Bryozoan faunas at the Tortonian-Messinian transition. A palaeoenvironmental case study from Crete Island, eastern Mediterranean

Four sedimentary sections were logged and sampled from upper Tortonian-lower Messinian outcrops on the island of Crete (Greece). The collected material yielded about 60 bryozoan species belonging to nine different colonial morphotypes. A few are stenobathic, indicating either shallow- or deep-water environments, but most them eurybathic (with bathymetric ranges extending in some instances shelf down several hundreds metres). Bryozoan communities point sea-level variations modulated by local tectonics. Deep circalittoral environments recognized at base three (whereas fourth section starts with infralittoral/shallow passing deep circalittoral. Shallow bathyal habitats follow upwards, succeeded turn assemblages indicative subsequently shallow circalittoral/infralittoral depths. Inferred fluctuations diachronous throughout island. Shallow-water found associated, sometimes abundantly, rarer faunas a levels, interpreted as transported currents. Several dysoxic episodes have been also detected: likely result water column stratification enhanced productivity. These processes probably boosted combination changes oceanic circulation, climate, global sea-level, local/regional tectonics (in and/or marine gateways between Mediterranean Atlantic).