Thallium isotope evidence for a permanent increase in marine organic carbon export in the early Eocene

Nielsen, Sune G.; Mar-Gerrison, Sarah; Gannoun, Abdelmouhcine; LaRowe, Douglas E.; Klemm, Veronika; Halliday, Alex N.; Burton, Kevin W.; Hein, James R.

doi:10.1016/j.epsl.2008.12.010

Cited by 117 publications

(131 citation statements)

References 60 publications

Supporting

Mentioning

117

Contrasting

Unclassified

Order By: Relevance

“…Assuming that the vent systems at 9°N-10°N along the East Pacific Rise (EPR) remained active during the Oligocene, and that the predominantly east-to-west geostrophic flow at these depths also persisted at this time (60), it is conceivable that CD29-2 simply moved through a distal plume of hydrothermally influenced deep waters. Since there are no textural or elemental indications of hydrothermal input to CD29-2 at this-or any other-time (18) during its ∼76-My growth history (22), the Fe isotopic systematics of CD29-2 require an unprecedented degree of Fe isotopic source modification to waters bathing CD29-2 during this epoch. However, testing whether or not this isotopically heavy Fe reflects a Pacific basin-wide increase in hydrothermally derived Fe during the Oligocene, or simply a local phenomenon, will require a better spatial resolution of seawater δ 56=54 Fe from other Fe−Mn crusts in the region.…”

Section: Cd29-2 Latitude (°)mentioning

confidence: 99%

“…Sample CD29-2 has an average growth rate of ∼1.4 mm·My −1 (22), with each discrete sample for δ 56=54 Fe (between 0.2 and 0.5 mm) integrating between 140 and 350 ky of Earth history. Since the residence time of dissolved Fe in the deep ocean [∼270 y (23)] is less than the mixing time of the oceans [∼1,000 y (24)], our record provides a local history of the central Pacific, rather than of global seawater…”

mentioning

confidence: 99%

See 1 more Smart Citation

Persistence of deeply sourced iron in the Pacific Ocean

Horner¹,

Williams

Hein

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe−Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface.

show abstract

Section: Cd29-2 Latitude (°)mentioning

confidence: 99%

mentioning

confidence: 99%

Persistence of deeply sourced iron in the Pacific Ocean

Horner¹,

Williams

Hein

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…If this increase was as gradual as MKD13 or D11-1 over a time scale of more than 10 Ma, this would yield a growth rate for MDD53 of less than 0.5 mm/Ma, an extremely low growth rate never reported for hydrogenic ferromanganese crusts (the reported growth rates are usually 1-15 mm/Ma [37,41,54]). In addition, Figure 3 Plot of ε Nd values versus age of the Pacific ferromanganese crusts (Nd isotope data for D11-1 is from Ling et al [6], and the age data is based on 10 Be dating and minorly revised according to Tl isotope stratigraphy [53]; data for Tasman is from van de Flierdt et al [19]). …”

Section: Resultsmentioning

confidence: 99%

“…(a) Shallower crust MKD13 and D11-1 (Nd isotope data for D11-1 is from Ling et al [6], and the age data is based on 10 Be dating and minorly revised according to Tl isotope stratigraphy [53]). (b) Deeper cust MDD53 and carbonate fraction of the western equatorial sediment core Site 807 [55].…”

Section: Closing Of Indonesian Gateway To Surface-and Mid-water Exchamentioning

confidence: 99%

Late Cenozoic history of deep water circulation in the western North Pacific: Evidence from Nd isotopes of ferromanganese crusts

Chen

2012

Chin. Sci. Bull.

View full text Add to dashboard Cite

“…1). Temporal changes of the marine Tl isotope ratio are most likely controlled solely by the ratio between the two marine output fluxes (Nielsen et al, 2009a), which display highly fractionated and contrasting Tl isotope compositions (Nielsen et al, 2006;Rehkämper et al, 2002). The two output fluxes are 1) scavenging by authigenic ferromanganese (Fe-Mn) oxy-hydroxides and 2) uptake of Tl during low temperature (low-T) alteration of oceanic crust.…”

Section: Introductionmentioning

confidence: 99%

Thallium isotopes in early diagenetic pyrite – A paleoredox proxy?

Nielsen

Goff

Hesselbo

et al. 2011

Geochimica et Cosmochimica Acta

Self Cite

View full text Add to dashboard Cite

-This paper presents the first study of Tl isotopes in early diagenetic pyrite.Measurements from two sections deposited during the Toarcian Ocean Anoxic Event (T-OAE, ~183Ma) are compared with data from Late Neogene (<10Ma) pyrite samples from ODP legs 165 and 167 that were deposited in relatively oxic marine environments. The Tl isotope compositions of Late Neogene pyrites are all significantly heavier than seawater, which most likely indicates that Tl in diagenetic pyrite is partially sourced from ferromanganese oxyhydroxides that are known to display relatively heavy Tl isotope signatures. One of the T-OAE sections from Peniche in Portugal displays pyrite thallium isotope compositions indistinguishable from Late Neogene samples, whereas samples from Yorkshire in the UK are depleted in the heavy isotope of Tl. These lighter compositions are best explained by the lack of ferromanganese precipitation at the sediment-water interface due the sulphidic (euxinic) conditions thought to be prevalent in the Cleveland Basin where the Yorkshire section was deposited. The heavier signatures in the Peniche samples appear to result from an oxic water column that enabled precipitation of ferromanganese oxy-hydroxides at the sediment-water interface.The Tl isotope profile from Yorkshire is also compared with previously published molybdenum isotope ratios determined on the same sedimentary succession. There is a suggestion of an anti-correlation between these two isotope systems, which is consistent with the expected isotope shifts that occur in seawater when marine oxic (ferromanganese minerals) fluxes fluctuate.The results outlined here represent the first evidence that Tl isotopes in early diagenetic pyrite have potential to reveal variations in past ocean oxygenation on a local scale and potentially also for global oceans. However, much more information about Tl isotopes in 3 different marine environments, especially in anoxic/euxinic basins, is needed before Tl isotopes can be confidently utilized as a paleo-redox tracer.4

show abstract

Thallium isotope evidence for a permanent increase in marine organic carbon export in the early Eocene

Cited by 117 publications

References 60 publications

Persistence of deeply sourced iron in the Pacific Ocean

Persistence of deeply sourced iron in the Pacific Ocean

Late Cenozoic history of deep water circulation in the western North Pacific: Evidence from Nd isotopes of ferromanganese crusts

Thallium isotopes in early diagenetic pyrite – A paleoredox proxy?

Contact Info

Product

Resources

About