TY - JOUR
T1 - Exceptional preservation of organic matter and iron-organic colloidal mineralization in hydrothermal black smoker-type sulfide mineralization from the Paleoarchean seafloor
AU - Baumgartner, Raphael J.
AU - Teece, Bronwyn L.
AU - Rasmussen, Birger
AU - Muhling, Janet
AU - Rickard, William D.A.
AU - Pejcic, Bobby
AU - Hu, Siyu
AU - Bourdet, Julien
AU - Caruso, Stefano
AU - Van Kranendonk, Martin J.
AU - Grice, Kliti
N1 - Funding Information:
The authors acknowledge the facilities and technical assistance of the Australian Microscopy and Microanalysis Research Facility at CMCA, UWA. Part of this research was undertaken using the ToF-SIMS facility (ARC LE190100053) at the John de Laeter Centre, Curtin University. Derek Winchester (CSIRO, Perth) is acknowledged for his help with sample preparation. Bonnie Teece conducted her research at UNSW, Sydney, and at the Jet Propulsion Laboratory, California Institute of Technology. The work at the Jet Propulsion Laboratory, California Institute of Technology was conducted under a contract with the National Aeronautics and Space Administration (80NM0018D0004). Michael Verrall (CSIRO, Perth) is thanked for his assistance with the SEM experiments. We thank Hailiang Dong for his editorial handling. Three anonymous reviewers are thanked for their constructive comments.
Publisher Copyright:
© 2022 The Authors
PY - 2023/2/20
Y1 - 2023/2/20
N2 - Fossil organic matter (OM) in Paleoarchean rocks is an invaluable tracer of ancient life, yet it is often contentious due to low preservation potentials of its original organic molecular characteristics under generally high metamorphic grades. This study reports on exceptionally preserved OM within black smoker-type sulfide mineralizations from the 3.24 billion-years-old Sulphur Springs volcanic-hosted massive sulfide deposit, East Pilbara Terrane, northwestern Australia. Fine scale mineralogical and organic molecular variations – documented by SEM and TEM techniques, Raman and FTIR Spectroscopy, as well as ToF-SIMS analysis – trace the formation of millimetre-scale pyritic hydrothermal orifices. Overmature OM (≳200–250 °C) enriched in aromatic hydrocarbons occurs within earliest formed colloform-banded pyrite that could have precipitated at high temperature upon mixing of hot hydrothermal fluids with cold seawater. In contrast, mature OM (within the catagenesis window; ∼100–150 °C) with lower proportions of aromatic hydrocarbons occasionally occurs alongside pyrite within barite near the inner paleofluid conduits of the hydrothermal orifices. A deposition of this OM generation from cooler fluids enriched in sulfate during waning hydrothermal activity is corroborated by its association with original mineralogy, particularly the occurrence of isolated nanoinclusions of OM within hydrothermal barite away from grain boundaries or fissures and cracks, which renders impossible an origin from post-depositional hydrocarbon migration. When compared to the overmature OM within colloform-banded pyrite, the better-preserved inner OM not only contains less abundant, smaller, and less ordered aromatic hydrocarbons, but also higher amounts of aliphatic molecules with longer chain lengths and higher proportions of carbonyl and amide functional groups. Although the latter characteristics are consistent with contributions by microbial biomass, abiotic origins are equally plausible because hydrothermal processes can produce OM with similar organic molecular attributes. Irrespective of these uncertainties on the ultimate sourcing of OM, common intergrowths of the cooler OM with nanoscopic iron oxides – hematite and lesser magnetite – hint at its hydrothermal deposition from colloidal particles that have been stabilized by iron-organic complexation. Further research is required to ascertain the significance of this process for the hydrothermal cycling and release of organic carbons and bound iron into the Paleoarchean oceans. Collectively, our results show that ancient marine hydrothermal systems can preserve OM with differing degrees of thermal degradation, which allows for insights into its sourcing, cycling, and deposition.
AB - Fossil organic matter (OM) in Paleoarchean rocks is an invaluable tracer of ancient life, yet it is often contentious due to low preservation potentials of its original organic molecular characteristics under generally high metamorphic grades. This study reports on exceptionally preserved OM within black smoker-type sulfide mineralizations from the 3.24 billion-years-old Sulphur Springs volcanic-hosted massive sulfide deposit, East Pilbara Terrane, northwestern Australia. Fine scale mineralogical and organic molecular variations – documented by SEM and TEM techniques, Raman and FTIR Spectroscopy, as well as ToF-SIMS analysis – trace the formation of millimetre-scale pyritic hydrothermal orifices. Overmature OM (≳200–250 °C) enriched in aromatic hydrocarbons occurs within earliest formed colloform-banded pyrite that could have precipitated at high temperature upon mixing of hot hydrothermal fluids with cold seawater. In contrast, mature OM (within the catagenesis window; ∼100–150 °C) with lower proportions of aromatic hydrocarbons occasionally occurs alongside pyrite within barite near the inner paleofluid conduits of the hydrothermal orifices. A deposition of this OM generation from cooler fluids enriched in sulfate during waning hydrothermal activity is corroborated by its association with original mineralogy, particularly the occurrence of isolated nanoinclusions of OM within hydrothermal barite away from grain boundaries or fissures and cracks, which renders impossible an origin from post-depositional hydrocarbon migration. When compared to the overmature OM within colloform-banded pyrite, the better-preserved inner OM not only contains less abundant, smaller, and less ordered aromatic hydrocarbons, but also higher amounts of aliphatic molecules with longer chain lengths and higher proportions of carbonyl and amide functional groups. Although the latter characteristics are consistent with contributions by microbial biomass, abiotic origins are equally plausible because hydrothermal processes can produce OM with similar organic molecular attributes. Irrespective of these uncertainties on the ultimate sourcing of OM, common intergrowths of the cooler OM with nanoscopic iron oxides – hematite and lesser magnetite – hint at its hydrothermal deposition from colloidal particles that have been stabilized by iron-organic complexation. Further research is required to ascertain the significance of this process for the hydrothermal cycling and release of organic carbons and bound iron into the Paleoarchean oceans. Collectively, our results show that ancient marine hydrothermal systems can preserve OM with differing degrees of thermal degradation, which allows for insights into its sourcing, cycling, and deposition.
KW - Hydrothermal vent
KW - Marine hydrothermal system
KW - Metal-organic complexation
KW - Organic matter
KW - Organic molecular heterogeneity
KW - Organo-ferric colloidal particle
KW - Paleoarchean
KW - Thermal maturation
UR - http://www.scopus.com/inward/record.url?scp=85146099731&partnerID=8YFLogxK
U2 - 10.1016/j.chemgeo.2022.121296
DO - 10.1016/j.chemgeo.2022.121296
M3 - Article
AN - SCOPUS:85146099731
SN - 0009-2541
VL - 618
JO - Chemical Geology
JF - Chemical Geology
M1 - 121296
ER -