Overview
I study ancient fossils in the form of stromatolites (macroscopic structures built by communities of microorganisms) and microfossils (cellularly-preserved remains of microorganisms), as well as their mineralogic and isotopic signatures, to contribute to our understanding of the type and diversity of life present early on in Earth's history. My primary field site is a ~2.3-2.4 billion-year-old microbialite reef deposit within rocks of the Turee Creek Group in the Hamersley Ranges of Western Australia.
My current Postdoc research with the Laboratory for Agnostic Biosignatures utilises field observations paired with multiple, in situ geochemical techniques to explore the concept of past agnostic biosignatures (a.k.a. universal signs of life in rocks). The long-term goal of this work is to be able to recognise and describe fossilised life ‘as we don’t know it’ elsewhere.
I'm also interested in:
- using isotopic systems to unearth ancient microfossil metabolisms and to investigate how these may be tied to habitat;
- how Precambrian microfossils initially became silicified and then remained morphologically-preserved through quartz mineralisation/recrystallisation;
- how biological information is altered across deep (billion-year) time periods;
- how we better distinguish between physical (abiotic) artefacts and biological structures;
- how life may have changed as a result of the significant increase in atmospheric oxygen at ~2.4 Ga (a.k.a. the Great Oxidation Event, GOE);
- the apparent increase in microfossil complexity through time; and
- the timing of the emergence of eukaryotes from a morphological perspective.
My current Postdoc research with the Laboratory for Agnostic Biosignatures utilises field observations paired with multiple, in situ geochemical techniques to explore the concept of past agnostic biosignatures (a.k.a. universal signs of life in rocks). The long-term goal of this work is to be able to recognise and describe fossilised life ‘as we don’t know it’ elsewhere.
I'm also interested in:
- using isotopic systems to unearth ancient microfossil metabolisms and to investigate how these may be tied to habitat;
- how Precambrian microfossils initially became silicified and then remained morphologically-preserved through quartz mineralisation/recrystallisation;
- how biological information is altered across deep (billion-year) time periods;
- how we better distinguish between physical (abiotic) artefacts and biological structures;
- how life may have changed as a result of the significant increase in atmospheric oxygen at ~2.4 Ga (a.k.a. the Great Oxidation Event, GOE);
- the apparent increase in microfossil complexity through time; and
- the timing of the emergence of eukaryotes from a morphological perspective.
Honours research (2013-2014)
My Honours research involved 4 weeks of remote field work, where I mapped the distribution of various Turee Creek Group units for ~15 km along strike and pieced together the lithostratigraphy. I documented several types of shallow-water microbialites, including stratiform, domal and columnar (± branching) forms, which I used to reconstruct transgression-regression cycles (relative sea-level change). This work is detailed in my Honours thesis (Barlow, 2014) and a paper in the journal Geobiology (Barlow et al., 2016).
PhD research (2015-2019)
During my PhD, I investigated black chert units from the deeper-water portion of the same Turee Creek Group sequence. Inside the black cherts, I discovered there were numerous microfossil morphologies preserved. Based on cell shape and size, I divided these forms into 19 specific categories, or morphotypes.
Using field and petrographic observations, I determined that these morphotypes were actually distributed within four distinct microfossil communities, and that these communities could be tied into different habitats within the ancient ecosystem. I also inferred the possible metabolisms of the microfossils using in situ C and S isotopic analyses.
Two of the microfossil morphotypes are new to science - they have no known counterparts in either older or younger rocks. In addition, a number of forms I've documented are remarkably similar to microfossils described from the well-known, but much younger, ~1.9 Ga Gunflint Iron Formation in Canada.
Part of these findings are reported in Geobiology (Barlow & Van Kranendonk, 2018; Barlow et al., 2023), while the rest of this work is detailed in my PhD thesis (Barlow, 2019) and in papers in prep.
Due to a worldwide sparse fossil record from this time period, the potential impact of the GOE on life is unknown. My research has shown that life during the GOE was both diverse and relatively complex, revealing the Turee Creek Group as a substantial new reference point in the sparse fossil record of the early Paleoproterozoic.
My Honours research involved 4 weeks of remote field work, where I mapped the distribution of various Turee Creek Group units for ~15 km along strike and pieced together the lithostratigraphy. I documented several types of shallow-water microbialites, including stratiform, domal and columnar (± branching) forms, which I used to reconstruct transgression-regression cycles (relative sea-level change). This work is detailed in my Honours thesis (Barlow, 2014) and a paper in the journal Geobiology (Barlow et al., 2016).
PhD research (2015-2019)
During my PhD, I investigated black chert units from the deeper-water portion of the same Turee Creek Group sequence. Inside the black cherts, I discovered there were numerous microfossil morphologies preserved. Based on cell shape and size, I divided these forms into 19 specific categories, or morphotypes.
Using field and petrographic observations, I determined that these morphotypes were actually distributed within four distinct microfossil communities, and that these communities could be tied into different habitats within the ancient ecosystem. I also inferred the possible metabolisms of the microfossils using in situ C and S isotopic analyses.
Two of the microfossil morphotypes are new to science - they have no known counterparts in either older or younger rocks. In addition, a number of forms I've documented are remarkably similar to microfossils described from the well-known, but much younger, ~1.9 Ga Gunflint Iron Formation in Canada.
Part of these findings are reported in Geobiology (Barlow & Van Kranendonk, 2018; Barlow et al., 2023), while the rest of this work is detailed in my PhD thesis (Barlow, 2019) and in papers in prep.
Due to a worldwide sparse fossil record from this time period, the potential impact of the GOE on life is unknown. My research has shown that life during the GOE was both diverse and relatively complex, revealing the Turee Creek Group as a substantial new reference point in the sparse fossil record of the early Paleoproterozoic.
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My Honours and PhD research was generously supported by my advisor, Prof. Martin Van Kranendonk, as well as funding from the School of BEES, Australian Centre for Astrobiology, and PANGEA Research Centre, all based at UNSW, and the ARC CoE for Core to Crust Fluid Systems, based at Macquarie University.
I also acknowledge the Traditional Custodians, the Puutu Kunti Kurrama and Pinikura peoples of WA, on whose land I conducted field work for this research.
My Honours and PhD research was generously supported by my advisor, Prof. Martin Van Kranendonk, as well as funding from the School of BEES, Australian Centre for Astrobiology, and PANGEA Research Centre, all based at UNSW, and the ARC CoE for Core to Crust Fluid Systems, based at Macquarie University.
I also acknowledge the Traditional Custodians, the Puutu Kunti Kurrama and Pinikura peoples of WA, on whose land I conducted field work for this research.