Metal/Ca ratios in pockmarks and adjacent sediments on the SW Atlantic slope: Implications for redox potential and modern seepage

Rosangela Felício dos Santos; Doris Nagaoka; Raissa Basti Ramos; Alexandre Barbosa Salaroli; Satie Taniguchi; Rubens Cesar Lopes Figueira; Marcia Caruso Bícego; Francisco José Lobo; Uri Schattner; Michel Michaelovitch de Mahiques

doi:10.1016/j.gexplo.2018.06.014

Metal/Ca ratios in pockmarks and adjacent sediments on the SW Atlantic slope: Implications for redox potential and modern seepage

Rosangela Felício dos Santos, Doris Nagaoka, Raissa Basti Ramos, Alexandre Barbosa Salaroli, Satie Taniguchi, Rubens Cesar Lopes Figueira, Marcia Caruso Bícego, Francisco José Lobo, Uri Schattner, Michel Michaelovitch de Mahiques

Department of Marine Geosciences

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

Abstract

Metal/Ca ratios and their corresponding enrichment factors (EFs) in bulk sediment samples collected at a mixed carbonate-siliciclastic continental slope setting with an extensive pockmark field were measured and analyzed to find evidence of lateral differences in the redox potential and recent seepage activity inside the pockmarks. The analyzed ratios point to metal enrichments that indicate variations in the redox potential inside the pockmarks compared to the adjacent areas, as shown by the Cu/Ca, Ni/Ca and Zn/Ca EFs. Slight but statistically significant differences in the Mg/Ca ratios indicated that the formation of Mg-enriched carbonates within the pockmarks is presently taking place, attesting the maintenance of seepage in the shallow sedimentary column. Recent seepage activity was also confirmed by the upward enrichment of Ba in the sedimentary column. Our study provides direct evidence for pockmark activity and reinforces the need for an extended analysis of the geochemistry of natural seepages on the SW Atlantic margin, an area that has still not been studied in relation to this subject.

Original language	English
Pages (from-to)	163-173
Number of pages	11
Journal	Journal of Geochemical Exploration
Volume	192
DOIs	https://doi.org/10.1016/j.gexplo.2018.06.014
State	Published - Sep 2018

Bibliographical note

Funding Information:
This work was funded by the São Paulo Science Foundation ( FAPESP ) (grants 2010/06147-5 , 2014/08266-2 , and 2016/22194-0 ). M.M. de Mahiques acknowledges the Brazilian Research Council (CNPq) for grants no. 303132/2014-0 and 401041/2014-0 ; Rosangela F. Santos is funded by FAPESP (grant 2016/24379-7 ). Partnerships between M.M. de Mahiques, U. Schattner and F.J. Lobo, are maintained by FAPESP (grant SPRINT 2017/50191-8 ) and the Brazilian National Research Council (CNPq, grant 401041/2014-0 ), respectively.

Funding Information:
This work was funded by the S?o Paulo Science Foundation (FAPESP) (grants 2010/06147-5, 2014/08266-2, and 2016/22194-0). M.M. de Mahiques acknowledges the Brazilian Research Council (CNPq) for grants no. 303132/2014-0 and 401041/2014-0; Rosangela F. Santos is funded by FAPESP (grant 2016/24379-7). Partnerships between M.M. de Mahiques, U. Schattner and F.J. Lobo, are maintained by FAPESP (grant SPRINT 2017/50191-8) and the Brazilian National Research Council (CNPq, grant 401041/2014-0), respectively.

Publisher Copyright:
© 2018 Elsevier B.V.

Keywords

Metal/Ca ratio
Pockmarks
SW Atlantic
Seepage

ASJC Scopus subject areas

Geochemistry and Petrology
Economic Geology

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10.1016/j.gexplo.2018.06.014

Cite this

dos Santos, R. F., Nagaoka, D., Ramos, R. B., Salaroli, A. B., Taniguchi, S., Figueira, R. C. L., Bícego, M. C., Lobo, F. J., Schattner, U., & de Mahiques, M. M. (2018). Metal/Ca ratios in pockmarks and adjacent sediments on the SW Atlantic slope: Implications for redox potential and modern seepage. Journal of Geochemical Exploration, 192, 163-173. https://doi.org/10.1016/j.gexplo.2018.06.014

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title = "Metal/Ca ratios in pockmarks and adjacent sediments on the SW Atlantic slope: Implications for redox potential and modern seepage",

abstract = "Metal/Ca ratios and their corresponding enrichment factors (EFs) in bulk sediment samples collected at a mixed carbonate-siliciclastic continental slope setting with an extensive pockmark field were measured and analyzed to find evidence of lateral differences in the redox potential and recent seepage activity inside the pockmarks. The analyzed ratios point to metal enrichments that indicate variations in the redox potential inside the pockmarks compared to the adjacent areas, as shown by the Cu/Ca, Ni/Ca and Zn/Ca EFs. Slight but statistically significant differences in the Mg/Ca ratios indicated that the formation of Mg-enriched carbonates within the pockmarks is presently taking place, attesting the maintenance of seepage in the shallow sedimentary column. Recent seepage activity was also confirmed by the upward enrichment of Ba in the sedimentary column. Our study provides direct evidence for pockmark activity and reinforces the need for an extended analysis of the geochemistry of natural seepages on the SW Atlantic margin, an area that has still not been studied in relation to this subject.",

keywords = "Metal/Ca ratio, Pockmarks, SW Atlantic, Seepage",

author = "{dos Santos}, {Rosangela Fel{\'i}cio} and Doris Nagaoka and Ramos, {Raissa Basti} and Salaroli, {Alexandre Barbosa} and Satie Taniguchi and Figueira, {Rubens Cesar Lopes} and B{\'i}cego, {Marcia Caruso} and Lobo, {Francisco Jos{\'e}} and Uri Schattner and {de Mahiques}, {Michel Michaelovitch}",

note = "Funding Information: This work was funded by the S{\~a}o Paulo Science Foundation ( FAPESP ) (grants 2010/06147-5 , 2014/08266-2 , and 2016/22194-0 ). M.M. de Mahiques acknowledges the Brazilian Research Council (CNPq) for grants no. 303132/2014-0 and 401041/2014-0 ; Rosangela F. Santos is funded by FAPESP (grant 2016/24379-7 ). Partnerships between M.M. de Mahiques, U. Schattner and F.J. Lobo, are maintained by FAPESP (grant SPRINT 2017/50191-8 ) and the Brazilian National Research Council (CNPq, grant 401041/2014-0 ), respectively. Funding Information: This work was funded by the S?o Paulo Science Foundation (FAPESP) (grants 2010/06147-5, 2014/08266-2, and 2016/22194-0). M.M. de Mahiques acknowledges the Brazilian Research Council (CNPq) for grants no. 303132/2014-0 and 401041/2014-0; Rosangela F. Santos is funded by FAPESP (grant 2016/24379-7). Partnerships between M.M. de Mahiques, U. Schattner and F.J. Lobo, are maintained by FAPESP (grant SPRINT 2017/50191-8) and the Brazilian National Research Council (CNPq, grant 401041/2014-0), respectively. Publisher Copyright: {\textcopyright} 2018 Elsevier B.V.",

year = "2018",

month = sep,

doi = "10.1016/j.gexplo.2018.06.014",

language = "English",

volume = "192",

pages = "163--173",

journal = "Journal of Geochemical Exploration",

issn = "0375-6742",

publisher = "Elsevier",

}

dos Santos, RF, Nagaoka, D, Ramos, RB, Salaroli, AB, Taniguchi, S, Figueira, RCL, Bícego, MC, Lobo, FJ, Schattner, U & de Mahiques, MM 2018, 'Metal/Ca ratios in pockmarks and adjacent sediments on the SW Atlantic slope: Implications for redox potential and modern seepage', Journal of Geochemical Exploration, vol. 192, pp. 163-173. https://doi.org/10.1016/j.gexplo.2018.06.014

TY - JOUR

T1 - Metal/Ca ratios in pockmarks and adjacent sediments on the SW Atlantic slope

T2 - Implications for redox potential and modern seepage

AU - dos Santos, Rosangela Felício

AU - Nagaoka, Doris

AU - Ramos, Raissa Basti

AU - Salaroli, Alexandre Barbosa

AU - Taniguchi, Satie

AU - Figueira, Rubens Cesar Lopes

AU - Bícego, Marcia Caruso

AU - Lobo, Francisco José

AU - Schattner, Uri

AU - de Mahiques, Michel Michaelovitch

N1 - Funding Information: This work was funded by the São Paulo Science Foundation ( FAPESP ) (grants 2010/06147-5 , 2014/08266-2 , and 2016/22194-0 ). M.M. de Mahiques acknowledges the Brazilian Research Council (CNPq) for grants no. 303132/2014-0 and 401041/2014-0 ; Rosangela F. Santos is funded by FAPESP (grant 2016/24379-7 ). Partnerships between M.M. de Mahiques, U. Schattner and F.J. Lobo, are maintained by FAPESP (grant SPRINT 2017/50191-8 ) and the Brazilian National Research Council (CNPq, grant 401041/2014-0 ), respectively. Funding Information: This work was funded by the S?o Paulo Science Foundation (FAPESP) (grants 2010/06147-5, 2014/08266-2, and 2016/22194-0). M.M. de Mahiques acknowledges the Brazilian Research Council (CNPq) for grants no. 303132/2014-0 and 401041/2014-0; Rosangela F. Santos is funded by FAPESP (grant 2016/24379-7). Partnerships between M.M. de Mahiques, U. Schattner and F.J. Lobo, are maintained by FAPESP (grant SPRINT 2017/50191-8) and the Brazilian National Research Council (CNPq, grant 401041/2014-0), respectively. Publisher Copyright: © 2018 Elsevier B.V.

PY - 2018/9

Y1 - 2018/9

N2 - Metal/Ca ratios and their corresponding enrichment factors (EFs) in bulk sediment samples collected at a mixed carbonate-siliciclastic continental slope setting with an extensive pockmark field were measured and analyzed to find evidence of lateral differences in the redox potential and recent seepage activity inside the pockmarks. The analyzed ratios point to metal enrichments that indicate variations in the redox potential inside the pockmarks compared to the adjacent areas, as shown by the Cu/Ca, Ni/Ca and Zn/Ca EFs. Slight but statistically significant differences in the Mg/Ca ratios indicated that the formation of Mg-enriched carbonates within the pockmarks is presently taking place, attesting the maintenance of seepage in the shallow sedimentary column. Recent seepage activity was also confirmed by the upward enrichment of Ba in the sedimentary column. Our study provides direct evidence for pockmark activity and reinforces the need for an extended analysis of the geochemistry of natural seepages on the SW Atlantic margin, an area that has still not been studied in relation to this subject.

AB - Metal/Ca ratios and their corresponding enrichment factors (EFs) in bulk sediment samples collected at a mixed carbonate-siliciclastic continental slope setting with an extensive pockmark field were measured and analyzed to find evidence of lateral differences in the redox potential and recent seepage activity inside the pockmarks. The analyzed ratios point to metal enrichments that indicate variations in the redox potential inside the pockmarks compared to the adjacent areas, as shown by the Cu/Ca, Ni/Ca and Zn/Ca EFs. Slight but statistically significant differences in the Mg/Ca ratios indicated that the formation of Mg-enriched carbonates within the pockmarks is presently taking place, attesting the maintenance of seepage in the shallow sedimentary column. Recent seepage activity was also confirmed by the upward enrichment of Ba in the sedimentary column. Our study provides direct evidence for pockmark activity and reinforces the need for an extended analysis of the geochemistry of natural seepages on the SW Atlantic margin, an area that has still not been studied in relation to this subject.

KW - Metal/Ca ratio

KW - Pockmarks

KW - SW Atlantic

KW - Seepage

UR - http://www.scopus.com/inward/record.url?scp=85049331126&partnerID=8YFLogxK

U2 - 10.1016/j.gexplo.2018.06.014

DO - 10.1016/j.gexplo.2018.06.014

M3 - Article

AN - SCOPUS:85049331126

SN - 0375-6742

VL - 192

SP - 163

EP - 173

JO - Journal of Geochemical Exploration

JF - Journal of Geochemical Exploration

ER -

Metal/Ca ratios in pockmarks and adjacent sediments on the SW Atlantic slope: Implications for redox potential and modern seepage

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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