Sprecher
Beschreibung
Plant macrofossil-preservation potential (PMPP) is restricted to a limited number of depositional environments (EOD). In turn, the record’s quantity and quality are dictated by biological and geochemical factors operating therein. Outcrops present a continental stratigraphy of stacked, laterally contiguous landscapes. Each overlying landscape has similar, but spatially offset, EODs. Their distribution is controlled by the (1) original fluvial systems and associated floodplains, and (2) following exposure, subsequent erosion resulting in an outcrop’s extent and accessibility from which material may be studied.
Often interpretations of ecosystem-and-vegetation response over various stratigraphic thicknesses are based on few, coarsely correlated stratigraphic sections. An underlying, and implied, assumption exists that there is an equal probability to find fossil assemblages in each superposed landscape. Various degrees of ecological perturbation are invoked to explain the absence of macrofossils from the record over decimeter to decameter intervals. Yet, such interpretations may be unwarranted.
Theoretical test results are presented on the probability of crossing one or more EODs across 500, 20 km-long transects in four 502 km modern equatorial localities. The frequencies of water (high PMPP) versus non-water (low PMPP) pixels were determined using the Copernicus Database Ecosystem in one limnic site (Lake Mai Ndome, DRC) and three fluvial regions (Santa Bábara and Japurá Rivers, Amazonia; Kawatngwa, Papua New Guinea). The median value of water controlling preservation, a very low probability exists that a “continuous” record can be obtained from limited stratigraphic sampling, biasing interpretations of ecosystem dynamics.