Plenty of fore reef debris according to ref.
1025.

Abstract of ref. 979:
Carbonate rocks of the central Lahn (Germany) syncline were examined and sampled. In general, the development of biostromes begins in the Middle varcus zone of the conodont biostratigraphy after the interruption of the volcanic activity of the Givetian/Adorfian phase. Dendroid stromatoporoids and tabulate corals and sponges or platy stromatoporoids and rugose corals settle on top of the pyroclastic sediments resulting in a stabilisation of the substrate, depending on the bathymetric position. In favoured ecologic positions bioherms could develop, whereas deeper situated biostromes were buried by pyroclastics during the revived volcanism. Allochthonous carbonates are derived from reefs persisting into the Adorf-Stage of the Late Devonian. 