040203 Isotope Geochemistry 040309 Petroleum and Coal Geology 040303 Geochronology 850103 Oil and Gas Exploration Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy |
spellingShingle |
Isotope Geochemistry Geochronology Petroleum and Coal Geology Rhenium Osmium Source rocks Oils Isotopes Taranaki Basin East Coast Basin Coals School: School of Geography Environment and Earth Sciences 040203 Isotope Geochemistry 040309 Petroleum and Coal Geology 040303 Geochronology 850103 Oil and Gas Exploration Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy Enock Rotich Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils |
topic_facet |
Isotope Geochemistry Geochronology Petroleum and Coal Geology Rhenium Osmium Source rocks Oils Isotopes Taranaki Basin East Coast Basin Coals School: School of Geography Environment and Earth Sciences 040203 Isotope Geochemistry 040309 Petroleum and Coal Geology 040303 Geochronology 850103 Oil and Gas Exploration Degree Discipline: Geology Degree Level: Doctoral Degree Name: Doctor of Philosophy |
description |
The Re-Os radiogenic isotope system has over the past three decades been successfully applied to organic-rich sedimentary rocks and oils as a geochronometer and geochemical tracer. The Re-Os geochronometer has provided a direct way of constraining the depositional age of organic-rich sediments as well as the timing of oil generation events. Osmium isotopic compositions have further been utilised in understanding past climatic, oceanographic and geological events recorded in sediments, and in correlating oils to their source. Thus far, however, Re-Os studies of organic-rich sediments have mainly focused on marine black shales where Re and Os are primarily sourced from seawater. The work presented in this thesis seeks to investigate factors controlling Re-Os systematics and potential for geochronology in a range of fluvio-deltaic coaly rocks and terrestrial organic matter-dominated marine sediments, and associated oils from New Zealand’s Taranaki and East Coast basins. The Re-Os data presented here yield the first radiometric age for the late Paleocene Waipawa Formation (57.5 ± 3.5 Ma), a marine sedimentary unit that was formed by episodic input of large amounts of terrestrial woody plant matter resulting in high average sedimentation rates of up to ~10.6 cm/ky. This age is consistent with available biostratigraphic age determinations. The formation possesses Re (38.9 ± 17.6 ppb) and Os (526 ± 75.8 ppt) concentrations similar to those found in typical marine sediments containing amorphous organic matter deposited under much lower sedimentation rates. This indicates that organic matter type and sedimentation rate may not play a significant role in sequestration of these elements in organic-rich sediments. Unlike the Waipawa Formation, coals and coaly mudstones with varying degrees of marine influence (purely terrestrial to strongly marine-influenced) from the Rakopi, North Cape, Farewell and Mangahewa formations record low average Re (0.37 ± 0.25 ppb) and Os (24.5 ± 11.9 ppt) concentrations. These concentrations ... |
format |
Thesis |
author |
Enock Rotich |
author_facet |
Enock Rotich |
author_sort |
Enock Rotich |
title |
Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils |
title_short |
Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils |
title_full |
Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils |
title_fullStr |
Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils |
title_full_unstemmed |
Rhenium-osmium geochronology and isotopic systematics in New Zealand source rocks and oils |
title_sort |
rhenium-osmium geochronology and isotopic systematics in new zealand source rocks and oils |
publishDate |
2020 |
url |
https://doi.org/10.26686/wgtn.17151119.v1 https://figshare.com/articles/thesis/Rhenium-osmium_geochronology_and_isotopic_systematics_in_New_Zealand_source_rocks_and_oils/17151119 |
long_lat |
ENVELOPE(165.700,165.700,-70.650,-70.650) |
geographic |
New Zealand North Cape |
geographic_facet |
New Zealand North Cape |
genre |
North Cape |
genre_facet |
North Cape |
op_relation |
doi:10.26686/wgtn.17151119.v1 https://figshare.com/articles/thesis/Rhenium-osmium_geochronology_and_isotopic_systematics_in_New_Zealand_source_rocks_and_oils/17151119 |
op_rights |
Author Retains Copyright |
op_doi |
https://doi.org/10.26686/wgtn.17151119.v1 |
_version_ |
1766138221108920320 |