LATE JURASSIC (KIMMERIDGIAN-TITHONIAN) MACROFOSSIL ASSEMBLAGE FROM JASON PENINSULA, GRAHAM LAND - EVIDENCE FOR A SIGNIFICANT NORTHWARD EXTENSION OF THE LATADY FORMATION

New exposures of fossiliferous sedimentary rocks at Cape Framnes, Jaso n Peninsula (65 degrees 57'S, 60 degrees 33'W) are assigned to the Mid dle-Late Jurassic Latady Formation of the south-eastern Antarctic Peni nsula region. A sequence of fine to coarse-grained sandstones of unkno wn thickness has yielded a molluscan and plant macrofossil assemblage rich in the following elements: perisphinctid ammonites, belemnopseid belemnites, oxytomid, trigoniid and astartid bivalves, and bennettita lean fronds and fructifications. The overwhelming age affinities are w ith the Kimmeridgian-early Tithonian part of the Latady Formation, as exposed on the Orville and Lassiter coasts. The Cape Framnes sedimenta ry rocks help to constrain the age of a major sequence of acid volcani c rocks on Jason Peninsula, and show that the Latady Basin was geograp hically much more extensive than recognized previously. It was the pri ncipal depositional centre of Middle-Late Jurassic sedimentation in th e Antarctic Peninsula back-are region and in areal extent may have riv alled the essentially Cretaceous Larsen Basin.