Figure 9: (A) Box and whisker plots comparing the long axes, aspect ratios, and areas of pit craters measured at two stratigraphic levels, distinguishing those that have different geometries (i.e. funnel-like and pipe-like) and/or associated with different structures (i.e. dykes, dyke-induced faults, and tectonic faults) (Supporting Table 1). n = number. The plots also highlight data median (thin black line), mean (dashed black line), and outliers. See Figure 3B for explanation of measured parameters. (B) Rose plots showing the orientation of pit crater long axes, grouped based on their morphology and/or association with different structures (Supporting Table 1). Arrows show the mean vector of select populations. Orientation of dyke segments is also shown (Magee & Jackson, 2020a). (C and D) Graphs comparing the area (C) and aspect ratio (B) of pit crater expressions at their tops and at the Top Athol Formation. Two plots are provided for area and aspect ratio comparison, with one grouping the data based on the associated dyke or tectonic faults, and the other highlighting different between pit craters located directly above dykes, dyke-induced faults, and tectonic faults.
Cross-section geometry
In cross-section, pit crater walls typically bound zones within which stratigraphic reflections locally have a lower amplitude and are deflected (e.g., E4b) or displaced (e.g., F13) downwards relative to those in the flanking host rock (Figs 4A, 6-8). Pit crater centroids typically occur within the Dingo Claystone, ~16–188 m (i.e. 0.5–5.5 seismic cycles where one cycle is a peak and trough pair) beneath the Base Cretaceous unconformity (Figs 4A, 6-8, 10A, and B). Only B1-B3 and D1-D2 are expressed at the Base Cretaceous unconformity (Fig. 10A). Stratigraphic reflections overlying some pit craters appear locally thickened (e.g., F13; Fig. 7B) whereas others seem to onlap onto crater walls (e.g., G10a; Fig. 7D).