engleski

Albian Facies Within a Cyclic Peritidal Platform-Interior Sequence, Adriatic Platform, Southern Croatia

The Albian carbonate succession (approximately 400 m thick) of Adriatic Platform in southern Croatia, although predominantly peritidal, locally contains basal several meters thick sequence of deeper lagoon laminated limestones that were deposited during a regional deepening of the platform concomitant to oceanic anoxic event (OAE) 1B. Limestones are thin-bedded, platy, and planar laminated pellet packstone and lime mudstone, locally fine dolomite with petroliferous odor ; these rapidly pass up into meter-scale cycles dominated by fenestral caps suggesting relatively humid conditions. The cyclic peritidal carbonates that are markedly different from those described above make up the rest of the Albian. These meter-scale cycles consist of, from bottom to top: (1) Lime mudstone, locally heavily burrowed, with peloidal fills and scattered clam and gastropod fragments ; locally, this member is represented by coarse dolomite with rare oncoids and clam/gastropod moulds ; (2) pellet-skeletal wackestone with oncoids, calcareous algae and benthic foraminifera ; (3) peloid-skeletal-intraclast wacke-packstone with abundant calcareous algae (Salpingoporella) and benthic foraminifera, and scattered rudists and gastropods ; (4) intraclast-peloid-skeletal grainstone ; (5) gastropod and rudist floatstone to rudstone with lime mudstone, skeletal-peloid, or course dolomite matrix ; locally, oncoid-lump and pisoid rudstone ; (6) barren lime mudstone with tubular fenestrae and greenish infills, rare gastropod moulds ; (7) fenestral laminite ; platy and microbial laminite are subordinate ; (8) intra/lithoclast floatstone-rudstone with black and/or tan lime fenestral mudstone clasts or pebbles in a green clay, tubular fenestral wacke-mudstone, or dolomitized matrix. Cycles may also have basal thin transgressive lag of intraclast-oncoid floatstone in muddy matrix that grades up into skeletal bioturbated mudstone with gastropod fragments. Cycle tops are commonly microcarstic with mud-filled green vugs of leached mollusks, or with clay mm-seams.

Albian; Peritidal Carbonates; Adriatic Platform; Croatia

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