Postspreading rifting in the Adare Basin, Antarctica: Regional tectonic consequences

摘要: Extension during the middle Cenozoic (43–26 Ma) in north end of West Antarctic rift system (WARS) is well constrained by seafloor magnetic anomalies formed at extinct Adare spreading axis. Kinematic solutions for this time interval suggest a southward decrease relative motion between East and Antarctica. Here we present multichannel seismic reflection mapping data acquired within near Basin on recent geophysical cruise. We have traced ANTOSTRAT stratigraphic framework from northwest Ross Sea into Basin, verified tied to DSDP drill sites 273 274. Our results reveal three distinct periods tectonic activity. An early localized deformational event took place close cessation (~24 Ma). It reactivated few normal faults initiated formation Trough. A prominent pulse rifting Miocene (~17 resulted faulting that tilted blocks. The overall trend structures was NE–SW, linking with activity outside basin. major uplift Trough marks last extensional phase Basin. Recent volcanic vents (Pliocene day) tend align on-land Hallett province. This latest also involves near-vertical (still active places) negligible horizontal consequences. found does not require change However, lack subsequent coupled Terror Rift an subice extension WARS pronounced kinematics rift. These observations indicate increased southward, therefore suggesting plate Miocene. late pole rotation might been located opposite opening sign compared Eocene-Oligocene pole.