Zealandia 2008

Abstract

Zealandia is a submerged continent in the southwest Pacific Ocean that can be regarded as a rifted part of eastern Australia and West Antarctica. Described simply, the preGondwana-breakup Zealandia geological record is one of a Cambrian to Early Cretaceous Gondwana convergent margin, followed by Late Cretaceous continental rifting.

The Thermal Structure of Central Te Riu a Māui/Zealandia Continent as Determined From the Depth to Base of Magnetic Sources

“…Our new data set affirms many of the earlier matches of New Zealand magnetic anomalies with national-scale geological and tectonic features (e.g., B. W. Davy, 1992;Hunt, 1978;Sutherland, 1999;Wellman, 1973). For this study we use recent geological compilations by Edbrooke et al (2015) and Mortimer et al (2020b). We restrict our comment to general aspects and do not try and explain every individual anomaly.…”

“…(2020), Mortimer et al. (2020b), and Mortimer, Williams, et al. (2023), many of the positive magnetic anomalies in the continental offshore region are likely to mark the location of <100 Ma gabbroic and basaltic intraplate igneous rocks.…”

“…Magnetically low and quiet regions over the Chatham Rise and Challenger and Campbell Plateaus are the along-strike offshore continuations of onland greywacke and schist terranes. Following Tulloch et al (2019), Bischoff et al (2020), Mortimer et al (2020b), andMortimer, Williams, et al (2023), many of the positive magnetic anomalies in the continental offshore region are likely to mark the location of <100 Ma gabbroic and basaltic intraplate igneous rocks. Anomalies with rectilinear shapes are plausibly related to Late Cretaceous Gondwana-Zealandia rifting.…”

“…Geological data from Mortimer et al. (2020b). Areas with EMAG2 data are enclosed by the white line in panel (b).…”

“…New Zealand represents most of the onland extent of the continent, 94% of which is submerged. Much of the knowledge of Zealandia's basement structure is derived from interpretation of onland mapping, with sparse geological samples from off shore drilling and dredging, and on land drilling, together with geophysical data including satellite gravity-derived bathymetry, and magnetic data derived from airborne, ship-borne and satellite measurements (B. Davy & Wood, 1994;Mortimer et al, 2020aMortimer et al, , 2020bSutherland, 1999). One unexplored aspect of Zealandia is the depth to base of magnetic sources (DBMS).…”