• journal_title：Geology
• Contributor：Roy Livermore ; Juan Carlos Balanyá ; Andrés Maldonado ; José Miguel Martínez ; José Rodríguez-Fernández ; Carlos Sanz de Galdeano ; Jesús Galindo Zaldívar ; Antonio Jabaloy ; Antonio Barnolas ; Luis Somoza ; Javier Hernández-Molina ; Emma Suriñach ; César Viseras
• Publisher：Geological Society of America
• Date：2000-
• Format：text/html
• Language：en
• Identifier：10.1130/0091-7613(2000)28<607:AOADSC>2.0.CO;2
• journal_abbrev：Geology
• issn：0091-7613
• volume：28
• issue：7
• firstpage：607

New bathymetric and magnetic anomaly data from the Phoenix Ridge, Antarctica, show that extinction of all three remaining segments occurred at the time of magnetic chron C2A (3.3 ± 0.2 Ma), synchronous with a ridge-trench collision south of the Hero Fracture Zone. This implies that the ultimate cause of extinction was a change in plate boundary forces occasioned by this collision. Spreading rates slowed abruptly at the time of chron C4 (7.8 ± 0.3 Ma), probably as a result of extinction of the West Scotia Ridge, which would have led to an increase in slip rate and transpressional stress across the Shackleton Fracture Zone. Spectacular, high-relief ridges flanking the extinct spreading center, mapped for the first time using multibeam swath bathymetry, are interpreted as a consequence of a reduction in spreading rate, involving a temporary magma oversupply immediately prior to extinction.