My major research interests concern the evolution of the early biosphere and Archean earth environments. Current field and laboratory work focuses on 3.5 billion year old rocks from the Pilbara region of West Australia and the Barberton region of South Africa. This page gives a quick overview of some of these topics. More broadly I am interested in the co-evolution of microbes with the lithosphere and atmosphere and events such as the rise of photosynthetic microorganisms; also the use of stromatolites as an environmental indicators; and the interaction of sediments, wrinkle-mats and bioturbators.

Together with Prof. Harald Furnes and colleuges I am currently working on a project "Life in the volcanic crust: conditions timing and depth". This project focuses on granular and tubular bioalteration textures in the formerly glassy rims of volcanic pillow lavas and inter pillow hayloclastites and the development of techniques to document their distribution in time and space. We also hope to better understand the metabolisms of the microorganisms involved in creating these bioalteration textures and how they are preserved.   
                             

                                                                                                       (right) pillow basalts of the 3.5 Ga Apex Basalts, WA.

As part of my doctoral work with Prof Martin Brasier and colleuges at Oxford University I worked on criteria for testing the biogenicity of ancient stromatolites. Stromatolites are laminated sedimentary structures that are thought to accrete by a combination of physical, chemical and biological processes that may or may not involve microbial mats. Establishing the contribution of microbial processes in ancient stromatolites can be extremely difficult - with serious implications for our understanding of the emergence of the microbial world.
                               
My fieldwork focussed on mapping the morphologies and depositional setting of the ~3.4Ga Strelley Pool chert stromatolites which have received much attention after recent reports that they represent the world's oldest phototrophic reef community (Allwood et al. 2006). Our work contests these claims and we are currently preparing field and morphological data for publication.   
                                                                                                                       

(above left) ~3.4 Ga stromatolite from the Strelley Pool chert;                                                                 (above right) modern subtidal stromatolite from Shark Bay, WA.


My laboratory work focussed on experiments to synthesise abiotic stromatolites from colloidal media. This work highlighted several environments under which mini-columnar, branched stromatolites can form in the absence of microbial mats and emphasised that macro-morphology alone is an ambiguous indicator of stromatolite biogenicity.
                                                                                                                        (right) synthetic bulbous, branched ministromatolite.

I am also very interested in modern microbial mat processes and experimental studies of stromatolite accretion. With my collaborator Bekah Shepard at UCD we have enjoyed many lively discussions about modern and ancient stromatolite processes.
                                                                                                                     

(left) thin section image of carbonaceous "microfossil" artifact from the ~3.45 Ga Apex Chert, scale bar 10 microns.

Whilst working in the Pilbara in 2003 we discovered microtubular structures in grains within a silicified sandstone from the Strelley Pool chert that appeared remarkably similar to volcanic bioalteration textures - initial findings are presented in Brasier et al. (2006), and Wacey et al. (2006). We are using a range of techniques to test the syngenicity of these structures and to establish whether they were created by the actions of ancient microbes. Arising from this work I have written a manuscript which begins to formulate criteria for testing the biogenicity of candidate endolithic microborings drawing together work on modern and ancient euendoliths in both sedimentary and volcanic substrates - see McLoughlin et al. 2007.