Orocline‐driven transtensional basins: Insights from the Lower Permian Manning Basin (eastern Australia)

Abstract

The New England Orogen in eastern Australia exhibits an oroclinal structure, but its geometry and geodynamic evolution are controversial. Here we present new data from the southernmost part of the oroclinal structure, the Manning Orocline, which supposedly developed in the Early Permian, contemporaneously and/or shortly after the deposition of the Lower Permian Manning Basin. New U‐Pb detrital zircon data provide a maximum depositional age of ~288 Ma. Structural evidence from rocks of the Manning Basin indicates that both bedding and preoroclinal fold axial planes are approximately oriented parallel to the trace of the Manning Orocline. Brittle deformation was dominated by sinistral strike‐slip faulting, particularly along a major fault zone (Peel‐Manning Fault System), which is marked by the occurrence of a serpentinitic mélange, and separates tectonostratigraphic units of the New England Orogen. Our revised geological map shows that the Manning Basin is bounded by faults and serpentinites, thus indicating that basin formation was intimately linked to deformation along the Peel‐Manning Fault System. The Manning Basin is thus interpreted to be a transtensional pull‐apart basin associated with the Peel‐Manning Fault System. Age constraints and structural relationships indicate that basin formation likely occurred during the incipient stage of oroclinal bending, with block rotations and fragmentation of the transtensional pull‐apart system occurring subsequently. The intimate link between oroclinal bending and basin formation in the New England oroclines indicates that back‐arc extension, accompanied by transtensional deformation, could have played an important role in the early stage of orocline development.

Subduction accretion and orocline development in modern and ancient settings: Implications of Japanese examples for development of the New England Orogen of eastern Australia

“…Subsequent Early Permian development of the Texas and Coffs Harbour oroclines and formation of the Manning Orocline accompanying sinistral offset and rotation of the Hastings Block as outlined by Phillips et al (2016), which is similar to block rotations about a vertical axis of the Hastings and Nambucca blocks suggested by Fielding et al (2016) and White et al (2016). Generally, oroclinal development in the southern New England Orogen has been related to several factors including: seamount/oceanic plateau impingement on the subduction complex during subduction accretion (herein), nucleation of oroclines on original bends in the convergent margin (Cawood et al, 2011b;Phillips et al, 2016), strike-slip faulting accompanying buckling of the orogenic belt , and rollback induced extension in a backarc basin setting Rosenbaum et al, 2012;Shaanan et al, 2015a, b).…”

“…These oroclines have been widely discussed in the literature (e.g. Cawood et al, 2011a, b;Rosenbaum et al, 2012;White et al, 2016) but it is still unclear why and how they were initiated.…”

“…The position of the Hastings Block is puzzling; it is an offset and rotated portion of the forearc basin (Yan et al, 2016), that was possibly displaced during formation of the Manning Orocline (Fielding et al, 2016;White et al, 2016). Much emphasis has been placed on the development of these features in the recent literature with tectonic interpretations (Cawood et al, 2011a, b;Shaanan et al, 2015a, b), descriptions of structural trends Li et al, 2012;White et al, 2016), considerations of timing Shaanan et al, 2015b), and documentation of palaeomagnetic data (Aubourg et al, 2004;Mochales et al, 2014;Shaanan et al, 2015a). Some authors have queried the existence of these oroclines (Buckman et al, 2015) and others have challenged the southern Manning Orocline (Offler et al, 2015).…”

“…The southern New England Orogen has several examples of orogenic curvature (oroclines, Carey, 1955) developed in subduction complex units ( Fig. 3) and attributed to bending and/or vertical axis block rotations (Cawood, 2011a, b;Fielding et al, 2016;Shaanan et al, 2014;White et al, 2016). In the adjacent Lachlan Orogen (Fig.…”

The Rio Pardo salient, northern Araçuaí orogen: an example of a complex basin-controlled fold-thrust belt curve

“…Salients and recesses, the most common and prominent categories of f-t-belt curves, attracted the attention of researchers already in the first tectonic studies of mountain belts (see Marshak 2004 for a comprehensive review). The interest in f-t-belt curves has persisted over the years, resulting in a robust foundation of knowledge based on their geometric, kinematic and dynamic aspects (e.g., Laubscher 1972, Beutner 1977, Eldredge et al 1985, Marshak & Wilkerson 1992, Macedo & Marshak 1999, Marshak & Flöttmann 1996, Paulsen & Marshak 1999, Spraggins & Dunne 2002, Gutiérrez-Alonso et al 2004, Marshak 2004, Weil & Sussman 2004, Tull & Holm 2005, Wilkerson et al 2007, Silva & Oliveira 2009, Williams et al 2009, Pastor-Galán et al 2011, Prasad et al 2011, Rosembaum et al 2012, Chatzaras et al 2013, Weil et al 2013, Whisner et al 2014, White et al 2016, Szaniawski et al 2017. The majority of these studies are based on the critical taper theory of the development of thrust wedges (Davis et al 1983, Boyer 1995.…”