Tube structures of probable microbial origin in the Neoarchean Carawine Dolomite, Hamersley Basin, Western Australia

Abstract

The approximately 2.63 Ga Carawine Dolomite, Hamersley Basin, Western Australia, preserves tube structures of probable microbial origin that formed in a low energy environment. The tubes are 0.4-1.8 cm in diameter and at least 10-16 cm long in outcrop. The tubes are defined by dark, 45-microm-thick dolomicritic walls, whereas the tube fill and host rock are composed of 30 microm, cloudy dolomite crystals and rare 170- to 425-microm-wide, dark well-sorted clasts. Closely spaced, rarely discontinuous laminae coat the insides of tubes; less closely spaced, peaked, discontinuous laminae coat the outsides of tubes. The laminae on the outsides of tubes are often intercalated with mammilate structures. The presence of probable microbial coatings on both the insides and the outsides of the tube walls requires that the tubes formed above the sediment-water interface. These tube structures probably formed during gas-charged fluid escape, similar to tubes observed in ancient and modern hydrocarbon seeps and cylindrical water transfer structures in sandstones. The laminae that coat the tubes have very similar geometries to modern biofilms that form in both turbulent and laminar flow, and their geometries probably reflect flow conditions during the fluid escape. The identification of these structures suggests that the preserved interaction between fluid escape and microbial growth in carbonates may be more common than previously thought.

Oxygen-Dependent Morphogenesis of Modern Clumped Photosynthetic Mats and Implications for the Archean Stromatolite Record

“…Briefly noted as "lenticular fenestrae" in modern stromatolites from Yellowstone National Park (YNP; [16]), these textures were recently described in much more detail, discussed as biosignatures of oxygenic photosynthesis and contrasted to the more common fabric-destroying fenestrae produced during extensive organic decay [17][18][19]. With possible exceptions [10,16,20], analogous fenestrate textures are yet to be identified or confirmed in Archean stromatolites.…”

Formation and stability of oxygen‐rich bubbles that shape photosynthetic mats

“…Some fossil counterparts of these are Upper Cretaceous tubular structures from Tepee Buttes Member of the Pierre Shale Formation in Colorado (Krause et al, 2009) and cm-scale tubestones recognized in the Neorchean Carawine Dolomite (Murphy & Sumner, 2008). Some fossil counterparts of these are Upper Cretaceous tubular structures from Tepee Buttes Member of the Pierre Shale Formation in Colorado (Krause et al, 2009) and cm-scale tubestones recognized in the Neorchean Carawine Dolomite (Murphy & Sumner, 2008).…”

“…The former are described as circular to oval in horizontal cross-section, a few millimeters to tens of millimeters wide and several centimeters to decimeters long, with walls lined with microparticles but not finely laminated (Krause et al, 2009). The latter are described as shallow-water structures 0.4-1.8 cm in diameter that pinch, swell and coalesce along their 10-16 cm length and have mammillate structures on the finely laminated outer walls (Murphy & Sumner, 2008). More morphological similarities exist between photosynthetic tubes and Archean tubestones.…”

“…Adapted fromMurphy & Sumner (2008, Figure 8A). (A) Transmitted light micrograph (mosaic) of a vertical thin section through a cm-scale tube.…”

Variations in Neoarchean microbialite morphologies: clues to controls on microbialite morphologies through time

“…, 2001, 2002; Corsetti & Grotzinger, 2005). Tubes in the Carawine Dolomite are significantly different to those in the Noonday Dolomite (Murphy & Sumner, 2007). The Carawine Formation tubes are typically smaller and are variably oriented with respect to bedding.…”