ABSTRACT

Saucer-like structures (one to two m. in diameter when observed in cross-section) of dolomitized laminar fenestral intramicrite are interbedded with dense burrowed Ladinian micrite of the Esino Formation. This Triassic sedimentary sequence is interpreted as representing a subtidal and intertidal carbonate mud flat capped by a supratidal flat of laminar fenestrate carbonate. This fenestral horizon shows evidence of early cementation, dolomitization, fracturing, upward folding and some overthrusting. A later subtidal carbonate mud fills the fractures and covers them. Similar deformation of bedding occurs in the Holocene subtidal intertidal, and supratidal sediments of the Persian Gulf off Qatar and Abu Dhabi, and in the supratidal sediments of Shark Bay, West Australia. The Ladinian pol gons of fenestrate sediment are interpreted to be the result of either desiccation contraction, or cementation expansion or more probably a combination of both.