The environment of Venice area in the past two million years

摘要: A ca. 950 m thick succession that was continuously cored in 1971 Venice has been revisited, order to reconstruct the environmental history of area since about 2.15 Ma. Magnetic polarity stratigraphy, integrated with refined calcareous nannofossil biostratigraphy, provides a firm chronostratigraphic framing succession. In improve chronological resolution, we derived astrochronological refinements lower Pleistocene sapropel-bearing interval by comparison other time-correlative sections Mediterranean. The pollen record is used as proxy climatic changes and an indirect tool reconstruction upper part following inferred: (1) late Gelasian (late Pliocene), depositional strongly subsiding shelf which shoaled near sea level; (2) hiatus minimum duration 0.2 Myr, encompassing most Olduvai Subchron, rapidly drowned bathyal depths over early (biozones MNN 19a 19e: from 1.947 Ma 0.96 Ma). This characterized starved sedimentation (less than 10 cm/kyr), represented hemipelagic muds interbedded sapropel layers; (3) during biozone MNN19f (Pseudoemiliania lacunosa Zone, 0.96–0.42 Ma) package turbidites laid down result massive terrigenous input eastern Southern Alps; (4) later, middle Chron 1n (Brunhes), deltaic sedimentation, primarily related progradation paleo-Po system, led progressive infill basin. progradational episode major building phase, ended first appearance continental sediments, tentatively correlated marine oxygen isotope substage 8.4; (5) shows cyclic organization, upward increasing amount marginal-marine subaerial deposits. this below level glacioeustatic highstands but became emergent subsequent lowstands. Pollen data support overall good correspondence sediment packages sequences glacial conditions maximum flooding intervals interglacial conditions.