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Sulfur isotope behavior during metamorphism and anatexis of Archean sedimentary rocks: A case study from the Ghost Lake batholith, Ontario, Canada

Bucholz, Claire E. and Biasi, Joseph A. and Beaudry, Patrick and Ono, Shuhei (2020) Sulfur isotope behavior during metamorphism and anatexis of Archean sedimentary rocks: A case study from the Ghost Lake batholith, Ontario, Canada. Earth and Planetary Science Letters, 549 . Art. No. 116494. ISSN 0012-821X. https://resolver.caltech.edu/CaltechAUTHORS:20200817-094633188

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Abstract

Recycling of surface-derived sulfur into the deep earth can impart distinct sulfur isotope signatures to magmas. The details of sulfur transfer from sedimentary rocks to magmas (and ultimately igneous rocks) through metamorphism and devolatilization and/or partial melting, however, is difficult to trace. To understand this process in detail we studied multiple-sulfur isotope compositions of sulfides in the Archean (c. 2685 Ma) Ghost Lake batholith (GLB) and its surrounding host metasedimentary rocks of the Superior Craton (Ontario, Canada) by high spatial resolution secondary ion mass spectrometry, complemented by high-precision gas source isotope ratio mass spectrometry measurements. The GLB comprises strongly peraluminous biotite+cordierite, biotite+muscovite, and muscovite+garnet+tourmaline granites to leucogranites, which are thought to represent the partial melts of surrounding metagreywackes and metapelites. The metasedimentary rocks display a range of metamorphic grades increasing from biotite-chlorite (280-380 °C) at ∼5 km away from the GLB to sillimanite-K-feldspar grade (∼660 °C) immediately adjacent to the batholith, thus providing a natural experiment to understand sulfur isotope variations from low- to high-grade Archean sedimentary rocks, as well as granites representative of their partial melts. We find that metasedimentary sulfide δ³⁴S values increase with progressive metamorphism at most 2-3‰ (from −1‰ up to +1 to +2‰). An increase in δ³⁴S values in pyrrhotite during prograde metamorphism can be explained through Rayleigh fractionation during pyrite desulfidation reactions. Pyrite from all but one of the granite samples preserve δ³⁴S values similar to that of the high-grade metasedimentary rocks, indicating that partial melting did not result in significant fractionation of δ³⁴S. The exception to this is one granite sample from a part of the batholith characterized by abundant metasedimentary inclusions. This sample contains pyrite with heterogeneous and low δ³⁴S values (down to −16‰) which likely resulted from incomplete homogenization of sulfur between the granitic melt and metasedimentary inclusions. Small (several tenths of a permil), mostly positive Δ³³S are observed in both the metasedimentary rocks and granites. Our results suggest that Archean strongly peraluminous granites could be a high-fidelity archive to quantify the bulk sulfur isotope composition of the Archean siliciclastic sediments. Further, our findings indicate that subduction of reduced sulfur-bearing sediments in the Archean with δ³⁴S at or near 0‰ should result in release of sulfur-bearing fluids in the mantle wedge with similar values (within a few permil). S-MIF (if initially present in Archean surface material) may be preserved during this process. However, the absence of S-MIF in igneous rocks does not preclude assimilation of Archean sedimentary material as either S-MIF may not be originally present in the Archean sedimentary sulfur and/or homogenization or dilution could obscure any S-MIF originally present in assimilated Archean sediments.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.epsl.2020.116494DOIArticle
ORCID:
AuthorORCID
Bucholz, Claire E.0000-0003-3252-7109
Biasi, Joseph A.0000-0003-1196-7877
Ono, Shuhei0000-0002-1348-9584
Additional Information:© 2020 Elsevier B.V. Received 4 March 2020, Revised 13 June 2020, Accepted 18 July 2020, Available online 13 August 2020. We thank Madeline Lewis and Allyson Trussell for help collecting samples, Yunbin Guan for assistance with SIMS analyses, and Gareth Izon for assistance with the IRMS analyses. C. Bucholz thanks Fred Breaks for spending time in the field introducing her to the Ghost Lake batholith, John Eiler for discussion of sulfur isotope analyses via SIMS, and Doug Crowe and Woody Fischer for generously providing sulfide standard materials. This work was supported by NSF grant EAR-1943629 awarded to C. Bucholz. We are grateful for the comments of two anonymous reviewers which help to clarify and improve the presentation of this work. CRediT authorship contribution statement: Claire E. Bucholz: Conceptualization, Funding acquisition, Investigation, Methodology, Resources, Supervision, Visualization, Writing - original draft. Joseph A. Biasi: Investigation, Resources, Writing - review & editing. Patrick Beaudry: Investigation, Writing - review & editing. Shuhei Ono: Writing - review & editing. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funders:
Funding AgencyGrant Number
NSFEAR-1943629
Subject Keywords:sulfur; anatexis; metasedimentary rocks; granite; Archean
Record Number:CaltechAUTHORS:20200817-094633188
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200817-094633188
Official Citation:Claire E. Bucholz, Joseph A. Biasi, Patrick Beaudry, Shuhei Ono, Sulfur isotope behavior during metamorphism and anatexis of Archean sedimentary rocks: A case study from the Ghost Lake batholith, Ontario, Canada, Earth and Planetary Science Letters, Volume 549, 2020, 116494, ISSN 0012-821X, https://doi.org/10.1016/j.epsl.2020.116494. (http://www.sciencedirect.com/science/article/pii/S0012821X20304386)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104973
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Aug 2020 20:47
Last Modified:17 Aug 2020 20:47

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