Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Geobiology 11 (2013): 295-306, doi:10.1111/gbi.12036.
Description:
Here we explore enrichments in paleomarine Zn as recorded by authigenic iron oxides
including Precambrian iron formations, ironstones and Phanerozoic hydrothermal
exhalites. This compilation of new and literature-based iron formation analyses track
dissolved Zn abundances and constrain the magnitude of the marine reservoir over
geological time. Overall, the iron formation record is characterized by a fairly static range
in Zn/Fe ratios throughout the Precambrian, consistent with the shale record (Scott et al.,
2013, Nature Geoscience, 6, 125-128). When hypothetical partitioning scenarios are
applied to this record, paleomarine Zn concentrations within about an order of magnitude
of modern are indicated. We couple this examination with new chemical speciation
models used to interpret the iron formation record. We present two scenarios: first, under
all but the most sulfidic conditions and with Zn binding organic ligand concentrations
similar to modern oceans, the amount of bioavailable Zn remained relatively unchanged
through time. Late proliferation of Zn in eukaryotic metallomes has previously been
linked to marine Zn biolimitation, but under this scenario, the expansion in eukaryotic Zn
metallomes may be better linked to biologically intrinsic evolutionary factors. In this case
zinc’s geochemical and biological evolution may be decoupled, and viewed as a function
of increasing need for genome regulation and diversification of Zn-binding transcription
factors. In the second scenario, we consider Archean organic ligand complexation in such
excess that it may render Zn bioavailability low. However, this is dependent on Zn
organic ligand complexes not being bioavailable, which remains unclear. In this case,
although bioavailability may be low, sphalerite precipitation is prevented, thereby
maintaining a constant Zn inventory throughout both ferruginous and euxinic conditions.
These results provide new perspectives and constraints 50 on potential couplings between
the trajectory of biological and marine geochemical coevolution.
Description:
This work was supported by a NSERC Discovery
Grant to KOK, a NSERC PDF to SVL, a NSERC CGSM to LJR, and an NSF-EAR-PDF
to NJP. MAS acknowledges support from the Gordon and Betty Moore Foundation Grant
#2724. This work was also supported by grants from the Deutsche
Forschungsgemeinschaft (DFG) to A.K. (KA 1736/4-1 and 12-1).
Keywords:
Paleomarine zinc
;
Metallome evolution
;
Metalloenzymes
;
Eukaryotic evolution
;
Iron formations
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
Format:
application/vnd.ms-excel
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