Microfacies and origin of some Archean cherts (Pilbara, Australia)

Orberger, B.; Rouchon, Virgile; Westall, F.; Vries, Sjoukje T. de; Pinti, Daniele L.; Wagner, Christiane; Wirth, Richard; Hashizume, K.

doi:10.1130/2006.2405(08)

Cited by 31 publications

(36 citation statements)

References 62 publications

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“…Prior to silicification, the precursor rock of zone I had a porphyritic or porphyroclastic texture, typical of volcaniclastic rocks. Precursor minerals were most likely pyroxenes, amphiboles and feldspars, suggesting a basaltic protolith (Figure 2c) [Orberger et al, 2006b]. The presence of euhedral Fe-sulfides point to a reducing environment during silicification ( Figure 2c).…”

Section: Introductionmentioning

confidence: 99%

“…[10] Focused Ion Beam-Transmission Electron Microscope (FIB -TEM) investigations at the GFZ-Potsdam showed that each microband of FeMnOH is composed of nanometric filaments, each of them consisting of euhedral hematite crystals with an average size of 100 nm [Orberger et al, 2006a[Orberger et al, , 2006b]. The vermicular microscopic textures and filamentous, clustered nanotextures of the hematite can possibly be related to microbial activity.…”

Section: Introductionmentioning

confidence: 99%

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Biogenic nitrogen and carbon in Fe‐Mn‐oxyhydroxides from an Archean chert, Marble Bar, Western Australia

Pinti

Hashizume

Orberger

et al. 2007

Geochem Geophys Geosyst

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[1] To quantify and localize nitrogen (N) and carbon (C) in Archean rocks from the Marble Bar formation, Western Australia, and to gain insights on their origin and potential biogenicity, we conducted nuclear reaction analyses (NRA) and carbon and nitrogen isotope ratio measurements on various samples from the 3460-Myr-old Fe-rich Marble Bar chert. The Marble Bar chert formed during the alteration of basaltic volcanoclastic rocks with Fe-and Si-rich hydrothermal fluids, and the subsequent precipitation of magnetite, carbonates, massive silica, and, locally, sulfides. At a later stage, the magnetite, sulfides, and carbonates were replaced by Fe-Mn-oxyhydroxides. Nuclear reaction analyses indicate that most of the N and C resides within these Fe-Mn-oxyhydroxides, but a minor fraction is found in K-feldspars and Ba-mica dispersed in the silica matrix. The N and C isotopic composition of Fe-oxides suggests the presence of a unique biogenic source with d 15 N AIR values from +6.0 ± 0.5% to 7.3 ± 1.1% and a d 13 C PDB value of À19.9 ± 0.1%. The C and N isotope ratios are similar to those observed in Proterozoic and Phanerozoic organic matter. Diffusion-controlled fractionation of N and C released during high combustion temperatures indicates that these two elements are firmly embedded within the iron oxides, with activation energies of 18.7 ± 3.7 kJ/mol for N and 13.0 ± 3.8 kJ/mol for C. We propose that N and C were chemisorbed on iron and were subsequently embedded in the crystals during iron oxidation and crystal growth. The Fe-isotopic composition of the Marble Bar chert (d 56 Fe = À0.38 ± 0.02%) is similar to that measured in iron oxides formed by direct precipitation of iron from hydrothermal plumes in contact G 3

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Biogenic nitrogen and carbon in Fe‐Mn‐oxyhydroxides from an Archean chert, Marble Bar, Western Australia

Pinti

Hashizume

Orberger

et al. 2007

Geochem Geophys Geosyst

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“…1; Buick & Barns, 1984;Van Kranendonk, 2006). Previous studies on the sedimentary rocks of the Marble Bar Chert Member focused on the chemical and thermal conditions associated with the precipitation of these cherts (Sugitani, 1992;Minami et al 1995;Kojima et al 1998;Orberger et al 2006;van den Boorn et al 2007van den Boorn et al , 2010. However, the depositional environment and the mode of formation of the Marble Bar Cherts remain subject to debate, and both hydrothermal †Author for correspondence: Nicolas.Olivier@univ-lyon1.fr environments on a mid-oceanic ridge and large submarine caldera settings have been proposed (Oliver & Cawood, 2001;Kato & Nakamura, 2003;Van Kranendonk, 2006;Hoashi et al 2009;van den Boorn et al 2010).…”

Section: Introductionmentioning

confidence: 99%

A deep subaqueous fan depositional model for the Palaeoarchaean (3.46 Ga) Marble Bar Cherts, Warrawoona Group, Western Australia

et al. 2012

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International audienceThe 3.46 Ga Marble Bar Chert Member of the East Pilbara Craton, Western Australia, is one of the earliest and best-preserved sedimentary successions on Earth. Here, we interpret the finely laminated thin-bedded cherts, mixed conglomeratic beds, chert breccia beds and chert folded beds of the Marble Bar Chert Member as the product of low-density turbidity currents, high-density turbidity currents, mass transport complexes and slumps, respectively. Integrated into a channel-levee depositional model, the Marble Bar Chert Member constitutes the oldest documented deep-sea fan on Earth, with thin-bedded cherts, breccia beds and slumps composing the outer levee facies tracts, and scours and conglomeratic beds representing the channel systems

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“…However, in terrestrial Fe-oxide grains and spherules, organic matter can be present (McConchie, 1987;Klein and Beukes, 1992;Yoshioka et al, 2001;Orberger et al, 2006;Pinti et al, 2007) and thus the Fe-oxide spherules on Mars may represent an important target in the search of biomarkers. Among terrestrial environments, banded iron formations (BIFs) are potential time equivalent analogues.…”

Section: Introductionmentioning

confidence: 99%

Origin of iron oxide spherules in the banded iron formation of the Bababudan Group, Dharwar Craton, Southern India

Orberger

Wagner

Wirth

et al. 2012

Journal of Asian Earth Sciences

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The banded iron formation of the Bababudan Group (Western Dhawar Craton, India) is composed of millimetric to centimetric alternating quartz and grey to red Fe-oxide bands.Major phases are quartz and martite (hematized magnetite) with minor Fe-sulfides and CaMg-Fe-carbonates. Micrometric Fe-oxide spherules fill cavities in discontinuous micrometric layers of Fe-oxides that occur in the massive quartz layers and at the interface of massive Feoxide and quartz layers. The spherules are composed of micrometric radial plates of hematite intergrown with nanometric magnetite. These spherules contain carbonaceous matter (CM) with nanometric Fe-particles and have low N contents (~ 900 ppm; CM1). The spherule formation is attributed to a low temperature hydrothermal process (150-200°C) at around 2.52 Ga, possibly favored by the presence of CM. These hydrothermal fluids dissolved diagenetic interstitial sulfides or carbonates creating cavities which, provided space for the spherule precipitation. Carbonaceous matter of semi-anthracite maturity is encapsulated in quartz grains adjacent to the Fe-oxide spherules (CM2) and it is thus concluded that CM1 and CM2 are most likely contemporaneous and of the same origin, either incorporated at the time of BIF formation or during the hydrothermal event at 2.52 Ga from the underlying phyllitised black shales. Carbonaceous matter (CM3) was also found around the Fe-oxide spherules and the martite grains. CM3 has much higher N contents (> 5000 ppm) and is of a lower maturity than CM1 and CM2 and is related to weathering, also indicated by the presence of goethite and kaolinite. The  13 C of all CMs varies from -19.4 to -24.7 ‰, similar to values measured in the underlying phyllitised black shales and likely reflect denitrifying microbial activity.

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Microfacies and origin of some Archean cherts (Pilbara, Australia)

Cited by 31 publications

References 62 publications

Biogenic nitrogen and carbon in Fe‐Mn‐oxyhydroxides from an Archean chert, Marble Bar, Western Australia

Biogenic nitrogen and carbon in Fe‐Mn‐oxyhydroxides from an Archean chert, Marble Bar, Western Australia

A deep subaqueous fan depositional model for the Palaeoarchaean (3.46 Ga) Marble Bar Cherts, Warrawoona Group, Western Australia

Origin of iron oxide spherules in the banded iron formation of the Bababudan Group, Dharwar Craton, Southern India

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