The Weddell Sea Formation: post−Late Pliocene terrestrial glacial deposits on Seymour Island, Antarctic Peninsula

• Main Authors: Andrzej Gaździcki, Andrzej Tatur, Urszula Hara, Rodolfo A. Del Valle
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Antarctic Peninsula; Cockburn; Cockburn Island; Ross Island; Seymour; Seymour Island; The Antarctic; Weddell; Weddell Sea; Antarc*; James Ross Island
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.626.7439; http://www.polar.pan.pl/ppr25/ppr25-189.pdf

ABSTRACT: A sequence of glacial deposits up to 4 m thick unconformably overlies the Eocene La Meseta Formation on the Seymour Island plateau (meseta) and forms a litho− stratigraphically distinct unit in the succession of the James Ross Basin, which is formally named here as the Weddell Sea Formation. The formation is thus far known only from Sey− mour Island. This is a terrestrial melt−out till which contains abundant erratics and also re− worked Cretaceous–Tertiary micro − and macrofossils within a silty clay matrix. The terres− trial origin of this till is shown by glacial striations at the base of the unit. The largest erratics (up to 3 m in diameter) are composed of plutonic (granitoids) and metamorphic (gneiss and crystalline schist) rocks of the Antarctic Peninsula provenance. Smaller in size and much more numerous are erratics of volcanic rocks, represented by andesite, basalt and corre− sponding pyroclastics of the James Ross Island Volcanic Group. Less common are erratics of sedimentary rocks, sometimes bearing fossils derived from the underlying Tertiary and Cretaceous strata. A few erratics from the top of the studied sequence are conglomerates of the Cockburn Island Formation with a foraminifer fauna. These are the youngest clasts within the Weddell Sea Formation. The presence of the Pliocene index fossil Ammo−