b'Education matters away from the ridge axis. This subsidence,Yi He, University of Adelaide: CurnamonaThe magnetic field of Earth and its measured as the evolution of bathymetry,Cube: 3D lithospheric architecture of abehaviour over time is linked to its provides a unique constraint on theProterozoic province. origin within Earths liquid outer dynamics and evolution of the mantlescore. Complex internal processes upper thermal boundary layer. Thethat operate within the outer core variation in depth with age of oceanicare not only responsible for the lithosphere is controlled by heat transfercreation of the geomagnetic field, and can be described by a cooling model.but also the magnetic fields strength, Despite developments in cooling modelsstability, and position on Earth. since the 1970s, some observations of theThe magnetic field acts as a critical seaoor remain enigmatic and are notbarrier of protection, shielding explained by these models. Earth from harmful solar radiation To enable exploration of prevalent,from the sun and confining Earths regionally-variable inuences on oceanicatmosphere beneath the exosphere. lithosphere, we have designed a robustAs Earths core evolves and cools set of owlinestime series of oceanicover time, it releases heat at the lithosphere created at the same locationcore-mantle boundary (CMB), the on a mid-ocean ridge. Analysis of coolingmagnetic field reflects this evolution models at the regional-scale, using theseby weakening, strengthening, and owlines, reveals the global ubiquity of thereversing in polarity over time. It is effect of hydrothermal circulation in stallingimportant to study and form a better The Curnamona Cube project wasunderstanding of the behaviour of conductive cooling at young ages (0-5 Ma),developed to define the properties of thethe magnetic field and its intensity and the regional-variability in the extent ofProvince over a scale of 400 km by 400 km,over time, as its ability to weaken deviations from linear cooling behaviourand from the surface to 400 km depth,may give rise to biological and at old ages ( 70 Ma). It has been proposeddefining a cube of geophysical information.technological damage to Earth and its that such regional variability could be aIn this first part of the project, broadbandinhabitants.consequence of dynamic topography, theMT data were collected and over 200 response of Earths surface to underlyingsites with site spacing of 25 km or less, toVariation in magnetic field mantle ow. This study provides theobserve the entire Curnamona Provincebehaviour over time is preserved rst quantitative, regional-scale analysisat higher resolution at crustal depths. Inin the geologic record, but data of oceanic lithosphere cooling usingthis paper, new Curnamona Cube MT datais scarce and poorly constrained, bathymetry corrected for predictedare combined with legacy broadbandthus, numerical modelling solutions dynamic topography. and long-period MT data from the lastremain an essential aspect of paleo-Analysis at this scale provides noveldecades to provide further constraints ongeomagnetic field analysis. In this insight into the inuence of dynamicthe morphology. The primary outputs are astudy, we analyse model-predicted topography on the spatio-temporalnew 3D resistivity model that maps out thecore-mantle boundary heat flux as evolution of oceanic lithosphere. Alithosphere with long-period MT responses,a proxy indicator of the dynamic synthetic dynamic topography predictionand more detailed crustal images from newevolution of the magnetic field, from is used to correct bathymetry, showingbroadband MT. The 3D models indicate1 Ga to present for four model cases. an improvement in the quality andsignificant low-resistivity structures ( 1We do this in aim of including periods consistency of t to both global andOhm.m) that extend from depths of 5 kmknown to exhibit the weakening of regional-scale amalgamations. Thisto 30 km depth, dipping from the easternthe magnetic field (superchrons, correction allows us to better highlightmargin of the Province towards the centre.hyperactive periods and periods oceanic lithosphere cooling trends inSuch models show correlations of low- of biological extinction), and also isolation, revealing signicant regionalresistivity lower-crust with known copperinvestigate the spherical harmonics variability in the presence, onset, andoccurrences and resources, and diamond- and Pearson correlation between expression of deviations from a half- bearing kimberlites with the thickenedthese data and the current paleo-space cooling regime beyond 70 Ma.lithosphere to the west of the Province. geomagnetic reversal rate data of Dynamic topography appears to accounttwo previous studies (Hounslow Annalise Cucchiaro, University ofetal. 2018, Olson etal. 2013). Results for a portion of attening behaviourWollongong: An investigation into the seen in global amalgamations, but it doesconclude that CMB heat flux correlates not completely account for deviations inbehaviour of the magnetic field from 1 Gaweakly with the geomagnetic reversal cooling behaviour at old ages. to present day. rates, with equatorial CMB heat flux variability (q* equatorial) correlating Our study has implications for thethe greatest of all quantities understanding of the physical basis forinvestigated. Spherical harmonics the behaviour of oceanic lithosphereanalysis reveals a 200 Myr cycle in in the context of cooling trends. Whilemagnetic field intensity that may the plate model provides an acceptablecorrelate with Earths 200 Myr deep empirical t to the variation of bathymetrymantle convection cycle.with age in the majority of regions, there is no necessity for the plate thickness parameter to be underlain by a single, globally ubiquitous physical mechanism.DECEMBER 2021 PREVIEW 44'