Exploring a link between Atlantic coral mounds and Phanerozoic carbonate mudmounds: Insights from pore water fluorescent dissolved organic matter (FDOM), Pen Duick mounds, offshore Morocco

Permineralizing fluids that are characteristic for ISOM are locally present within the shallow subsurface and reach a maximum intensity at about 1 m of sediment depth. However, no ISOM-related authigenic carbonate was observed. Both the lack of organic substrates that is due to the absence of degrading connective tissues from a cryptic community and the high amount of infiltrated mud that acts as a sorbent might explain the absence of ISOM in Gamma mound sediments. Labyrinthine deposits of coral rubble or current-swept coral mounds are prone to host a sponge-rich cryptic community and therefore, in their deeper parts, should provide a variety of substrates for ISOM during suboxic cycling of natural organic matter. In such a view, the modern coral-rich mound system, which by itself appears diverse and with a variety of controlling factors, maintains an excellent potential to drive ISOM and to share a crucial process of early diagenesis with Phanerozoic sponge-rich carbonate mudmounds.