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

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The Coromandel Peninsula comprises the central subaerial part of the late Cenozoic Coromandel Volcanic Zone (CVZ) of New Zealand and hosts the Hauraki Goldfield. Some 73 K-Ar and 9 zircon fission-track dates representative of 28 lithostratigraphic volcanic units mapped on the peninsula are reported, and more than 250 major element analyses of volcanic rocks, including all the dated rocks, have been collated and their broad geochemical affinities used to underpin the stratigraphy and volcanic history of the region.The age data confirm that the central part of the CVZ evolved more or less continuously throughout the late Cenozoic from c. 18 to 4 Ma ago (late-early Miocene to early Pliocene), with regional time breaks of no more than i -2 Ma. From c. 18 to 9 Ma, an andesite-dominated volcanic arc was active, and at c. 10 Ma initiation of the Kapowai Caldera began with the first eruption of ignimbrite. A bimodal basalt to basaltic andesite/rhyolite association developed from c. 9 to 7 Ma and accompanied major caldera collapse, ignimbrite eruption, and postcaldera andesite eruption. Bimodal eruptions of basalt to basaltic andesite (with minor andesite) plus rhyolite and rhyolitic ignimbrite began once more from c. 6 to 5.5 Ma, and these became entirely basaltic from 4.7 to 4.2 Ma. At about the same time (c. 5.5 Ma), basalt was also erupted on the southern Colville Ridge. During late Miocene to early Pliocene time, andesitic to dacitic eruptions continued in the south and southwest of the CVZ. With time, the locus of volcanism moved irregularly eastwards at c. 3 mm/yr and southwards at c. 8 mm/yr, such that minimum ages are younger progressively southwards.Volcanism in the Coromandel Peninsula is mainly calcalkaline and medium-K, with some early and late lavas showing tholeiitic affinities. The rocks range from highalumina basalts (including picritic basalt) through basaltic andesites and (dominant) andesites to dacites. There is an apparent gap between dacites at 63-68% SiO 2 and rhyolites/ ignimbrites at 73-78% SiO 2 , several of which have high-K affinities. Many of the volcanic formations have distinct chemical signatures, confirming earlier suggestions that each has an independent magmatic history.

Sr ratios (at metamorphism) and detrital zircon patterns that in part are transitional between Rakaia and Pahau Terrane rocks and in part similar to Waipapa Terrane rocks. Combined detrital zircon age data for all Torlesse and Waipapa Terrane data reveal an essential unity, with a long persistence (260-120 Ma) of predominant Permian-Triassic sources in the form of a major Cordilleran-style batholith, a decline in major early Paleozoic-Precambrian sources between 260 and 220 Ma, and presence of minor Early Carboniferous to Late Devonian sources between 180 and 120 Ma. Rb-Sr and K-Ar ages indicate latest Triassic to Early Cretaceous metamorphism in an evolving accretionary wedge.

Thermal or chemical treatment of crystalline 4,4′‐bipyridinium salts of [MCl4]2− (M=Co, Zn, Fe, or Pt) leads to HCl loss and formation of coordination network solids [{MCl2(4,4′‐bipy)}n]. For M=Co, Zn, and Fe, these solids can also be prepared by mechanochemical means. Their exposure to HCl vapor or the mechanochemical reaction of metal dichlorides with [4,4′‐H2bipy]Cl2 gives [4,4′‐H2bipy]2+ salts of [CoCl4]2−, [ZnCl4]2−, and, for the first time, [FeCl4]2−.