PRYDZ BAY-PRINCE CHARLES MOUNTAINS AS A TEST FOR THE THEORY OF ANTARCTIC LATE NEOGENE TERRESTRIAL VEGETATION

The margins of Prydz Bay, and the Prince Charles Mountains, contain many outcrops of in situ fossiliferous marine sediments representing much of the late Neogene. The region is free of the tectonic/volcanic influences of the Transantarctic Mountains (TAM). It is likely that the area was considerably warmer than now through much of the time, and marine conditions penetrated at least 300 km farther south within the Lambert Graben than they do today, consistent with a more southerly ice-sheet margin.

The region provides an ideal site for testing the hypothesis that Antarctica carried terrestrial vegetation, other than mosses and lichen, during this time, as postulated from studies in the controversial Sirius Group of the TAM. If vegetation reached 86°S in the TAM, it would be expected farther north in warmer climes through colonisation via a coastal margin route.

Despite dedicated search, Pliocene sections at Marine Plain, Larsemann Hills and Heidemann Valley have yielded no palynological evidence of terrestrial vegetation. Samples from the Prince Charles Mountains are currently under study but are complex because of the flood of recycled palynomorphs from the Permo-Triassic Amery Group widespread in the region. To date, they also have yielded no evidence of Neogene vegetation. The results of this examination will be made available.

In addition to its role in providing evidence for a diverse marine fauna (cetaceans, crustaceans, molluscs, diatoms, foraminifera) through parts of the Neogene, the region is also emerging as a major source of information on Jurassic and younger fauna and flora, and their evolution. Features of the fauna and flora, in both coastal and open marine environments in the early Pliocene, were significantly different from the modern and it is likely that there was a major extinction/evolution event around Antarctica sometime in the mid-Pliocene.