GRAVITY AND MAGNETIC CHARACTERISTICS OF THE POWELL BASIN AND THEIR TECTONIC IMPLICATIONS

The Powell Basin is a typical high latitude marginal sea in the southern hemisphere, located between the northeast of Antarctic Peninsula and the South Orkney Microcontinent. Gravity and magnetic data, historical documents and the research products of tectonic evolution of the basin have been comprehensively collected in order to describe the characteristics of magnetic and gravity fields and the opening history of the basin. A buried spreading ridge is found in the middle of the Powell Basin, trending approximately in NW 30°. Residual basements can be found on both sides of the ridge. A rift basin occurs on the shelf margin. The symmetric linear magnetic anomalies and age dating data made us possible to reconstruct the history of the Powell Basin which consists of the closure stage (40 Ma), post-rifting stage (29.7 Ma) and mid ridge spreading stage (27 Ma).