Andy Clark | Searcharxiv

arXiv2026

A magnetotelluric image of the Curnamona Province and the adjacent Delamerian Orogen margin: new insights into the crustal architecture

We have used new magnetotelluric data collected in the Curnamona Province and the adjacent part of the Delamerian Orogen margin to image electrical conductivity structures and to inform the understanding of the crustal architecture within the regional geological context. The preferred 3D resistivity model confirms, and resolves in greater detail, crustal-scale conductive features that have been mapped by the long-period data collected at half-degree spacing as part of the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), that is, the prominent Curnamona Province Conductor and the two Nackara Arc conductors. The new model reveals that the eastern Nackara Arc (ENAC) conductor continues as the Broken Hill Conductor (BHC) into the Curnamona Province. Regional geological considerations suggest that its formation is possibly linked to rifting/extension in the early Cambrian. Although we recognise that the east-west trending Wilcannia Conductor could be a possible continuation of the ENAC-BHC zone, integration with recently acquired deep seismic reflection data and evaluation of the geological setting lead us to suggest that they are not genetically linked. We suggest that the Wilcannia Conductor is younger and most likely is related to late Delamerian (~500 Ma) or Siluro-Devonian magmatism. Finally, these conductivity anomalies may represent large-scale trans-crustal structures that control the emplacement of low volume alkaline ultramafic magmas, and show a spatial relationship with certain mineral deposit types, suggesting a possible control on the distribution and formation of metallogenic provinces/belts in the region. This will be further investigated in future work.

physics.geo-ph↗

arXiv2021

Persistent Ionic Photo-responses and Frank-Condon Mechanism in Proton-transfer Ferroelectrics

Photoexcitation is well-known to trigger electronic metastable states and lead to phenomena like long-lived photoluminescence and photoconductivity. In contrast, persistent photo-response due to ionic metastable states is rare. In this work, we report persistent structural and ferroelectric photo-responses due to proton metastable states via a nuclear quantum mechanism in ferroelectric croconic acid, in which the proton-transfer origin of ferroelectricity is important for the ionic metastable states. We show that, after photoexcitation, the changes of structural and ferroelectric properties relax in about 1000 s, while the photoconductivity decays within 1 s, indicating the dominant ionic origin of the responses. The photogenerated internal bias field that survives polarization switching process suggests another proton transfer route and metastable state, in addition to the metastable states resulting from proton transfer along the hydrogen bonds proposed previously. Analysis based on Frank Condon principle reveals the quantum mechanical nature of the proton-transfer process both within the hydrogen bonds and out of the hydrogen bonds, where small mass of proton and significant change of potential landscape due to the excited electronic states are the key. The demonstration of persistent photo-responses due to the proton metastable states unveils a nuclear quantum mechanism for photo-tunability of materials, which is expected to impact many material properties sensitive to ionic positions.

cond-mat.mtrl-sci↗