A 4.9 Mkm 2 region of the southwest Pacific Ocean is made up of continental crust. The region has elevated bathymetry relative to surrounding oceanic crust, diverse and silica-rich rocks, and relatively thick and low-velocity crustal structure. Its isolation from Australia and large area support its definition as a continent-Zealandia. Zealandia was formerly part of Gondwana. Today it is 94% submerged, mainly as a result of widespread Late Cretaceous crustal thinning preceding supercontinent breakup and consequent isostatic balance. The identification of Zealandia as a geological continent, rather than a collection of continental islands, fragments, and slices, more correctly represents the geology of this part of Earth. Zealandia provides a fresh context
We formally introduce 14 new high-level stratigraphic names to augment existing names and to hierarchically organise all of New Zealand's onland and offshore Cambrian-Holocene rocks and unconsolidated deposits. The two highest-level units are Austral Superprovince (new) and Zealandia Megasequence (new). These encompass all stratigraphic units of the country's Cambrian-Early Cretaceous basement rocks and Late Cretaceous-Holocene cover rocks and sediments, respectively. Most high-level constituents of the Austral Superprovince are in current and common usage: Eastern and Western Provinces consist of 12 tectonostratigraphic terranes, 10 igneous suites, 5 batholiths and Haast Schist. Ferrar, Tarpaulin and Jaquiery suites (new) have been added to existing plutonic suites to describe all known compositional variation in the Tuhua Intrusives. Zealandia Megasequence consists of five predominantly sedimentary, partly unconformity-bounded units and one igneous unit. Momotu and Haerenga supergroups (new) comprise lowermost rift to passive margin (terrestrial to marine transgressive) rock units. Waka Supergroup (new) includes rocks related to maximum marine flooding linked to passive margin culmination in the east and onset of new tectonic subsidence in the west. Māui and Pākihi supergroups (new) comprise marine to terrestrial regressive rock and sediment units deposited during Neogene plate convergence. Rūaumoko Volcanic Region (new) is introduced to include all igneous rocks of the Zealandia Megasequence and contains the geochemically differentiated Whakaari, Horomaka and Te Raupua supersuites (new). Our new scheme, Litho2014, provides a complete, high-level stratigraphic classification for the continental crust of the New Zealand region.Keywords: igneous rocks; metamorphic rocks; New Zealand; Zealandia; sedimentary rocks; stratigraphy; tectonics Introduction It has been 40 years since Carter et al. (1974) proposed a tripartite high-level stratigraphic nomenclature for New Zealand rocks. Their Kaikoura, Rangitata and Tuhua sequences were broad, unconformity-bounded stratigraphic units, with the Rangitata Sequence being subdivided into formal assemblages and zones. Following revisions to the International Stratigraphic Guide, Carter (1988) amended the sequences to synthems.The high-level nomenclature of Carter et al. (1974) and Carter (1988) has not been widely adopted. The orogenies, assemblages, zones, sequences and synthems proposed for New Zealand's Cambrian-Early Cretaceous basement rocks were supplanted by a different, stable and well-used classification based on provinces, terranes and batholiths ( Fig. 1; e.g. Coombs et al. 1976;Tulloch 1988). Carter (1988 defined the Kaikoura Synthem to encompass Late Cretaceous-Holocene cover strata in eastern South Island which he divided into five formal groups onshore, four of which he correlated to informal seismic sequences offshore. While Carter's (1988) use of offshore seismic stratigraphy and his concepts for developing a 'lumping rather than splitting' approach were...
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.
Detailed mapping of Fraser Formation has revealed a different relationship between mylonitic and gneissic rocks than found by previous workers. Mylonitic zones envelop areas of amphibolite facies gneisses and granitoid rocks, ranging up to several square kilometre~, throug~ out the area. Mylonitisation does not mcrease m intensity towards either the Fraser _Fault or the Alpine Fault. Numerous lamprophync and trachytic dikes intrusive into Fraser Formation have not been observed to cut the foliation in the mylonite zones and several of the dikes have been truncated
Diverse, mappable, and variably mylonitised highgrade gneisses and granitoids, and lamprophyre, trachyte, and basalt dikes comprise the Fraser Complex, which is a new name proposed to replace the existing Fraser Formation. Sillimanite-bearing pelitic gneisses have an upper amphibolite facies metapelitic mineralogy, indicating temperatures >600°C. Quartzofeldspathic gneisses, lacking sillimanite, are migmatitic, and hornblende gneisses have a diverse epidote-amphibolite mineralogy. The high-grade gneisses form a metamorphic suite within the Fraser Complex. Granite, granodiorite, and tonalite are intrusive into the high-grade gneiss suite, and may have been derived from partial melts of the high-grade gneisses. Swarms of camptonite lamprophyre, trachyte, and basalt dikes intrude the high-grade gneisses and the granitoids. Mylonite zones now envelop the gneisses, granitoids, and dikes, and mylonitic deformation occurred at mid-greenschist facies conditions and resulted in some retrogressive alteration of the protoliths. The Fraser Complex forms part of a regional gneissic and granitic basement to the Greenland Group in Westland. The juxtapostion of the Fraser Complex, with Mesozoic highgrade metamorphism, against the low-grade Ordovician Greenland Group sediments can be explained by vertical movement along the Fraser Fault rather than by invoking large-scale normal detachment faulting, as has been suggested in North Westland.
In 1994 the QMAP 1:250 000 Geological Map of New Zealand project began with compilation of the Dunedin sheet. Nearly 18 years later, publication of the Hawke's Bay sheet marks the completion of all 21 maps. The adoption of geographic information systems (GIS) software for data capture, data management and map production has not only produced high cartographic quality maps, but also built the attribute-rich, nationally consistent QMAP GIS spatial database. The project cost about NZD $24M, and the results are now being used by government, industry and research organisations across infrastructure, geological hazard, resource and environmental areas. QMAP has added significantly to general knowledge of New Zealand's geological composition and history due to new discoveries and validation of concepts. Notable advances include work on the allochthons of Northland and East Coast; rationalisation of the Taupo Volcanic Zone and East Coast stratigraphic successions; differentiation of the Torlesse basement terranes; clarification of the transition from Otago Schist to Alpine Schist; determining the complex spatial and temporal history of igneous intrusions in Fiordland and Stewart Island; and mapping Quaternary sediments by oxygen isotope stage and depositional processes.
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