Petrography, chemostratigraphy, and depositional controls on the Paleoproterozoic Weeli Wolli Iron Formation, Hamersley Basin, Western Australia
Abstract
The ca. 2.45 Ga Weeli Wolli Iron Formation (IF) of Western Australia, situated between the underlying Brockman Iron Formation and overlying Boolgeeda Iron Formation, remains one of the least stratigraphically and chemostratigraphically resolved units within the Hamersley Basin. Here, we present a comprehensive petrographic and geochemical investigation of a 272-meter-deep drill core that preserves well-developed oxide-and silicatefacies IF, as well as some carbonates. Gradational lithofacies transitions indicate that the Weeli Wolli IF documents evolving seawater chemistry and depositional conditions. Petrographic relationships suggest that ferrihydrite (Fe[OH] 3 ), hematite (Fe 2 O 3 ), and magnetite (Fe 3 O 4 ) represent the earliest formed phases, as supported by the preservation of primary sedimentary textures. Chemostratigraphic patterns reveal that silicate-facies deposition corresponded with increased hydrothermal input, intermittently overprinted by pulses of continental runoff delivering detrital material. Relative to the underlying Joffre Member of the Brockman IF and the overlying Boolgeeda IF, Mn concentrations are consistently low, suggesting that the redox-buffering effect of dissolved Fe(II) limited MnO 2 precipitation. Elevated Cr/Ti ratios imply enhanced oxidative weathering and the delivery of solubilized Cr to the oceans, consistent with rising atmospheric O 2 levels. These seemingly contradictory signals, together with transient geochemical excursions, support a model of episodic rather than sustained oxygenation during deposition of the Weeli Wolli IF. Lithofacies distributions and sedimentary structures are consistent with accumulation during a modest marine transgression. Carbonates host various iron-oxide and iron-silicate inclusions, and were developed in relatively shallow settings where higher biomass likely stimulated dissimilatory Fe(III) reduction (DIR), whereas deeper-water environments favored diminished biological activity and the preservation of oxide-facies IF. Collectively, these data indicate that deposition of the Weeli Wolli IF coincided with dynamic redox fluctuations and shifting marine conditions at the onset of the Great Oxidation Event (GOE).
Related
- Middle Jurassic–Lower Cretaceous Depositional Facies Evolution and a Fan-Delta–Beach-Bar Model Based on a Case Study from the Anjihai Section in the Southern Junggar Basin
- Tectono-magmatic evolution of the Amet granite-gneiss terrane, Sandmata Complex (NW India): Implications for Paleoproterozoic crustal accretion during Columbia assembly
- Integrating multi-source remote sensing, field work, and petrography for automatic lithological mapping and mineralization potential in the Gabal El-Faraid, Egypt
- From rifting to collision: deep closure of a Wilson cycle during the Archean–Paleoproterozoic transition at the Carajás-Bacajá boundary, Amazonian Craton
- Stratigraphic noise and post depositional effects in isotopic record of Antarctic firn: insights from a snow trench at Dome C
BibTeX
@article{li2026petrography,
title = {{Petrography, chemostratigraphy, and depositional controls on the Paleoproterozoic Weeli Wolli Iron Formation, Hamersley Basin, Western Australia}},
author = {Zhiquan Li and Kurt O Konhauser and Ernesto Pecoits and Natalie R Aubet and Stefan V Lalonde and Shannon Zurevinski and Daniel S Alessi and Leslie J Robbins},
journal = {Precambrian Research},
year = {2026},
month = oct,
doi = {10.1016/j.precamres.2026.108281},
url = {https://univ-brest.hal.science/hal-05841699v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Petrography, chemostratigraphy, and depositional controls on the Paleoproterozoic Weeli Wolli Iron Formation, Hamersley Basin, Western Australia
AU - Zhiquan Li
AU - Kurt O Konhauser
AU - Ernesto Pecoits
AU - Natalie R Aubet
AU - Stefan V Lalonde
AU - Shannon Zurevinski
AU - Daniel S Alessi
AU - Leslie J Robbins
PY - 2026
DA - 2026/10/14
JO - Precambrian Research
DO - 10.1016/j.precamres.2026.108281
UR - https://univ-brest.hal.science/hal-05841699v1
AB - The ca. 2.45 Ga Weeli Wolli Iron Formation (IF) of Western Australia, situated between the underlying Brockman Iron Formation and overlying Boolgeeda Iron Formation, remains one of the least stratigraphically and chemostratigraphically resolved units within the Hamersley Basin. Here, we present a comprehensive petrographic and geochemical investigation of a 272-meter-deep drill core that preserves well-developed oxide-and silicatefacies IF, as well as some carbonates. Gradational lithofacies transitions indicate that the Weeli Wolli IF documents evolving seawater chemistry and depositional conditions. Petrographic relationships suggest that ferrihydrite (Fe[OH] 3 ), hematite (Fe 2 O 3 ), and magnetite (Fe 3 O 4 ) represent the earliest formed phases, as supported by the preservation of primary sedimentary textures. Chemostratigraphic patterns reveal that silicate-facies deposition corresponded with increased hydrothermal input, intermittently overprinted by pulses of continental runoff delivering detrital material. Relative to the underlying Joffre Member of the Brockman IF and the overlying Boolgeeda IF, Mn concentrations are consistently low, suggesting that the redox-buffering effect of dissolved Fe(II) limited MnO 2 precipitation. Elevated Cr/Ti ratios imply enhanced oxidative weathering and the delivery of solubilized Cr to the oceans, consistent with rising atmospheric O 2 levels. These seemingly contradictory signals, together with transient geochemical excursions, support a model of episodic rather than sustained oxygenation during deposition of the Weeli Wolli IF. Lithofacies distributions and sedimentary structures are consistent with accumulation during a modest marine transgression. Carbonates host various iron-oxide and iron-silicate inclusions, and were developed in relatively shallow settings where higher biomass likely stimulated dissimilatory Fe(III) reduction (DIR), whereas deeper-water environments favored diminished biological activity and the preservation of oxide-facies IF. Collectively, these data indicate that deposition of the Weeli Wolli IF coincided with dynamic redox fluctuations and shifting marine conditions at the onset of the Great Oxidation Event (GOE).
SN - 0301-9268
ER -