engleski

Glass spherules in Upper Uocene flysch of Croatian Adriatic - evidence of an impact into carbonate target?

Glass spherules occur at 7 levels in Late Eocene flysch marls of Central Dalmatian Basin (Croatian Eastern Adriatic), which are exposed in hinterland of the city of Solin. The spherules occur at one level in Globigerinatheka semiinvoluta zone, and in six levels of Globigerinatheka index zone, and their stratigraphic spacing ranges from 1, 5 m to 93, 3 m. The best studied, and with most spherules recovered, is a composite turbidite 2-7, which is youngest in the sequence. It comprises impact-generated debris in its marl part, which is represented by perfectly clear (sometimes slightly dimmed) glass spherules 91 to 530 μ across ; teardrop transparent microtektites 1225 μ long, and fragments of vesicular glass 450 to 1000 μ across. Some spherules and microtektites comprise small bubbles with diameter up to 41 μ . Chemical composition of the spherules, poor in SiO2 and relatively rich in CaO and MgO indicates possible carbonate target.

impact spherules; turbidites; flysch; Eocene; Adriatic

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