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-Discriminant function diagram for the provenance signature of metapsammites and -argillites from northern Victoria Land and Oates Land according to Roser and Korsch (1988); a) Robertson Bay Group (rb) (Robertson Bay Terrane), b) Molar Formation (bmo) (Bowers Terrane), c) Morozumi Phyllites (wsm), Rennick Schists (wsr), Berg Group (ws/BM) and from McCain Bluff (ws/MC) (all Wilson Terrane), d) Lanterman Metamorphics (wsl) and from Kavrayskiy Hills (wg/KH) and Wilson Hills (wg/WH) (all Wilson Terrane). DF1 = -1.773TiO 2 + 0.607Al 2 O 3 + 0.76Fe 2 O 3(total) -1.5 MgO + 0.616CaO + 0.50Na 2 O -1.224K 2 O -9.09 DF2 = 0.445TiO 2 + 0.07Al 2 O 3 -0.25Fe 2 O 3(total) -1.142 MgO + 0.438CaO + 1.475Na 2 O -1.426K 2 O -6.861

-Discriminant function diagram for the provenance signature of metapsammites and -argillites from northern Victoria Land and Oates Land according to Roser and Korsch (1988); a) Robertson Bay Group (rb) (Robertson Bay Terrane), b) Molar Formation (bmo) (Bowers Terrane), c) Morozumi Phyllites (wsm), Rennick Schists (wsr), Berg Group (ws/BM) and from McCain Bluff (ws/MC) (all Wilson Terrane), d) Lanterman Metamorphics (wsl) and from Kavrayskiy Hills (wg/KH) and Wilson Hills (wg/WH) (all Wilson Terrane). DF1 = -1.773TiO 2 + 0.607Al 2 O 3 + 0.76Fe 2 O 3(total) -1.5 MgO + 0.616CaO + 0.50Na 2 O -1.224K 2 O -9.09 DF2 = 0.445TiO 2 + 0.07Al 2 O 3 -0.25Fe 2 O 3(total) -1.142 MgO + 0.438CaO + 1.475Na 2 O -1.426K 2 O -6.861

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Metasediments in the three early Palaeozoic Ross orogenic terranes in northern Victoria Land and Oates Land (Antarctica) are geochemically classified as immature litharenites to wackes and moderately mature shales. Highly mature lithotypes with Chemical Index of Weathering values of ≥ 95 are typically absent. Geochemical and Rb-Sr and Sm-Nd isotope...

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... & Korsch (1988) have proposed a discriminant function diagram which is based on the concentrations of all major elements exept Si in order to distinguish between four different types of provenance of sedimentary rocks. This discriminant function diagram is shown in figure 5 for the metasediments from the RBT, BT, and WT. The data points of the rb metasediments again exhibit a very restricted scatter and collectively plot in the field of "quartzose sedimentary provenance" (Fig. 5 a). ...
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... Si in order to distinguish between four different types of provenance of sedimentary rocks. This discriminant function diagram is shown in figure 5 for the metasediments from the RBT, BT, and WT. The data points of the rb metasediments again exhibit a very restricted scatter and collectively plot in the field of "quartzose sedimentary provenance" (Fig. 5 a). A very similar position in the discriminant function diagram is found for most of the bmo metasediments (Fig. 5b). There are, however, some significant outliers. While a group of argillitic samples display a trend into the field of "mafic igneous provenance", 2 psammitic and 2 argillitic specimens plot in the field of "felsic igneous ...
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... diagram is shown in figure 5 for the metasediments from the RBT, BT, and WT. The data points of the rb metasediments again exhibit a very restricted scatter and collectively plot in the field of "quartzose sedimentary provenance" (Fig. 5 a). A very similar position in the discriminant function diagram is found for most of the bmo metasediments (Fig. 5b). There are, however, some significant outliers. While a group of argillitic samples display a trend into the field of "mafic igneous provenance", 2 psammitic and 2 argillitic specimens plot in the field of "felsic igneous provenance". A relatively local provenance from felsic igneous rocks has already been indicated for the 2 ...
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... (Fig. 4b). Metapsammites and meta-argillites from the WT cannot be distinguished on the basis of the two discrimant functions. Data points of samples from the investigated units display a relatively large scatter and mostly plot on both sides of the boundary line separating the fields of felsic-igneous and quartzosesedimentary provenances (Fig. 5 c,d). One sample from the Rennick Schists which plots in the maficigneous-provenance field may contain a significant input from more primitive magmatic ...
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... Ga. Metasedimentary series in a more outboard easternmost position (wg/KH; wsl) on the contrary document somewhat stronger local influence of more primitive source rocks with younger model ages. These differences in the nature of the source rocks of WT metasedimentary series are not obvious from the provenance and tectonic discrimination diagrams (Figs. 5 c,d & 6 c,d, respectively). Only for the Wilson gneisses from Kavrayskiy Hills, the position of the data points in the felsic-and intermediateigneous provenance fields may be correlated with the isotope evidence in order to argue for a greater contribution from magmatic rocks with less evolved isotope compositions. Although the geochemical and isotopic ...

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... Mudstones + thin beds of sandstone ± conglomerates of the Molar Formation were deposited from dominant northwest-to-southeast paleocurrents in a southwest-sloping basin (Bradshaw et al., 1985;Wodzicki and Robert Jr., 1986) that was possibly fault-bounded. Clasts in the conglomerates were derived from Antarctica and comprise volcanic detritus, granitoids, quartzites, metamorphic quartz, and rare limestone (Weaver et al., 1984;Bradshaw et al., 1985;Cooper et al., 1996;Henjes-Kunst and Schüssler, 2003). ...
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... In addition, the c. 500 Ma thermal event indicates post-or pre-D 2 migmatization. The GHI (granite and granodiorite) related to the Ross Orogeny has been reported at Mt. Murchison and its western region [46]. Several types of granites crosscut the gneissosity of the Mt. ...
... In addition, the c. 500 Ma thermal event indicates post-or pre-D2 migmatization. The GHI (granite and granodiorite) related to the Ross Orogeny has been reported at Mt. Murchison and its western region [46]. Several types of granites crosscut the gneissosity of the Mt. ...
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... Here, I will refer to this assemblage generally as Wilson Group. The Wilson assemblage consists of micaceous paragneiss, mica schist, psammitic schist, quartzite, marble and local migmatite (Ravich et al., 1965;Gair et al., 1969;Sturm and Carryer, 1970;Stump, 1995;Henjes-Kunst and Schüssler, 2003;Estrada et al., 2016). The other units are mainly metamorphosed siliciclastic rocks (including greywacke, psammite, and argillite protoliths) with minor calcareous units. ...
... Sr-and Nd-isotope compositions of S-type Granite Harbour intrusions within the Wilson assemblage indicate derivation by melting of pre-existing continental crust (Borg et al., 1987), which likely reflects a cratonic sedimentary source of detritus. The geochemical and isotopic compositions of Preistley Formation samples likewise indicate that Wilson material was derived from a crustal source with an average early Paleoproterozoic formation age (Henjes-Kunst and Schüssler, 2003). Other units within the Wilson metamorphics show Ross Orogen sources and have maximum depositional ages of 525-560 Ma, indicating a Cambrian or younger stratigraphic age. ...
... The geology of northern Victoria Land is dominated by three tectonic assemblages that developed largely during the Ross Orogeny -the Wilson, Bowers, and Robertson Bay terranes -consisting mostly of sedimentary and volcanic material of early Paleozoic age and volumetrically significant arc-type intrusions. As discussed above, many of the rocks assigned to the Wilson terrane are actually Cambrian in age (detrital zircon and muscovite ages indicating deposition b550-525 Ma; Henjes-Kunst and Schüssler, 2003;Henjes-Kunst et al., 2004;Di Vincenzo et al., 2014;Paulsen et al., 2016) and have a combined cratonic and early Ross Orogen provenance. The detrital zircon provenance data illustrate that, rather than representing reworked Precambrian crust, much of the Wilson terrane consists of Cambrian syn-orogenic clastic deposits sourced from, and metamorphosed during, the Ross Orogeny. ...
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... Also selected is sample SAX20 (Table 2), which is overall the most incompatible element enriched sample (Fig. 6) and has been equated to a primary (metasomatic) melt by Coltorti et al. (2004) and Perinelli et al. (2006). Crustal rocks from the NVL consist of gabbro, diorite and granodiorite (Di Vincenzo & Rocchi, 1999;Dallai et al., 2003), metasediment (Henjes-Kunst & Schussler, 2003;Di Vincenzo et al., 2014) and eclogite (Di Vincenzo et al., 1997;Ghiribelli, 2000). Gray fields encompass AFC model curves [shown in detail in (c) and (d)] using D Rb ¼ 0Á01, D Sr ¼ 0Á1, D Nd ¼ 0Á4 and proportion of assimilation to crystallization (r) ¼ 0Á8. ...
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Alkaline magmatism associated with the West Antarctic rift system in the northwest Ross Sea (NWRS) includes a north-south chain of shield volcano complexes extending 260 km along the coast of Northern Victoria Land (NVL) as well as numerous small volcanic seamounts located on the continental shelf and hundreds more within a ~35,000 km2 area of the oceanic Adare Basin. New 40Ar/39Ar age dating and geochemistry confirm that the seamounts are Pliocene‒Pleistocene in age and petrogenetically akin to the mostly middle to late Miocene volcanism on the continent as well as to a much broader region of diffuse alkaline volcanism that altogether encompasses areas of West Antarctica, Zealandia and eastern Australia. All of these continental regions were contiguous prior to the late‒stage breakup of Gondwana at ~100 Ma, suggesting that the magmatism is interrelated, yet mantle source and cause of melting remain controversial. The NWRS provides a rare opportunity to study cogenetic volcanism across the transition from continent to ocean and consequently offers a unique perspective from which to evaluate mantle processes and roles of lithospheric and sub-lithospheric sources for mafic alkaline magmas. Mafic alkaline magmas with > 6 wt.% MgO (alkali basalt, basanite, hawaiite, and tephrite) erupted across the transition from continent to ocean in the NWRS show a remarkable systematic increase in silica-undersaturation, P2O5, Sr, Zr, Nb and light rare earth element (LREE) concentrations as well as LREE/HREE and Nb/Y ratios. Radiogenic isotopes also vary with Nd and Pb ratios increasing and Sr ratios decreasing ocean-ward. These variations cannot be explained by shallow-level crustal contamination or by changes in degree of mantle partial melting but are considered to be a function of the thickness and age of the mantle lithosphere. We propose that the isotopic signature of the most silica-undersaturated and incompatible element enriched basalts best represent the composition of the sub-lithospheric source with low 87Sr/86Sr (≤ 0.7030) and δ18Oolivine (≤ 5.0 ‰), high 143Nd/144Nd (~ 0.5130) and 206Pb/204Pb (≥ 20) ratios. The isotopic ‘endmember’ signature of the sub-lithospheric source is derived from recycled subducted materials and was transferred to the lithospheric mantle by small degree melts (carbonate-rich silicate liquids) to form amphibole-rich metasomes. Later melting of the metasomes produced silica-undersaturated liquids that reacted with the surrounding peridotite. This reaction occurred to a greater extent as the melt traversed through thicker and older lithosphere continent-ward. Ancient and/or more recent (~550‒100 Ma) subduction along the Pan-Pacific margin of Gondwana supplied the recycled subduction-related residue to the asthenosphere. Melting and carbonate metasomatism were triggered by major episodes of extension beginning in the Late Cretaceous but alkaline magmatism was very limited in its extent. Significant delay of ~30 to 20 Myr between extension and magmatism was likely controlled by conductive heating and the rate of thermal migration at the base of the lithosphere. Heating was facilitated by regional mantle upwelling, possibly driven by slab detachment and sinking into the lower mantle, and/or by edge‒driven mantle flow established at the boundary between the thinned lithosphere of the West Antarctic rift and the thick East Antarctic craton.
... The WT mostly comprises of poly-deformed medium-to high-grade metamorphic rocks such as schists, gneisses and migmatites (GANOVEX Team, 1987;Henjes-Kunst and Schussler, 2003;Talarico et al., 2004). These rocks were intruded by the Granite Harbour Intrusives (GHI), a calc-alkaline plutonic suite including both S-and I-type granitoids with magmatic arc affinity, of Cambrian-Ordovician age Black and Sheraton, 1990;Di Vincenzo and Rocchi, 1999;Giacomini et al., 2007;Renna et al., 2011). ...
... The RBT consists of a thick succession of very low-grade metaturbidites of the Cambro-Ordovician period (Wright et al., 1984;Stump, 1995;Henjes-Kunst and Schussler, 2003;Rossetti et al., 2006). The Robertson Bay Group (Late Cambrian to Early Ordovician) with very thick, folded successions of monotonous turbiditic greywackes alternating with silty mudstones represents a roughly 200 km wide metasedimentary unit east of the BT. ...
... The Robertson Bay Group (Late Cambrian to Early Ordovician) with very thick, folded successions of monotonous turbiditic greywackes alternating with silty mudstones represents a roughly 200 km wide metasedimentary unit east of the BT. Their base is unexposed and a minimum thickness of 3000 m has been estimated (GANOVEX Team, 1987;Henjes-Kunst and Schussler, 2003). This succession represents a mainly very low-grade to low-grade metamorphosed flysch sequence originally deposited in a deep-sea fan to basin plain environment. ...
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... Chemical and isotopic data indicate that siliciclastic rocks in NVL are primarily derived from continental crust sources with active to passive continental margin signatures (Henjes-Kunst and Schüssler, 2003;Di Vincenzo et al., 2014), a result that is consistent with about two-thirds of all of the detrital zircon age data (n = 1092 of 1718) from our samples yielding Archean to early Neoproterozoic ages (3600-900 Ma) (Paulsen et al., 2016). Previous studies of detrital zircons from sandstones of the Pacific-Gondwana margin revealed a record of long-lived Cryogenian-Ordovician magmatism with a prominent period of activity centered at ca. 650-550 Ma (Sircombe, 1999;Paulsen et al., 2016, and references therein). ...
... The results indicate that NVL zircons are primarily derived from granitoid protoliths (granitoid >65% SiO 2 and larvikite) with smaller, but significant, contributions from mafic, carbonatite-alkaline, and metamorphic (U/Th > 10) source rocks (see the Data Repository). The high percentage of granitoid zircons is consistent with formation in a continental arc rather than oceanic arc setting, as suggested by previous studies that point to continental sources for siliciclastic rocks in the region (Henjes-Kunst and Schüssler, 2003;Di Vincenzo et al., 2014). ...
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The integration of detrital zircon age and trace element analyses provides a powerful tool with which to reconstruct continental arc evolution. Detrital zircons from the Ross-Delamerian orogen along the Pacific-Gondwana margin in north Victoria Land in Antarctica yield a broad 700–500 Ma U-Pb age population that shows a prominent period of activity centered at ca. 630–550 Ma. This activity is well correlated with the highest zircon Th/U and U/Yb ratios, suggesting an increase in lithospheric contribution coincident with fluid input from oceanic slab subduction, respectively. A low Yb/Gd ratio over this same period also suggests crustal thickening. Determination of zircon parent rock types using trace element proxies reveals the presence of previously unrecognized distinct pulses of granitoid activity that occur over tens of millions of years. Lulls between granitoid flare-ups overlap with increases in mafic-carbonatite-alkaline magma production , suggesting an influx of mantle or lower crustal melts during syn-subduction extension. A concomitant increase in the number of metamorphic zircons (U/Th > 10) and 40 Ar/ 39 Ar white mica cooling ages found during these extensional episodes suggest that significant thermal perturbations of the crust coincided with orogenic cooling, which was possibly influenced by uplift and exhumation.
... Although there are differences in age probability peaks among individual samples and provinces ( Fig. 8), these are considered second-order and most likely due to spatial variability in source areas and depositional systems over what is a relatively large region. Differences in sedimentary transport directions between the Wilson, Bowers (from the southwest, southeast, and northwest), and Robertson Bay (from the south to south-southeast) groups, as well as specific source rocks (Wright, 1981;Laird, 1981;Field and Findlay, 1983;Wright et al., 1984;Wright, 1985;Wodzicki & Robert, 1986;Henjes-Kunst and Schüssler, 2003; Di Vincenzo et al., ...
... 2014), could in part explain these small differences observed in age probability peaks. These differences notwithstanding, the first-order similarities in the zircon age probability distributions indicate the tectonostratigraphic assemblages of the three terranes share a common provenance signature, a result supported by Nd model ages obtained from silicilastic rocks, which indicate similar 1.9 Ga to 1.6 Ga crustal sources for sedimentary rocks in all three of the terranes (Henjes- Kunst and Schüssler, 2003;Tessensohn and Henjes-Kunst, 2005). Collectively, the new data presented in this paper indicate that the stratigraphic assemblages in the outboard terranes are not particularly exotic with respect to each other and to those within the inboard Wilson Terrane, which is typically taken to represent the Pacific-Gondwana margin of the Antarctic continent (e.g., Rocchi et al., 2011). ...
... Collectively, the new data presented in this paper indicate that the stratigraphic assemblages in the outboard terranes are not particularly exotic with respect to each other and to those within the inboard Wilson Terrane, which is typically taken to represent the Pacific-Gondwana margin of the Antarctic continent (e.g., Rocchi et al., 2011). A C C E P T E D M A N U S C R I P T Henjes-Kunst and Schüssler, 2003;Haines et al., 2004;Gibson et al., 2011). Additionally, Cambrian (Furongian) to Ordovician sandstones have also been found in the Pensacola Mountains (Storey et al., 1996;Curtis and Storey, 2003) of Antarctica and in the outboard Lachlan Orogen of southeast Australia Fergusson et al., 2013). ...
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We present new U–Pb isotopic age data for detrital zircons from 16 deformed sandstones of the Ross Supergroup in north Victoria Land, Antarctica. Zircon U/Th ratios primarily point to dominantly igneous parent rocks with subordinate contributions from metamorphic sources. Comparative analysis of detrital zircon age populations indicates that inboard stratigraphic successions (Wilson Terrane) and those located outboard of the East Antarctic craton (the Bowers and Robertson Bay terranes) have similar ~ 1200–950 Ma (Mesoproterozoic-Neoproterozoic) and ~ 700–490 Ma (late Neoproterozoic-Cambrian, Furongian) age populations. The affinity of the age populations of the sandstones to each other, as well as Gondwana sources and Pacific-Gondwana marginal stratigraphic belts, challenges the notion that the outboard successions form exotic terranes that docked with Gondwana during the Ross orogeny and instead places the terranes in proximity to each other and within the peri-Gondwana realm during the late Neoproterozoic to Cambrian. The cumulative zircon age suite from north Victoria Land yields a polymodal age spectra with a younger, primary 700–480 Ma age population that peaks at ~ 580 Ma. Cumulative analysis of zircons with elevated U/Th ratios (> 20) indicating metamorphic heritage yield ~ 657–532 Ma age probability peaks, which overlap with the younger dominantly igneous zircon population. The data are interpreted to give important new evidence that is consistent with ongoing convergent arc magmatism by ~ 626 Ma, which provided the dominant zircon-rich igneous rocks and subordinate metamorphic rocks. Maximum depositional ages as young as ~ 493–481 Ma yielded by deformed sequences in the outboard Bowers and Robertson Bay terrane samples provide new support for late Cambrian to Ordovician deformation in outboard sectors of the orogen, consistent with tectonic models that call for cyclic phases of contraction along the north Victoria Land sector of the Ross-Delamerian orogen.
... The Wilson Terrane mostly consists of polydeformed low-to highgrade metasedimentary rocks up to migmatites (e.g., GANOVEX Team, 1987;Henjes-Kunst and Schüssler, 2003). Between ca. ...
... The Cambrian to Early Ordovician low-grade Robertson Bay Group is a thick, folded monotonous turbiditic succession of alternating greywackes and mudstones. Neither volcanic intercalations nor coarse conglomerates are known (GANOVEX Team, 1987;Henjes-Kunst and Schüssler, 2003). ...
... To compare the samples of this study with published Sm-Nd isotope whole-rock data from the northern Wilson, Bowers and Robertson Bay terranes (Henjes-Kunst and Schüssler, 2003), additional Sm-Nd isotope data from the Priestley Formation of the southern Wilson Terrane were obtained at BGR and are presented in Table 2. Analytical details are reported in Henjes- Kunst and Schüssler (2003). ...
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The Ross-Delamerian orogenic belt was formed along the eastern side of the Australian-East Antarctic continent during west-directed subduction of the Palaeo-Pacific Ocean in the early Palaeozoic. Northern Victoria Land (NVL) in Antarctica was located at a central position of the Ross-Delamerian system. Its metamorphic basement is formed by three lithotectonic units formerly interpreted as terranes: the Wilson, Bowers and Robertson Bay terranes (from west to east). Dating of detrital zircons from 14 meta¬sedimentary samples of these terranes combined with petrographical and whole-rock geochemical studies give new insights into the stratigraphic and tectonic evolution of NVL. All samples show very similar zircon age spectra with two main intervals, a Ross/Pan-African-age interval (470–700 Ma) and a Grenville-age interval (900–1300 Ma), as well as subordinate craton-related ages dispersed over the range of ca. 1600–3500 Ma. The Ross/Pan-African-age zircon population tends to get more dominant from the Priestley Formation of the Wilson Terrane to the Molar Formation of the Bowers Terrane, and finally to the Robertson Bay Group, whereas the number of craton-related ages diminishes in this direction. A common East Antarctic source area is indicated for all analyzed samples. The Priestley Formation was deposited on the Palaeo-Pacific passive continental margin of East Gondwana in the late Neoproterozoic after Rodinia breakup. The sequence was subsequently metamorphosed and intruded by the Granite Harbour Intrusives during the Ross Orogeny. The Molar Formation of the Bowers Terrane is interpreted as a turbiditic sequence deposited in an accretionary setting on the active continental margin in the Late Cambrian during and after accretion of the Glasgow island arc allochthon. The thick, homogeneous sequence of the Robert¬son Bay Group resulted from continuous turbiditic sedimentation in an accretionary wedge in front of the Ross Orogen after docking and imbrication of the Glasgow island arc in the Early Ordovician.
... In addition, monazites in seven metapsammitic to metapelitic paragneiss and migmatite samples from the northern Wilson Terrane (locations are indicated inFig. 8, descriptions are detailed in Kunst and Schüssler, 2003) were newly analysed by the EMP Th–U–Pb dating method. These are the samples US-227 from Mt. Shield, and US-273 from Mt. Gorton, both migmatites from the Eastern Zone of the Wilson Terrane with biotite + cordierite ± sillimanite + K-feldspar + plagioclase + quartz, with sillimanite included in cordierite, and with retrograde formation of muscovite. ...
... Amphibolite-facies gneisses in the Kavrayskiy Hills to the east of the Wilson Thrust show no signs of migmatisation (Schubert et al., 1984). In the northern part of the Lanterman Range, the studied samples are amphibolite-facies biotite gneisses with sillimanite (Kunst and Schüssler, 2003; Roland et al., 1984; Talarico et al., 1998 ). These samples show no further indications of high-pressure metamorphism as described from other parts of the region (Di Vincenco et al., 1997). ...
... In addition, monazites in seven metapsammitic to metapelitic paragneiss and migmatite samples from the northern Wilson Terrane (locations are indicated in Fig. 8, descriptions are detailed in Henjes-Kunst and Schüssler, 2003) were newly analysed by the EMP Th-U-Pb dating method. These are the samples US-227 from Mt. Shield, and US-273 from Mt. Gorton, both migmatites from the Eastern Zone of the Wilson Terrane with biotite + cordierite ± sillimanite + K-feldspar + plagioclase + quartz, with sillimanite included in cordierite, and with retrograde formation of muscovite. ...
... Amphibolite-facies gneisses in the Kavrayskiy Hills to the east of the Wilson Thrust show no signs of migmatisation . In the northern part of the Lanterman Range, the studied samples are amphibolite-facies biotite gneisses with sillimanite (Henjes-Kunst and Schüssler, 2003;Roland et al., 1984;Talarico et al., 1998). These samples show no further indications of high-pressure metamorphism as described from other parts of the region (Di Vincenco et al., 1997). ...