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
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