TY - JOUR
T1 - Formation of micro-spherulitic barite in association with organic matter within sulfidized stromatolites of the 3.48 billion-year-old Dresser Formation, Pilbara Craton
AU - Baumgartner, Raphael J.
AU - Van Kranendonk, Martin J.
AU - Fiorentini, Marco L.
AU - Pagès, Anais
AU - Wacey, David
AU - Kong, Charlie
AU - Saunders, Martin
AU - Ryan, Chris
N1 - Funding Information:
The authors acknowledge the facilities, and the scientific and technical assistance of the Microscopy Australia research facility at the Centre for Microscopy, Characterization and Analysis (UWA). We thank Pascal Philippot for his editorial handling and anonymous reviewers for their thoughtful comments. This study was supported by the Australian Research Council (ARC) Centre of Excellence for Core to Crust Fluid Systems (www.ccfs.mq.edu.au). Additional support came from the University of New South Wales (Sydney), and ARC Discovery Project 180103204.
Funding Information:
The authors acknowledge the facilities, and the scientific and technical assistance of the Microscopy Australia research facility at the Centre for Microscopy, Characterization and Analysis (UWA). We thank Pascal Philippot for his editorial handling and anonymous reviewers for their thoughtful comments. This study was supported by the Australian Research Council (ARC) Centre of Excellence for Core to Crust Fluid Systems ( www.ccfs.mq.edu.au ). Additional support came from the University of New South Wales (Sydney), and ARC Discovery Project 180103204.
Publisher Copyright:
© 2020 John Wiley & Sons Ltd
PY - 2020/7/1
Y1 - 2020/7/1
N2 - The shallow marine and subaerial sedimentary and hydrothermal rocks of the ~3.48 billion-year-old Dresser Formation are host to some of Earth's oldest stromatolites and microbial remains. This study reports on texturally distinctive, spherulitic barite micro-mineralization that occur in association with primary, autochthonous organic matter within exceptionally preserved, strongly sulfidized stromatolite samples obtained from drill cores. Spherulitic barite micro-mineralization within the sulfidized stromatolites generally forms submicron-scale aggregates that show gradations from hollow to densely crystallized, irregular to partially radiating crystalline interiors. Several barite micro-spherulites show thin outer shells. Within stromatolites, barite micro-spherulites are intimately associated with petrographically earliest dolomite and nano-porous pyrite enriched in organic matter, the latter of which is a possible biosignature assemblage that hosts microbial remains. Barite spherulites are also observed within layered barite in proximity to stromatolite layers, where they are overgrown by compositionally distinct (Sr-rich), coarsely crystalline barite that may have been sourced from hydrothermal veins at depth. Micro-spherulitic barite, such as reported here, is not known from hydrothermal systems that exceed the upper temperature limit for life. Rather, barite with near-identical morphology and micro-texture is known from zones of high bio-productivity under low-temperature conditions in the modern oceans, where microbial activity and/or organic matter of degrading biomass controls the formation of spherulitic aggregates. Hence, the presence of micro-spherulitic barite in the organic matter-bearing Dresser Formation sulfidized stromatolites lend further support for a biogenic origin of these unusual, exceptionally well-preserved, and very ancient microbialites.
AB - The shallow marine and subaerial sedimentary and hydrothermal rocks of the ~3.48 billion-year-old Dresser Formation are host to some of Earth's oldest stromatolites and microbial remains. This study reports on texturally distinctive, spherulitic barite micro-mineralization that occur in association with primary, autochthonous organic matter within exceptionally preserved, strongly sulfidized stromatolite samples obtained from drill cores. Spherulitic barite micro-mineralization within the sulfidized stromatolites generally forms submicron-scale aggregates that show gradations from hollow to densely crystallized, irregular to partially radiating crystalline interiors. Several barite micro-spherulites show thin outer shells. Within stromatolites, barite micro-spherulites are intimately associated with petrographically earliest dolomite and nano-porous pyrite enriched in organic matter, the latter of which is a possible biosignature assemblage that hosts microbial remains. Barite spherulites are also observed within layered barite in proximity to stromatolite layers, where they are overgrown by compositionally distinct (Sr-rich), coarsely crystalline barite that may have been sourced from hydrothermal veins at depth. Micro-spherulitic barite, such as reported here, is not known from hydrothermal systems that exceed the upper temperature limit for life. Rather, barite with near-identical morphology and micro-texture is known from zones of high bio-productivity under low-temperature conditions in the modern oceans, where microbial activity and/or organic matter of degrading biomass controls the formation of spherulitic aggregates. Hence, the presence of micro-spherulitic barite in the organic matter-bearing Dresser Formation sulfidized stromatolites lend further support for a biogenic origin of these unusual, exceptionally well-preserved, and very ancient microbialites.
KW - dresser formation
KW - organic matter
KW - paleoarchean
KW - spherulitic barite
KW - stromatolites
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U2 - 10.1111/gbi.12392
DO - 10.1111/gbi.12392
M3 - Article
C2 - 32359013
AN - SCOPUS:85084194201
SN - 1472-4677
VL - 18
SP - 415
EP - 425
JO - Geobiology
JF - Geobiology
IS - 4
ER -
