Porifera-microbialites of the Lower Liassic (Northern Calcareous ...

Plate 8
Tannhauser Berg –
Liassic sequence at the northern slope of the Hagengebirge.
(A): Adnet breccias and limestones cropping out at site A, at a loop of a forest track.
(B): T-J boundary section from outcrop B. Triassic Dachsteinkalk (with foraminifers of
Triasina sp.) discordantly overlain by red echinoderm biomicrite (Hierlatz facies,
Pliensbachian?).
(C): Ammonite-rich echinoderm biomicrite (Hierlatz facies, Lias γ) from vertical cracks
penetrating the Dachsteinkalk at outcrop B. The section encompasses hexactinosid
sponges, characterized by a dictyonal skeleton of cubic meshwork and a dense top layer
formed by irregular fused spicules.
(D): Same facies as in (C) displaying accumulation of ammonites side by side with the remains
of lyssacinosid (ly) and hexactinosid (h) sponges.
(E): Section through the skeleton of a hexactinosid sponge. Syndiagenetic formation of peloidal
microbialites caused characteristic features of small collaps structures (arrow) inside the
former sponge mesohyle.
(F): In situ preserved hexactinosid sponge in the Hierlatz limestone.
(G): In situ preserved hexactinosid sponge that grew on microbial substrate, highlighting the
lighter colored automicrite that formed inside decaying sponge organic matter.
(H): Adnet facies type encompassing a dislocated clust with ferromanganese encrustation.