ISSN: 1525‐2027 Postspreading rifting in the Adare Basin, Antarctica: Regional tectonic consequences

[1] Extension during the middle Cenozoic (43–26 Ma) in the north end of the West Antarctic rift system (WARS) is well constrained by seafloor magnetic anomalies formed at the extinct Adare spreading axis. Kinematic solutions for this time interval suggest a southward decrease in relative motion betw...

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Bibliographic Details
Main Authors: R. Granot, S. C. Cande, J. M. Stock, F. J. Davey, R. W. Clayton
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Published: 2010
Subjects:
Antarctic
Ross Sea
West Antarctica
Hallett
Adare
Adare Basin
Adare Trough
Antarc*
Antarctica
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.721.7489
http://www.bgu.ac.il/%7Ergranot/Publications/2010GC003105.pdf
Description
Summary:[1] Extension during the middle Cenozoic (43–26 Ma) in the north end of the West Antarctic rift system (WARS) is well constrained by seafloor magnetic anomalies formed at the extinct Adare spreading axis. Kinematic solutions for this time interval suggest a southward decrease in relative motion between East and West Antarctica. Here we present multichannel seismic reflection and seafloor mapping data acquired within and near the Adare Basin on a recent geophysical cruise. We have traced the ANTOSTRAT seismic stratigraphic framework from the northwest Ross Sea into the Adare Basin, verified and tied to DSDP drill sites 273 and 274. Our results reveal three distinct periods of tectonic activity. An early localized deforma-tional event took place close to the cessation of seafloor spreading in the Adare Basin (∼24 Ma). It reacti-vated a few normal faults and initiated the formation of the Adare Trough. A prominent pulse of rifting in the early Miocene (∼17 Ma) resulted in normal faulting that initiated tilted blocks. The overall trend of structures was NE–SW, linking the event with the activity outside the basin. It resulted in major uplift of the Adare Trough and marks the last extensional phase of the Adare Basin. Recent volcanic vents (Pli-ocene to present day) tend to align with the early Miocene structures and the on‐land Hallett volcanic prov-ince. This latest phase of tectonic activity also involves near‐vertical normal faulting (still active in places)

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