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The Early Mesozoic magmatism of southwestern Gondwana is reviewed in the light of new U-Pb SHRIMP zircon ages (181 ± 2 Ma, 181 ± 3 Ma, 185 ± 2 Ma, and 182 ± 2 Ma) that establish an Early Jurassic age for the granites of the Subcordilleran plutonic belt in northwestern Argentine Patagonia. New geochemical and isotopic data confirm that this belt represents an early subduction-related magmatic arc along the proto-Pacific margin of Gondwana. Thus, subduction was synchronous with the initial phase of Chon Aike rhyolite volcanism ascribed to the thermal effects of the Karoo mantle plume and heralding rifting of this part of the supercontinent. Overall, there is clear evidence that successive episodes of calc-alkaline arc magmatism from Late Triassic times until establishment of the Andean Patagonian batholith in the Late Jurassic involved westerly migration and clockwise rotation of the arc. This indicates a changing geodynamic regime during Gondwana break-up and suggests differential rollback of the subducted slab, with accretion of new crustal material and/or asymmetrical ‘scissor-like’ opening of back-arc basins. This almost certainly entailed dextral displacement of continental domains in Patagonia.

The process of terrane accretion is vital to the understanding of the formation of continental crust. Accretionary orogens affect over half of the globe and have a distinctively different evolution to Wilson-type orogens. It is increasingly evident that accretionary orogenesis has played a significant role in the formation of the continents. The Pacific-margin of Gondwana preserves a major orogenic belt, termed here the 'Australides', which was an active site of terrane accretion from Neoproterozoic to Late Mesozoic times, and comparable in scale to the Rockies from Mexico to Alaska, or the Variscan-Appalachian orogeny. The New Zealand sector of this orogenic belt was one of the birthplaces of terrane theory and the Australide orogeny overall continues to be an important testing ground for terrane studies. This volume summarizes the history and principles of terrane theory and presents 16 new works that review and synthesize the current state of knowledge for the Gondwana margin, from Australia through New Zealand and Antarctica to South America, examining the evolution of the whole Gondwana margin through time.

A review of evidence for deformation and terrane accretion on the Late Triassic–Early Jurassic margins of Pangea and the mid-Cretaceous margins of the palaeo-Pacific ocean shows that deformation was global and synchronous with probable superplume events. Late Triassic–Early Jurassic deformation appears to be concentrated in the period 202–197 Ma and was coeval with eruption of the Central Atlantic Magmatic Province, onset of Pangaea break-up, a period of extended normal magnetic polarity and a major mass extinction event, all possible expressions of a superplume event. Mid-Cretaceous deformation occurred in two brief periods, the first from approximately 116 to 110 Ma in the west palaeo-Pacific and the second from roughly 105 to 99 Ma in the east palaeo-Pacific, with both events possibly represented in northeast Siberia. This deformation was coeval with eruption of major oceanic plateaus, core-complex formation and rifting of New Zealand from Gondwana, the Cretaceous normal polarity epoch, and a major radiation of flowering plants and several animal groups, all linked with the mid-Cretaceous superplume event. A simple unifying mechanism is presented suggesting that large continental or oceanic plates, when impacted by a superplume, tend to break-up/reorganize, associated with gravitational spreading away from a broad, thermally generated topographic high and with a resulting short-lived pulse of plate-marginal deformation and terrane accretion.

The process of terrane accretion is vital to the understanding of the formation of continental crust. Accretionary orogens affect over half of the globe and have a distinctively different evolution to Wilson-type orogens. It is increasingly evident that accretionary orogenesis has played a significant role in the formation of the continents. The Pacific-margin of Gondwana preserves a major orogenic belt, termed here the ‘Australides’, which was an active site of terrane accretion from Neoproterozoic to Late Mesozoic times, and comparable in scale to the Rockies from Mexico to Alaska, or the Variscan-Appalachian orogeny. The New Zealand sector of this orogenic belt was one of the birthplaces of terrane theory and the Australide orogeny overall continues to be an important testing ground for terrane studies. This volume summarizes the history and principles of terrane theory and presents 16 new works that review and synthesize the current state of knowledge for the Gondwana margin, from Australia through New Zealand and Antarctica to South America, examining the evolution of the whole Gondwana margin through time.

The <80 ka basalts–basanites of the Potrillo Volcanic Field (PVF) form scattered scoria cones, lava flows and maars adjacent to the New Mexico–Mexico border. MgO ranges up to 12·5%; lavas with MgO < 10·7% have fractionated both olivine and clinopyroxene. Cumulate fragments are common in the lavas, as are subhedral megacrysts of aluminous clinopyroxene (with pleonaste inclusions) and kaersutitic amphibole. REE modelling indicates that these megacrysts could be in equilibrium with the PVF melts at ~1·6–1·7 GPa pressure. The lavas fall into two geochemical groups: the Main Series (85% of lavas) have major- and trace-element abundances and ratios closely resembling those of worldwide ocean-island alkali basalts and basanites (OIB); the Low-K Series (15%) differ principally by having relatively low K2O and Rb contents. Otherwise, they are chemically indistinguishable from the Main Series lavas. Sr- and Nd-isotopic ratios in the two series are identical and vary by scarcely more than analytical error, averaging 87Sr/86Sr = 0·70308 (SD = 0·00004) and 143Nd/144Nd = 0·512952 (SD=0·000025). Such compositions would be expected if both series originated from the same mantle source, with Low-K melts generated when amphibole remained in the residuum. Three PVF lavas have very low Os contents (<14 ppt) and appear to have become contaminated by crustal Os. One Main Series picrite has 209 ppt Os and has a {gamma}Os value of +13·6, typical for OIB. This contrasts with published 187Os/188Os ratios for Kilbourne Hole peridotite mantle xenoliths, which give mostly negative {gamma}Os values and show that Proterozoic lithospheric mantle forms a thick Mechanical Boundary Layer (MBL) that extends to ~70 km depth beneath the PVF area. The calculated mean primary magma, in equilibrium with Fo89, has Na2O and FeO contents that give a lherzolite decompression melting trajectory from 2·8 GPa (95 km depth) to 2·2 GPa (70 km depth). Inverse modelling of REE abundances in Main Series Mg-rich lavas

The Jutulstraumen ice stream in western Dronning Maud Land may conceal a Jurassic continental rift. Delineating the geometry and the magmatic patterns of this inferred glaciated rift in East Antarctica is important to improve our understanding of the regional tectonic and magmatic processes associated with Gondwana break-up. A high-resolution aeromagnetic survey provides new insights over the largely buried tectonic and magmatic patterns of the Jutulstraumen area. Prominent NE-SW oriented aeromagnetic trends are detected over the Jutulstraumen. These trends delineate major inherited structural boundaries, active in Grenvillian (about 1.1 Ga) and Pan-African times (about 500 Ma), which appear to strongly control the location of the later Jurassic rift. The postulated east-ern flank of the rift is marked by a broad positive anomaly over H. U. Sverdrupfjella. Buried Grenvillian age rocks may be the source of the long-wavelength anomaly. However, the higher frequency components correlate with granitoids of late Pan-African age. The inferred western flank of the rift features short-wavelength anoma-lies over the Borgmassivet and Ahlmannryggen areas, indicating a considerably greater extent of mid-Proterozoic tholeiitic sills than apparent in outcrop. In contrast, aeromagnetic signatures suggest that alkaline plutons, which relate to Jurassic rifting, are restricted to outcrop areas along the eastern rift flank. The prominent magnetic low over the Jutulstraumen indicates either a largely amagmatic rift, or perhaps subglacial sediments within the rift basin.

Determining the location and geometry of possible subglacial rifts in western Dronning Maud Land is a key element to address processes leading to early Gondwana break-up. However, previous geophysical investigations did not lead to unambiguous delineation of rift structures over this region. We interpret high-resolution airborne radar and aerogravity data to image subglacial rift structures. Subglacial topography, free-air and Bouguer gravity maps, coupled with 3D inverse gravity models, image a rift-rift-rift triple junction at the intersection of the Jutulstraumen ice stream and the Pencksökket glacier. These continental rifts were associated with alkaline and tholeiitic intrusions, minor dyke swarms and flood basalts of Jurassic age, but not with huge volumes of Karoo magmatism, such as that which characterizes the southern Africa conjugate margin. The western Dronning Maud Land triple junction may be linked to the Karoo mantle plume and represents an early stage of magmatism and rifting during Gondwana break-up.

An Nd-Sr isotope database, including c. 200 new analyses, is presented for Palaeozoic and Mesozoic metasedimentary successions extending through southeastern Australia, New Zealand, West Antarctica and the Antarctic Peninsula to southern South America. Combining with U-Pb detrital zircon age data, this enables characterization of New Zealand terranes, especially within the Eastern Province, where there is a progression from westernmost terranes of both volcanic/volcaniclastic and accretionary origin with primitive sediment sources, to easternmost terranes with mature continental sediment inputs. In southern South America, West Antarctica and the Antarctica Peninsula, similar accretionary complexes have Nd model ages principally reflecting mixing of sedimentary material from multiple sources, both mature and juvenile. A mature Gondwana continental provenance dominates in sedimentary basins inboard of the active margin, especially in the Palaeozoic (Western Province, New Zealand, interior West Antarctica and NW Argentina), and contributes significantly to pre-Mesozoic sedimentary rocks of Patagonia east of the Andes. Along the Gondwanaland margin, Nd systematics for younger (late Palaeozoic to early Mesozoic) accretionary complex metasediments reflect younger source inputs, notably in the Scotia metamorphic complex. Many of the accretionary complex deposits must involve significant crustal reworking. There is no apparent South American equivalent of the primitive provenance of the westernmost accretionary terranes of New Zealand.

The intra-oceanic South Sandwich subduction system is distinctive in having a narrow slab with slab edges at its northern and southern ends. We present new geochemical data to investigate magma genesis beneath the parts of the arc and back-are segments that lie close to the two slab edges: Kemp and Nelson seamounts at the southern edge of the South Sandwich arc, and segments E1 and E2 in the south, plus segments E9 and E10 in the north, of the East Scotia Sea. In the arc, Kemp and Nelson seamounts exhibit enhanced subduction fluxes compared to the remainder of the arc. The southernmost (Nelson) has the isotope (low Nd and high Sr isotope ratios) and elemental (ultra-high Th and Ba and high Hf/Nd ratios) characteristics of a sediment melt, or supercritical aqueous fluid, component. The more northerly (Kemp) has the same characteristics as the remainder of the arc (high Nd and slightly raised Sr isotope ratios, high Nd/Hf ratios, high Ba/Th ratios), indicative of a fluid component derived mainly from subducted crust, but has a greater mass fraction of that component than the rest of the arc. In the back-are basin, the slab-edge segments are generally fed by more fertile mantle (E-MOR-B in all but E I) than the segments in the centre of the basin (N-MORB). At the edges, segments furthest from the trench (E2, E9) have small subduction components while those nearer to the trench (E1, E10) have larger subduction components and slightly more depleted mantle. We argue that several processes were important at the slab edges: roll-back of the slab, forcing sideways flow of relatively enriched mantle into the mantle wedge; convergence of the arc with the back-are spreading centre, imparting a greater subduction component into the back-arc lavas; and anomalous heating of the subducting slab, increasing subduction fluxes and the contribution of sediment melts to the subduction component.

The East Scotia Ridge, situated in the South Atlantic, is the back-arc spreading centre to the intra-oceanic South Sandwich arc. Samples from the ridge show a wide diversity in erupted magma compositions. Segment E2, in the northern part of the ridge, has an axial topographic high, which contrasts with the rift-like topography common to most of the ridge. Lava compositions in the segment have been modelled by mixing of magmas derived from normal mid-ocean ridge basalt (N-MORB)-like mantle, a mantle plume component similar in composition to that sampled by Bouvet Island and mantle modified by addition of components from the subducting slab. The ‘Bouvet’-like plume signature has higher 87Sr/86Sr, 206Pb/204Pb, Nb/Yb, and lower 143Nd/144Nd and 4He/3He, than the local upper mantle. It can be traced geochemically from the Bouvet Island hot spot to segment E2, via the South American-Antarctic Ridge, which connects the Bouvet triple junction to the South Sandwich subduction system. Four samples dredged from segment E2 have 4He/3He ratios of 85 000–90 200 (8.5–8.0 R/RA, where) R/RA is the 4He/3He ratio normalized to air) and three wax core samples taken from the segment axis have values of 104 300, 101 560 and 176 620 (6.9, 7.1 and 4.1 R/RA). These latter data are similar to values from the South American-Antarctic Ridge which have no discernable plume input. Whilst the dredge samples have a measurably lower 4He/3He ratio than the South American-Antarctic Ridge and samples from the segment axis, these He isotope data contrast with a dominant plume signature recorded by other petrogenetic tracers. This is interpreted to be due to re-melting of an entrained plume component, with an inherent low He concentration, incorporated into the E2 mantle. Helium depletion from the plume component can be seen to be a consequence of mantle processing and does not imply shallow-level degassing prior to entrainment within the upper-mantle-melting zone. As a consequence, He is characterized i

The Earth's convecting upper mantle can be viewed as comprising three main reservoirs, beneath the Pacific, Atlantic and Indian oceans. Because of the uneven global distribution and migration of ridges and subduction zones, the surface area of the Pacific reservoir is at present contracting at about 0.6 km2 x y(r-1), while the Atlantic and Indian reservoirs are growing at about 0.45 km2 x yr(-1) and 0.15 km2 x yr(-1), respectively. Garfunkel and others have argued that there must accordingly be net mantle flow from the Pacific to the Atlantic and Indian reservoirs (in order to maintain mass balance), and Alvarez further predicted that this flow should be restricted to the few parts of the Pacific rim (here termed 'gateways') where there are no continental roots or subduction zones that might act as barriers to shallow mantle flow. The main Pacific gateways are, according to Alvarez, the southeast Indian Ocean, the Caribbean Sea and the Drake passage. Here we report geochemical data which confirm that there has been some outflow of Pacific mantle into the Drake passage--but probably in response to regional tectonic constraints, rather than global mass-balance requirements. We also show that a mantle domain boundary, equivalent to the Australian-Antarctic discordance, must lie between the Drake passage and the east Scotia Sea.

Segment E2 is situated in the back-arc East Scotia Ridge. The segment is unusual in that it has an axial topographic high underlain by a seismically imaged melt lens. The axis of the segment, which is 70 km long, was sampled at ∼2 km spacing. There is strong correlation between compositions and bathymetry, and there is no evidence that lateral flow of magmas along dykes within the segment was more than 25 km. Magmas are more evolved towards the summit, indicating that magma fractionation took place within the imaged melt lens. Na8·0 is roughly constant at ∼2·6, implying uniform degree of partial melting, except for some samples at the summit that have Na8·0 = 2·2. Compositions closest to N-MORB occur at the segment tips, and LREE/HREE ratios increase toward the summit. None of the magmas were derived from depleted sub-arc mantle. Nevertheless, most compositions in the segment were modified by slab-derived components. The low-Na8·0 samples have high Ba/Nb compared with the rest of the segment. Dredged lavas from the lateral flanks of the summit have the most extreme compositions, including ones derived from plume mantle, and are end-members for magma mixing processes that controlled compositions

An ultramafic lamprophyre dyke is described from the otherwise tholeiitic Ferrar magmatic province of Antarctica. We report an Ar-Ar age of 183 ± 2.2 Ma for the dyke, indistinguishable from those of the Ferrar tholeiites. However, the dyke has mineralogical and major and trace element compositions, and radiogenic isotopes ratios, very different from the Ferrar tholeiites. The sample consists of olivine and rare clinopyroxene phenocrysts with perovskite and spinel microphenocrysts in a groundmass of amphibole, nepheline and biotite. Carbonatitic globules contain calcite, dolomite, Fe-rich carbonate, nepheline, biotite, orthoclase, pyrite, clinopyroxene, apatite and silicate glass, and were formed by liquid immiscibility. The rock is mildly potassic and classifies as an ouachitite. It is strongly enriched in both moderately and highly incompatible trace elements and is the first high-Ti rock to be described from the Ferrar magmatic province. The rock has similar initial 143Nd/144Nd to OIB, notably Bouvet, Crozet and Réunion, but significantly higher initial 87Sr/86Sr. The lamprophyre magma is interpreted as having been generated by low-degree partial fusion of metasomatized lithospheric mantle as a result of heat conducted from an underlying Jurassic mantle plume. The same mantle plume was probably also responsible for generating one of the world’s largest layered gabbro bodies, the Dufek-Forrestal intrusions.

The Middle Jurassic–Lower Cretaceous Fossil Bluff Group of Alexander Island, Antarctica represents the fill of a fore-arc basin unconformably overlying an accretionary complex. Like most fore-arc basins, this example had been considered to have a passive origin, as a topographic hollow between the arc and the trench-slope break. Recent discoveries of igneous rock coeval with sedimentation have altered this view. Oxfordian–Kimmeridgian basaltic and rhyolitic sills and lava flows are found in a restricted area at the north of the basin, within a single formation. Chemically, most basalts are high-Nb types, which cannot have originated in a supra-subduction zone setting. Since the age of emplacement of these rocks coincides with a gap in the record of plutonism in the Antarctic Peninsula volcanic arc, it is concluded that a late Jurassic pause in subduction led to active rifting to form the fore-arc basin.

The field occurrence, age, classification and geochemistry of the Mesozoic volcanic rocks of Patagonia and West Antarctica are reviewed, using published and new information. Dominated by rhyolitic ignimbrites, which form a bimodal association with minor mafic and intermediate lavas, these constitute one of the largest silicic igneous provinces known, equivalent in size to many mafic LIPs. Diachronism is recognized between the Early–Middle Jurassic volcanism of eastern Patagonia (Marifil and Chon Aike formations) and the Middle Jurassic–earliest Cretaceous volcanism of the Andean Cordillera (El Quemado, Ibañez and Tobı́fera formations). This is accompanied by a change in geochemical characteristics, from relatively high-Zr and -Nb types in the east to subalkaline arc-related rocks in the west, although the predominance of rhyolites remains a constant factor. All of the associated mafic rocks are well fractionated compared to direct mantle derivatives. Petrogenetic models favour partial melting of immature lower crust as a result of the intrusion of basaltic magmas, possibly with some hybridisation of the liquids and subsequent fractionation by crystal settling or solidification and remelting. The formation of large amounts of intracrustal silicic melt acted as a density barrier against the further rise of mafic magmas, which are thus rare in the province.

geologi

Compositions and distributions of mafic dykes in the Antarctic Peninsula continental arc show that tapping of several mantle sources was tectonically controlled. In the Cretaceous to Tertiary, between 135 Ma and 55 Ma, calc-alkaline dykes intruded the arc. In the late Cretaceous, however, between 95 Ma and 65 Ma, there was a pulse of compositionally diverse magmatism. This change resulted from collision of an ocean spreading centre with the trench. As a consequence, non-partitioned dextral transtensional shear in the overriding plate became partitioned into strike-slip and extensional domains. Calc-alkaline magmatism was, therefore, replaced by strike-slip-related shoshonitic magmatism towards the rear-arc and extensionrelated tholeiitic magmatism towards the fore-arc. OIB-like dykes were emplaced because of the break in otherwise continuous subduction. During the early Tertiary subduction continued but ceased after a late Tertiary ridge-trench collision.

At Mount Charity, north-eastern Palmer Land, Rb–Sr whole-rock dating has identified three successive phases of granitoid emplacement in Triassic (232 ± 4 Ma), Jurassic (168 ± 1 Ma), and Cretaceous (120 ± 4 Ma) times. The Triassic suite comprises tonalites, granodiorites (including one two-mica granodiorite), monzogranite and a granite having either I-type or S-like mineralogies. The Jurassic suite includes only S-like granites, and the Cretaceous biotite tonalites and biotite granodiorite are all I-type. The three suites have negative ∈Nd and positive ∈Sr, and have subtly different Nd and Sr isotope characteristics: Suite A, ∈Srt =+30 to +53 and ∈Ndt =−0.9 to −3.1, Suite B, ∈Srt =+43 to +64 and ∈Ndt =−2 to −5.3, Suite C, ∈Srt =+22 to +23 and ∈Ndt =−2.5 to −2.6. Mineralogical and compositional differences between the three suites suggest that different sources were tapped. All the granitoids are isotopically intermediate in composition between Palmer Land crust and depleted asthenosphere. We suggest that the I-type granitoids were produced by melting of meta-igneous crust; by contrast, the S-like granitoids represent partial melts of garnet-bearing sedimentary crust. Syn-magmatic structures in Suite A are compared with known structural events in western Palmer Land and suggest that extension controlled Triassic pluton emplacement. The Jurassic magmas were also emplaced during an episode of arc extension, and intrusion of the Cretaceous magmas was probably controlled by regional extension and dextral transtension. Successive phases of magmatism focussed at Mount Charity are consistent with reactivated faults acting as magma conduits.

The crust and upper mantle structure beneath a single, three-component broadband seismic station may be determined using cnergy from distant earthquakes. Features such as the depth of the seismic Moho, the abruptness of the change in seismic velocity across the Moho. the velocity profile through the crust and the seismic velocity of the upper mantle may be found using receiver function teehniques. Waveforms are analysed which contain energy arising from the interaction 01 incoming signals with the Earth structure beneath the receiving station. Seismic characteristies of the deep crust are olten continuous or slowly varying across a single tcrrane and. moreover. show sudden contrasts aeross tcrrane and other major tectonic boundaries. Such techniques are, therefore, appropriate tools in the exploration of deep structure and. henee, in the understanding of large-seale eontinentalassembly. They complement geologieal and geochronologieal investigations of surface rocks by providing the (hird spatiai dimension. In regions of no surface basemcnt exposure, scismic and other gcophysieal methods provide the only means of mapping the lateral extent of a given terrane and/or tracing province boundaries. Receiver function methods are presented here in the context of terrane tectonics with illustrative examples from former Gondwanan provinees and locations on the Pacific margin.

The crust and upper mantle structure beneath a single, three-component broadband seismic station may be determined using cnergy from distant earthquakes. Features such as the depth of the seismic Moho, the abruptness of the change in seismic velocity across the Moho. the velocity profile through the crust and the seismic velocity of the upper mantle may be found using receiver function teehniques. Waveforms are analysed which contain energy arising from the interaction 01 incoming signals with the Earth structure beneath the receiving station. Seismic characteristies of the deep crust are olten continuous or slowly varying across a single tcrrane and. moreover. show sudden contrasts aeross tcrrane and other major tectonic boundaries. Such techniques are, therefore, appropriate tools in the exploration of deep structure and. henee, in the understanding of large-seale eontinentalassembly. They complement geologieal and geochronologieal investigations of surface rocks by providing the (hird spatiai dimension. In regions of no surface basemcnt exposure, scismic and other gcophysieal methods provide the only means of mapping the lateral extent of a given terrane and/or tracing province boundaries. Receiver function methods are presented here in the context of terrane tectonics with illustrative examples from former Gondwanan provinees and locations on the Pacific margin.

The crust and upper mantle structure beneath a single, three-component broadband seismic station may be determined using cnergy from distant earthquakes. Features such as the depth of the seismic Moho, the abruptness of the change in seismic velocity across the Moho. the velocity profile through the crust and the seismic velocity of the upper mantle may be found using receiver function teehniques. Waveforms are analysed which contain energy arising from the interaction 01 incoming signals with the Earth structure beneath the receiving station. Seismic characteristies of the deep crust are olten continuous or slowly varying across a single tcrrane and. moreover. show sudden contrasts aeross tcrrane and other major tectonic boundaries. Such techniques are, therefore, appropriate tools in the exploration of deep structure and. henee, in the understanding of large-seale eontinentalassembly. They complement geologieal and geochronologieal investigations of surface rocks by providing the (hird spatiai dimension. In regions of no surface basemcnt exposure, scismic and other gcophysieal methods provide the only means of mapping the lateral extent of a given terrane and/or tracing province boundaries. Receiver function methods are presented here in the context of terrane tectonics with illustrative examples from former Gondwanan provinees and locations on the Pacific margin.

The crust and upper mantle structure beneath a single, three-component broadband seismic station may be determined using cnergy from distant earthquakes. Features such as the depth of the seismic Moho, the abruptness of the change in seismic velocity across the Moho. the velocity profile through the crust and the seismic velocity of the upper mantle may be found using receiver function teehniques. Waveforms are analysed which contain energy arising from the interaction 01 incoming signals with the Earth structure beneath the receiving station. Seismic characteristies of the deep crust are olten continuous or slowly varying across a single tcrrane and. moreover. show sudden contrasts aeross tcrrane and other major tectonic boundaries. Such techniques are, therefore, appropriate tools in the exploration of deep structure and. henee, in the understanding of large-seale eontinentalassembly. They complement geologieal and geochronologieal investigations of surface rocks by providing the (hird spatiai dimension. In regions of no surface basemcnt exposure, scismic and other gcophysieal methods provide the only means of mapping the lateral extent of a given terrane and/or tracing province boundaries. Receiver function methods are presented here in the context of terrane tectonics with illustrative examples from former Gondwanan provinees and locations on the Pacific margin.