TY - JOUR
T1 - Carbonate facies-specific stable isotope data record climate, hydrology, and microbial communities in Great Salt Lake, UT
AU - Ingalls, Miquela
AU - Frantz, Carie M.
AU - Snell, Kathryn E.
AU - Trower, Elizabeth J.
N1 - Funding Information:
MI would like to thank Usha Lingappa for assistance in performing DNA extraction and amplification, and initial bioinformatics. MI also thanks Chi Ma for assistance with SEM imaging, and Nathan Dalleska for use of the Caltech Environmental Analysis Center, and valuable insight in designing dissolved ion analytical protocols for GSL brines. MI thanks John Eiler for use of clumped isotope facilities at Caltech and discussions of data quality and isotopic disequilibrium. MI and KS thank Brett Davidheiser-Kroll and Andrew Chan for assistance in measurements made in the CUBES-SIL facility and Camsizer analyses. Sampling at Great Salt Lake was carried out under permits to CF from the State of Utah Department of Natural Resources Division of Forestry, Fire and State Lands (No. 42000074) and Antelope Island State Park. Funding for this work was provided by NSF EAR #1826850 to ET and KS and #1826869 to CF. MI acknowledges financial support from the Barr Foundation.
Publisher Copyright:
© 2020 John Wiley & Sons Ltd
PY - 2020/9/1
Y1 - 2020/9/1
N2 - Organic and inorganic stable isotopes of lacustrine carbonate sediments are commonly used in reconstructions of ancient terrestrial ecosystems and environments. Microbial activity and local hydrological inputs can alter porewater chemistry (e.g., pH, alkalinity) and isotopic composition (e.g., δ18Owater, δ13CDIC), which in turn has the potential to impact the stable isotopic compositions recorded and preserved in lithified carbonate. The fingerprint these syngenetic processes have on lacustrine carbonate facies is yet unknown, however, and thus, reconstructions based on stable isotopes may misinterpret diagenetic records as broader climate signals. Here, we characterize geochemical and stable isotopic variability of carbonate minerals, organic matter, and water within one modern lake that has known microbial influences (e.g., microbial mats and microbialite carbonate) and combine these data with the context provided by 16S rRNA amplicon sequencing community profiles. Specifically, we measure oxygen, carbon, and clumped isotopic compositions of carbonate sediments (δ18Ocarb, δ13Ccarb, ∆47), as well as carbon isotopic compositions of bulk organic matter (δ13Corg) and dissolved inorganic carbon (DIC; δ13CDIC) of lake and porewater in Great Salt Lake, Utah from five sites and three seasons. We find that facies equivalent to ooid grainstones provide time-averaged records of lake chemistry that reflect minimal alteration by microbial activity, whereas microbialite, intraclasts, and carbonate mud show greater alteration by local microbial influence and hydrology. Further, we find at least one occurrence of ∆47 isotopic disequilibrium likely driven by local microbial metabolism during authigenic carbonate precipitation. The remainder of the carbonate materials (primarily ooids, grain coatings, mud, and intraclasts) yield clumped isotope temperatures (T(∆47)), δ18Ocarb, and calculated δ18Owater in isotopic equilibrium with ambient water and temperature at the time and site of carbonate precipitation. Our findings suggest that it is possible and necessary to leverage diverse carbonate facies across one sedimentary horizon to reconstruct regional hydroclimate and evaporation–precipitation balance, as well as identify microbially mediated carbonate formation.
AB - Organic and inorganic stable isotopes of lacustrine carbonate sediments are commonly used in reconstructions of ancient terrestrial ecosystems and environments. Microbial activity and local hydrological inputs can alter porewater chemistry (e.g., pH, alkalinity) and isotopic composition (e.g., δ18Owater, δ13CDIC), which in turn has the potential to impact the stable isotopic compositions recorded and preserved in lithified carbonate. The fingerprint these syngenetic processes have on lacustrine carbonate facies is yet unknown, however, and thus, reconstructions based on stable isotopes may misinterpret diagenetic records as broader climate signals. Here, we characterize geochemical and stable isotopic variability of carbonate minerals, organic matter, and water within one modern lake that has known microbial influences (e.g., microbial mats and microbialite carbonate) and combine these data with the context provided by 16S rRNA amplicon sequencing community profiles. Specifically, we measure oxygen, carbon, and clumped isotopic compositions of carbonate sediments (δ18Ocarb, δ13Ccarb, ∆47), as well as carbon isotopic compositions of bulk organic matter (δ13Corg) and dissolved inorganic carbon (DIC; δ13CDIC) of lake and porewater in Great Salt Lake, Utah from five sites and three seasons. We find that facies equivalent to ooid grainstones provide time-averaged records of lake chemistry that reflect minimal alteration by microbial activity, whereas microbialite, intraclasts, and carbonate mud show greater alteration by local microbial influence and hydrology. Further, we find at least one occurrence of ∆47 isotopic disequilibrium likely driven by local microbial metabolism during authigenic carbonate precipitation. The remainder of the carbonate materials (primarily ooids, grain coatings, mud, and intraclasts) yield clumped isotope temperatures (T(∆47)), δ18Ocarb, and calculated δ18Owater in isotopic equilibrium with ambient water and temperature at the time and site of carbonate precipitation. Our findings suggest that it is possible and necessary to leverage diverse carbonate facies across one sedimentary horizon to reconstruct regional hydroclimate and evaporation–precipitation balance, as well as identify microbially mediated carbonate formation.
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U2 - 10.1111/gbi.12386
DO - 10.1111/gbi.12386
M3 - Article
C2 - 32196875
AN - SCOPUS:85082061337
VL - 18
SP - 566
EP - 593
JO - Geobiology
JF - Geobiology
SN - 1472-4677
IS - 5
ER -