Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years
abstract: Iron (Fe) scarcity limits biological productivity in high-nutrient low-chlorophyll (HNLC) ocean regions. Thus, the input, output and abundance of Fe in seawater likely played a critical role in shaping the development of modern marine ecosystems and perhaps even contributed to past changes...
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ftarizonastateun:item:48122 2023-05-15T18:25:56+02:00 Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years Tegler, Logan Ashley (Author) Anbar, Ariel (Thesis Director) Herckes, Pierre (Committee Member) Romaniello, Stephen (Committee Member) Department of English School of Molecular Sciences Barrett, The Honors College 2018-05 14 pages http://hdl.handle.net/2286/R.I.48122 eng eng Academic Year 2017-2018 http://hdl.handle.net/2286/R.I.48122 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved Geochemistry Isotopes Global Climate Change Chemical Oceanography Chemistry Marine Geology Text 2018 ftarizonastateun 2019-04-06T22:51:57Z abstract: Iron (Fe) scarcity limits biological productivity in high-nutrient low-chlorophyll (HNLC) ocean regions. Thus, the input, output and abundance of Fe in seawater likely played a critical role in shaping the development of modern marine ecosystems and perhaps even contributed to past changes in Earth’s climate. Three sources of Fe—wind-blown dust, hydrothermal activity, and sediment dissolution—carry distinct Fe isotopic fingerprints, and can therefore be used to track Fe source variability through time. However, establishing the timing of this source variability through Earth’s history remains challenging because the major depocenters for dissolved Fe in the ocean lack well-established chronologies. This is due to the fact that they are difficult to date with traditional techniques such as biostratigraphy and radiometric dating. Here, I develop age models for sediments collected from the International Drilling Program Expedition 329 by measuring the Os (osmium) isotopic composition of the hydrogenous portion of the clays. These extractions enable dating of the clays by aligning the Os isotope patterns observed in the clays to those in a reference curve with absolute age constraints through the Cenozoic. Our preliminary data enable future development of chronologies for three sediment cores from the high-latitude South Pacific and Southern Oceans, and demonstrate a wider utility of this method to establish age constraints on pelagic sediments worldwide. Moreover, the preliminary Os isotopic data provides a critical first step needed to examine the changes in Fe (iron) sources and cycling on millions of years timescales. Fe isotopic analysis was conducted at the same sites in the South Pacific and demonstrates that there are significant changes in the sources of Fe to the Southern Ocean over the last 90 Ma. These results lay the groundwork for the exploration of basin-scale sources to Fe source changes, which will have implications for understanding how biological productivity relates to Fe source variability over geological timescales. Text Southern Ocean Arizona State University: ASU Digital Repository Pacific Southern Ocean |
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Open Polar |
collection |
Arizona State University: ASU Digital Repository |
op_collection_id |
ftarizonastateun |
language |
English |
topic |
Geochemistry Isotopes Global Climate Change Chemical Oceanography Chemistry Marine Geology |
spellingShingle |
Geochemistry Isotopes Global Climate Change Chemical Oceanography Chemistry Marine Geology Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years |
topic_facet |
Geochemistry Isotopes Global Climate Change Chemical Oceanography Chemistry Marine Geology |
description |
abstract: Iron (Fe) scarcity limits biological productivity in high-nutrient low-chlorophyll (HNLC) ocean regions. Thus, the input, output and abundance of Fe in seawater likely played a critical role in shaping the development of modern marine ecosystems and perhaps even contributed to past changes in Earth’s climate. Three sources of Fe—wind-blown dust, hydrothermal activity, and sediment dissolution—carry distinct Fe isotopic fingerprints, and can therefore be used to track Fe source variability through time. However, establishing the timing of this source variability through Earth’s history remains challenging because the major depocenters for dissolved Fe in the ocean lack well-established chronologies. This is due to the fact that they are difficult to date with traditional techniques such as biostratigraphy and radiometric dating. Here, I develop age models for sediments collected from the International Drilling Program Expedition 329 by measuring the Os (osmium) isotopic composition of the hydrogenous portion of the clays. These extractions enable dating of the clays by aligning the Os isotope patterns observed in the clays to those in a reference curve with absolute age constraints through the Cenozoic. Our preliminary data enable future development of chronologies for three sediment cores from the high-latitude South Pacific and Southern Oceans, and demonstrate a wider utility of this method to establish age constraints on pelagic sediments worldwide. Moreover, the preliminary Os isotopic data provides a critical first step needed to examine the changes in Fe (iron) sources and cycling on millions of years timescales. Fe isotopic analysis was conducted at the same sites in the South Pacific and demonstrates that there are significant changes in the sources of Fe to the Southern Ocean over the last 90 Ma. These results lay the groundwork for the exploration of basin-scale sources to Fe source changes, which will have implications for understanding how biological productivity relates to Fe source variability over geological timescales. |
author2 |
Tegler, Logan Ashley (Author) Anbar, Ariel (Thesis Director) Herckes, Pierre (Committee Member) Romaniello, Stephen (Committee Member) Department of English School of Molecular Sciences Barrett, The Honors College |
format |
Text |
title |
Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years |
title_short |
Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years |
title_full |
Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years |
title_fullStr |
Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years |
title_full_unstemmed |
Dating Deep-Sea Pelagic Clays with Osmium Isotopes to Reconstruct Sources of Iron to the South Pacific Gyre over 90 Million Years |
title_sort |
dating deep-sea pelagic clays with osmium isotopes to reconstruct sources of iron to the south pacific gyre over 90 million years |
publishDate |
2018 |
url |
http://hdl.handle.net/2286/R.I.48122 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
Academic Year 2017-2018 http://hdl.handle.net/2286/R.I.48122 |
op_rights |
http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved |
_version_ |
1766207666661621760 |