Structural parallels between terrestrial microbialites and Martian sediments: are all cases of ‘Pareidolia’?

Abstract

The study analyses possible parallels of the microbialite-known structures with a set of similar settings selected by a systematic investigation from the wide record and data set of images shot by NASA rovers. Terrestrial cases involve structures both due to bio-mineralization processes and those induced by bacterial metabolism, that occur in a dimensional field longer than 0.1 mm, at micro, meso and macro scales. The study highlights occurrence on Martian sediments of widespread structures like microspherules, often organized into some higher-order settings. Such structures also occur on terrestrial stromatolites in a great variety of ‘Microscopic Induced Sedimentary Structures’, such as voids, gas domes and layer deformations of microbial mats. We present a suite of analogies so compelling (i.e. different scales of morphological, structural and conceptual relevance), to make the case that similarities between Martian sediment structures and terrestrial microbialites are not all cases of ‘Pareidolia’.

Why should geological criteria used on Earth not be valid also for Mars? Evidence of possible microbialites and algae in extinct Martian lakes

“…Thrombolites often build bread-shaped small edifices and might be recognized also based on their morphology. Several examples of thrombolitic structures and crusts were also observed at meso scale on Mars and reported in previous works (Rizzo and Cantasano, 2017, their fig. 9, and fig.…”

“…Evidence, the latter, that arises from an initial subjective interpretation, but then appears validated by the precise and faithful reporting of laminae and void position, precisely located and reported on amplified images. The occurrence of single conical forms, isolated by erosion and widespread on the surface, was shown in previous work (Rizzo and Cantasano, 2017). The presence of circular voids surrounded by a more resistant structure (such a shell) was also reported for the image of Fig.…”

“…Similar voids, plastic deformations and 'construction morphologies', resembling stromatolites, dendrolites and thrombolites, have been recognized on micro-images by all the rovers International Journal of Astrobiology on Mars (Bianciardi et al, 2014;fig. 7 in Rizzo and Cantasano, 2017). Other structures of 'constructive' type that on Earth are formed by continuous, biologically-related building up that assume peculiar shapes at different scales (columnar, spherical, filamentous, lamp-or donut-shaped) have a counterpart on Mars (Bianciardi et al, 2015;Rizzo and Cantasano, 2017).…”

“…7 in Rizzo and Cantasano, 2017). Other structures of 'constructive' type that on Earth are formed by continuous, biologically-related building up that assume peculiar shapes at different scales (columnar, spherical, filamentous, lamp-or donut-shaped) have a counterpart on Mars (Bianciardi et al, 2015;Rizzo and Cantasano, 2017). An example is the spherical concretions of hematite (the well-known 'blueberries') often cited as evidence for sea-lacustrine environments on Mars (Moore, 2004).…”

“…The results of these morphological and morphometric approaches should be considered relevant, especially when they are obtained in a frame of various and convergent collected clues and when also exist a reasonable assessment on the sedimentary environment in relation to the possible genesis of the structures under examination. Previous works have already shown the occurrence of possible structural matches between terrestrial microbialites and Martian sediments, prevalently at the micro and meso scale, based on visual recognition (Rizzo and Cantasano, 2009, 2017; Noffke, 2015), geochemistry (Ruff and Farmer, 2016) and mathematical analysis of the images (Bianciardi et al ., 2014, 2015). Here we shall focus on morphological evidence at the micro and meso scale, and especially at the macro scale (meaning at scales between centimeters and few meters), from images taken from the rovers.…”