Sedimentology, chemostratigraphy, and stromatolites of lower Paleoproterozoic carbonates, Turee Creek Group, Western Australia

Rowan C Martindale,Justin V Strauss,Erik A Sperling,Jena E Johnson,Martin J Van Kranendonk,David Flannery,Katherine French,Kevin Lepot,Rajat Mazumder,Melissa S Rice,Daniel P Schrag,Roger Summons,Malcolm Walter,John Abelson,Andrew H Knoll

doi:10.1016/j.precamres.2015.05.021

Abstract

The ca. 2.45–2.22Ga Turee Creek Group, Western Australia, contains carbonate-rich horizons that postdate earliest Proterozoic iron formations, bracket both Paleoproterozoic glaciogenic beds and the onset of the Great Oxidation Event (GOE), and predate ca. 2.2–2.05Ga Lomagundi-Jatuli C-isotopic excursion(s). As such, Turee Creek carbonate strata provide an opportunity to characterize early Paleoproterozoic carbonate sedimentation and carbon cycle dynamics in the context of significant global change. Here, we report on the stratigraphy, sedimentology, petrology, carbon isotope chemostratigraphy, and stromatolite development for carbonate-rich successions within the pre-glacial part of the Kungarra Formation and the postglacial Kazput Formation.Kungarra carbonate units largely occur as laterally discontinuous beds within a thick, predominantly siliciclastic shelf deposit. While this succession contains thin microbialite horizons, most carbonates consist of patchy calcite overgrowths within a siliciclastic matrix. C-isotopic values show marked variation along a single horizon and even within hand samples, reflecting spatially and temporally variable mixing between dissolved inorganic carbon in seawater and isotopically light inorganic carbon generated via syn- and post-depositional remineralization of organic matter.In contrast, the Kazput carbonates consist of subtidal stromatolites, grainstones, and micrites deposited on a mixed carbonate–siliciclastic shelf. These carbonates exhibit moderate δ13C values of −2‰ to +1.5‰ and likely preserve a C-isotopic signature of seawater. Kazput carbonates, thus, provide some of the best available evidence that an interval of unexceptional C-isotopic values separates the Lomagundi-Jatuli C-isotopic excursion(s) from the initiation of the GOE as inferred from multiple sulfur isotopes (loss of mass independent fractionation). The Kazput Formation also contains unusual, m-scale stromatolitic buildups, which are composed of sub-mm laminae and discontinuous, convex upward lenticular precipitates up to a few mm in maximum thickness. Laminae, interpreted as microbial mat layers, contain quartz and clay minerals as well as calcite, whereas precipitate lenses consist of interlocking calcite anhedra, sometimes showing faint mm-scale banding. These cements formed either as infillings of primary voids formed by gas emission within penecontemporaneously lithified mats, or as local seafloor precipitates that formed on, or within, surface mats. It is possible that both mechanisms interacted to form the unique Kazput stromatolites. These microbialites speak to a distinctive interaction between life and environment early in the Paleoproterozoic Era.

Highlights

IntroductionLower Paleoproterozoic sedimentary rocks record a number of first-order changes in the Earth system, including globally extensive ice sheets, one or more extreme states of the carbon cycle characterized by uniquely high δ13C in carbonates, and the initial accumulation of oxygen in the atmosphere and surface oceans (Akin et al, 2013; Asael et al, 2013; Bekker and Holland, 2012; Bekker et al, 2004, 2013; Farquhar et al, 2000; Fralick et al, 2011; Hoffman, 2013; Konhauser et al, 2011; Lyons et al, 2012, 2014; Melezhik and Fallick, 2010; Partin et al, 2013; Planavsky et al, 2012, 2014; Pufahl andHiatt, 2012; Pufahl et al, 2010, 2011; Reinhard et al, 2013; Scott et al, 2014; Swanner et al, 2014; and references therein)
Two fabrics make up the Kazput stromatolites: wavy to crenulated siliciclastic laminae, 30 to 400 μm thick, that are continuous on the scale of a single dome, and interbedded, convex upward, lenticular carbonates that are generally discontinuous on a mm to cm-scale and are common or absent in alternating zones (Fig. 10)
This study provides new litho- and chemostratigraphic data for carbonate-bearing intervals of the 2.45–2.22 Ga Turee Creek Group, Western Australia, which spans a pivotal time in Earth history after the deposition of global banded iron formation and across the Great Oxidation Event (GOE)

Summary

Introduction

Lower Paleoproterozoic sedimentary rocks record a number of first-order changes in the Earth system, including globally extensive ice sheets, one or more extreme states of the carbon cycle characterized by uniquely high δ13C in carbonates, and the initial accumulation of oxygen in the atmosphere and surface oceans (Akin et al, 2013; Asael et al, 2013; Bekker and Holland, 2012; Bekker et al, 2004, 2013; Farquhar et al, 2000; Fralick et al, 2011; Hoffman, 2013; Konhauser et al, 2011; Lyons et al, 2012, 2014; Melezhik and Fallick, 2010; Partin et al, 2013; Planavsky et al, 2012, 2014; Pufahl andHiatt, 2012; Pufahl et al, 2010, 2011; Reinhard et al, 2013; Scott et al, 2014; Swanner et al, 2014; and references therein). 2.2 Ga onset of the Lomagundi-Jatuli C-isotopic excursion(s), and hosts carbonate and glacially-influenced strata that record onset of the Great Oxidation Event (GOE) (Bekker et al, 2004; Martin et al, 2013; Van Kranendonk and Mazumder, 2015). These carbonates provide an opportunity to characterize the response of early The ca. 2.45–2.22 Ga Turee Creek Group, exposed in the Hamersley Range of Western Australia, conformably overlies earliest Paleoproterozoic iron formations, predates the ca. 2.2 Ga onset of the Lomagundi-Jatuli C-isotopic excursion(s), and hosts carbonate and glacially-influenced strata that record onset of the Great Oxidation Event (GOE) (Bekker et al, 2004; Martin et al, 2013; Van Kranendonk and Mazumder, 2015).

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