Karamea Suite Research Articles

Extension-facilitated pulsed S-I-A-type “flare-up” magmatism at 370 Ma along the southeast Gondwana margin in New Zealand: Insights from U-Pb geochronology and geochemistry

New U-Pb zircon geochronology on S-, I-, and A-type granitic plutons in New Zealand refines the magmatic and tectonic history along the mid-Paleozoic Gondwana margin and provides constraints on the episodicity and dynamics of continental arc magmatism under “flare-up” conditions. High-precision isotope-dilution thermal ionization mass spectrometry (ID-TIMS) ages confirm that the voluminous (≥38,500 km3) predominantly S-type granites of the ca. 370–368 Ma Karamea Suite were emplaced within a brief ca. 2.1 Ma window. The Karamea Suite magmatic event represents a short-lived thermal perturbation that resulted in rapid crustal melting and granite emplacement that punctuated the steady-state arc “tempo” of the active Gondwana margin. Recognition of three distinct pulses of silicic magmatism within this ca. 2.1 Ma burst of magmatism, and calculation of flux rates that are comparable to those estimated for Cenozoic ignimbrite “flare-up” events indicate that time scales observed in volcanic complexes at the surface are directly analogous to those observed in plutonic complexes at depth. A genetic association with contemporaneous high-Sr/Y I-type and A-type granitoids suggests a thickened crust immediately prior to, and an extensional setting during Karamea Suite emplacement, respectively. Compositionally, Karamea Suite granites are compatible with an origin by dehydration melting of older infracrustal and supracrustal sources. However, thermal requirements suggest it is unlikely that the overthickened crust was able to reach temperatures hot enough to induce dehydration melting without an additional heat and/or fluid source. Direct involvement of hydrous mantle partial melts (supported by isotopic compositions) and/or an elevated asthenospheric heat flow is therefore advocated as the mechanism that induced extensive melting of the crust. An early postorogenic intra-arc extensional setting is proposed whereby thinning of the crust permitted hot asthenospheric mantle to rise to shallow mantle depths and facilitate melting. Application of laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) has further resolved a distinct zircon inherited (premagmatic) age component within Karamea Suite granites. This inherited age component is interpreted to represent a previously undocumented episode of magmatism along the New Zealand margin of Gondwana at ca. 387 ± 3 Ma, ca. 15 Ma prior to Karamea Suite emplacement. The ca. 387 Ma premagmatic zircon grains were preserved within the ca. 370 Ma Karamea Suite granites as a result of low zircon saturation temperatures ( T Zr < 800 °C). This ca. 387 Ma magmatic episode was volumetrically small, and it may have occurred as a result of Buller-Takaka terrane amalgamation—a crustal thickening event that thermally matured the crust and predisposed it to future melting. Slab rollback and/or delamination of a dense mafic root are suggested as possible triggers that facilitated the rapid change in tectonism from orogenic compression to postorogenic extension. Cessation of voluminous S-type magmatism by ca. 368 Ma was likely caused by depletion of the fertile metasedimentary source rocks that had undergone significant partial melting. Tectonic depletion of the source, by way of stretching the soft, partially melted crust, may also have served to halt production of S-type magmatism, resulting in small-volume production of I- and A-type granites from the less-fertile lower-crustal mafic source rocks.

Carboniferous U–Pb zircon age for S-type Karamea Suite Redjacket Granite, Paparoa Metamorphic Core Complex lower plate, northern Westland

Laser-ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS) U–Pb zircon dating combined with whole-rock geochemical analysis indicate that the Redjacket Granite was emplaced at 350.9±2.3 Ma (2σ) and belongs to the S-type Karamea Suite. This is the first report of Karamea Suite-type magmatism occurring after 368 Ma in the Nelson block and the first confirmation of Karamea Suite granitoids in the lower-plate of the Paparoa Metamorphic Core Complex.

Zetland Diorite, Karamea Batholith, west Nelson: field relationships, geochemistry and geochronology demonstrate links to the Carboniferous Tobin Suite

Field observations, petrography, geochemistry and U–Pb geochronology of the I-type Zetland Diorite from New Zealand's Western Province reveal a Carboniferous age of emplacement and chemical affinity with the Tobin dioritic suite. New U–Pb zircon dating by isotope-dilution thermal-ionisation mass spectrometry (ID-TIMS) provides a robust age of 347.19±0.24 Ma for a sample of Zetland Diorite. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb zircon dating of a Zetland quartz leucodiorite sample is complicated by significant inheritance from Karamea and Paringa granitoid suites but yields an estimated crystallisation age of 350.6±8.7 Ma, consistent with the field evidence for emplacement coeval with the dated mafic dioritic phase. Our results show that Zetland Diorite is at least c. 10 Ma younger and geochemically distinct from the 369–360 Ma I-type dioritic intrusives of the Paringa Suite, including the Riwaka Complex, as well as from the 370–368 Ma Karamea Suite S-type granites with which the Zetland Diorite had previously been deemed coeval. It therefore cannot serve as a mafic end-member source component of the Karamea Suite and its emplacement does not constrain the minimum age of amalgamation of the Buller and Takaka terranes.

U-Pb geochronology of mid-Paleozoic plutonism in western New Zealand: Implications for S-type granite generation and growth of the east Gondwana margin

Research Article| September 01, 2009 U-Pb geochronology of mid-Paleozoic plutonism in western New Zealand: Implications for S-type granite generation and growth of the east Gondwana margin A.J. Tulloch; A.J. Tulloch † 1GNS Science, Private Bag 1930, Dunedin 9054, New Zealand †E-mail: a.tulloch@gns.cri.nz Search for other works by this author on: GSW Google Scholar J. Ramezani; J. Ramezani 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA Search for other works by this author on: GSW Google Scholar D.L. Kimbrough; D.L. Kimbrough 3Department of Geological Sciences, San Diego State University, San Diego, California 92182, USA Search for other works by this author on: GSW Google Scholar K. Faure; K. Faure 4GNS Science, P.O. Box 30368, Lower Hutt 5040, New Zealand Search for other works by this author on: GSW Google Scholar A.H. Allibone A.H. Allibone 5Rodinian Pty Ltd., P.O. Box 1970, Queanbeyan, NSW 2620, Australia Search for other works by this author on: GSW Google Scholar GSA Bulletin (2009) 121 (9-10): 1236–1261. https://doi.org/10.1130/B26272.1 Article history received: 16 Jun 2007 rev-recd: 07 Aug 2008 accepted: 12 Aug 2008 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation A.J. Tulloch, J. Ramezani, D.L. Kimbrough, K. Faure, A.H. Allibone; U-Pb geochronology of mid-Paleozoic plutonism in western New Zealand: Implications for S-type granite generation and growth of the east Gondwana margin. GSA Bulletin 2009;; 121 (9-10): 1236–1261. doi: https://doi.org/10.1130/B26272.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract New U-Pb isotope-dilution–thermal ionization mass spectrometry (ID-TIMS) ages (371–305 Ma) for 30 granitic plutons along the New Zealand sector of the East Gondwanan active margin reveal a highly episodic emplacement history and crustal growth pattern. The Late Devonian–late Carboniferous ages also establish specific links with both the mostly older, Lachlan and the mostly younger, New England fold belts of eastern Australia. Dated plutons are representative of two S- and I-type suite pairs, the volumetrically predominant Karamea-Paringa (371–360 Ma) and minor Ridge-Tobin (355–342 Ma) pulses, as well as sporadic Foulwind Suite A-type granites (350–305 Ma). Emplacement of the bulk of the dominant ~3400 km2 Karamea Suite S-type granite-granodiorite plutons within a 2.1 Ma interval is explained by major and intimate intrusion of mantle-derived magma into largely metasedimentary crust during intra-arc extension of previously overthickened crust. Transient emplacement rates were thus of similar magnitude as some young ignimbrite flare-ups and an order of magnitude greater than long-term averages for Mesozoic-Cenozoic cordilleran batholiths of the western Americas. Extension likely was terminated abruptly by resumption of convergence, possibly associated with amalgamation of the Buller and Takaka terranes, between 368 and 355 Ma. Significant crustal growth occurred during generation of the two S-type suites, where mantle basalt contributed mass, and heat for rapid melting, during transient intra- or backarc extensional episodes. In contrast, the I-type suites were dominated by partial melting of meta-igneous crust, and they are relatively small in volume. The Karamea S-type suite shares striking similarities in terms of age, composition, and extensional tectonic setting with S-type granites of the Melbourne terrane of the Lachlan fold belt. Both regions may have formed in a backarc position with respect to the Late Devonian–early Carboniferous subduction zone in the New England fold belt. Foulwind Suite A-type magmatism in New Zealand overlaps in age with the widespread 320–285 Ma A- and I-type magmatism in the northern New England fold belt. The likely continuation of the New England subduction system must have subsequently been removed from outboard of the New Zealand region after 320–285 Ma magmatism, and prior to Triassic accretion of a Permian oceanic arc terrane to the New Zealand margin. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Plutonic rocks of the Median Batholith in eastern and central Fiordland, New Zealand: Field relations, geochemistry, correlation, and nomenclature

This paper provides a comprehensive description of all major plutonic rock units in Fiordland between Lakes Poteriteri and Te Anau, and the heads of Doubtful and George Sounds. Plutonic rocks comprise c. 80% of the basement in the area described, the remainder being metase dim entary and metavolcaniclastic rocks. The plutonic rocks, of which c. 50% are granitoids, were emplaced in three phases—at c. 492 Ma, between c. 365 and 318 Ma, and between 168 and 116 Ma. Correlatives of the Devonian Karamea Suite emplaced between c. 375 and 367 Ma, and the Triassic to Early Jurassic part of the Darran Suite emplaced between c. 230 and 168 Ma, are not present in the area described here. The strongly deformed Late Cambrian to Early Ordovician Jaquiery Granitoid Gneiss is one of the oldest plutonic rocks yet discovered in New Zealand and is of similar age to plutonic rocks within the Ross and Delamerian Orogens of Victoria Land and South Australia. Rocks emplaced between c. 365 and 318 Ma include Ridge Suite S‐type granitoids and closely related S/A‐type plutons, Foulwind Suite A‐type mafic and granitoid plutons, Tobin Suite I‐type granitoids, and several unassigned mafic plutons. Rocks emplaced between 168 and 116 Ma include extensive c. 168–128 Ma old calc‐alkaline LoSY gabbros, diorites, and granitoids of the Darran Suite, c. 165–135 Ma old hypersolvus perthitic syenogranites and peralkaline granitoids, c. 125 Ma gneissic diorite similar to the Western Fiordland Orthogneiss, and c. 123–116 Ma old quartz diorites and granitoids of the HiSY Separation Point Suite. Plutons from each suite tend to be concentrated in distinct NNE‐striking parallel belts up to 20 km wide and 110+ km long. These belts are one of the key features which define the regional structural grain of Fiordland basement geology. Their strike remains constant from the Carboniferous through to the Cretaceous. S, S/A, and A‐type plutons of the Carboniferous Ridge and Foulwind Suites are confined to a 125 km long but discontinuous belt in southern and central Fiordland, wholly within the areal extent of early Paleozoic metase dim entary basement. Volumetrically minor Carboniferous Tobin Suite I‐type granitoids are confined to the area east of exposed early Paleozoic metasedimentary basement. Much of eastern Fiordland is underlain by an extensive belt of heterogeneous Darran Suite rocks. Darran Suite rocks extend from Stewart Island to the Darran Mountains of northern Fiordland, forming a belt c. 15 km wide and 300 km long. Correlative Darran Suite rocks also occur further west where they intrude early Paleozoic metasediments, indicating that Jurassic to Early Cretaceous arc‐related plutonism and volcanism occurred inboard of the edge of early Paleozoic basement in some parts of the Median Batholith. Distinctive Jurassic, pink, hypersolvus syenogranite and alkalic granitoids form a narrow discontinuous belt within the wider calcalkaline Darran Suite. Cretaceous Separation Point Suite plutons form two major belts, one in easternmost Fiordland partially covered by Cenozoic sedimentary rocks, and the other stitching inboard and outboard parts of the Median Batholith in central Fiordland.

Plutonic rocks of the Median Batholith in southwest Fiordland, New Zealand: Field relations, geochemistry, and correlation

This paper provides a first description of all major plutonic rock units between Resolution Island and Lake Poteriteri in southwest Fiordland. Plutonic rocks, of which c. 95% are granitoids, comprise c. 60% of the basement in southwest Fiordland. Approximately 50% of the plutonic rocks were emplaced between c. 355 and 348 Ma, 5% at c. 164 Ma, 25%between c. 140 and 125 Ma, and 20% between c. 125 and 110 Ma. These episodes of plutonism occurred in response to terrane amalgamation, continental thickening, and subduction along the convergent margin of Gondwana. Correlatives of Devonian plutonic rocks which occur in Nelson are absent from the area described here. A wide variety of plutonic rocks were emplaced at c. 355–348 Ma. These include relatively small plutons of K‐ and Rb‐rich gabbro‐diorite and members of at least three distinct suites of granitoids. Plutons of two‐mica ± garnet granodiorite, granite, and minor tonalite share affinities with the S‐type Ridge Suite and are the most widespread c. 355–348 Ma old granitoids in southern Fiordland. Plutons rich in Ca, Fe and Zr, depleted in K and Na, and containing quartz diorite, tonalite, and minor granodiorite with the unusual assemblage red‐brown biotite, garnet ± hornblende ± clinopyroxene also occur widely in southern Fiordland. These plutons are similar to peraluminous A‐type granitoids, indicating A as well as I and S‐type plutonism occurred in the Western Province at this time. The Newton River and Mt Evans Plutons have no correlatives amongst c. 355–348 Ma granitoids in southern Fiordland, but their chemistry is similar to that of the older Karamea Suite. Three regional‐scale metasedimentary units—locally fos‐siliferous Fanny Bay Group Buller Terrane rocks in southern Fiordland, Edgecumbe and Cameron Group Takaka Terrane rocks in south‐central Fiordland, and undifferentiated Deep Cove Gneiss high‐grade metasedimentary rocks of western Fiordland—are all stitched by c. 355–348 Ma old plutons, indicating they have been in close proximity since at least c. 355–348 Ma. In south‐central Fiordland, c. 355–348 Ma old plutons cut across fabrics defined by upper amphibolite facies mineral assemblages, indicating low pressure/high temperature metamorphism in this area before this time. The c. 164 Ma old leucocratic Lake Mike Granite is a unique pluton in southwest Fiordland with no obvious correlatives. Plutons emplaced between c. 140 and 125 Ma are similar to the Rahu Suite, although isotopic data are required to confirm this correlation. Rahu Suite plutonism may therefore have begun by c. 140 Ma, rather than c. 120 Ma as previously suggested. Plutons emplaced between c. 125 and 110 Ma have high Sr/Y ratios comparable with the Separation Point Suite. They occur in both an outboard location around Lake Poteriteri and an inboard location around the western end of Dusky Sound. The c. 115 Ma two‐mica garnet granites of the Anchor Island Intrusives #2 probably formed by partial melting of adjacent ortho‐ and paragneisses, indicating that upper amphibolite facies metamorphism in western Dusky Sound occurred during the Early Cretaceous. The Dusky Fault does not pass directly out to the coast through outer Dusky Sound as previously mapped. Instead it merges with the major northeast‐striking Lake Fraser Fault at Cascade Cove, which crosses the outer coast near West Cape. The Last Cove Fault is a minor structure which cannot be traced beyond Last Cove rather than a major fault of regional extent as has been previously suggested.

SHRIMP monazite and zircon geochronology of high‐grade metamorphism in New Zealand

Ion microprobe dating of zircon and monazite from high‐grade gneisses has been used to (1) determine the timing of metamorphism in the Western Province of New Zealand, and (2) constrain the age of the protoliths from which the metamorphic rocks were derived. The Western Province comprises Westland, where mainly upper crustal rocks are exposed, and Fiordland, where middle to lower crustal levels crop out. In Westland, the oldest recognisable metamorphic event occurred at 360–370 Ma, penecontemporaneously with intrusion of the mid‐Palaeozoic Karamea Batholith (c. 375 Ma). Metamorphism took place under low‐pressure/high‐temperature conditions, resulting in upper‐amphibolite sillimanite‐grade metamorphism of Lower Palaeozoic pelites (Greenland Group). Orthogneisses of younger (Cretaceous) age formed during emplacement of the Rahu Suite granite intrusives (c. 110 Ma) and were derived from protoliths including Cretaceous Separation Point suite and Devonian Karamea suite granites. In Fiordland, high‐grade paragneisses with Greenland Group zircon age patterns were metamorphosed (M1) to sillimanite grade at 360 Ma. Concomitant with crustal thickening and further granite emplacement, M1 mineral assemblages were overprinted by higher‐pressure kyanite‐grade metamorphism (M2) at 330 Ma. It remains unclear whether the M2 event in Fiordland was primarily due to tectonic burial, as suggested by regional recumbent isoclinal folding, or whether it was due to magmatic loading, in keeping with the significant volumes of granite magma intruded at higher structural levels in the formerly contiguous Westland region. Metamorphism in Fiordland accompanied and outlasted emplacement of the Western Fiordland Orthogneiss (WFO) at 110–125 Ma. The WFO equilibrated under granulite facies conditions, whereas cover rocks underwent more limited recrystallization except for high‐strain shear zones where conditions of lower to middle amphibolite facies were met. The juxtaposition of Palaeozoic kyanite‐grade rocks against Cretaceous WFO granulites resulted from late Mesozoic extensional deformation and development of metamorphic core complexes in the Western Province.

Basement geology of Taranaki and Wanganui Basins, New Zealand

We present a revised interpretation of the basement geology beneath Late Cretaceous to Cenozoic Taranaki and Wanganui Basins of central New Zealand, based on new petrographic, geochemical, and geo‐chronological data from 30 oil exploration wells. Recently published structural and magnetic interpretations of the area assist in the interpolation and extrapolation of geological boundaries. Torlesse and Waipapa Terranes have been identified in Wanganui Basin, and Murihiku Terrane in eastern Taranaki Basin, but Maitai and Brook Street Terrane rocks have not been recognised. Separation Point Suite, Karamea Suite, and Median Tectonic Zone igneous rocks are all identified on the basis of characteristic petrography, geochemistry, and/or age. SHRIMP U‐Pb zircon measurements on igneous samples from western Taranaki wells do not give precise ages but do provide useful constraints: Motueka‐1 granite is latest Devonian — earliest Carboniferous; Tangaroa‐1 and Toropuihi‐1 are Carboniferous; and Surville‐1 is Cretaceous (cf. Separation Point Suite). Our interpretation of sub‐basin geology is compatible with previously observed onland relationships in the North and South Islands.

Carboniferous granite basement dredged from a site on the southwest margin of the Challenger Plateau, Tasman Sea

Abstract Discordant zircon fractions from a granite sample dredged off a basement horst on the western margin of the Challenger Plateau yield a 335 ± 7 Ma lower intercept date interpreted as the crystallisation age of the granite. This age, and the modal composition of the granite, is similar to that of the Karamea Suite of Westland and Nelson, New Zealand, and some Tasmanian granites. The concordia upper intercept date of 1747 ± 300 Ma implies the presence of Proterozoic continental crustal material in the source region of the granite. The Challenger granite is distinct from older S‐type granites of southeastern Australia and I‐type granites of northern Victoria Land and Marie Byrd Land, Antarctica. Subsequent to emplacement, the granite was brecciated and hydrothermally altered. A K‐Ar age of 95 Ma on hydrothermal sericite indicates that this event overlapped with a major crustal extension event recorded in Westland and Nelson, and predates the oldest known sea floor in the Tasman Basin by at least 11 Ma.

Distribution and provenance of heavy minerals in the South Island: A review

Abstract South Island heavy mineral distribution has been studied to help determine provenance and distinguish lithostratigraphic units in Cretaceous and Cenozoic sedimentary basins. Most Cretaceous and Cenozoic sediments reflect derivation from local basement rocks, chiefly granitoids of the Karamea and Golden Bay terranes and older sedimentary rocks of the Karamea, Torlesse, Caples, Murihiku, and Maitai terranes. The granitoid rocks in Fiordland are characterised by both hornblende and biotite, but in Westland and west Nelson biotite predominates. Biotite is also dominant in most sedimentary rocks of the Karamea terrane (Greenland Group and Preservation Formation). Torlesse and Caples samples are characterised by epidote and “semi-opaque debris”, which are also prominent in derived sediments. Much of the Torlesse is biotite rich, reflecting its granitic (Karamea Suite) source, but in derived sediments biotite is not prominent, probably because it did not withstand recycling. Caples terrane samples contain hornblende and pyroxene, reflecting their more volcanic source. Post-mid-Cretaceous volcanics have contributed new material to the basins in Canterbury and east Otago; volcanics decreasing in age to the south have provided magnetite (Cretaceous-Eocene) and hornblende (Eocene-Oligocene). Garnet varieties indicate a range of sources, largely granitic and volcanic. High-grade metamorphic minerals are present only in the Charleston Metamorphic Group, some schists, contact aureoles, and in the limited sediments derived from them. Post-depositional changes due to intrastratal solution, evident especially in Cretaceous-Paleocene sediments, have removed epidote and titanite, and concentrated ilmenite, zircon, garnet, and tourmaline. A widespread change in provenance near the base of the Miocene, especially prominent in the Murchison Basin and south of Westport, may have been related to the inception of major movement on the Alpine Fault.

Tectonic implications of granite cobbles from the mid-Cretaceous Pororari Group, southwest Nelson, New Zealand

Abstract Petrographic and geochemical data confirm the source of granitic detritus in the Hawks Crag Breccia of the lower Buller Gorge to be the Early Cretaceous Buckland, Blackwater, and Steele Plutons, presently disposed to the south and southwest. Detritus in the Hawks Crag Breccia in the Fox River and Bullock Creek may also be derived from the Buckland Pluton, but the provenance of the granitic detritus in this formation in the Pike Stream remains unclear. However, granitic clasts in the Ohika Formation were derived from Paleozoic granites of the Karamea Suite, of which potential source plutons are presently widely distributed to the WNW (Orowaiti River), the north (Britannia Pluton), and to the east (Dunphy Granite). Clasts derived from the deformed basement of the Paparoa Metamorphic Core Complex first appear in the upper part of the Ohika Formation, indicating initial unroofing of the complex at that time. The indicated source directions are consistent with a northwest-southeast trend for the two detachment faults that formed the two Pororari Group basins across the northern and southern ends of the Paparoa Range. The detachment faults formed the footwalls to the asymmetrical basins on the northeast side, and southwest side, of the southern and northern basins, respectively. K-Ar data suggest uplift on the southern Pike Detachment Fault continued after uplift of the northern PaparoaRange on the Ohika Detachment Fault, and that the Pike Fault is more directly associated with the rifting that formed the passive margins to the Tasman Sea. A wide range in Sr-isotopic compositions of granite clasts may reflect primary variations in the source plutons, or Sr exchange between plutonic basement and Greenland Group cover rocks, or increased Rb/Sr, due to alteration along the detachment faults. Muscovite K-Ar ages of 111–113 Ma from clasts collected from the Hawks Crag Breccia in the northern Paparoa Range provide minimum ages for the Buckland and Blackwater Granites, respectively. They indicate minimum uplift rates of 1.1–1.4 mm/a, and suggest that the continental crust in the vicinity of the Paparoa Range was at least 45–55 km thick prior to the onset of Cretaceous extension.

The Britannia Granite pluton in the Karamea Batholith, South Island, New Zealand

Abstract The Britannia Granite pluton (4 × 7 km), 25 km northeast of Westport, New Zealand, is intruded into Greenland Group metasediments, and is part of the Karamea Batholith. It is composed mainly of muscovite-biotite granites of three types distinguished in the field by grain-size differences. Petrographic and geochemical characters suggest that the granite belongs to the Karamea Suite rocks of Devonian—Carboniferous age. After consolidation, the southern part of the pluton underwent local high-temperature shearing, forming a gneissic granite with andalusite and/or sillimanite. Near the southern contact, the granites are greisenised, and cassiterite exists in greisenised apophyses. In the surrounding Greenland Group metasediments, gold-bearing quartz lodes occur suggesting a genetic relationship with the granite. Petrological characteristics and geochemical patterns of the Britannia Granite, as well as other Karamea Suite granitoids, show that they belong to postcollision granites. Their development w...