Anderson, John B.1
(1) Rice University, Houston, TX
ABSTRACT: How Did the Quaternary Submarine Fans of the Antarctic Region Form and What Do They Tell Us About the Role of Sediment Mass Transport in Fan Evolution?
The Antarctic continental shelf averages 500 meters deep and, in most areas, slopes toward the continent. Rivers have not flowed across the shelf for millions of years, as evidenced by the lack of fluvial valleys and deltas in the Pliocene and younger stratigraphic section. Yet, several large submarine fans occur around the continent, fans that have remained active long after the continent became glaciated. The Weddell Fan encompasses an area more than 290,000 square kilometers, making it one of the largest fans in the world. It connects to a large slope canyon network and includes extensive sandy lobes that are quartz rich and well sorted. Other large fans occur off Wilkes Land and the Antarctic Peninsula. A lingering question concerns the manner in which these fans are nourished, given the absence of fluvial deltaic sources and minimal impact of eustatic fluctuations on shelf sediment transport and bypass. The most probable mechanism for nourishing Antarctic fans involves sediment mass movement (slumping, debris flows and other sediment gravity flow mechanisms). Indeed, this is the dominant means of sediment delivery from the continent to the deep sea. The efficiency with which these processes convert poorly sorted glacial sediments into relatively well-sorted, quartzose turbidites is impressive, as are the great volumes of material produced by these mechanisms. Given that these mechanisms are so efficient in Antarctica, have we underestimated their role in the formation of other fan systems of the world?
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004