Tectonic and denudational history of the Rennick Graben (North Victoria Land): Implications for the evolution of rifting between East and West Antarctica

Abstract

The tectonic depression of the Rennick Graben (northern Victoria Land, Antarctica) is a key element for deciphering the Cenozoic separation history between East and West Antarctica and evolution of the West Antarctic rift system. The geometry, kinematics and timing of the boundary faults of the Rennick Graben are presented, on the basis of a detailed structural study of the major fault segments combined with apatite fission track data. The structural architecture of the Rennick Graben is controlled by distributed and partitioned right‐lateral strike‐slip faulting. Fission track data indicate that the last significant denudation stage of the Rennick Graben shoulders started from Eocene times, with increasing cooling and denudation since 40–50 Ma. A direct structural connection is then established between Cenozoic denudation and the activation of the dextral strike‐slip regime in north Victoria Land during the Cenozoic. In this framework, the Rennick Graben is interpreted as a localized tectonic depression generated as a displacement accommodation area of the regionally sized dextral strike‐slip shearing. The results of this study (1) invalidate the commonly assumed link between Mesozoic Ross Sea rifting and opening of the Rennick Graben; (2) argue against orthogonal rifting models for the Cenozoic evolution of the Ross Sea region; and (3) provide constraints to the modalities and timing of the separation between the East Antarctic craton and the West Antarctica extensional province.

Constraining the timing of fault reactivation: Eocene coseismic slip along a Late Ordovician ductile shear zone (northern Victoria Land, Antarctica)

“…(Fitzgerald and Stump, 1997;Balestrieri et al, 1994Balestrieri et al, , 1997Fitzgerald, 2002). The rift kinematics (orthogonal vs. oblique) and role of Cenozoic versus Mesozoic intraplate deformation in the West Antarctic Rift System are still debated (e.g., Salvini et al, 1997;Cande et al, 2000;Fitzgerald, 2002;Siddoway et al, 2004;Steinberger et al, 2004;Davey and De Santis, 2006;Rossetti et al, 2003Rossetti et al, , 2006Storti et al, 2007Storti et al, , 2008, with potential implications for the global plate-motion circuit (cf. Cande et al, 2000;Steinberger et al, 2004).…”

Seismic stratigraphy of the Adare Trough area, Antarctica

“…The SU2 terminating faults halt below the Miocene-Pliocene unconformity indicating that extensional/transtensional forces were active until approximately 5-15 Ma. On the adjacent continental crust, the Western Ross Sea also has a dominant set of right-lateral, strike-slip faults trending NW-SE, with N-S transtensional faults extending between the NW trending faults (Salvini et al, 1997;Salvini and Storti, 1999;Rossetti et al, 2003). Other NW-SE trending faults such as the Bower structure and the Rennick Graben occur in North and South Victoria Land (Davey and Brancolini, 1995;Rossetti et al, 2003).…”

Miocene-to-Quaternary oblique rifting signature in the Western Ross Sea from fault patterns in the McMurdo Volcanic Group, north Victoria Land, Antarctica

“…2a;Salvini et al, 1997), reactivating the Delamerian-Ross orogenic fabric (Di Vincenzo et al, 2013). A dominant Cenozoic dextral strike-slip kinematics, evolving to transtensional in the Ross Sea, has been documented by field data (Capponi et al, 1999;Rossetti et al, 2002Rossetti et al, , 2003Rossetti et al, , 2006Storti et al, 2001Storti et al, , 2006Storti et al, , 2008. The regional pattern of strike-slip and extensional fault systems has been well constrained by seismic profile interpretation (Salvini et al, 1997), magnetic anomaly maps (e.g., Ferraccioli et al, 2000Ferraccioli et al, , 2009, and GPS measurements (Dubbini et al, 2010), revealing a complex tectonic framework of crustal-scale NW-SE dextral faults interacting with major N-S-striking extensional faults.…”

“…Soft-sediment deformation (producing bending and local shear zones) is a recurrent, but local, effect produced during slumping mechanisms in sub-glacial hyaloclastites (see also Lanzafame and Villari, 1991). As a whole, the new data combined with structural datasets collected for the Cenozoic fault network in NVL Rossetti et al, 2002Rossetti et al, , 2003Rossetti et al, , 2006Storti et al, 2001Storti et al, , 2008 and south Victoria Land (Wilson, 1995;Jones, 1997;Martin and Cooper, 2010) emphasise the dominant role of continental-scale dextral shear zones along the western shoulder of the WARS (Salvini et al, 1997;Storti et al, 2007), where magma ascent and volcanic activity are localised by the NW-SE transtensional tectonic regime (Rocchi et al, 2002(Rocchi et al, , 2003Salvini and Storti, 1999) rather than a persisting orthogonal extensional scenario (e.g., Davey et al, 2006). In particular, our structural pattern is consistent with evidence of deformation partitioning from dominant NW-SE striking strike-slip fault systems in NVL to a complex, N-S striking fault pattern along the western shoulder of the WARS (Storti et al, 2008), the latter being ascribed to interaction and intersection between pure strike-slip fault zones and extensional ones (Salvini et al, 1997;Storti et al, 2007).…”