Stromatolites, so what?! A tribute to Robert N. Ginsburg

Abstract

In tribute to Dr. Robert N. Ginsburg (1925–2017), we examine his 1991 seminal paper Controversies about Stromatolites: Vices and Virtues, which summarized current ideas about stromatolites including controversies of definition, whether ancient stromatolites should be interpreted as sedimentary structures and mechanisms of carbonate fixation. The accepted model of stromatolite morphogenesis in 1991 was that biology controls microscale internal structure whereas environment controls macroscale morphology. Ginsburg, however, predicted that biology and environmental influences on stromatolite growth were closely coupled at macro, meso and micro scales. Recent research in Hamelin Pool and the Bahamas has advanced our understanding of the inherent duality of stromatolites and associated controversies. These studies suggest that at the macroscale, when physical forces are strong, the environment is the main control on the morphology; however, when physical forces are weak, biological communities become the main drivers of morphology. Therefore, stromatolites can be considered both as fossils and as sedimentary structures dependent on the energy in the environment of deposition. At the mesoscale, as predicted by Trompette, stromatolite fabrics are influenced equally by environment and biology. As the degree of lamination is often unknown or heterogeneous, a generic genetic term such as ‘microbialite’ is considered the most appropriate terminology for structures of probable microbial origin. At the microscale, stromatolite microfabrics reflect environmentally driven cycling of microbial communities, reflecting both biology and environment. With respect to carbonate fixation, research on modern stromatolites provides a model for biofilm precipitation of micritic laminae lacking microfossils in ancient stromatolites. As pointed out by Ginsburg, the inherent duality of environmental and biological controls of morphogenesis at all scales is at the root of many long‐standing controversies. Recent investigations corroborate the foresight of Ginsburg nearly 30 years ago, further confirming well‐preserved stromatolites can provide insight into both biology and environmental factors in ancient ecosystems.

Metazoan activity facilitates passive sediment trapping in modern supratidal microbialites: Revealed using µ‐CT‐scanning and microscopy

“…Two issues relating to the formation of microbialites remain unresolved: (a) the drivers of the decline of laminated stromatolite varieties (Bernhard et al, 2013;Kennard & James, 1986); and (b) the formative drivers resulting in coarser-grained fabrics rather than finegrained fabrics (Suosaari et al, 2019). In both cases, possible agents include eukaryotic organisms.…”

“…A matter of debate surrounding microbialite formation is the discrepancy that exists between the microfabrics of micritic carbonate precipitated and coarse trapped-and-bound microbialites (e.g. Frantz et al, 2015;Suosaari et al, 2019). A possible explanation for the different modes of formation is that cyanobacteria are responsible for the precipitation of micrite, whereas the coarser trapped and bound fabrics are formed by eukaryotic algae, such as diatoms (Awramik & Riding, 1988).…”

“…In addition to changes in diversity and abundance, another issue surrounding microbialite formation is the different mechanisms driving the observed microfabrics (Suosaari et al, 2019). The definition of microbialites takes into account two formation processes, namely trapping and binding of sediment grains and mineral precipitation (Walter, 1976).…”

A predictive model for the ichnological suitability of the Jezero crater, Mars: searching for fossilized traces of life-substrate interactions in the 2020 Rover Mission Landing Site

“…Modern subtidal Bahamian stromatolites are positively associated with strong tidal currents because these are unfavorable for competitors such as metazoans and macroalgae (Noffke & Awramik, 2013). Exclusion of competitors is also the reason explaining why stromatolites are common in hypersaline lagoons, exceedingly warm waters and macrotidal settings (Noffke & Awramik, 2013;Suosaari, Reid & Andres, 2019). Some MISS are associated to bland erosional regimes, e.g., erosional pockets are produced where pieces of microbial mat are removed by erosion, leaving an irregularly shaped mat border surrounding a depression through which the underlying sediment is exposed (Bose & Chafetz, 2009).…”

Preface: Celebration of the Career of Robert Nathan Ginsburg

“…Another theme dear to Bob’s heart was the study of stromatolites. The papers of Suosaari, Reid, and Andres () and Eymard et al () update his important 1991 paper (Ginsburg, ) which summarized the current ideas about stromatolites including controversies of definition, whether ancient stromatolites should be interpreted as sedimentary structures and mechanisms of carbonate fixation. Throughout his career, Bob was extremely interested in the formation of carbonate buildups and papers by Gischler and Hudson (), Counts et al (), Meeder and Harlem (), and McNeill, Pederson, Brownlow, Klaus, and Blackwelder () cover this topic, drawing on examples from the Pleistocene Miami Limestone, reefs and platforms from the Caribbean and Pacific and Indian Oceans.…”