Sulfur isotope composition of individual compounds in immature organic-rich rocks and possible geochemical implications

Lubna Shawar; Ward Said-Ahmad; Geoffrey S. Ellis; Alon Amrani

doi:10.1016/j.gca.2020.01.034

Sulfur isotope composition of individual compounds in immature organic-rich rocks and possible geochemical implications

Lubna Shawar, Ward Said-Ahmad, Geoffrey S. Ellis, Alon Amrani^*

^*Corresponding author for this work

Fredy & Nadine Herrmann Institute of Earth Sciences

Research output: Contribution to journal › Article › peer-review

9 Scopus citations

Abstract

We applied compound-specific sulfur isotope analysis (CSSIA) to organic matter (OM) extracted from ancient and immature organic-rich rocks from the Cretaceous Ghareb (Shefela Basin locality, Israel) and Miocene Monterey (Naples Beach locality, California, USA) Formations. Large variations in the δ³⁴S values of different organosulfur compounds (OSCs), that reach up to 28‰ and 36‰, were observed in the Ghareb and Monterey samples, respectively. Additionally, some common OSCs in both locations showed consistent ³⁴S trends relative to each other. The consistent enrichment in ³⁴S of C₃₅ hopane thiophene relative to iC₂₀ thiophene in the studied sections probably resulted from differences in the timing of OM sulfurization. Reactive organic precursors quickly consume the most ³⁴S-depleted reduced S, while less reactive species incorporate the heavier residual S at a later time. Despite the differences in the depositional environments, ages, and the initial δ³⁴S values of the reduced S (represented by the δ³⁴S of pyrite) between the Ghareb and the Monterey Formations, the sulfurization order of common organic compounds seems to be similar. All of the δ³⁴S values of OSCs are ³⁴S enriched relative to that of the coexisting pyrite with the exception of the C₂₅ highly branched isoprenoid (HBI) thiophene in several samples from the Monterey Formation. The existence of ³⁴S-depleted sulfurized HBI may point to OM sulfurization that occurred at or near the sediment-water interface during the deposition of the Monterey. Moreover, the δ³⁴S of steroid sulfides shows an inverse trend with the pristane/phytane ratio, which may indicate that the sulfurization mechanism of these OSCs are affected by redox conditions. Further investigation of CSSI values in immature rocks from other basins may help constrain the OM sulfurization process, timescale, and depositional conditions and their possible use as paleoenvironmental proxies.

Original language	American English
Pages (from-to)	20-44
Number of pages	25
Journal	Geochimica et Cosmochimica Acta
Volume	274
DOIs	https://doi.org/10.1016/j.gca.2020.01.034
State	Published - 1 Apr 2020

Bibliographical note

Funding Information:
We are grateful to Harold Vinegar and Yuval Bartov from IEI Ltd. for providing the core samples. The Monterey Formation samples were graciously provided by Paul Lillis of the U.S. Geological Survey. We appreciate the discussions with Shimon Feinstein, Sigal Abramovich, Ari Meilijson and Yoav Oved Rosenberg about the geology and stratigraphy of the study area and the help with the core sample selection. L.S. is grateful for Ph.D. scholarships from the Ministry of National Infrastructures, Energy and Water Resources of Israel, and the Harry and Sylvia Hoffman Fund. A.A. thanks the Israeli Science Foundation grant No. 1738/16 for partial support for this study. We appreciate the constructive and thoughtful comments by Paul Lillis, Pierre Adam, and two anonymous reviewers that greatly improved the paper. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Funding Information:
We are grateful to Harold Vinegar and Yuval Bartov from IEI Ltd. for providing the core samples. The Monterey Formation samples were graciously provided by Paul Lillis of the U.S. Geological Survey. We appreciate the discussions with Shimon Feinstein, Sigal Abramovich, Ari Meilijson and Yoav Oved Rosenberg about the geology and stratigraphy of the study area and the help with the core sample selection. L.S. is grateful for Ph.D. scholarships from the Ministry of National Infrastructures, Energy and Water Resources of Israel, and the Harry and Sylvia Hoffman Fund. A.A. thanks the Israeli Science Foundation grant No. 1738/16 for partial support for this study. We appreciate the constructive and thoughtful comments by Paul Lillis, Pierre Adam, and two anonymous reviewers that greatly improved the paper. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Publisher Copyright:
© 2020 Elsevier Ltd

Keywords

Biomarkers
C HBI thiophene
Compound-specific S isotope analysis
Organic S compounds
Pyrite
Sulfurization

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10.1016/j.gca.2020.01.034

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title = "Sulfur isotope composition of individual compounds in immature organic-rich rocks and possible geochemical implications",

abstract = "We applied compound-specific sulfur isotope analysis (CSSIA) to organic matter (OM) extracted from ancient and immature organic-rich rocks from the Cretaceous Ghareb (Shefela Basin locality, Israel) and Miocene Monterey (Naples Beach locality, California, USA) Formations. Large variations in the δ34S values of different organosulfur compounds (OSCs), that reach up to 28‰ and 36‰, were observed in the Ghareb and Monterey samples, respectively. Additionally, some common OSCs in both locations showed consistent 34S trends relative to each other. The consistent enrichment in 34S of C35 hopane thiophene relative to iC20 thiophene in the studied sections probably resulted from differences in the timing of OM sulfurization. Reactive organic precursors quickly consume the most 34S-depleted reduced S, while less reactive species incorporate the heavier residual S at a later time. Despite the differences in the depositional environments, ages, and the initial δ34S values of the reduced S (represented by the δ34S of pyrite) between the Ghareb and the Monterey Formations, the sulfurization order of common organic compounds seems to be similar. All of the δ34S values of OSCs are 34S enriched relative to that of the coexisting pyrite with the exception of the C25 highly branched isoprenoid (HBI) thiophene in several samples from the Monterey Formation. The existence of 34S-depleted sulfurized HBI may point to OM sulfurization that occurred at or near the sediment-water interface during the deposition of the Monterey. Moreover, the δ34S of steroid sulfides shows an inverse trend with the pristane/phytane ratio, which may indicate that the sulfurization mechanism of these OSCs are affected by redox conditions. Further investigation of CSSI values in immature rocks from other basins may help constrain the OM sulfurization process, timescale, and depositional conditions and their possible use as paleoenvironmental proxies.",

keywords = "Biomarkers, C HBI thiophene, Compound-specific S isotope analysis, Organic S compounds, Pyrite, Sulfurization",

author = "Lubna Shawar and Ward Said-Ahmad and Ellis, {Geoffrey S.} and Alon Amrani",

note = "Funding Information: We are grateful to Harold Vinegar and Yuval Bartov from IEI Ltd. for providing the core samples. The Monterey Formation samples were graciously provided by Paul Lillis of the U.S. Geological Survey. We appreciate the discussions with Shimon Feinstein, Sigal Abramovich, Ari Meilijson and Yoav Oved Rosenberg about the geology and stratigraphy of the study area and the help with the core sample selection. L.S. is grateful for Ph.D. scholarships from the Ministry of National Infrastructures, Energy and Water Resources of Israel, and the Harry and Sylvia Hoffman Fund. A.A. thanks the Israeli Science Foundation grant No. 1738/16 for partial support for this study. We appreciate the constructive and thoughtful comments by Paul Lillis, Pierre Adam, and two anonymous reviewers that greatly improved the paper. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Funding Information: We are grateful to Harold Vinegar and Yuval Bartov from IEI Ltd. for providing the core samples. The Monterey Formation samples were graciously provided by Paul Lillis of the U.S. Geological Survey. We appreciate the discussions with Shimon Feinstein, Sigal Abramovich, Ari Meilijson and Yoav Oved Rosenberg about the geology and stratigraphy of the study area and the help with the core sample selection. L.S. is grateful for Ph.D. scholarships from the Ministry of National Infrastructures, Energy and Water Resources of Israel, and the Harry and Sylvia Hoffman Fund. A.A. thanks the Israeli Science Foundation grant No. 1738/16 for partial support for this study. We appreciate the constructive and thoughtful comments by Paul Lillis, Pierre Adam, and two anonymous reviewers that greatly improved the paper. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: {\textcopyright} 2020 Elsevier Ltd",

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doi = "10.1016/j.gca.2020.01.034",

language = "American English",

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AU - Shawar, Lubna

AU - Said-Ahmad, Ward

AU - Ellis, Geoffrey S.

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N1 - Funding Information: We are grateful to Harold Vinegar and Yuval Bartov from IEI Ltd. for providing the core samples. The Monterey Formation samples were graciously provided by Paul Lillis of the U.S. Geological Survey. We appreciate the discussions with Shimon Feinstein, Sigal Abramovich, Ari Meilijson and Yoav Oved Rosenberg about the geology and stratigraphy of the study area and the help with the core sample selection. L.S. is grateful for Ph.D. scholarships from the Ministry of National Infrastructures, Energy and Water Resources of Israel, and the Harry and Sylvia Hoffman Fund. A.A. thanks the Israeli Science Foundation grant No. 1738/16 for partial support for this study. We appreciate the constructive and thoughtful comments by Paul Lillis, Pierre Adam, and two anonymous reviewers that greatly improved the paper. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Funding Information: We are grateful to Harold Vinegar and Yuval Bartov from IEI Ltd. for providing the core samples. The Monterey Formation samples were graciously provided by Paul Lillis of the U.S. Geological Survey. We appreciate the discussions with Shimon Feinstein, Sigal Abramovich, Ari Meilijson and Yoav Oved Rosenberg about the geology and stratigraphy of the study area and the help with the core sample selection. L.S. is grateful for Ph.D. scholarships from the Ministry of National Infrastructures, Energy and Water Resources of Israel, and the Harry and Sylvia Hoffman Fund. A.A. thanks the Israeli Science Foundation grant No. 1738/16 for partial support for this study. We appreciate the constructive and thoughtful comments by Paul Lillis, Pierre Adam, and two anonymous reviewers that greatly improved the paper. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: © 2020 Elsevier Ltd

PY - 2020/4/1

Y1 - 2020/4/1

N2 - We applied compound-specific sulfur isotope analysis (CSSIA) to organic matter (OM) extracted from ancient and immature organic-rich rocks from the Cretaceous Ghareb (Shefela Basin locality, Israel) and Miocene Monterey (Naples Beach locality, California, USA) Formations. Large variations in the δ34S values of different organosulfur compounds (OSCs), that reach up to 28‰ and 36‰, were observed in the Ghareb and Monterey samples, respectively. Additionally, some common OSCs in both locations showed consistent 34S trends relative to each other. The consistent enrichment in 34S of C35 hopane thiophene relative to iC20 thiophene in the studied sections probably resulted from differences in the timing of OM sulfurization. Reactive organic precursors quickly consume the most 34S-depleted reduced S, while less reactive species incorporate the heavier residual S at a later time. Despite the differences in the depositional environments, ages, and the initial δ34S values of the reduced S (represented by the δ34S of pyrite) between the Ghareb and the Monterey Formations, the sulfurization order of common organic compounds seems to be similar. All of the δ34S values of OSCs are 34S enriched relative to that of the coexisting pyrite with the exception of the C25 highly branched isoprenoid (HBI) thiophene in several samples from the Monterey Formation. The existence of 34S-depleted sulfurized HBI may point to OM sulfurization that occurred at or near the sediment-water interface during the deposition of the Monterey. Moreover, the δ34S of steroid sulfides shows an inverse trend with the pristane/phytane ratio, which may indicate that the sulfurization mechanism of these OSCs are affected by redox conditions. Further investigation of CSSI values in immature rocks from other basins may help constrain the OM sulfurization process, timescale, and depositional conditions and their possible use as paleoenvironmental proxies.

AB - We applied compound-specific sulfur isotope analysis (CSSIA) to organic matter (OM) extracted from ancient and immature organic-rich rocks from the Cretaceous Ghareb (Shefela Basin locality, Israel) and Miocene Monterey (Naples Beach locality, California, USA) Formations. Large variations in the δ34S values of different organosulfur compounds (OSCs), that reach up to 28‰ and 36‰, were observed in the Ghareb and Monterey samples, respectively. Additionally, some common OSCs in both locations showed consistent 34S trends relative to each other. The consistent enrichment in 34S of C35 hopane thiophene relative to iC20 thiophene in the studied sections probably resulted from differences in the timing of OM sulfurization. Reactive organic precursors quickly consume the most 34S-depleted reduced S, while less reactive species incorporate the heavier residual S at a later time. Despite the differences in the depositional environments, ages, and the initial δ34S values of the reduced S (represented by the δ34S of pyrite) between the Ghareb and the Monterey Formations, the sulfurization order of common organic compounds seems to be similar. All of the δ34S values of OSCs are 34S enriched relative to that of the coexisting pyrite with the exception of the C25 highly branched isoprenoid (HBI) thiophene in several samples from the Monterey Formation. The existence of 34S-depleted sulfurized HBI may point to OM sulfurization that occurred at or near the sediment-water interface during the deposition of the Monterey. Moreover, the δ34S of steroid sulfides shows an inverse trend with the pristane/phytane ratio, which may indicate that the sulfurization mechanism of these OSCs are affected by redox conditions. Further investigation of CSSI values in immature rocks from other basins may help constrain the OM sulfurization process, timescale, and depositional conditions and their possible use as paleoenvironmental proxies.

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KW - C HBI thiophene

KW - Compound-specific S isotope analysis

KW - Organic S compounds

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KW - Sulfurization

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DO - 10.1016/j.gca.2020.01.034

M3 - Article

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SN - 0016-7037

VL - 274

SP - 20

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JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

ER -

Sulfur isotope composition of individual compounds in immature organic-rich rocks and possible geochemical implications

Abstract

Bibliographical note

Keywords

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