Precambrian, Cambrian, and Ordovician orthoquartzites in Scotland, California, and Nevada are characterized by primary features that are indicative of sediment transport by tidal currents. Sedimentary structures in these quartzites are grouped as follows. Association 1. cross-stratification organized into herringbone sets with bipolar-bimodal orientation; parallel laminae; Association 2. reactivation surfaces; multi-modal frequency distributions of cross-strata set thickness; bimodal frequency distributions of cross-strata dip angles; Association 3. interference ripples; ripples superimposed at 90 and 180° on underlying cross-strata and slip faces of dunes and sand waves; Association 4. tidal bedding; flaser bedding; lenticular bedding; and Association 5. burrows, in luding escape structures.

Suggested tidal transport mechanisms are: Association 1. reversing tidal current bedload transport; Association 2. time-velocity asymmetry of tidal current bedload transport; Association 3. ebb-emergent sheet-runoff; Association 4. alternation of tidal bedload and mud suspension deposition; and Association 5. organic reworking.

These observations indicate that some orthoquartzites are analogs to modern tidal sand bodies. Association of orthoquartzites with (1) mudstones containing flaser, tidal, and lenticular bedding, and (2) shallow subtidal, intertidal, and supratidal carbonates, indicates that perhaps many orthoquartzites are tidalites (sediments deposited by tidal bedload transport, tidal fluctuations, alternation of bedload and suspension deposition, and suspension slack water deposition). A tidal sediment transport model for sedimentary quartzites is consistent with their extensive areal distribution patterns (averaging 23,000 sq km) on Paleozoic and Mesozoic platforms.

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