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Rock thin sections of Long 11 typical lamina in the Zigong Block. (a) Authigenic quartz–organic lamina; (b) felsic–carbonate lamina; (c) terrigenous clastic lamina; (d) clay mineral lamina; (e) pyrite lamina, with calcareous bioclastic in the lower section; and (f) terrigenous quartz with interbedded thin double-clay mineral rhythmic lamina.
