[BPT03-P08] Macrofauna Activity in Quaternary Bottom Water Environments off Western Australia: Fecal Pellets Evidence
Keywords:Macrobenthos, Fecal pellet, Ooid, Quaternary
We focused on horizons that clearly exhibited sedimentary cycles. The upper part of the core mainly comprised of alternating beds of dark-colored packstone/wackestone and light-colored wackestone/mudstone. Well-preserved molluscan fossils and peloids occurred in the light-colored wackestone/mudstone in the upper part of the sedimentary sequence.
The morphological character and size of the peloids within the studied sediments are similar to modern fecal pellets of shallow water polychaetes. The abundance of fossil fecal pellets shows fluctuating trends similar to those of macrofossils (e.g., bivalve, gastropod, scaphopod, and echinoderm) and it is likely that the fecal pellet abundance is an indicator of paleo-macrobenthos activity. This activity was compared to ostracode abundance and temporal changes in fossil fecal pellet abundance and an inverse correlation was found.
In the other intervals, the peloids are replaced by superficial ooids and occurred in conjunction with larger benthic foraminifera, indicating deposition within the photic zone. Thus, these intervals may indicate a shallow water environment during deposition.
In this research, we reveal that the abundance of fossil fecal pellets shows macrobenthic activity, reflecting the evolutions of bottom water environments during the Quaternary.