Miocene Coralline Algae

Daniel W. J. Bosence

The coralline algae (Order Corallinales) were sedimentologically and ecologically important during the Miocene, a period when they were particularly abundant. The many poorly described and illustrated species and the lack of quantitative data in coralline thalli make specific determinations particularly difficult, but some species are well known and widespread in the Tethyan area.

The sedimentologic importance of the Miocene coralline algae is reflected in the abundance of in-situ coralline buildups, rhodoliths, and coralline debris facies at Malta and Spain; similar sequences are known throughout the Tethyan Miocene.

In-situ buildups vary from leafy crustose biostromes to walled reefs with dense coralline crusts and branches. Growth forms are apparently related to hydraulic energy. Rhodoliths vary from leafy, crustose, and open-branched forms in muddy sediments to dense, crustose, and radial-branching forms in coarse grainstones. Rhodolith form and internal structure correlate closely with hydraulic energy.

Coralline genera are conservative and, as such, are useful in paleoenvironmental analysis. Of particular interest are the restricted depth ranges of recent coralline genera.

More research is needed on the sedimentology, paleoecology, and systematics of the Cenozoic corallines, as they have particular value in paleoenvironmental analysis.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.