Selective agglutination of tourmaline grains by foraminifera in deep-water flysch environment (Eocene Hieroglyphic beds, Silesian Nappe, Polish Outer Carpathians)

Abstract

Detrital fragments of automorphic tourmaline crystals are commonly incorporated in tests of simple agglutinated foraminifera that lived in the deep-marine Carpathian turbidite basin, in which deposition of the Hieroglyphic beds (Eocene) took place. Such grains were observed in the tests of 37 taxa representing 20 species. However tourmaline occurs in the Carpathian Flysch sediments as an accessory mineral, still it was selected by the foraminifera as the only heavy mineral to be incorporated in their tests. The proportion of tourmaline-bearing specimens in an assemblage usually amounts to a few percent, but may reach 29% in extreme cases. The particular preference for tourmaline segregation and incorporation in the test walls is shown by the following genera: Psammosiphonella, Reophax, Bathysiphon and Nothia.