Assessing the biogenicity and syngenicity of candidate bioalteration textures in pillow lavas of the ∼2.52 Ga Wutai greenstone terrane of China

Abstract

Microorganisms that inhabit sub-seafloor lavas are capable of etching volcanic glass and creating micron-sized tunnels and pits. Mineralization of these bioalteration traces ensures that these textures survive deformation and transformation of the host glass to metamorphic minerals. The fossil record of such bioalteration textures extends far beyond volcanic glass from in-situ oceanic crust to include meta-volcanic glass from ophiolites and Precambrian greenstone belts. Investigation of petrographic thin section reported here from ~2.52 Ga tholeiitic pillow lavas from the Wutai Group of N. China found filamentous micro-textures. Laser Raman spectroscopy confirmed that these textures are mineralized by titanite. Moreover, the Wutai micro-textures are comparable in size, morphology and distribution to bioalteration textures from Archean greenschist facies pillow lavas. In-situ U-Pb dating of the titanite by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) gives an age of 1.81 ± 0.12 Ga (2σ, n=22, 206 Pb/ 238 U weighted average). This provides a minimum age for the mineralization of these candidate bioalteration textures and corresponds to a regional metamorphic event. This also represents a minimum age estimate for the timing of bioalteration and is compatible with the existence of a Late Archean-Proterozoic sub-seafloor biosphere. meta-volcanic glass, microbial bioalteration, titanite, sub-seafloor biosphere, Archean, North China Craton Citation:McLoughlin N, Fliegel D J, Furnes H, et al. Assessing the biogenicity and syngenicity of candidate bioalteration textures in pillow lavas of the ~2.52 Ga

Septate‐tubular textures in 2.0‐Ga pillow lavas from the Pechenga Greenstone Belt: a nano‐spectroscopic approach to investigate their biogenicity

“…Unlike bioalteration textures previously dated from the Hooeggenoeg Complex of the Barberton Greenstone Belt, the Euro basalt of the Pilbara Craton (Banerjee et al. , 2007), and the Wutai belt of north‐China (McLoughlin et al. , 2010a,b), the textures investigated here are not mineralized by titanite and hence direct in situ dating of the textures themselves is not possible.…”

“…Additionally, we did not find terminal organic matter as has been described for possible AIT in Archean tubular textures (Lepot et al. , 2009; McLoughlin et al. , 2010a,b).…”

“…Figure 13(E) probably represents the end of a tube given the more chaotically crystallized pumpellyite and presence of two walls of chlorite. There is no indication of a terminal crystal in the tubular textures we investigated as is sometimes observed in ambient inclusion trails (AIT) (Tyler & Barghoorn, 1963; McLoughlin et al. , 2010a,b).…”

Discovery of Naturally Etched Fission Tracks and Alpha-Recoil Tracks in Submarine Glasses: Reevaluation of a Putative Biosignature for Earth and Mars

“…It then follows that "older" examples of titanitemineralized tubular textures attributed to microbial activity that are preserved along healed fractures in the metamorphosed margins of pillow lavas in Archean greenstone belts [25,35,37,91,94] might also simply represent the preserved (titanite-mineralized) relicts of preferential corrosion of radiation damage and/or pressure solution etch-tunnelling (i.e., "abiotic" microtextures) that formed during the encroachment of seawater into these basaltic glass pillow margins in Archean times.…”

Tubular textures in pillow lavas from a Caledonian west Norwegian ophiolite: A combined TEM, LA-ICP-MS, and STXM study

“…The biogenicity of such textures has been discussed using various approaches such as morphology [ McLoughlin et al , 2009b], elemental distributions (C, N, S and P) [ Banerjee et al , 2007; Banerjee and Muehlenbachs , 2003], DNA staining [ Banerjee and Muehlenbachs , 2003], organic carbon analysis [ Benzerara et al , 2007], and stable isotope signatures [ Furnes et al , 2002; Torsvik et al , 1998]. Such textures have been described within glassy pillow lava rims from in situ oceanic crust [ Banerjee and Muehlenbachs , 2003], ophiolites [ Furnes et al , 2002, 2008], and even from Archean greenstone belts [ Banerjee et al , 2004, 2007; Furnes et al , 2004; McLoughlin et al , 2009a; Staudigel et al , 2008] that represent some of the oldest oceanic crustal fragments on Earth [ Staudigel et al , 2008].…”