b'Education matters lithologies are: a monzogranite migmatitePrevious tectonic reconstructions forthe continent rifted away from eastern gneiss (I-type and magnetite-series)the breakup of eastern Gondwana areGondwana. The Middleton Basin provides characterised by high MS, a syenograniteof low resolution, which only considera relatively unexplored location in (I-type and magnetite-series) with highthe evolution of large, aerial landmasses,which Gondwanas rifting history can be MS, a monzogranite (S-type and ilmenitesuch as Australia and New Zealand.unravelled.series) with low MS and a porphyriticDespite Zealandia (Te Riu-a-Maui) beingA new tectonic model for the evolution monzogranite with two subgroups: onerecently de\x1dned as New Zealands ownof the Middleton Basin is presented, with high MS (I-type and magnetite series)continent, 95% of the new continent lieshighlighting the two-stage rifting and the other with bimodal MS (boundaryunderwater, meaning the informationhistory of the basin. The Middleton of I-type and S-type and magnetite-series). about the submerged regions has beenBasin is suggested to have formed MS data demonstrates a high amount ofinaccessible by \x1drst-order geologicalduring Mesozoic backarc extension, variation within rock types at the outcropmapping techniques. Zealandia containsfollowed by rifting and subsidence as scale necessitating a substantial numberat least 20 sedimentary basins, all ofpart of Zealandia in the Cenozoic, as the of measurements per outcrop for reliablewhich preserve an immaculate record ofcontinent broke away from Gondwana.tectonism.MS averages, hence populations of MSThis study deduces that the Greater are studied. Signi\x1dcant \x1dndings includeContinental breakup is an enigmaticMiddleton does not appear to be a the observation that MS bimodality intectonic process that irreversiblyfault-controlled region and the basins certain rock types is related to the degreechanges the structure of land ondo not contain oceanic crust. The of martitization of magnetite, change inthe Earth. However, modern platepresented genesis model addresses ma\x1dc-mineral content and the presencereconstructions barely recognise thethe formation of multiple, proximal of unevenly distributed secondaryEarths eighth continent: Zealandia (Tebasins by insinuating that extension coarse-grained magnetite. Riu-a-Maui), meaning the geologicaltook place over two distinct phases. history of a large portion of the Earth isThe model allows basin extension Aeromagnetic data was processed toleft unaccounted for. Zealandia is unlike generate a series of products, aidingany other continent, being submergedto take place over time periods in the identi\x1dcation of key geologicaland containing signi\x1dcantly thinnersufficient for slow strain rates. This features, such as faults, regional scalecontinental crust (~20-24 km to themodel highlights why extensional shears, ma\x1dc dikes, and lithologicalusual ~40 km), therefore providing astrain propagated from one region to contacts between four observedunique context in which continentalanother adjacent area and suggests granitoid units and one inferred ma\x1dcrifting and extensional processes canthat strain hardening of northwestern gneiss unit. The existing regional bedrockbe analysed. A better understandingZealandia was responsible for the geology map is re\x1dned, underlining theof Zealandias place on Earth provideswestward ridge jump that ultimately in\x1buence of oxygen fugacity conditionssigni\x1dcant value to the understanding offormed the Tasman Sea. Consequently, and lithotypes on magnetic responses inplate tectonics and will better constrainthe Dampier Ridge and the Lord Howe the area. future tectonic models. Rise are considered undeformed basin margins. The model also acknowledges Jessica Latimer, The University ofBoth Australia and Zealandia were onceorogenesis in the development of Melbourne: Insights into the tectonica part of the megacontinent, Gondwana,eastern Gondwana and proposes evolution of the Middleton Basin,which resided on Earth during thethat pre-existing lithospheric-scale northwestern Zealandia (Te Riu-a-Mui). early Phanerozoic. The breakup ofheterogeneities, inherited from earlier Gondwana began at ca. 105 Ma asorogenesis, may have governed the megacontinent separated and thethe nucleation of extensional strain bounds of many modern southernduring Mesozoic rifting. This may have hemisphere continents were established.contributed to the location of basin A considerable knowledge gap isformation throughout northwestern presented by the lack of geological dataZealandia.present throughout much of o\x1eshoreFurther study into the Zealandian region, Zealandia, especially in the northwesternespecially the nature of basins in the section where few drillholes are found.northwest would be bene\x1dcial to the Despite the evolution of Australia andunderstanding of Gondwana evolution New Zealand being well understood,and breakup.this presents a di\x1ccult situation in which the adjoining continental region is notRebecca Latto, University of Tasmania: accounted for, which contains a wealthActive glacier processes from machine of information about the evolution oflearning applied to seismic records.eastern Gondwana. The buttressing, outlet glaciers of Zealandia contains key information,Antarctica are largely experiencing mass much of which is preserved withinloss, a\x1eecting sea level rise, which creates sedimentary basins and it is here thatchanges to climates and communities. insight into the rifting history of theGlacier seismology, or cryoseismology, continent can be found. Here, modernis a unique method for monitoring geophysical and seismic re\x1bectancechanges in motion through the glacier data is synthesised to investigate basinbody in continuous data streams. formation in northwestern Zealandia, asCryoseismology o\x1eers a geophysical lens 31 PREVIEW DECEMBER 2023'