Early Permian strike-slip basin formation and felsic volcanism in the Manning Group, southern New England Orogen, eastern Australia

Abstract The Manning Group is characterised by rapidly filled strike-slip basins that developed during the early Permian along the Peel--Manning Fault System in the southern New England Orogen. Typically, the Manning Group has been difficult to date owing to the lack of fossiliferous units or igneous rocks. Thus, the timing of transition from an accretionary convergent margin in the late Carboniferous to dominantly strike-slip tectonic regimes that involved development and emplacement of the Great Serpentinite Belt (Weraerai terrane) is not well constrained. One exception are rhyolites of the Ramleh Volcanics that were erupted into the Echo Hills Formation. These developed along the dextral Monkey Creek Fault splay east of the Peel--Manning Fault System. Zircons extracted from the Ramleh Volcanics yield a U–Pb (SHRIMP) age of 295.6 ± 4.6 Ma that constrains the minimum age of deposition in this basin to earliest Permian. Whole-rock geochemistry indicates these are peraluminous felsic melts enriched in LREE and incompatible elements with strong depletions in U, Nb, Sr and Ti. These are similar in age and composition to the nearby S-type Bundarra and Hillgrove plutonic supersuites. We suggest that extensive movement along the east-dipping Peel--Manning Fault System was responsible, not only for strike-slip basin development at the surface (Manning Group), but was also the locus for crustal melting that was responsible for generating S-type felsic melts that utilised hanging-wall fault splays as conduits to the surface or to coalesce in the crust as batholiths exclusively to the east of the Peel--Manning Fault System.

In this paper, we provide U-Pb zircon ages, and wholerock geochemistry for rhyolites collected from the Ramleh Volcanics interbedded within the upper section of the Echo Hills Formation at Mulla Creek in the southern New England Orogen. These data provide age constraints as to the timing of strike-slip basin development along the Peel-Manning Fault System and insights into the generation and channelling of S-type magmas along major transtensional structures.

Southern New England Orogen
Carboniferous continental convergent assemblages largely dominate the southern New England Orogen although a small volume of lower Paleozoic ophiolitic and island arc rocks occur along the Peel-Manning Fault System Buckman et al., 2015;Manton et al., 2017aManton et al., , 2017b. The Peel-Manning Fault System separates the fore-arc component of the system to the west from its associated accretionary complex to the east. Rocks making up the fore-arc basin sequence are termed the Tamworth Belt. It consists of volcaniclastic deposits and ample felsic volcanic rocks (Roberts & James, 2010). The Anaiwan terrane (Flood & Aitchison, 1988) or Tablelands Complex (Roberts & Engel, 1987) is the accompanying accretionary wedge to the east. Isoclinaly folded turbidites are abundant throughout the terrane, as well as chert and oceanic basalt (Fergusson, 1984).
The Currabubula-Connors-Auburn continental arc was established in the early Carboniferous (Glen, 2013), although it has since been largely covered by the back-arc or foreland Sydney-Gunnedah Basin. The youngest manifestation of the continental arc is the Werrie Basalt and Boggabri Volcanics (300-269 Ma; Korsch et al., 2009) following which magmatism migrated east into its respective accretionary complex, the Anawian terrane (Flood & Aitchison, 1988). This early Permian period of slab-steepening (Phillips, Hand & Offler, 2008) or slab break-off (Caprarelli & Leitch, 1998) resulted in the influx of young, hot melt into the asthenospheric mantle wedge. The increase in the geothermal gradient, led to the melting of the overlying accretionary complex and culminated in the emplacement of extensive S-type granites, such as the Bundarra and Hillgrove plutonic supersuites (Cawood, Leitch, Merle, & Nemchin, 2011;Jeon, Williams, & Chappell, 2012;Phillips et al., 2011;Rosenbaum, Li, & Rubatto, 2012).
Other notable occurrences of early Permian volcanics are the I-type Halls Peak Volcanics (Figure 1; 295.7 ± 2.2 Ma; McKibbin et al., 2017). These have a mixed arc to depleted rift geochemical signature (Moody et al., 1993). The thoelitic gabbros of the Bakers Creek Suite gabbros (Figure 1  fore-arc melts, with both arc-like and mantle-like geochemical characteristics as the arc migrated to the east. These melts are the depleted, mantle-derived end-members (Phillips et al., 2011), with mingling noted between these gabbroic rocks and the Hillgrove Plutonic Supersuite (Jenkins, Landenberger, & Collins, 2002). However, it is unlikely that the primary melts from the S-type Hillgrove Plutonic Supersuite were derived directly from the mafic Itype Bakers Creek Suite gabbros as magmatic zircons from the Hillgrove Plutonic Supersuite do not record the same juvenile/unradiogenic epsilon Hf values as the I-type Bakers Creek Suite gabbros, which typically plot on the depleted mantle evolution line. If the S-type Hillgrove Plutonic Supersuite were a result of the I-type Bakers Creek Suite gabbros with sediments, then juvenile, magmatic zircons from the latter already precipitated. Blair (1983) mapped and described the Echo Hills Formation, which is one of many small isolated strike-slip basins that developed along the Peel-Manning Fault System during the early Permian (Flood & Aitchison, 1988;Jenkins & Offler, 1996;Mayer, 1972;Voisey, 1958). Regionally, these early Permian diamictites and mass-flow deposits are grouped together as the Manning Group (Mayer, 1972) or Barnard Beds (Allan & Leitch, 1990).  (Sun & McDonough, 1989).
Small-localised early Permian strike-slip basins are also reported along the Peel-Manning Fault System at Attunga (Manton et al., 2017a), Nundle, Barry Station (Aitchison, Stratford, & Buckman, 1997;Allan & Leitch, 1990;Buckman, 1993;Manton et al., 2017b) and Glenrock (Vickers & Aitchison, 1993). Provenance studies by Buckman (1993) and Aitchison et al. (1997) indicate the small, elongate basins at Barry and Glenrock are derived from adjacent terranes and experienced syn-depositional deformation. They suggest that the en echelon shape of the basin, as well as kinematic shear fabric indicators within the adjacent serpentinites indicate a dextral sense of movement. Extensive outcrops occur further south where they are referred to as the Barnard Beds (Allan, 1987;Allan & Leitch, 1990;Heugh, 1971;Leitch, 1988). These authors suggest they belonged to a single basin that was dissected and dispersed by strike-slip faulting. The Ramleh Volcanics within the Echo Hills Formation at Mulla Creek is the only recorded occurrence of volcanics interbed with the Manning Group and therefore provides an important age constraint for the development of these early Permian strike-slip basins along the Peel-Manning Fault System. Late Carboniferous to early Permian fossils have been described by Price (1973) from the Manning Group and recently, detrital zircon ages of ca 288 Ma (White, Rosenbaum, Allen, & Shaanan, 2016) provide a maximum age of deposition for one of the larger southern basins ( Figure 1).

Whole-rock X-ray florescence and ICP-MS analysis
Hand samples of lava flows at Echo Hills were crushed using Cr-Ni TEMA ring mill. Fused beads were created from the powder and subjected to X-ray fluorescence (XRF) major-element analysis. Li metaborate and Li tetraborate were added for flux. Sample carbonate, non-metallic base oxide and aluminosilicates geochemical characteristics determined the resultant Li metaborate contents added, which were either 12%; 22%; 57%, 43% or 100% Li metaborate. Oxidation of the samples was carried by adding 5 mL of lithium nitrate solution then left overnight at 60 C, following which were fused in a furnace. Trace-element analysis was carried out on pressed pellets that were created by mixing polyvinyl acetate binder with $5 g of sample, the mix was then pressed into an aluminium cup. Whole-rock geochemical analysis was carried out on a SPECTRO XEPOS energy-dispersive polarisation X-ray fluorescence spectrometer at the University of Wollongong. All major elements were within a relative percentage standard deviation of <3% during the period of analysis based on the W-2 dolerite (n ¼ 4) standard.
REE analysis was carried out at the ALS Minerals Division via ICP-MS, Brisbane (geochemical procedure ME-MS81). Fluxes used were Li metaborate and Li tetraborate prior to fusing in a furnace, where the subsequent melt was dissolved in a progressively stronger acid mixtures of nitric hydrochloric and hydrofluoric acid. The solution was then run through an ICP-MS. Standards were OREAS 120 and STSD-1 and were within 10% of error.

Zircon separation and cathodoluminescence imaging
Zircons were concentrated using heavy liquid and isodynamic separation techniques at the mineral separation laboratory of the Research School of Earth Sciences, the Australian National University (ANU). Using a binocular microscope, concentrates were hand-picked and selected grains, along with reference Temora zircons (Black et al., 2003), were cast into an epoxy resin disc. Once cured, the disc was ground to a mid-section level through the grains and then polished with 1 mm diamond paste. Reflected, transmitted light and cathodoluminescence (CL) imaging was used to document the grains.

U-Pb ion-microprobe zircon geochronology
Zircon U-Th-Pb analysis was undertaken on the SHRIMP II instrument at the ANU (Table 2) following analytical protocols of Williams (1998). The raw data were reduced offline using the new ANU software 'POXI-SC'-a unified and Table 2. Summary SHRIMP zircon U-Th-Pb data. Corrected age for common Pb by the 207 method with the 500 Ma model Pb of Cumming and Richards (1975 more data-rich version of the old ANU software packages 'PRAWN' and 'Lead' (which requires redundant MAC OS 9 platforms). Measurements of 206 Pb/ 238 U in unknown zircons were calibrated using the Temora standard (U-Pb ages concordant at 417 Ma; Black et al., 2003). The reference zircon SL13 (U ¼ 238 ppm) located in a set-up mount was used to calibrate U and Th in unknown zircons. The ISOPLOT program (Ludwig, 2003) was used to assess and plot the reduced and calibrated data. 206 Pb/ 238 U ratios were used to determine the Phanerozoic ages. Correction for common Pb was by the 207 Pb method (Compston, Williams, & Meyer, 1984; concordancy assumed). Weighted mean ages of the corrected 206 Pb/ 238 U ratios are reported at a 95% confidence level.

Field relationships of the Echo Hills Formation
The steeply dipping beds of the Echo Hills Formation strike N-S along the main axis of the basin (Figure 2). The western and eastern margins of the basin are bound by spays off the Monkey Creek Fault, which join at the northern and southern ends of the basin forming an en echelon 'lazy Z' configuration. Clasts within the Echo Hills Formation have been sourced locally with green chert fragments resembling rocks of the adjacent Carboniferous accretionary complex, the Anaiwan terrane (Blair, 1983). Individual channelfill packages within the $1700 m-thick sedimentary sequence locally grade from coarser grain diamictites and conglomerates into fine grain siltstones (Blair, 1983). Rhyolite flows were first described by Blair (1983) and named the Ramleh Volcanics. Columnar jointed rhyolite displaying distinct flow banding is evident in outcrop (Figure 3a-c) indicating near-vertical dipping, N-S-striking beds consistent with the sedimentary units in the lower (eastern) sections of the Echo Hills Formation. The rhyolite flows occur predominantly on the western edge of the basin in the uppermost stratigraphic position. However, discontinuous sills and dykes intrude the lower sections closer to the eastern margin and these probably represent the feeder dykes to the upper rhyolite lava flows. These felsic volcanics are typically aphanitic and glassy with rare quartz and plagioclase phenocrysts. Contacts between the volcanic rocks and the Echo Hills Formation are rare as they are sites of preferential weathering but a contact in Mulla Creek displays well-developed autoclastic breccia at the base of the volcanic flow consistent with eruption into wet, soft sediments (Blair, 1983).
In the SW corner of the basin, a small sliver of granitic rock is located, termed the 'Dungowan Adamellite' (Figure  2; Blair, 1983). Blair (1983) relates the intrusive body to the early Permian Bundarra Plutonic Supersuite based on its geochemical affinity and minor quartz and feldspar intercrystal deformation. No zircon U-Pb ages have been reported for this rock.

Petrology and mineralogy
Overall the rhyolite is glomeroporphyritic in texture with sanidine and plagioclase clustering together to occupy $5% of the rock volume (Figure 4a, b). Some clusters of feldspars have been heavily weathered to iron oxides. Devitrification textures are common in the groundmass appearing as a 'felty' or pilotaxitic texture.

Geochemical discrimination plots
Geochemical analysis of Ramleh Volcanics are given in Table 1. All samples from the volcanic rocks plot as rhyolites on the total alkali silica (TAS) plot (Le Bas, Le Maitre, Streckeisen, & Zanettin, 1986; Figure 5a). On the Al-saturation plot of Shand (1943), the rhyolites are slightly peraluminous (Figure 5b). Based on granitic tectonic discrimination diagrams, the rhyolites plot as syn-collisional (syn-CLOG) S-type granites to typical volcanic arc granites (VAG; Figure 5c, d) and as syn-collisional (S-type) to volcanic arc granites on the Nb vs Y plot. The volcanic rocks demonstrate marginal fractionation based on the (K 2 O þ Na 2 O)/CaO vs Zr þ Nb þ Ce þ Y plot from Whalen, Currie, and Chappell (1987) (Figure 5e).

U-Pb zircon
Zircon separation was undertaken on several Ramleh Volcanics samples, but only the most coarse-grained sample, MC1614 (31 10 0 34.4388ʺS, 151 11 0 0.7188ʺE) yielded zircons ($200 grains from $3 kg of rock). Most of the grains are stubby with oscillatory zoning (Figure 7). Grains greater then 200 lm in length have oscillatory-zoned rims and cores with cloudy sector zoning. No correlation is apparent between zircon morphology and the calculated U-Pb age. Thirteen analyses were undertaken on 11 zircons. The grains have U abundances of 191-303 ppm, with Th/U ratios between 0.40 and 0.60. The amount of common Pb was small in all samples (mean f 206 ¼ 0.16%; Table 2). Even prior to correction for small amounts of common Pb, the data plot near to concordia on a 238 U/ 206 Pb-207 Pb/ 206 Pb plot (Figure 8). All common Pb correction 206 Pb/ 238 U ages yield a weighted mea mean of 296.5 ± 1.5 Ma with an  Blair (1983). 'MC' spots refer to sample locations. (b) Type-section of Echo Hills sedimentary succession from Blair (1983). An unconformity is present at the top of the sequence, below the lavas and autoclastic breccia. The base of the succession is fault bounded. (c) Cross-section of basin located between A 0 and Aʺ on Figure 2a. MSWD of 9.9, indicating the spread of ages is well beyond analytical error. Analyses #4.1 has a significantly younger apparent 206 Pb/ 238 U age and the highest amount of common Pb and displays the most clouded zoning in CL out of all zircons (Figure 7). This grain is interpreted to have been affected post magmatic recrystallisation, giving rise to a younger age. Four analyses yield a cluster of oldest ages (#1.1, 2.2, 9.1 and 10.1) with a weighted mean 206 Pb/ 238 U age of 304.5 ± 4.4 Ma (95% confidence, MSWD ¼ 0.82). The remaining seven analyses, including duplicate analyses on grain 3 yield a weighted mean 206 Pb/ 238 U age of 291.7 ± 2.9 Ma (95% confidence, MSWD ¼ 0.51). Pooling analyses (apart from #4.1) gives a weighted mean 206 Pb/ 238 U age of 295.6 ± 4.6 Ma (95% confidence, MSWD ¼ 2.8; Figure 8).

Nature of strike-slip basins
All early Permian sedimentary rocks within the southern New England Orogen were originally referred to as the Barnard Beds (Allan, 1987;Allan & Leitch, 1990;Heugh, 1971;Leitch, 1988). It was envisioned as a single basin, deposited over a large portion of the southern New England Orogen, where it was later dissected and dispersed by strike-slip faulting. Evidence provided by Buckman (1993) and Aitchison et al. (1997) suggest this theory for basin formation may be incorrect. Buckman (1993) and Aitchison et al. (1997) provide provenance data indicating rocks filling the small, elongate basins along the southern portion of the Peel-Manning Fault System were derived from adjacent terranes. Also kinematic shear fabric indicators within the adjacent serpentinites indicate a dextral sense of movement.
Lower Permian rhyolites were injected along the Monkey Creek Fault and erupted into the upper sections of the Echo Hills Formation as rhyolite flows. In places, the intrusive nature of the rhyolite is evident by the presence of autoclastic breccia between the rhyolites and the discontinuous nature of the sills and dykes. The rhyolite flows that did erupt into the basin are characterised by strong flow banding (Figure 3c, d) and well-developed columnar jointing that indicates near-vertical tilting of the sequence.
The steeply east-dipping Monkey Creek Fault is a synthetic N-S-trending strike-slip fault splay of the larger Peel-Manning Fault System $10 km to the west. Locally massflow deposits of the Echo Hills Formation have filled a transtensional depocentre formed owing to a strike-slip 'jog' in the fault. Rapid sedimentation rates are demonstrated by the dominance of coarse poorly sorted massflow deposits displaying normal and reverse grading beds that were deposited during initial stages of basin formation. These high-energy, mass-flow facies, described by Lowe (1982), are common in most strike-slip basins (Chough & Sohn, 2010;Wood et al., 1994), owing to the steep relief that develops along the fault-bound basin margin (Barnes et al., 2005).
The measured thickness of the basin at Echo Hills is $1700 m (Blair, 1983), although this is considered a minimal thickness owing to the faulted nature of the basin margin contacts and the erosional contacts present between each sedimentary channel-package. The finingupward nature of individual beds reflects the episodic influx of mass-flow deposits into a localised, rapidly subsiding, shallow marine basin. In turn, the overall finingupward nature of the basin is indicative of its rapid infilling and transition from a steep-sided, deep-marine basin dominated by high-energy mass-flow deposits to a shallow marine or terrestrial basin dominated by deposition of mud and silt. This is believed to be a function of active basin subsidence (Blair, 1983). Blair (1983) also notes that the volcanic rock fragments of siliceous to dacitic composition dominate the sandstone facies (21-39% by volume). Conglomerates and diamictites on the other hand, are dominated by locally derived chert and argillite, with minimal volcanic fragments. This led Blair (1983) to conclude there were two mechanisms by which sediments were deposited into the basin: (1) locally derived mass-flow deposits from the sides of the basin, and (2) distal turbidite currents, originating from an area of active siliceous volcanism that would have accompanied the emplacement of the Bundarra Supersuite.
The Hanmer Basin on the Hope Fault, New Zealand has long been regarded as the classical example of the 'spindle-shaped' strike-slip basin (Wood et al., 1994). The basin is 10 Â 20 km with dextral movement on the master  Bas et al., 1986). (b) Al(Na þ K)-Al/(Ca þ Na þ K) plot (Shand, 1943). (c, d) The rhyolites plot between syn-COLG and VAG (S-and I-type granites, respectively; Pearce, Harris, & Tindle,1984). This is supported by their location on the A-type granitic discrimination diagram (e) of Whalen et al. (1987). Hillgrove Plutonic Supersuite data from Chappell (2010) and Bundarra Plutonic Supersuite data compiled by Geological Survey of NSW (see Supplementary papers, Table S1). Andean Lower Barroso-Sencca Ignimbrite data from Lebti et al. (2006). transverse faults. The Upper Jurassic to Lower Cretaceous greywacke country rocks, occupying the higher ground, are currently being eroded into the Hanmer Basin. At the same time, these sediments filling the basin are being deformed asymetically along the axis of the basin. This leads to the recycling of sediments away from the uplifted compression ridges in the south, to areas of active sediment tilting to the north. Syn-sedimentary structures like those seen in the Figure 6. Whole-rock rare earth element (REE) data. All REE abundances are normalised with primitive mantle values of Sun and McDonough (1989). Comparison locality is from the Neogene and Quaternary ignimbrites of Arequipa, Southern Peru (Lebti et al., 2006).  Hanmer Basin are difficult to identify within the Echo Hills Formation. However, sandstone dykes that occur at 31 9 0 49.04ʺ S, 151 10 0 55.45ʺ E, suggesting the sediments were wet and unlithified as the basin experienced deformation or significant seismic events.
The eruption style of the Ramleh Volcanics is similar to that of volcanic rocks along the margin of the Cretaceous Eumsung Basin, Korea (Ryang, 2013). The Eumsung Basin is one of a series of non-marine basins that are controlled by NE-SW-trending strike-slip faults within the southwestern Korean Peninsula (Chough, Kwon, Ree, & Choi, 2000). Sediments on the margin of this basin in Korea host a large portion of volcaniclastics. The centre of the basin becomes dominated by clasts of granite and gneiss country rock bound by a more siltstone-rich matrix. As the Echo Hills Basin underwent roll-over, this lateral continuity of basin sediments, as seen in the Eumsung Basin, became obscured. Also, based on magnetotelluric profiling by Ryang, Chough, Kim, and Shon (1999), an igneous intrusive body is located at depth within the $8 km think sediment pile of the Eumsung Basin. Based on imagery derived from the two-way travel times, it does not appear to form thin sill-like structures within the basin, as we propose for the Ramleh Volcanics. However, this may be the equivalent mechanism for emplacement, i.e. spherical plutonism, for the Dungowan Adamallite at the southern end of the Echo Hills Basin (Figure 1).

Petrology
Many of these mineral phases in the Bundarra and Hillgrove plutonic supersuites are not seen in the Ramleh Volcanics. Hydrous phases such as biotite and/or muscovite are absent from the Ramleh Volcanics and indicates that the required water fugacity for the formation of these phases was not reached in the melt. The groundmass is dominated by apatite (Bryant & Chappell, 2010). In comparison with the homogenous Bundarra Plutonic Suite, which contains muscovite, cordierite and minor garnet, we suggest the Ramleh Volcanics formed from a dryer melt.

Geochemistry
The Ramleh Volcanics are peraluminous in nature (molar Al 2 O 3 /CaO þ Na 2 O þ K 2 O > 1). This suggests the melting of a sedimentary source has predominantly produced them. The geology surrounding the basin is Carboniferous turbidites, cherts and basalts of the Anaiwan terrane. The Bundarra and Hillgrove plutonic supersuites are derived largely from the melting of the Carboniferous Anaiwan terrane country rock. The general enrichment in LREE and incompatible elements, with strong depletions in U, Nb, Sr and Ti seen in the Ramleh Volcanics, is characteristic of arclike magmas (Davidson, 1987), although the melt still falls within S-type granitic geochemical constraints. This may be a function of the composition of the Carboniferous (Anawian terrane) country rocks, which are predominately basalt-chert-greywacke associations. The voluminous greywackes are sourced directly from the Carboniferous continental arc and may be responsible for producing the transitional S-to I-type LREE patterns.
Based on age correlation and subtle arc-like, HFSE contents, we suggest the formation of the Ramleh Volcanics was similar to the Hillgrove Plutonic Supersuite via mechanisms with Phillips et al. (2011) suggesting magma mingling occurred at depth between asthenosphericderived basalts and sedimentary melts.
The Bundarra Plutonic Supersuite is largely homogenous and magma mingling in outcrop is absent (Flood & Shaw, 1975, 1977. Mingling is observed between the Hillgrove Plutonic Suite and the Bakers Creek Suite gabbros (Jenkins et al., 2002). The Bakers Creek Suite gabbros show low Th/ Nb, high Y/Zr, high Ba/La, and MORB Ti-V values demonstrating asthenospheric mantle wedge source, with minimal slab contributions. McKibbin et al. (2017) suggest they represent early fore-arc melts as the arc migrated to the west. These melts are characterised by an incompatible element depleted end-member and a silica-enriched end-member (Phillips et al., 2011). It is unlikely the magmas making up the Hillgrove Plutonic Supersuite were derived directly from the mafic Bakers Creek Suite gabbros as a broard range of eHf zircon isotope ratios are not seen in the former (eHf ¼ þ5 to þ8), indicating zircon crystallisation in the Bakers Creek Suite gabbros occurred prior to the Hillgrove Plutonic Supersuite (Phillips et al., 2011).

Geochronology
SHRIMP dating of zircons from the Ramleh Volcanics Rhyolite within the Echo Hills Formation, yields an overall average age of 295.6 ± 4.6 Ma (MSWD ¼ 2.8). This constrains the age of the uppermost section of the Echo Hills Formation as earliest Permian. However, the age data contain two zircon U-Pb populations: 13 analyses of 11 zircons have two zircon populations of 304 ± 4.4 Ma (MSWD ¼ 0.51) and 291.7 ± 2.9 Ma (MSWD ¼ 0.51). The Carboniferous zircon population may represent an inherited age from the underlying Carboniferous accretionary complex and the younger age of 291.7 ± 2.9 Ma would be a more accurate estimate of the crystallisation age of the Ramleh Volcanics.
The youngest detrital zircons ages from the Coffs Harbour Block, the eastern portion of the Carboniferous accretionary complex are 323-320 Ma (Korsch et al., 2009). This minimum age for deposition is within error for a whole-rock Rb-Sr age of 318 ± 8 Ma (Graham & Korsch, 1985) from the same area, meaning volcanism to the west in the Currabubula-Connors-Auburn continental arc was coeval to deformation and metamorphism within the accretionary complex. Zircon inheritance from the Carboniferous accretionary complex is found in the Hillgrove Plutonic Supersuite, with an older population at 324.3 ± 3.3 Ma (MSWD ¼ 0.94) from the sedimentary country rock and a crystallisation age of ca 305 Ma (Cawood et al., 2011). Detrital zircons ages from the eastern Coffs Harbour Block and the Bundarra Plutonic Supersuite are older than the apparent inherited age for the Ramleh Volcanics (ca 304 Ma). With limited detrital zircon data for the Anawian terrane at this location, we adopt the 295.6 ± 4.6 Ma as a less well-defined magmatic age.
More regionally, the Manning Group has been difficult to date owing to the lack of fossils or dateable volcanic units within most of these strike-slip basins. Other age constraints for the Manning Group include upper Carboniferous to lower Permian fossils (Allan, 1987;Mayer, 1972;Price, 1973;Runnegar, 1970) but limited detrital zircon data are available. White et al. (2016) described detrital zircons providing a maximum depositional age of ca 288 Ma but a lack of age data for individual basins along the Peel-Manning Fault System make it difficult to determine whether the age for the basins is uniform or whether ages vary along strike. The Moonbi Suite intrudes and stiches the Peel-Manning Fault System thus constraining the minimum age of fault movement and basin development to ca 250 Ma (Chappell, Blevin, & Bryant, 1999). A tighter minimum age constraint can be inferred from K-Ar ages, 273 ± 5.8 and 280 ± 5.6 Ma, obtained from a nephrite deposit along the Peel-Manning Fault System (Lanphere & Hockley, 1976). In this particular case, nephrite formed via the reaction of ultramafic rock with siliceous Djungati/ Anawian terrane cherts and this age may constrain the minimum age of emplacement of serpentinite along the Peel-Manning Fault System.

Igneous activity along strike-slip faults
It is common for volcanics erupted along steeply dipping transverse faults to be rapidly buried (Mann Hempton, Bradley, & Burke, 1983) and obscured if deformation and subsequent uplift of the deeply buried units does not occur. If magma resided at depth, strike-slip faulting may have acted as a vertical conduit (Acocella et al., 2011;Aydin et al., 1990;Marra, 2001;Ryang, 2013), as normal faulting may result in shallow-dipping listric structures (Acocella, Salvini, Funiciello, & Faccenna, 1999). Magmas originating from strike-slip faults in some settings, may be more primitive in their geochemical nature and less volatile-rich than melts utilising shallow-dipping normal or thrust faults as conduits (Acocella & Funiciello, 2006;Tibaldi, Pasquar e, & Tormey, 2009). Marra (2001) suggested this occurs because the propensity for shallow-dipping structures to inhibit vertical magma transportation resulting in the formation of batholiths.
Volcanism associated with strike-slip basins may not be a simple relationship between faulting and magma injection. Mann et al. (1983) noted that based on the numerous strike-slip basins that are proximal to coeval volcanics, there is no clear correlation between the master transform faults and the location of the resultant volcanism. However, the development of large caldera complexes atop transtenstional dilation zones, or 'jogs' along strike-slips faults, are common throughout the central and southern South American cordillera (Acocella et al., 2011;Oriolo,   2004; Pasquar e, Garduño, Tibaldi, & Ferrari, 1988;Petrinovic et al., 2010).
All Permian granites and associated volcanics are found east of the Peel-Manning Fault System in the intensely faulted Carboniferous accretionary complex. These transtensional zones, would allow for the accumulation of magma at shallow depths (Figure 9a). We propose the rhyolites were erupted syn-kinematically into the upper section of the Echo Hills Formation with the felsic magmas probably generated at depth on the Monkey Creek Fault as a result of melting of the surrounding Anaiwan terrane sedimentary rocks. These S-type felsic magmas were focussed into dilation zones along the fault and intruded into the lower sections of the Echo Hills Formation that was rapidly deposited into a small en echelon strike-slip basin. The en echelon 'lazy Z' shape of the basin suggests dextral strike-slip movement was responsible for the opening of this pull-apart basin. Similar observations and interpretations were made for strike-slip basins at Barry Station to the south (Aitchison et al., 1997;Buckman, 1993) and coincide with the emplacement of the serpentinite dominated Weraerai terrane.
Emplacement of the Weraerai terrane along the Peel-Manning Fault System and the timing of transition from an accretionary convergent margin to one that is dominated by a strike-slip tectonic regime has previously been poorly constrained and data presented here contribute to resolving this (Figure 10). Serpentinite clasts have been described by Cross (1983) at the base of the Manning Group, meaning serpentinite and associated rocks within the Weraerai terrane were at current crustal levels during basin formation. Fossils described by Allan (1987), Mayer (1972), Price (1973) and Runnegar (1970) provide an upper Carboniferous to lower Permian age for the Manning Group. The U-Pb zircon ages from the Ramleh Volcanics thus constrain the timing of serpentinite emplacement and basin formation controlling the Manning Group.
The final stage of volcanism, from the western Currabubula-Connors-Auburn continental arc, is provided by the Werrie Basalt and Boggabri Volcanics (300-269 Ma). Volcanism following that from the Currabubula-Connors-Auburn continental arc is found within the Carboniferous Anaiwan terrane, east of the Peel-Manning Fault System. These volcanic rocks are the early fore-arc Bakers Creek Suite gabbros (299.3 ± 3.1 Ma). The Ramleh Volcanics erupted as the magmatic arc was migrating to the east. Arc magmatism then changed from predominantly I-type, to S-type with melting of the accretionary complex. The Ramleh Volcanics follow regional trends of volcanism seen across the southern New England Orogen during the late Carboniferous to early Permian.