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

Granot, R. and Cande, S. C. and Stock, J. M. and Davey, F. J. and Clayton, R. W. (2010) Postspreading rifting in the Adare Basin, Antarctica: Regional tectonic consequences. Geochemistry, Geophysics, Geosystems, 11 . Art. No. Q08005 . ISSN 1525-2027. doi:10.1029/2010GC003105.

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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 deformational event took place close to the cessation of seafloor spreading in the Adare Basin (~24 Ma). It reactivated 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 (Pliocene to present day) tend to align with the early Miocene structures and the on-land Hallett volcanic province. This latest phase of tectonic activity also involves near-vertical normal faulting (still active in places) with negligible horizontal consequences. The early Miocene extensional event found within the Adare Basin does not require a change in the relative motion between East and West Antarctica. However, the lack of subsequent rifting within the Adare Basin coupled with the formation of the Terror Rift and an on-land and subice extension within the WARS require a pronounced change in the kinematics of the rift. These observations indicate that extension increased southward, therefore suggesting that a major change in relative plate motion took place in the middle Miocene. The late Miocene pole of rotation might have been located north of the Adare Basin, with opposite opening sign compared to the Eocene-Oligocene pole.

Item Type:Article
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URLURL TypeDescription DOIArticle
Stock, J. M.0000-0003-4816-7865
Clayton, R. W.0000-0003-3323-3508
Additional Information:© 2010 American Geophysical Union. Received 26 February 2010; accepted 6 May 2010; published 4 August 2010. We would like to thank Captain M. Watson, the crew, and the Raytheon staff of the R/VIB Nathaniel B. Palmer for their dedicated work during cruise NBP0701. Also, we thank Dietmar Müller and Sean Gulick for their helpful reviews; Neal Driscoll, Donna Blackman, and Jeff Gee for helpful discussions; Paul Henkart for the continuous help with SIOSEIS; and Chris Sorlein for introducing us to SPW software. Detlef Damaske is thanked for making the aeromagnetic data available for us. Interpretation of the seismic profiles was done with Kingdom Suite, a contribution of Seismic Micro‐Technology. This project was funded by NSF grant OPP04‐40959 (SIO) and OPP04‐40923 (Caltech).
Group:Seismological Laboratory
Funding AgencyGrant Number
Subject Keywords:West Antarctic rift system; rift; Adare Basin; multichannel seismic reflection; magnetic anomalies; tectonics
Record Number:CaltechAUTHORS:20100830-113018904
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Official Citation:Granot, R., S. C. Cande, J. M. Stock, F. J. Davey, and R. W. Clayton (2010), Postspreading rifting in the Adare Basin, Antarctica: Regional tectonic consequences, Geochem. Geophys. Geosyst., 11, Q08005, doi:10.1029/2010GC003105.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19709
Deposited By: Tony Diaz
Deposited On:15 Sep 2010 20:00
Last Modified:08 Nov 2021 23:54

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