FN Archimer Export Format
PT J
TI Molybdenum Isotope Fingerprinting of Microbial Sulfate Reduction in Seep Carbonate Rocks
BT 
AF JIA, zice
   Hu, Yu
   BAYON, Germain
   Peckmann, Jörn
   Wang, Xudong
   Gong, Shanggui
   Li, Jie
   Roberts, Harry H.
   Chen, Duofu
   Feng, Dong
AS 1:1,2;2:1;3:3;4:4;5:1;6:1;7:5;8:6;9:1,2;10:1,2;
FF 1:;2:;3:PDG-REM-GEOOCEAN-ASTRE;4:;5:;6:;7:;8:;9:;10:;
C1 College of Oceanography and Ecological Science, Shanghai Ocean University, Shanghai, China
   Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
   University Brest, CNRS, Ifremer, Geo‐Ocean, Plouzané, France
   Center for Earth System Research and Sustainability, Institute for Geology, Universität Hamburg, Hamburg, Germany
   State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
   College of the Coastal and Environment, Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, USA
C2 UNIV SHANGHAI OCEAN, CHINA
   QINGDAO NATL LAB MARINE SCI & TECHNOL QNLM, CHINA
   IFREMER, FRANCE
   UNIV HAMBURG, GERMANY
   CHINESE ACAD SCI, CHINA
   UNIV LOUISIANA STATE, USA
SI BREST
SE PDG-REM-GEOOCEAN-ASTRE
UM GEO-OCEAN
IN WOS Ifremer UMR
   DOAJ
   copubli-europe
   copubli-int-hors-europe
   copubli-sud
IF 3.5
TC 0
UR https://archimer.ifremer.fr/doc/00882/99417/109455.pdf
LA English
DT Article
AB Understanding the interaction between molybdenum (Mo) and organic matter during microbial sulfate reduction is critical for the use of Mo to reconstruct marine redox conditions throughout Earth's history. However, little is known about Mo isotope fractionation and how it relates to organic matter remineralization during microbial sulfate reduction. Here, we report Mo abundances and isotopic (δ98Mo) compositions for bulk-rock, non-lithogenic and sequentially extracted fractions, including carbonate (carb), pyrite, and organic matter (OM), of seep carbonate rocks. Our data indicate that the difference between δ98Mocarb and δ98MoOM (Δ98Mocarb-OM) displays significant variability in the studied samples, ranging between 0.72 and 1.01‰. Remarkably, the obtained Δ98Mocarb-OM values indicate correlative trends with stable carbon isotope ratios and bulk abundances of (a) total organic carbon, (b) Mo, and (c) pyrite in seep carbonates, which we interpret as reflecting sustained adsorption of isotopically light Mo onto organic matter during enhanced sulfate reduction. On this basis, we put forward the concept that Δ98Mocarb-OM of authigenic carbonate rocks can be used as a measure of the intensity of sulfate reduction and for reconstructing past interactions between Mo and organic matter in marine sediments. Key Points Organic matter tends to adsorb isotopically light Mo, resulting in low δ98Mo values of organic matter in marine environments Isotopically light Mo is inferred to be preferentially adsorbed onto organic matter during enhanced sulfate reduction δ98Mo offset between carbonate and organic phases in authigenic carbonates is promising to trace the past intensity of sulfate reduction Plain Language Summary Molybdenum (Mo) is a useful element for reconstructing marine redox conditions throughout the Earth's history. The sequestration of Mo through sulfate-reducing bacterial activity acts as a significant pathway for Mo burial in the ocean. However, the impact of microbial sulfate reduction in Mo isotope fractionation remains unclear, preventing the understanding of the interaction between Mo and organic matter. We report Mo abundances and isotopic (δ98Mo) compositions for different phases extracted from seep carbonate rock fractions, including carbonate (carb), pyrite, and organic matter (OM). Our findings indicate that organic matter tends to preferentially adsorb isotopically light Mo. The observed δ98Mo difference between carbonate and organic matter fractions (Δ98Mocarb-OM from 0.72 to 1.01‰) represents the first report of the extent of Mo isotope fractionation during Mo adsorption to organic matter in marine environments. We attribute greater Δ98Mocarb-OM offsets to the preferential adsorption of isotopically light Mo onto organic matter during enhanced sulfate reduction, and in turn put forward the idea that such offsets can be possibly used in the sedimentary record to trace the intensity of sulfate reduction and to reconstruct the past interaction between Mo and organic matter in marine sediments. 
PY 2024
PD MAR
SO Geochemistry Geophysics Geosystems
SN 1525-2027
PU American Geophysical Union
VL 25
IS 3
UT 001186256000001
DI 10.1029/2023GC011379
ID 99417
ER

EF