UWSpace is currently experiencing technical difficulties resulting from its recent migration to a new version of its software. These technical issues are not affecting the submission and browse features of the site. UWaterloo community members may continue submitting items to UWSpace. We apologize for the inconvenience, and are actively working to resolve these technical issues.
 

An expanded shale δ98Mo record permits recurrent shallow marine oxygenation during the Neoarchean

Simple item page
dc.contributor.authorOstrander, Chadlin
dc.contributor.authorKendall, Brian
dc.contributor.authorOlson, Stephanie
dc.contributor.authorLyons, Timothy
dc.contributor.authorGordon, Gwyneth
dc.contributor.authorRomaniello, Stephen
dc.contributor.authorZheng, Wang
dc.contributor.authorReinhard, Christopher
dc.contributor.authorRoy, Moutusi
dc.contributor.authorAnbar, Ariel
dc.date.accessioned2020-07-02T16:10:24Z
dc.date.available2020-07-02T16:10:24Z
dc.date.issued2020-01-20
dc.description.abstractMultiple attempts have been made using the ancient shale record to track the molybdenum isotope composition (δ98Mo) of seawater during the final two-hundred million years of the Archean Eon (2.7 to 2.5 billion-years-ago, or Ga). This seawater δ98Mo value is important because it should have scaled with levels of ocean oxygenation during the runup to the Great Oxidation Event (GOE). Unfortunately, however, it is difficult to tell if the majority of the existing late-Archean shale δ98Mo record tracks an ancient seawater value. Here, we further attempt to track pre-GOE seawater δ98Mo using an expanded and well-characterized shale sample set from Western Australia (Jeerinah, Wittenoom, and Mt. Sylvia formations) and South Africa (Nauga and Klein Naute formations). Most importantly, and in contrast to most previous Mo isotope studies of similarly aged shales, local redox conditions for our shales have been independently constrained using the iron (Fe) speciation proxy and bottom water Mo contents at the time of deposition have been qualitatively estimated using Mo/TOC ratios. Local redox conditions and bottom water Mo availability are important parameters because transfer of the seawater δ98Mo to sediments today is shown to be dependent on these conditions. According to our updated sedimentary δ98Mo record, seawater δ98Mo commonly exceeded 1.0‰ between ~2.69 Ga and 2.50 Ga. In order to drive such a heavy seawater δ98Mo, there must have been a marine sink with a strong preference for lighter-mass Mo isotopes frequently present over this timeframe. The operation of some anaerobic processes in late-Archean marine settings could theoretically explain the heavier seawater δ98Mo. Such processes are known to promote the preferential retention of lighter-mass Mo isotopes in marine sediments today (e.g., interactions between Mo and organic matter or the formation of thio-complexes). Alternatively, or in addition, adsorption of lighter-mass Mo isotopes to Fe and Mn oxide minerals formed in oxygenated marine environments can explain the heavier seawater δ98Mo. A compilation of previous work suggests that oxygenated shallow marine environments were fairly common during the late-Archean, and thus Mo adsorption to Fe-Mn oxides formed in these settings probably played an important role in driving heavy seawater δ98Mo over this timeframe.en
dc.description.sponsorshipNSERC Discovery Grant RGPIN-435930en
dc.identifier.urihttp://hdl.handle.net/10012/16023
dc.language.isoenen
dc.publisherElsevieren
dc.titleAn expanded shale δ98Mo record permits recurrent shallow marine oxygenation during the Neoarcheanen
dc.typeArticleen
dcterms.bibliographicCitationOstrander C.M., Kendall B., Olson S.L., Lyons T.W., Gordon G.W., Romaniello S.J., Zheng W., Reinhard C.T., Roy M., Anbar A.D., 2020. An expanded shale δ98Mo record permits recurrent shallow marine oxygenation during the Neoarchean. Chemical Geology, v. 532, #119391.en
uws.contributor.affiliation1Faculty of Scienceen
uws.contributor.affiliation2Earth and Environmental Sciencesen
uws.peerReviewStatusRevieweden
uws.scholarLevelFacultyen
uws.typeOfResourceTexten

Files

Original bundle
Now showing 1 - 2 of 2
Thumbnail Image
Name:
Accepted Pre-Proof.pdf
Size:
7.69 MB
Format:
Adobe Portable Document Format
Description:
Main article
Download
No Thumbnail Available
Name:
36 - Ostrander et al. (2020) Chemical Geology Data.xlsx
Size:
90.42 KB
Format:
Microsoft Excel XML
Description:
Data
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
4.47 KB
Format:
Item-specific license agreed upon to submission
Description:
Download

Collections

Waterloo Research
Earth and Environmental Sciences