--> ABSTRACT: Coprolite Carbonate Sequence Stratigraphy: Use or Euphemism, by R. G. Peebles; #91021 (2010)

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Coprolite Carbonate Sequence Stratigraphy: Use or Euphemism

PEEBLES, ROSS G.

In the carbonate-evaporite Arab Formation (Upper Jurassic) of the southern Arabian Gulf, coprolites are frequent constituents of the carbonates as pellet grains in limestones and as pellet ghosts in dolostones. In particular, the crustacean coprolite Favreina and the gastropod coprolite Prethocoprolithus are common and diagnostic of the Arab Formation. These coprolites have been used as indicators of very shallow marine and intertidal paleoenvironments and as biostratigraphic markers for the Late Jurassic. It has also been noticed that their occurrence is frequently constrained to specific horizons, making them useful for stratigraphic correlation between wells. Recent, high-resolution sequence stratigraphic analysis of the Arab Formation has revealed that Favreina and Prethocoprolithus occupy distinct and predictable locations within Arab Formation depositional cycles or sequences (parasequences). Favreina occurs rarely and is restricted to thin transgressive lag deposits found at the base of sequences and at hardgrounds/firmgrounds associated with condensed sections or maximum flooding surfaces. In both cases Favreina is found overlying dense, nonporous facies (marginal marine evaporites or dolomites) and can be associated with permeability baffles or barriers. Prethocoprolithus on the contrary is frequently the dominant grain in transgressive carbonate sands (pellet packstones/grainstones) formed during marine flooding over intertidal settings and as highstand pellet packstones/grainstones deposited when the depositional sequence has shallowed (aggraded) to intertidal conditions. These Prethocoprolithus sands are commonly porous and permeable, with the pores and pore network preserved by well-developed rim cements that protect the good interparticle (intercrystalline) and pelmouldic porosity during burial. 

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.