Orocline-Driven Transtensional Basins: Insights from the Lower Permian Manning Basin

PUBLICATIONS

Tectonics

RESEARCH ARTICLE Orocline-driven transtensional basins: Insights 10.1002/2015TC004021 from the Lower Permian Manning Key Points: Basin (eastern Australia) • Structures in the Manning Basin conﬁrm the existence of the Llyam White1, Gideon Rosenbaum1, Charlotte M. Allen2, and Uri Shaanan1 Manning Orocline • The Manning Basin is an Early 1School of Earth Sciences, University of Queensland, Brisbane, Queensland, Australia, 2Institute for Future Environments, Permian sinistral transtensional pull-apart basin Queensland University of Technology, Brisbane, Queensland, Australia • Spatiotemporal relationships link basin formation to oroclinal bending 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 Supporting Information: • Supporting Information S1 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 Correspondence to: a maximum depositional age of ~288 Ma. Structural evidence from rocks of the Manning Basin indicates that L. White, both bedding and preoroclinal fold axial planes are approximately oriented parallel to the trace of the Manning [email protected] 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 Citation: tectonostratigraphic units of the New England Orogen. Our revised geological map shows that the Manning White, L., G. Rosenbaum, C. M. Allen, and U. Shaanan (2016), Orocline-driven Basin is bounded by faults and serpentinites, thus indicating that basin formation was intimately linked to transtensional basins: Insights from the deformation along the Peel-Manning Fault System. The Manning Basin is thus interpreted to be a transtensional Lower Permian Manning Basin (eastern pull-apart basin associated with the Peel-Manning Fault System. Age constraints and structural relationships Australia), Tectonics, 35, 690–703, doi:10.1002/2015TC004021. 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 Received 4 SEP 2015 link between oroclinal bending and basin formation in the New England oroclines indicates that back-arc Accepted 15 FEB 2016 extension, accompanied by transtensional deformation, could have played an important role in the early stage Accepted article online 22 FEB 2016 Published online 16 MAR 2016 of orocline development.

1. Introduction The origin of curved orogenic belts (oroclines) is a contentious issue that has attracted much attention in recent literature [e.g., Johnston et al., 2013; Rosenbaum, 2014]. A large volume of publications, particularly those that deal with Paleozoic oroclines in Variscan Europe and central Asia, assume that oroclinal bending has involved buckling of the whole lithosphere in response to orogen-parallel compression [Xiao et al., 2010; Gutiérrez-Alonso et al., 2012; Pastor-Galán et al., 2012; Weil et al., 2013]. In contrast, other models suggest that the origin of many oroclines was intimately linked to trench retreat and associated back-arc extension [Royden, 1993; Lonergan and White, 1997; Rosenbaum and Lister, 2004; Schellart and Lister, 2004; Morra et al., 2006; Rosenbaum, 2014]. The latter type of orocline formation is likely to incorporate sedimentary basins that develop simultaneously with the process of oroclinal bending [Rosenbaum, 2014]. While these processes are relatively well constrained in modern tectonic environments (e.g., the Mediterranean region), the relationship between basin formation and oroclinal bending in Paleozoic oroclines is not fully understood. The southern New England Orogen in eastern Australia is an area where this relationship can be investigated. The southern New England Orogen (Figure 1) is characterized by several tight oroclines that developed during the Early Permian [Rosenbaum et al., 2012; Shaanan et al., 2015b]. Many recent studies have focused on the geometry of the oroclines [Glen and Roberts, 2012; Rosenbaum, 2012; Mochales et al., 2014], the timing of oroclinal bending [Ofﬂer and Foster, 2008; Cawood et al., 2011; Rosenbaum et al., 2012; Shaanan et al., 2014], and the possible geodynamic processes responsible for orocline formation [Li et al., 2014; Shaanan et al., 2015a]. Nonetheless, the structure and tectonic origin of the southernmost part of the oroclinal structure (Manning Orocline; Figure 1b) has remained controversial [e.g., Lennox et al., 2013; Li and Rosenbaum, 2015; Ofﬂer et al., 2015]. The reason for this controversy is partly related to the fact that Devonian and

©2016. American Geophysical Union. Carboniferous rocks in the hinge zone of the Manning Orocline are strongly faulted [Collins, 1991] and folded All Rights Reserved. [Dirks et al., 1992; Li and Rosenbaum, 2014], thus impeding our ability to understand the three-dimensional

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 690 Tectonics 10.1002/2015TC004021

Figure 1. (a) Inset map shows the location of the New England Orogen and Bowen-Gunnedah-Sydney basins in eastern Australia. (b) Geological map of the southern New England Orogen. PFS = Peel Fault System. MFS = Manning Fault System. Numbered purple stars indicate the location of suggested outliers of the Manning Basin: 1 = Ironbark Creek [Price, 1973], 2 = Kensington [Brown, 1987], 3 = Willow Tree Hill [Skilbeck et al., 1994], 4 = Hanging Rock [Skilbeck et al., 1994], and 5 = Upper Barnard River [Allan, 1987; Allan and Leitch, 1990].

geometry of the orocline. One way to address this shortcoming is to investigate Lower Permian rocks in the area of the Manning Orocline, which did not experience a long history of preoroclinal deformation. The Lower Permian rocks of the Manning Basin occur at the hinge of the Manning Orocline (Figure 1b) and represent one of the least understood sedimentary successions in the southern New England Orogen [Mayer, 1969, 1972]. Leitch [1988] suggested that these rocks were deposited in association with a larger rift-related basin that existed in the southern New England Orogen during the Early Permian. In contrast, Aitchison and Flood [1992] and Vickers and Aitchison [1993] advocated an orthogonal strike-slip mechanism for basin development. The exact time of deposition has hitherto remained poorly constrained, and although some structural work was conducted on the western part of the Manning Basin [Jenkins and Ofﬂer, 1996], the deformation history, and possible link to the Manning Orocline, has not been established. Given the spatial and

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 691 Tectonics 10.1002/2015TC004021

temporal relationships between the Manning Basin and the Manning Orocline, new structural and geochronological data from this basin could potentially provide direct insights into the mechanisms that controlled oroclinal bending in the Early Permian. In this paper, we present new structural data from the Manning Basin, complemented by geophysical aeromagnetic interpretations and new U-Pb detrital zircon ages. Together, these data deliver insights into the relationships between oroclinal bending and basin formation, conﬁrm the existence of the Manning Orocline, and further constrain the timing of oroclinal bending.

2. Geological Setting The New England Orogen is the youngest orogenic component in eastern Australia [Glen, 2005, 2013] and predominantly consists of Upper Devonian to Triassic rocks that originated in a convergent plate boundary. Devonian-Carboniferous fore-arc units (fore-arc basin and accretionary complex) [Leitch, 1974; Roberts and Engel, 1987] are intruded and overlain by Early Permian S-type granitoids (298–288 Ma [Rosenbaum et al., 2012]) and sedimentary rocks, respectively. Continental detrital zircons from these Lower Permian sedimentary successions suggest that these rocks developed in a back-arc setting [Shaanan et al., 2015a]. The occurrence of Lower Permian back-arc successions that overlay the Carboniferous fore-arc units suggests that during the Early Permian, the subduction boundary retreated oceanward and that the Early Permian magmatic arc was positioned eastward of the present-day coast [Shaanan et al., 2015a]. During the Late Permian to Triassic (260–230 Ma), the southern New England Orogen was affected by widespread arc-related magmatism [Shaw and Flood, 1981; Li et al., 2012a]. The change from an Early Permian back-arc position to a Late Permian magmatic arc is interpreted as evidence for westward trench advance, which was accompanied, at ~270–230 Ma, by contractional deformation referred to as the Hunter-Bowen Orogeny [Collins, 1991; Holcombe et al., 1997; Korsch et al., 2009]. The New England Orogen also contains remnants of Cambrian-Ordovician ophiolitic units, which are exposed along tectonic contacts. In the southern New England Orogen, Cambrian-Ordovician blocks occur along the Peel-Manning Fault System and consist of serpentinites and high-pressure metamorphic rocks (Figure 1b) [Cawood and Leitch, 1985; Korsch and Harrington, 1987; Aitchison et al., 1994]. The Peel-Manning Fault System separates Devonian-Carboniferous fore-arc basin rocks from accretionary complex rocks. The southern New England Orogen is characterized by four curvatures, commonly referred to as the Coffs Harbour, Texas, Manning, and Nambucca oroclines (Figure 1b). These oroclines are deﬁned by the curvature of bedding and dominant structural fabric [Korsch and Harrington, 1987; Lennox and Flood, 1997; Li et al., 2012b; Li and Rosenbaum, 2014], the map view arrangement of fore-arc basin rocks [Glen and Roberts, 2012], the trace of early Paleozoic serpentinites [Korsch and Harrington, 1987], and the curvature of Early Permian (298–288 Ma) granitoids [Rosenbaum, 2012; Rosenbaum et al., 2012]. The curved belt of Early Permian granitoids provides a maximum age constraint for the timing of oroclinal bending, indicating that the oroclines formed during or after emplacement [Rosenbaum et al., 2012]. Minimum age constraints are available from paleomagnetic data, which indicate that formation of the Manning Orocline was concluded prior to ~272 Ma [Shaanan et al., 2015b]. From ~270 to 265 until ~230 Ma, the region was subjected to contractional deformation (Hunter-Bowen Orogeny), associated with major west directed retrothrusting of Lower Permian rift basins [Korsch et al., 2009]. This deformation has likely tightened the already contorted structure of the New England oroclines [Rosenbaum, 2012; Rosenbaum et al., 2012]. Lower Permian sedimentary successions are found in the Bowen-Gunnedah-Sydney basins west of the New England Orogen (Figure 1a) and in a number of blocks within the oroclinal structure, including the Nambucca Block, Dyamberin Block, Manning Basin, and a number of smaller outliers in the area of the Texas Orocline (Figure 1b). The Manning Basin (Manning Group) [Voisey, 1958] is located in the area of the Manning Orocline (Figure 1b) and adjacent to the Peel-Manning Fault System. Early Paleozoic serpentinites associated with the Peel-Manning Fault System occur along the boundaries of the Manning Basin (Figure 2); however, the structural relationships between the formation of this basin and the Peel-Manning Fault System have hitherto not been established. The Manning Basin spans approximately 2500 km2 and is fault bound on all sides (Figure 2). Based on geographic and stratigraphic considerations, two major parts of the basin sequence have been identiﬁed

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 692 Tectonics 10.1002/2015TC004021

Figure 2. Structural map and cross sections (A-A′ and B-B′) of the Early Permian Manning Basin. Two areas (west and east) are identified, geographically divided at Mount George. Equal area lower hemisphere stereographic projections show poles to bedding and the axial planes of major folds (red lines) for the four identified structural domains. The light blue lines in eastern stereoplots demonstrate the common axial plane (87–129) for all three structural domains in the eastern part of the basin. The shaded light blue area in the stereoplot from the western part of the basin represents the possible field in which a common axial plane could exist.

(east and west) [Jenkins, 1992], adjoined centrally at Mount George (Figure 2). Outliers of the Manning Basin to the north occur in association with the Peel-Manning Fault System [Allan and Leitch, 1990; Skilbeck et al., 1994] and include Ironbark Creek [Price, 1973], Kensington [Brown, 1987], Willow Tree Hill and Hanging Rock [Skilbeck et al., 1994], and the Upper Barnard River [Allan, 1987; Allan and Leitch, 1990] (Figure 1b). The sedimentary succession, estimated to be ~4–6 km thick [Jenkins and Offler, 1996], is characterized by a diamictite-dominated deep marine sequence with provenance from both the adjacent fore-arc basin and accretionary complex [Mayer, 1972]. Varying submarine mass flow mechanisms have been suggested as the mode of primary deposition [Mayer, 1972]. The succession has been assigned a Lower Permian designation (latest Sakmarian to early or middle Artinskian) based on biostratigraphic observations of various marine fauna [Voisey, 1938, 1939; Mayer,1969;Voisey and Packham, 1969; Mayer, 1972; Brennan,1976;Laurie, 1976; Engel and Laurie, 1978; Briggs, 1987, 1991; Jenkins,1992;Vickers and Aitchison, 1992, 1993; Sharp, 1995]. However, no absolute ages have hitherto been reported from the Manning Basin. The rocks are metamorphosed at zeolite to prehnite/pumpellyite facies [Jenkins and Offler, 1996].

3. Geology of the Manning Basin A new geological map of the Manning Basin is presented in Figure 2. The map incorporates new ﬁeld observations, aeromagnetic data (ﬁrst vertical derivative, second vertical derivative, downward continuation, upward continuation, and tilt angle derivative), and previously obtained geological data [Mayer, 1972; Brennan, 1976; Laurie, 1976; Nano, 1987; Vickers and Aitchison, 1992, 1993; Roberts et al., 1995; Sharp, 1995;

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 693 Tectonics 10.1002/2015TC004021

Jenkins and Offler,1996;Jenkins, 1997]. The most significant amendment in the geological map is the extent of the easternmost boundary of the Manning Basin, which has been shifted westward following our new geochronological results and aeromagnetic interpretations. 3.1. Stratigraphy Mayer [1972] subdivided the western Manning Basin sequences into five units: the basal Wards Creek Beds, Giro Diamictite, Glory Vale Conglomerate, Colraine Mudstone, and Kywong Beds. The lowermost Wards Creek Beds is characterized by strongly silicified bedded/massive sedimentary breccia and sandstone. The conformably overlain Giro Diamictite, which makes up the vast majority of the Manning Basin sequence in the west, is a massive pebbly mudstone/fine-grained siltstone (or diamictite) with uncommon massive, bedded or turbidite sandstones, siltstones, and pebble conglomerates (Figure 3). Sheared serpentinite clasts were observed within both the Wards Creek Beds and Giro Diamictite. The Glory Vale Conglomerate consists of pebble conglomerate and less abundant fine-grained sandstone/siltstone and minor limestone. The Colraine Mudstone consists of black micaceous massive mudstone/fine- grained siltstone with less common sandstone and rare limestone. The uppermost unit proposed by Mayer [1972], the Kywong Beds, was not clearly identified in the study area.

Figure 3. Rocks of the Manning Basin. (a) Typical exposure of the massive The stratigraphy of the eastern part of Giro Diamictite characterized by fine to medium sandy matrix, and the basin, defined both by Voisey [1958] poorly sorted, rounded to angular clasts. The clasts are both siliciclastics and Engel and Laurie [1978], consists of and volcaniclastics with rare sheared serpentinite clasts (31.859918°S, the following four units (from bottom 151.873591°E). (b, c) Common bedding styles—moderate to steeply to top): Charity Creek Beds, Kimbriki interbedded sands and siltstones (31.82123297°S, 152.002898°E). (d) Photomicrograph of a typical diamictite—poorly sorted subrounded Formation, Cedar Party Limestone, to angular quartz (Qtz), feldspar, and lithic grains displaying strong and Colraine Mudstone. The lowermost chloritization (Chl). Charity Creek Beds comprise massive pebbly mudstones and diamictites commonly interbedded with massive sandstone horizons harboring thin siltstone and mudstone laminations. This unit is possibly correlative to the Giro Diamictite of the western part of the basin [Jenkins, 1992]. The conformably overlain Kimbriki Formation is characterized by interbedded sandstones, siltstones, (less common) mudstones, and rare pebble conglomerates at the base. The Cedar Party Limestone is sparsely exposed and comprises silty mudstones and pink calcarenites, micrites, and biosparites. The Colraine Mudstone exists at the top of the eastern stratigraphic succession and is characterized by dark abundantly micaceous massive mudstone and rare graded beds of very fine grained sandstone and siltstone.

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 694 Tectonics 10.1002/2015TC004021

The contacts between the stratigraphic units are poorly exposed, and there is evidence for extensive faulting throughout the area. Therefore, the identiﬁcation of lithological unit boundaries and the exact stratigraphic relationship between units remains ambiguous.

3.2. Structure and Deformation 3.2.1. Bedding Primary bedding is generally well defined in both the western and eastern sequences but can be difficult to recognize in thick diamictites. The strike orientations and inclinations of bedding vary throughout the Manning Basin, with more pronounced variations in the eastern part of the basin than in the western part (Figure 2). Way-up indicators commonly show stratigraphic younging toward the south. 3.2.2. Folds Foldsinthewesternpartofthebasinare primarily observed in alternating siltstone and sandstone beds within the Giro Diamictite. These folds are steeply to moderately inclined, gently to moderately plunging, and tight to isoclinal, with an axial trace commonly aligned NW-SE Figure 4. Typical fold styles in the Manning Basin. (a, b) Steeply to moderately inclined gently to moderately plunging isoclinal folds, class (~135°) (e.g., Figure 4a and 4b). Open 1C fold layers, N-E vergence and an axial trace aligned NW-SE (~135°) upright folds in a similar orientation were (31.85494599°S, 151.87839°E). (c) A large-scale open fold in interbedded also observed, with fold interlimb angles siltstone and medium grained sandstone units of Domain B in the apparently tightening closer to fault eastern part of the basin (31.80330802°S, 152.348258°E). zones. Stereographic projections of poles to bedding and the orientations of axial planes show that fold orientations are relatively uniform across the entire western part of the basin and southernmost extension of the eastern part (Figure 2). Direct field observations and asymmetric clustering of poles to bedding on stereographic plots indicate that folds in the western part of thebasinshareacommonvergencetotheNE,withmap- scale parasitic Z folds inferred for these structures. In contrast to the relatively consistent orientations of folds in the west, folds in the eastern part of the basin are noncylindrical and show variable orientations. Approximately cylindrical folds can be recognized only after subdivision of the area into three structural domains (A, B, and C in Figure 2). Domains A, B, and C (north, intermediate, and south, respectively) host steeply inclined to upright, gently to moderately plunging, open to closed, rounded folds (e.g., Figure 4c). Despite showing strong noncylindricity when plotted together, stratigraphic projections from all three domains of the eastern part of the basin demonstrate a common axial plane, which is calculated by the plane linking the β axes in the three domains. The dip/dip azimuth of this plane is 87–129 (Figure 2). Evidence for fold superposition was not found. 3.2.3. Faults The Manning Basin is fault bound on all sides and has numerous additional faults within the basin (Figure 2). In the western part of the basin, the dominant faults are steeply dipping and oriented approximately NW-SE. Field observations (e.g., slickenlines, slickenfibers, and Riedel shears) suggest that the movement on these faults is predominantly sinistral strike slip, and less commonly oblique slip (e.g., Figure 5). Faults in the eastern part of the basin show variable orientations, most notably in Domains B and C (Figure 2). Sinistral

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 695 Tectonics 10.1002/2015TC004021

strike-slip kinematics with a minor oblique-slip component is recognized in faults striking approximately E-W, NW-SE, and NNW-SSE, whereas faults striking approximately NE-SW show dextral kinematics. Field observations of steeply dipping fault surfaces south and southeast of Mount George displayed well-developed fractured fault steps and mineralized slickenline growth (e.g., Figure 5), with these fault surfaces likely representing the southern continuation of the Peel-Manning Fault System (Manning Fault). Observed slickenlines are consistently shallow (pitch of less than 12°), thus indicating strike-slip kinematics. Figure 6 presents a regional analysis of faults, which was achieved using publically available Landsat 7 Enhanced Thematic Mapper Plus imagery and reduced-to-pole gridded aeromagnetic data acquired from Geoscience Australia (80 m spatial resolution). The major faults identiﬁed appear as a conjugate array, with sinistral NW-SE and NNW-SSE faults and dextral NE-SW faults (Figure 6a). The predominant orientation is approximately NW-SE (Figure 6b). Figure 6c highlights the spatial distribution of deep magnetic anomalies in the area Figure 5. Typical fault exposures in the Manning Basin. (a) Slickenlines and fractured fault steps indicative of sinistral oblique shear. (b) projected over 600 m upward continua- Fractured fault steps and slickenlines indicative of near-pure sinistral tion aeromagnetic data. The deep-seated strike-slip kinematics. high magnetic anomalies correspond with serpentinite occurrence, although we emphasize that the surface exposure is limited thus resulting in major uncertainties. A restoration of correlative high magnetic anomalies (serpentinites) occurring at depth along the Manning Fault results in the realign- ment of a preexisting NNW-SSE trending fault and other identiﬁable lineaments and demonstrates ~20 km sinistral offset (Figures 6d and 6e).

4. Geochronology U-Pb dating of detrital and primary zircons using laser ablation induced coupled plasma–mass spectrometry (LA-ICP-MS) was performed in order to obtain constraints on the depositional age of Manning Basin rocks. 4.1. Sample Preparation and Analytical Methods Four clastic sedimentary rock samples and one interbedded volcanic ﬂow,~4kginweight,weretakenfrom selected sites (see locations and sample index in Figure 2). Samples MG-14-011, MG-14-012, and MG-14-015 from the western part of the basin were taken from sequences of the Giro Diamictite, while sample MG-14-018 from the eastern part of the basin represents the approximate stratigraphic equivalent [Jenkins, 1992], the Charity Creek beds. The exact stratigraphic relationship between sedimentary samples is not constrained due to the effect of faulting and the associated uncertainty in assigning lithological unit boundaries. Samples were washed to remove possible contamination of soils and dust. Each sample was crushed using a Jaw Crusher followed by a Fritisch (Pulverisette 13) Disc Mill. The crushed material was washed to remove ﬁne

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 696 Tectonics 10.1002/2015TC004021

Figure 6. Geophysical interpretation. (a) Schematic regional interpretation of major faults in the Manning Basin and surrounding area. (b) Rose diagram of major faults displaying dominant approximately NW-SE orientations. (c) The 600 m upward continuation filtered aeromagnetic data showing the spatial distribution of deep magnetic anomalies, which are interpreted to be serpentinite bodies bordering the Manning Basin. Surface serpentinite occurrences (in blue stroke) correspond well with the deep-seated high magnetic anomalies. (d) Tilt angle derivative filtered aeromagnetic data from the area of the Manning Orocline. Major faults immediate to the Manning Basin are mapped as thick black lines (interpreted from first vertical derivative, second vertical derivative, tilt angle derivative, 400 m downward continuation, and 600 m upward continuation filters; see supporting information). Sinistral strike-slip kinematics is inferred for the main extension of the Peel-Manning Fault System (~NW-SE trending Manning Fault), with piercing points A and B and a correlative magnetic anomaly (light blue dashed line) identified along this fault. (e) Restoration of the piercing points and high magnetic anomaly demonstrating ~20 km sinistral offset.

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 697 Tectonics 10.1002/2015TC004021

silt-sized particles and dry sieved to <600 μm to remove any larger grains carried through. The magnetic fraction of each sample was removed using a Frantz LB-1 magnetic separator. Separation of heavy minerals was done using Methyl Iodide heavy liquid in a tapped funnel. The heavy fraction separates were handpicked for zircons with preference for the larger, more euhedral crystals to encourage a robust youngest population constraint. Approximately 140–150 detrital zircon crystals were handpicked for each sedimentary sample and ~25 zircons picked for the volcanic flow. Zircon grains were mounted in a nonreactive epoxy (Struers Epofix resin and hardener) and polished to expose sections of the crystals. The polished mounts were imaged using a Zeiss AxioImager M2M micro- scope under both transmitted and reflected light to aid in target identifica- tion and tracking during analysis. Zircon crystals displaying numerous cracks and/or mineral/melt inclusions were excluded from the analysis. U-Pb isotope analyses were obtained using an Agilent 8800 LA-ICP-MS at the Queensland University of Technology Central Analytical Research Facility. Data acquisition involved 25 s of back- ground measurement followed by 30 s of sample ablation in a He atmosphere using a laser beam diameter of 30 μm. External standardization of mass bias and U-Pb fractionization was monitored and corrected for using Temora 2 as the calibration standard (416.78 ± 0.33 Ma [Black et al., 2004]) and the Plešovice zircon as a monitor or check standard (337.13 ± 0.37 Ma [Sláma et al., 2008]). The National Institute of Standards and Technology SRM 610 glass standard was used to calculate trace element concentrations [Longerich et al., 1996; Jochum et al., 2011], with internal standardization by stoichiometric ratios Figure 7. Geochronological data. (a) Relative probability plot and number (32.8% Si in zircon) employed. Raw data of detrital zircon ages for all sedimentary samples. Inset shows the relative were processed using IOLITE software probability curves of ages that are younger than 500 Ma for each sedi- [Paton et al., 2011] and population mentary sample and for all combined. (b) Mean-weighted average plot for the youngest population from all sedimentary samples combined. (c) weighted average ages calculated using Mean-weighted average plot for the single volcanic sample (MG-14-006). the Isoplot 3.7 toolkit [Ludwig, 2003].

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 698 Tectonics 10.1002/2015TC004021

Because samples were analyzed in different sessions, IOLITE’s propagated uncertainties were used [Paton et al., 2011]. The extra uncertainty, beyond homogeneity of the analysis itself, was ~80% larger, reflecting the uncertainty in the primary standard and how standards are fitted from one session to the next. 4.2. Geochronological Results U-Pb analyses of four clastic sedimentary samples and one interbedded andesitic flow yielded 478 concordant detrital zircon ages and 14 concordant primary zircon ages. For sedimentary samples, ~81% of concordant analyses were Carboniferous in age and ~13% Early Permian. All sedimentary samples presented a dominant zircon population between ~308 Ma and ~317 Ma (Figure 7a). Samples MG-14-011 and MG-14-012 presented additional significant age populations at ~338 Ma and ~333 Ma, respectively (Figure 7a). These age populations fall within the timeframe suggested for arc magmatism in the New England Orogen (~350–305 Ma [Glen, 2005]). The consistency in populations between the different sedimentary samples (Figure 7a) and the overlap (in 2σ error) of ages for the youngest grains (Figure 7b) suggest that the sedimentary samples can be merged to produce a single robust age constraint for deposition of the basin material. A combined mean-weighted average age for all sedimentary samples yielded a youngest age population of 288.5 ± 2.1 Ma (Figure 7b) for the Manning Basin sequence. The youngest population for any single sample was 285.9 ± 5.7 Ma (sample MG-14-012, n = 5, see supporting information). For the dated andesitic sample (MG-14-006, see Figures 2), 13 of the 14 concordant analyses revealed Late Devonian-Carboniferous ages of 370 to 344 Ma, with the single younger outlier dated to ~326 Ma. A mean-weighted average age (excluding the younger outlier) gave 357.6 ± 4.4 Ma (Figure 7c). This result is considerably older than the calculated maximum depositional age for sedimentary samples given above (288.5 ± 2.1 Ma). Thus, the sedimentary sequence, in which sample MG-14-006 is interbedded, must be older and is not a part of the Manning Basin. The dated andesite was taken from strata previously mapped as belonging to the easternmost part of the Manning Basin [e.g., Gilligan et al., 1987]. The early Carboniferous age of this andesite suggests that the confining sedimentary sequence likely represents a section of the adjacent Upper Devonian to Carboniferous fore-arc basin. This new age constraint also redefines the eastern spatial extent of the Manning Basin. The amended map now shows the Mooral Creek Serpentinite to be located at the easternmost boundary of the Manning Basin (Figure 2), consistent with the commonplace occurrence of serpentinites at the fringes of the basin.

5. Discussion 5.1. Depositional Age and Provenance of the Manning Basin U-Pb analyses of detrital zircons from the Manning Basin yielded a combined calculated youngest population of 288.5 ± 2.1 Ma from 33 youngest ages that overlap within error (Figure 7b), indicating that the depositional age of the sedimentary succession is younger than this age. The ~288 Ma maximum age constraint for the deposition of the Manning Basin is consistent with biostratigraphic observations of Lower Permian (Artinskian, 290–283 Ma) marine fauna within the sedimentary succession [Voisey, 1938, 1939; Mayer,1969; Voisey and Packham,1969;Mayer,1972;Brennan,1976;Laurie, 1976; Engel and Laurie, 1978; Briggs,1987, 1991; Jenkins, 1992; Vickers and Aitchison, 1992, 1993; Sharp, 1995]. Lower Permian sedimentary successions within the southern New England Orogen have been suggested to represent rift-related extensional basins [Leitch, 1988; Shaanan et al., 2015a]. These sedimentary successions (Nambucca Block, Dyamberin Block, Manning Basin, and other outliers in the area of the Texas Orocline; Figure 1b) were deposited contemporaneously with the Bowen, Gunnedah, and Sydney basins, which are collectively referred to as the Early Permian East Australian Rift System [Korsch et al., 2009]. Whether or not the Manning Basin was connected to the other Lower Permian successions in the southern New England Orogen remains to be established. However, the recognition of sheared serpentinite clasts within the sedimentary pile is unique to the Manning Basin. Given the propensity of fragile serpentinites to be destroyed during transport, this observation indicates a very localized derivation of sedimentary material. Throughout the southern New England Orogen, serpentinites occur almost exclusively within the Peel-Manning Fault System [Cawood and Leitch,1985;Korsch and Harrington, 1987; Aitchison et al., 1994], thus indicating proximal

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 699 Tectonics 10.1002/2015TC004021

Figure 8. Schematic tectonic reconstruction for the development of the Manning Basin at the hinge of the Manning Orocline. (a) Asymmetric rollback of an Andean- type subduction zone led to bending of the Peel-Manning Fault System and the development of a set of sinistral step overs. (b) Continued asymmetric rollback led to fragmentation of the Peel-Manning Fault System and brittle deformation of the Manning Basin, thus forming the Manning Orocline. (c) Present-day conﬁguration of the New England oroclinal structure, Devonian-Carboniferous fore-arc basin terrains, and the Manning Basin. Stereoplot showing the axial plane ﬁelds (light blue) of folds in the Manning Basin (west and east blocks; see Figure 2), with the orientation of basin structures demonstrating ~ 90° of relative rotation. Abbreviations: EC = Emu Creek Block; Gr = Gresford Block; Hs = Hastings Block; My = Myall Block; Ro = Rouchel Block; Tm = Tamworth Belt.

relationships between this fault system, the Manning Basin and its capture area. This link supports the previous suggestion by Aitchison and Flood [1992] that the formation of the Manning Basin was genetically linked to activity on the Peel-Manning Fault System.

5.2. Origin of the Manning Orocline Throughout the southern New England Orogen, the Peel-Manning Fault System marks the contact between Devonian-Carboniferous fore-arc basin units and accretionary complex units and is associated with the occurrence of early Paleozoic serpentinites (Figure 1b) [Cawood and Leitch, 1985; Korsch and Harrington, 1987; Aitchison et al., 1994]. In the study area, however, these two tectonostratigraphic units are not in direct contact and the Manning Basin intervenes. Faulted margins in the study area are marked by the occurrence of sheared serpentinite bodies (Figure 2), and ﬁltered aeromagnetic data indicate that these serpentinite bodies likely occur in association with strike-slip faults (Figure 6). These observations imply that the boundary faults of the Manning Basin are segments of the Peel-Manning Fault System. The apparent rapid sedimentation of a thick [Jenkins and Ofﬂer, 1996] succession of diamictites and the presence of sheared serpentinite clasts within it further suggest that the development of the Manning Basin was intimately linked to the Peel-Manning Fault System. We therefore propose that the Manning Basin formed as a pull-apart basin in a transtensional strike-slip setting, which likely accompanied the initial stage of oroclinal bending (Figure 8a). Our observations show that rocks in the Manning Basin are folded and faulted. Fold axial planes are oriented approximately NW-SE in the western part of the basin and approximately NNE-SSW in the eastern part (Figure 2), parallel to the trend of the major basin-bounding faults. The strike of bedding is more variable, particularly in the eastern part of the basin, but its general orientation is parallel to the trend of the macroscopic folds (Figure 2). The fact that the orientation of bedding, folds, and the bounding faults is quite consistent in each part of the basin but varies between the western and eastern parts may suggest that one part of the basin is rotated relative to the other (Figures 8b and 8c). The above mentioned structural grain of dominantly NW orientations in the western part of the basin and NNE orientations in the eastern part is consistent with the expected geometry of the Manning Orocline [Glen and Roberts, 2012; Li and Rosenbaum, 2014]. Accordingly, the central position where the eastern and western parts adjoin (near Mount George) may represent the approximate location of the hinge zone. In the area of Mount George (Figure 2), a large curved serpentinite body shows an apparent curvature that is consistent with this geometry (Figure 8d). Previous studies on the oroclinal structure were mainly focused on deformation in the older tectonostratigraphic units, such as the belt of early Paleozoic serpentinites [Korsch and Harrington, 1987] and the Devonian-Carboniferous fore-arc basin and accretionary complex rocks [Geeve et al., 2002; Glen and

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 700 Tectonics 10.1002/2015TC004021

Roberts, 2012; Li and Rosenbaum, 2014; Mochales et al., 2014]. Nonetheless, the question whether the Manning Orocline exists has remained controversial [Lennox et al., 2013; Li and Rosenbaum, 2015; Ofﬂer et al., 2015]. Our new data from the Manning Basin provide an independent set of observations that support the existence of a curved geometry, with one part of the basin rotated relative to the other (Figures 8b and 8c). The timing of block rotations has recently been constrained by Shaanan et al. [2015b], who conducted a palaeomagnetic study on ~272 Ma volcanic rocks within the Myall Block (see Figure 8). Their results indicate no signiﬁcant rotations of the Myall Block (relative to cratonic Gondwana) after ~272 Ma. Shaanan et al. [2015b] have concluded that block rotations took place prior to the initiation of E-W contraction associated with the Hunter-Bowen Orogeny (~270–230 Ma). Following the arguments by Shaanan et al. [2015b], it appears, therefore, that the Manning Orocline did not form by E-W buckling. Alternatively, it is possible that oroclinal bending and block rotations were predominantly controlled by plate boundary migration associated with trench retreat. Evidence for basin formation in the Early Permian, accompanied by crustal melting and extensional faulting, has been linked to back-arc extension, with the suggestion that oroclinal bending was ultimately controlled by trench retreat and the progressive curvature of the plate boundary [Shaanan et al., 2015a, 2015b]. The development of the Manning Basin in a transtensional setting (Figure 8a) is consistent with this hypothesis.

6. Conclusions Structural observations from the Manning Basin support the existence and proposed shape of the Manning Orocline. New age constraints indicate that deposition of the Manning Basin took place after ~288 Ma, simultaneously with the development of widespread sedimentary basins throughout the New England Orogen. The development of the Manning Basin was intimately linked to strike-slip faulting along the Peel-Manning Fault System, and it is interpreted that basin formation occurred in a transtensional back-arc setting. The ﬁrst stage of oroclinal bending possibly occurred simultaneously with basin formation, whereas a second stage was responsible for counterclockwise rotation of the eastern part of the basin relative to the western part. Both stages of oroclinal bending were likely concluded prior to the commencement of E-W contraction associated with the Hunter-Bowen Orogeny.

Acknowledgments References This research was funded by Australian Research Council grant DP130100130. Aitchison, J. C., and P. G. Flood (1992), Early Permian transform margin development of the southern New-England Orogen, eastern Australia – The manuscript benefited from input by (eastern Gondwana), Tectonics, 11(6), 1385 1391, doi:10.1029/92TC01003. Derek Hoy, Abbas Babaahmadi, and Aitchison, J. C., M. C. Blake, P. G. Flood, and A. S. Jayko (1994), Paleozoic ophiolitic assemblages within the southern New England Orogen of — – Matthew Campbell and constructive eastern Australia Implications for growth of the Gondwana margin, Tectonics, 13(5), 1135 1149, doi:10.1029/93TC03550. fi reviews by Evan Leitch and an Allan, A. D. (1987), Geology and tectonic signi cance of Devonian and Permian sequences in the upper Barnard River district, New South anonymous reviewer. Wales, B.Sc. (Hons) thesis, Univ. of Sydney, Sydney. Allan, A. D., and E. C. Leitch (1990), The tectonic significance of unconformable contacts at the base of early Permian sequences, southern New-England Fold Belt, Aust. J. Earth Sci., 37(1), 43–49. Black, L. P., et al. (2004), Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID–TIMS, ELA–ICP–MS and oxygen isotope documentation for a series of zircon standards, Chem. Geol., 205(1–2), 115–140. Brennan, P. V. (1976), The geology of the Marlee-Mooral Creek area, B.Sc. (Hons) thesis, 60 pp., Univ. of Newcastle, Newcastle. Briggs, D. J. C. (1987), Permian productid zones of NSW, in 21st Newcastle Symposium: Advances in the Study of the Sydney Basin, edited by C. F. K. Diessel and R. L. Boyd, pp. 135–142, Univ. of Newcastle, Newcastle, Aust. Briggs, D. J. C. (1991), Correlation charts for the Permian of the Sydney-Bowen basin and New England Orogen, in Proceedings of the Symposium: Advances in the Study of the Sydney Basin 25, edited by C. F. K. Diessel and R. L. Boyd, pp. 30–37, Univ. of Newcastle, Newcastle, Aust. Brown, R. E. (1987), Newly defined stratigraphic units from the western New England Fold Belt, Manilla 1:250,000 sheet area, Geol. Surv. New South Wales, Quart. Notes, 69,1–9. Cawood, P. A., and E. C. Leitch (1985), Accretion and dispersal tectonics of the southern New England Fold Belt, eastern Australia, in Tectonostratigraphic Terranes of the Circum-Pacific Region, edited by D. G. Howell, pp. 481–492, Circum-Pacific Council of Energy and Mineral Resources, Houston, Tex. Cawood, P. A., S. A. Pisarevsky, and E. C. Leitch (2011), Unraveling the New England orocline, east Gondwana accretionary margin, Tectonics, 30, TC5002, doi:10.1029/2011TC002864. Collins, W. J. (1991), A reassessment of the “Hunter-Bowen Orogeny”: Tectonic implications for the southern New England Fold Belt, Aust. J. Earth Sci., 38(4), 409–423. Dirks, P. H. G. M., M. Hand, W. J. Collins, and R. Offler (1992), Structural metamorphic evolution of the Tia Complex, New-England Fold Belt— Thermal overprint of an accretion subduction complex in a compressional back-arc setting, J. Struct. Geol., 14(6), 669–688. Engel, B. A., and J. R. Laurie (1978), A new species of the Permian trilobite Doublatia from the Manning District, New South Wales, Alcheringa, 2(1), 49–54.

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 701 Tectonics 10.1002/2015TC004021

Geeve, R. J., P. W. Schmidt, and J. Roberts (2002), Paleomagnetic results indicate pre-Permian counter-clockwise rotation of the southern Tamworth Belt, southern New England Orogen, Australia, J. Geophys. Res., 107(B9), 2196, doi:10.1029/2000JB000037. Gilligan, L. B., J. W. Brownlow, and R. G. Cameron (1987), Tamworth-Hastings New South Wales, 1:250 000 metallogenic series map, Sheets SH 56-13, SH/56-14, Geological Survey of New South Wales, Sydney. Glen, R. A. (2005), The Tasmanides of eastern Australia, in Terrane Processes at the Margins of Gondwana, Spec. Publ., vol. 246, edited by A. P. M. Vaughan, P. Y. Leat, and R. J. Pankhurst, pp. 23–96, Geological Society of London, London. Glen, R. A. (2013), Refining accretionary orogen models for the Tasmanides of eastern Australia, Aust. J. Earth Sci., 60(3), 315–370. Glen, R. A., and J. Roberts (2012), Formation of oroclines in the New England Orogen, eastern Australia, J. Virtual Explorer, 43(3), 1–38. Gutiérrez-Alonso, E., S. T. Johnston, A. B. Weil, D. Pastor-Galán, and V. Fernández-Suárez (2012), Buckling an orogen: The Cantabrian Orocline, GSA Today, 22(7), 4–9. Holcombe, R. J., C. J. Stephens, C. R. Fielding, D. Gust, A. Little, R. Sliwa, J. McPhie, and A. Ewart (1997), Tectonic evolution of the northern New England Fold Belt: Carboniferous to Early Permian transition from active accretion to extension, in Geological Society of Australia, Spec. Publ., vol. 19, edited by P. M. Ashley and P. G. Flood, pp. 66–79, Geological Society of Australia, Sydney. Jenkins, R. B. (1992), A geologic and thermal history of the Manning Group, in 26th Newcastle Symposium: Advances in the Study of the Sydney Basin, edited by C. F. K. Diessel and R. L. Boyd, pp. 39–46, Univ. of Newcastle, Newcastle, Aust. Jenkins, R. B. (1997), Crustal evolution of the southern New England Fold Belt during the Carboniferous and Early Permian: Evidence from volcanic rocks and the Early Permian Manning Group, MSc thesis, 205 pp., Univ. of Newcastle, Newcastle. Jenkins, R. B., and R. Offler (1996), Metamorphism and deformation of an Early Permian extensional basin sequence: The Manning Group, southern New England Orogen, Aust. J. Earth Sci., 43(4), 423–435. Jochum, K. P., et al. (2011), Determination of reference values for NIST SRM 610–617 glasses following ISO guidelines, Geostand. Geoanal. Res., 35(4), 397–429. Johnston, S. T., A. B. Weil, and G. Gutierrez-Alonso (2013), Oroclines: Thick and thin, Geol. Soc. Am. Bull., 125(5-6), 643–663. Korsch, R. J., and H. J. Harrington (1987), Oroclinal bending, fragmentation and deformation of terranes in the New England Orogen, eastern Australia, in Terrane Accretion and Orogenic Belts, edited by E. C. Leitch and E. Scheibner, pp. 129–139, AGU, Wash., D. C. Korsch, R. J., J. M. Totterdell, D. L. Cathro, and M. G. Nicoll (2009), Early Permian east Australian rift system, Aust. J. Earth Sci., 56(3), 381–400. Laurie, J. R. (1976), The geology of the Kimbriki Area, B.Sc. (Hons) thesis, 105 pp., Univ. of Newcastle, Newcastle. Leitch, E. C. (1974), The geological development of the southern part of the New England Fold Belt, Aust. J. Earth Sci., 21(2), 133–156. Leitch, E. C. (1988), The Barnard Basin and the Early Permian development of the southern part of the New England Fold Belt, in New England Orogen—Tectonics and Metallogenesis, edited by J. D. Kleeman, pp. 61–67, Univ. of New England, Armidale, Aust. Lennox, M., and P. G. Flood (1997), Age and structural characterization of the Texas megafold, southern New England Orogen, eastern Australia, in Tectonics and Metallogenesis of the New England Orogen 19: Alan Voisey Memorial, Spec. Publ., edited by P. M. Ashley and P. G. Flood, pp. 161–177, Geological Society of Australia. Lennox, P. G., R. Offler, and J. Yan (2013), Discussion of Glen R. A. and Roberts J. 2012: Formation of oroclines in the New England Orogen, eastern Australia, J. Virtual Explorer, 44(3), 1–10. Li, P., and G. Rosenbaum (2014), Does the Manning Orocline exist? New structural evidence from the inner hinge of the Manning Orocline (eastern Australia), Gondwana Res., 25(4), 1599–1613. Li, P., and G. Rosenbaum (2015), Reply to comment by Offler et al. on “Does the Manning Orocline exist? New structural evidence from the inner hinge of the Manning Orocline (eastern Australia)”, Gondwana Res., 27(4), 1689–1691. Li, P., G. Rosenbaum, and P. J. T. Donchak (2012a), Structural evolution of the Texas Orocline, eastern Australia, Gondwana Res., 22(1), 279–289. Li, P., G. Rosenbaum, and D. Rubatto (2012b), Triassic asymmetric subduction rollback in the southern New England Orogen (eastern Australia): The end of the Hunter-Bowen Orogeny, Aust. J. Earth Sci., 59(6), 965–981. Li, P., G. Rosenbaum, and P. Vasconcelos (2014), Chronological constraints on the Permian geodynamic evolution of eastern Australia, Tectonophysics, 617,20–30. Lonergan, L., and N. White (1997), Origin of the Betic-Rif mountain belt, Tectonics, 16(3), 504–522, doi:10.1029/96TC03937. Longerich, H. P., S. E. Jackson, and D. Gunther (1996), Inter-laboratory note. Laser ablation inductively coupled plasma mass spectrometric transient signal data acquisition and analyte concentration calculation, J. Anal. At. Spectrom., 11(9), 899–904. Ludwig, K. R. (2003), Isoplot 3.75: A geochronological toolkit for Microsoft Excel, in Berkeley Geochronology Center Special Publication, 75 pp., Berkeley Geochronology Centre, Berkeley, Calif. Mayer, W. (1969), Permian sedimentary rocks from southern New England, Aust. J. Sci., 32(2), 55–56. Mayer, W. (1972), Palaeozoic sedimenetary rocks from southern New England: A sedimentological evaluation, PhD thesis, 258 pp., Univ. of New England, Armidale. Mochales, T., G. Rosenbaum, F. Speranza, and S. A. Pisarevsky (2014), Unraveling the geometry of the New England oroclines (eastern Australia): Constraints from magnetic fabrics, Tectonics, 33, 2261–2282, doi:10.1002/2013TC003483. Morra, G., K. Regenauer-Lieb, and D. Giardini (2006), Curvature of oceanic arcs, Geology, 34(10), 877–880. Nano, S. C. (1987), Geology of the Mummel River area (folds, faults and gold)—Nowendoc, northeastern New South Wales, B.Sc. (Hons) thesis, 135 pp., Univ. of New England, Armidale. Offler, R., and D. A. Foster (2008), Timing and development of oroclines in the southern New England Orogen, New South Wales, Aust. J. Earth Sci., 55(3), 331–340. Offler, R., P. G. Lennox, G. Phillips, and J. Yan (2015), Comment on: “Does the Manning Orocline exist? New structural evidence from the inner hinge of the Manning Orocline (eastern Australia)” by Li and Rosenbaum (2014), Gondwana Res., 27(4), 1686–1688. Pastor-Galán, D., G. Gutiérrez-Alonso, G. Zulauf, and F. Zanella (2012), Analogue modeling of lithospheric-scale orocline buckling: Constraints on the evolution of the Iberian-Armorican Arc, Geol. Soc. Am. Bull., 124(7–8), 1293–1309. Paton, C., J. Hellstrom, B. Paul, J. Woodhead, and J. Hergt (2011), Iolite: Freeware for the visualisation and processing of mass spectrometric data, J. Anal. At. Spectrom., 26(12), 2508–2518. Price, I. (1973), A new Permian and upper Carboniferous (?) succession near Woodsreef, N.S.W. and its bearing on the palaeogeography of western New England, J. Proc. Linnaean Soc. New South Wales, 97, 202–210. Roberts, J., and B. A. Engel (1987), Depositional and tectonic history of the southern New England Orogen, Aust. J. Earth Sci., 34(1), 1–20. Roberts, J., E. C. Leitch, P. G. Lennox, and R. Offler (1995), Devonian-Carboniferous stratigraphy of the southern Hastings Block, New England Orogen, eastern Australia, Aust. J. Earth Sci., 42(6), 609–633. Rosenbaum, G. (2012), Oroclines of the southern New England Orogen, eastern Australia, Episodes, 35(1), 187–194.

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 702 Tectonics 10.1002/2015TC004021

Rosenbaum, G. (2014), Geodynamics of oroclinal bending: Insights from the Mediterranean, J. Geodyn., 82,5–15. Rosenbaum, G., and G. S. Lister (2004), Formation of arcuate orogenic belts in the western Mediterranean region, in Orogenic Curvature: Integrating Paleomagnetic and Structural Analyses, Spec. Pap., vol. 383, edited by A. J. Sussman and A. B. Weil, pp. 41–56, Geol. Soc. of Am., Boulder, Colo. Rosenbaum, G., P. Li, and D. Rubatto (2012), The contorted New England Orogen (eastern Australia): New evidence from U-Pb geochronology of Early Permian granitoids, Tectonics, 31, TC1006, doi:10.1029/2011TC002960. Royden, L. H. (1993), Evolution of retreating subduction boundaries formed during continental collision, Tectonics, 12(3), 629–638, doi:10.1029/92TC02641. Schellart, W. P., and G. S. Lister (2004), Tectonic models for the formation of arc-shaped convergent zones and backarc basins, in Orogenic Curvature: Integrating Paleomagnetic and Structural Analyses, Spec. Pap., vol. 383, edited by A. J. Sussman and A. B. Weil, pp. 237–258, Geol. Soc. of Am., Boulder, Colo. Shaanan, U., G. Rosenbaum, P. Li, and P. Vasconcelos (2014), Structural evolution of the Early Permian Nambucca Block (New England Orogen, eastern Australia) and implications for oroclinal bending, Tectonics, 33, 1425–1443, doi:10.1002/2013TC003426. Shaanan, U., G. Rosenbaum, and R. Wormald (2015a), Provenance of the Early Permian Nambucca Block (eastern Australia) and implications for the role of trench retreat in accretionary orogens, Geol. Soc. Am. Bull., 127(7–8), 1052–1063. Shaanan, U., G. Rosenbaum, S. Pisarevsky, and F. Speranza (2015b), Paleomagnetic data from the New England Orogen (eastern Australia) and implications for oroclinal bending, Tectonophysics, 664, 182–190. Sharp, T. R. (1995), The Manning Group of the Curricabark District—Stratigraphy, sedimentology and tectonics, MSc thesis, 200 pp., Univ. of Technology, Sydney. Shaw, S. E., and R. H. Flood (1981), The New England Batholith, eastern Australia—Geochemical variations in time and space, J. Geophys. Res., 86(B11), 530–544. Skilbeck, C. G., T. R. Sharp, and E. C. Leitch (1994), Sequence and sedimentology of Early Permian sections along the Peel-Manning Fault System, in Advances in the Study of the Sydney Basin, edited by C. F. K. Diessel and R. L. Boyd, pp. 78–85, Univ. of Newcastle, Newcastle, Aust. Sláma, J., et al. (2008), Plešovice zircon—A new natural reference material for U-Pb and Hf isotopic microanalysis, Chem. Geol., 249(1–2), 1–35. Vickers, M. D., and J. C. Aitchison (1992), Lower Permian Manning Group: Tectonic implications of sedimentary architecture & provenance studies in the Nowendoc-Cooplacurripa area, in 26th Newcastle Symposium: Advances in the Study of the Sydney Basin,editedbyC.F.K.Diessel and R. L. Boyd, pp. 31–38, Univ. of Newcastle, Newcastle, Aust. Vickers, M. D., and J. C. Aitchison (1993), Lower Permian Manning Group at Kangaroo Tops, southern New England Orogen: Tectonic implications of basin studies, in New England Orogen, Eastern Australia, edited by P. G. Flood and J. C. Aitchison, pp. 309–314, Univ. of New England, Armidale, Aust. Voisey, A. H. (1938), The upper Palaeozoic rocks in the neighbourhood of Taree, J. Proc. Linnaean Soc. New South Wales, 63, 453–463. Voisey, A. H. (1939), The upper Palaeozoic rocks between Mount George and Wingham, New South Wales, J. Proc. Linnaean Soc. New South Wales, 64, 242–254. Voisey, A. H. (1958), Further remarks on the sedimentary formations of New South Wales, J. Proc. R. Soc. New South Wales, 91, 165–189. Voisey, A. H., and G. H. Packham (1969), The New England region—Permian system, in The Geology of New South Wales,editedbyG.H.Packham, pp. 265–270, Geological Society of Australia, Sydney. Weil, A. B., G. Gutierrez-Alonso, S. T. Johnston, and D. Pastor-Galan (2013), Kinematic constraints on buckling a lithospheric-scale orocline along the northern margin of Gondwana: A geologic synthesis, Tectonophysics, 582,25–49. Xiao, W., B. Huang, C. Han, S. Sun, and J. Li (2010), A review of the western part of the Altaids: A key to understanding the architecture of accretionary orogens, Gondwana Res., 18(2–3), 253–273.

WHITE ET AL. OROCLINE-DRIVEN TRANSTENSIONAL BASINS 703