ORCID Profile
0000-0003-4666-0955
Current Organisations
CSIRO
,
CSIRO Australian Resources Research Centre
,
University of Western Australia
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Seismology and Seismic Exploration | Astronomical and Space Sciences | General Relativity and Gravitational Waves
Expanding Knowledge in the Physical Sciences | Scientific Instruments |
Publisher: Oxford University Press (OUP)
Date: 23-09-2011
Publisher: Authorea, Inc.
Date: 28-09-2023
Publisher: Springer Science and Business Media LLC
Date: 11-06-2021
DOI: 10.1007/S00414-021-02568-1
Abstract: Glial fibrillary acidic protein (GFAP) is a well-established astrocytic biomarker for the diagnosis, monitoring and outcome prediction of traumatic brain injury (TBI). Few studies stated an accumulation of neuronal GFAP that was observed in various brain pathologies, including traumatic brain injuries. As the neuronal immunopositivity for GFAP in Alzheimer patients was shown to cross-react with non-GFAP epitopes, the neuronal immunopositivity for GFAP in TBI patients should be challenged. In this study, cerebral and cerebellar tissues of 52 TBI fatalities and 17 controls were screened for immunopositivity for GFAP in neurons by means of immunohistochemistry and immunofluorescence. The results revealed that neuronal immunopositivity for GFAP is most likely a staining artefact as negative controls also revealed neuronal GFAP staining. However, the phenomenon was twice as frequent for TBI fatalities compared to non-TBI control cases (12 vs. 6%). Neuronal GFAP staining was observed in the pericontusional zone and the ipsilateral hippoc us, but was absent in the contralateral cortex of TBI cases. Immunopositivity for GFAP was significantly correlated with the survival time ( r = 0.306, P = 0.015), but no correlations were found with age at death, sex nor the post-mortem interval in TBI fatalities. This study provides evidence that the TBI-associated neuronal immunopositivity for GFAP is indeed a staining artefact. However, an absence post-traumatic neuronal GFAP cannot readily be assumed. Regardless of the particular mechanism, this study revealed that the artefact otential neuronal immunopositivity for GFAP is a global, rather than a regional brain phenomenon and might be useful for minimum TBI survival time determinations, if certain exclusion criteria are strictly respected.
Publisher: Elsevier BV
Date: 2010
Publisher: Springer Science and Business Media LLC
Date: 09-05-2023
Publisher: Informa UK Limited
Date: 11-11-2019
Publisher: AIP
Date: 2013
DOI: 10.1063/1.4820337
Publisher: American Geophysical Union (AGU)
Date: 16-06-2022
DOI: 10.1029/2022GL098062
Abstract: Despite public concerns, only a few CO 2 injections into saline aquifers have reported microseismicity. We analyze passive seismic monitoring of a small (15,000 tonnes and 0.15 MPa pressure) injection of supercritical CO 2 ‐rich mixture for Stage 2C of the CO2CRC Otway Project (Victoria, Australia), which induced 19 detectable events with maximum moment magnitude M W ‐0.5. The locations and dynamic parameters of the triggered events indicate a reactivation of a small fault patch where CO 2 flowed through the fault. Time‐lapse seismic images of the plume and reservoir simulations show that the reactivation occurred when the CO 2 plume reached this fault. This might be indicative of a fault weakening by the plume that enabled subsequent reactivation by pressure variations. Our observations suggest that a leakage from a commercial‐scale storage may trigger felt seismicity in the overburden without strong overpressure, thus, the de‐risking workflows should involve a detailed study of small faults.
Publisher: American Geophysical Union (AGU)
Date: 06-2019
DOI: 10.1029/2018JB017055
Publisher: Oxford University Press (OUP)
Date: 25-04-2020
DOI: 10.1093/GJI/GGAA201
Abstract: Seismic full waveform inversion (FWI) is a state-of-the-art technique for estimating subsurface physical models from recorded seismic waveform, but its application requires care because of high non-linearity and non-uniqueness. The final outcome of global convergence from conventional FWI using local gradient information relies on an informative starting model. Bayesian inference using Markov chain Monte Carlo (MCMC) s ling is able to remove such dependence, by a direct extensive search of the model space. We use a Bayesian trans-dimensional MCMC seismic FWI method with a parsimonious dipping layer parametrization, to invert for subsurface velocity models from pre-stack seismic shot gathers that contain mainly reflections. For the synthetic study, we use a simple four-layer model and a modified Marmousi model. A recently collected multichannel off-shore seismic reflection data set, from the Lord Howe Rise (LHR) in the east of Australia, is used for the field data test. The trans-dimensional FWI method is able to provide model ensembles for describing posterior distribution, when the dipping-layer model assumption satisfies the observed data. The model assumption requires narrow models, thus only near-offset data to be used. We use model stitching with lateral and depth constraints to create larger 2-D models from many adjacent overlapping submodel inversions. The inverted 2-D velocity model from the Bayesian inference can then be used as a starting model for the gradient-based FWI, from which we are able to obtain high-resolution subsurface velocity models, as demonstrated using the synthetic data. However, lacking far-offset data limits the constraints for the low-wavenumber part of the velocity model, making the inversion highly non-unique. We found it challenging to apply the dipping-layer based Bayesian FWI to the field data. The approximations in the source wavelet and forward modelling physics increase the multimodality of the posterior distribution the s led velocity models clearly show the trade-off between interface depth and velocity. Numerical ex les using the synthetic and field data indicate that trans-dimensional FWI has the potential for inverting earth models from reflection waveform. However, a sparse model parametrization and far offset constraints are required, especially for field application.
Publisher: Wiley
Date: 29-04-2022
Publisher: Society of Exploration Geophysicists
Date: 30-09-2020
Publisher: Elsevier BV
Date: 08-2020
Publisher: American Geophysical Union (AGU)
Date: 27-01-2017
DOI: 10.1002/2016GL071363
Publisher: Springer Science and Business Media LLC
Date: 19-10-2021
Publisher: Oxford University Press (OUP)
Date: 09-11-2013
DOI: 10.1093/GJI/GGS004
Publisher: European Association of Geochemistry
Date: 2021
Publisher: American Geophysical Union (AGU)
Date: 09-2021
DOI: 10.1029/2020JB021589
Abstract: We present a hybrid machine learning (HML) inversion method, which uses the latent space (LS) features of a convolutional autoencoder (CAE) to estimate the subsurface velocity model. The LS features are the effective low‐dimensional representation of the high‐dimensional seismic data. However, no equations exist to describe the relationship between the perturbation of an LS feature and the velocity perturbation. To address this problem, we use automatic differentiation (AD) to connect the two terms. Following this step, we use the wave‐equation inversion to invert the LS features for the subsurface velocity model. The HML misfit function measures the LS feature differences between the observed and predicted seismic data in a low‐dimensional space, which is less affected by the cycle‐skipping problem compared to the waveform mismatch in a high‐dimensional space. A low dimensional LS feature mainly contains the kinematic information of seismic data, while a large dimensional LS feature can also preserve the dynamic information of seismic data. Therefore, the HML inversion can recover the subsurface velocity model in a multiscale approach by inverting the LS features with different dimensions. Based on the different ways of utilizing AD to compute the velocity gradient, we propose full‐ and semi‐automatic approaches to solve this problem. These two approaches are mathematically equivalent the former is easier to implement, while the latter is computationally more efficient. Numerical tests show that the HML inversion method can effectively recover both the low‐ and high‐wavenumber velocity information by inverting the LS features with different dimensions.
Publisher: American Geophysical Union (AGU)
Date: 12-05-2018
DOI: 10.1029/2018GL077338
Publisher: Springer Science and Business Media LLC
Date: 13-06-2022
DOI: 10.1038/S41561-022-00963-W
Abstract: Oceanic crust forms at mid-ocean spreading centres through a combination of magmatic and tectonic processes, with the magmatic processes creating two distinct layers: the upper and the lower crust. While the upper crust is known to form from lava flows and basaltic dykes based on geophysical and drilling results, the formation of the gabbroic lower crust is still debated. Here we perform a full waveform inversion of wide-angle seismic data from relatively young (7–12-Myr-old) crust formed at the slow-spreading Mid-Atlantic Ridge. The seismic velocity model reveals alternating, 400–500 m thick, high- and low-velocity layers with ±200 m s −1 velocity variations, below ~2 km from the oceanic basement. The uppermost low-velocity layer is consistent with hydrothermal alteration, defining the base of extensive hydrothermal circulation near the ridge axis. The underlying layering supports that the lower crust is formed through the intrusion of melt as sills at different depths, which cool and crystallize in situ. The layering extends up to 5–15 km distance along the seismic profile, covering 300,000–800,000 years, suggesting that this form of lower crustal accretion is a stable process.
Publisher: American Geophysical Union (AGU)
Date: 02-2018
DOI: 10.1002/2017JB014904
Publisher: Informa UK Limited
Date: 10-2013
Publisher: Elsevier BV
Date: 2021
DOI: 10.2139/SSRN.3820206
Publisher: Oxford University Press (OUP)
Date: 18-02-2014
DOI: 10.1093/GJI/GGU016
Publisher: American Geophysical Union (AGU)
Date: 12-2021
DOI: 10.1029/2021JB023184
Abstract: Constraints on crustal and uppermost mantle structure provide key information for understanding the geodynamic processes that have shaped the geological expressions and are currently causing deformation in Anatolia. We apply a novel method of Bayesian inversion of autocorrelated teleseismic P‐wave coda data to retrieve the crustal and uppermost mantle structures beneath Anatolia and southeast Europe. Our inversion provides estimates of Moho depth variations and crustal velocity structure (e.g., Vp, Vs, and Vp/Vs ratio). The Moho architecture in the study area can be summarized by (a) an overall west‐to‐east increase in the Moho depth from Greece to eastern Anatolia, (b) a homogeneously thin crustal structure beneath Greece, (c) complex, small‐scale crustal features and variations in western and central Anatolia, and (d) relatively long‐wavelength variations, but overall thick crust in eastern Anatolia. The apparent relation between the Moho depth variations and suture/fault zones implies a dominant control of structural inheritance on the past deformation in Anatolia. The overall Moho architecture appears to correlate well with the topography in Anatolia, although with some exceptions, in particular at smaller wavelength. These local inconsistencies in the topography‐Moho depth relation suggest a more complex, wavelength‐dependent isostatic state compared to what is expected from simple Airy isostasy. The observed deviations may originate from elastic effects, lithospheric density changes, or sub‐lithospheric dynamic effects. Obvious large lateral variations in Vp, Vs and Vp/Vs ratio estimates in our model can relate to such density variations within the crust especially between tectonic domains.
Publisher: Oxford University Press (OUP)
Date: 20-10-2020
DOI: 10.1093/GJI/GGAA505
Abstract: Seismic full waveform inversion (FWI) is a powerful method for estimating quantitative subsurface physical parameters from seismic data. As the FWI is a nonlinear problem, the linearized approach updates model iteratively from an initial model, which can get trapped in local minima. In the presence of a high-velocity contrast, such as at Moho, the reflection coefficient and recorded waveforms from wide-aperture seismic acquisition are extremely nonlinear around critical angles. The problem at the Moho is further complicated by the interference of lower crustal (Pg) and upper mantle (Pn) turning ray arrivals with the critically reflected Moho arrivals (PmP). In order to determine velocity structure near Moho, a nonlinear method should be used. We propose to solve this strong nonlinear FWI problem at Moho using a trans-dimensional Markov chain Monte Carlo (MCMC) method, where the earth model between lower crust and upper mantle is ideally parametrized with a 1-D assumption using a variable number of velocity interfaces. Different from common MCMC methods that require determining the number of unknown as a fixed prior before inversion, trans-dimensional MCMC allows the flexibility for an automatic estimation of both the model complexity (e.g. the number of velocity interfaces) and the velocity–depth structure from the data. We first test the algorithm on synthetic data using four representative Moho models and then apply to an ocean bottom seismometer (OBS) data from the Mid-Atlantic Ocean. A 2-D finite-difference solution of an acoustic wave equation is used for data simulation at each iteration of MCMC search, for taking into account the lateral heterogeneities in the upper crust, which is constrained from traveltime tomography and is kept unchanged during inversion the 1-D model parametrization near Moho enables an efficient search of the trans-dimensional model space. Inversion results indicate that, with very little prior and the wide-aperture seismograms, the trans-dimensional FWI method is able to infer the posterior distribution of both the number of velocity interfaces and the velocity–depth model for a strong nonlinear problem, making the inversion a complete data-driven process. The distribution of interface matches the velocity discontinuities. We find that the Moho in the study area is a transition zone of 0.7 km, or a sharp boundary with velocities from around 7 km s−1 in the lower crust to 8 km s−1 of the upper mantle both provide nearly identical waveform match for the field data. The ambiguity comes from the resolution limit of the band-limited seismic data and limited offset range for PmP arrivals.
Publisher: American Geophysical Union (AGU)
Date: 02-2020
DOI: 10.1029/2019JB018261
Publisher: Oxford University Press (OUP)
Date: 29-04-2013
DOI: 10.1093/GJI/GGT118
Publisher: California Digital Library (CDL)
Date: 27-01-2020
Publisher: Oxford University Press (OUP)
Date: 08-01-2007
Abstract: Rapid Access Chest Pain Clinics have recently been introduced to assist in the management of primary care patients experiencing suspected cardiac chest pain. To study the longer term outcome for patients referred to a Rapid Access Chest Pain Clinic and then given a non-cardiac diagnosis. The study collected retrospective data from a cohort of all patients attending the Rapid Access Chest Pain Clinic based in the cardiorespiratory Department at the York District Hospital, England. Questionnaires were sent to all patients who attended the Rapid Access Chest Pain Clinic during the previous 14 months and were diagnosed with non-cardiac chest pain. Participants reported on their chest pain, subsequent episodes of primary and secondary care and their beliefs about causation of pain. Of the patients referred to the Rapid Access Chest Pain Clinic, 235 (52%) did not have cardiac chest pain. Of these patients, 161 (69%) returned the questionnaire, nearly half of whom reported ongoing chest pain. The mean time since Clinic attendance was approximately 8 months and the median duration of ongoing chest pain was 5.4 months. Women were twice as likely as men to continue to be experiencing pain but did not report more frequent or severe pain on average. More than 50% of the non-cardiac group were not convinced by their negative cardiac diagnosis. There is an ongoing challenge to support patients with non-cardiac chest pain, including the provision of reassurance that their pain is very unlikely to be caused by their heart.
Publisher: Oxford University Press (OUP)
Date: 14-01-2013
DOI: 10.1093/GJI/GGS107
Publisher: Elsevier BV
Date: 10-2012
Publisher: John Wiley & Sons, Ltd
Date: 08-10-2008
Publisher: California Digital Library (CDL)
Date: 08-08-2019
Publisher: Wiley
Date: 31-07-2021
Publisher: Oxford University Press (OUP)
Date: 07-2008
Publisher: Springer Science and Business Media LLC
Date: 02-03-2023
DOI: 10.1038/S41467-023-36514-Z
Abstract: The proliferation of seismic networks in Australia has laid the groundwork for high-resolution probing of the continental crust. Here we develop an updated 3D shear-velocity model using a large dataset containing nearly 30 years of seismic recordings from over 1600 stations. A recently-developed ambient noise imaging workflow enables improved data analysis by integrating asynchronous arrays across the continent. This model reveals fine-scale crustal structures at a lateral resolution of approximately 1-degree in most parts of the continent, highlighted by 1) shallow low velocities ( .2 km/s) well correlated with the locations of known sedimentary basins, 2) consistently faster velocities beneath discovered mineral deposits, suggesting a whole-crustal control on the mineral deposition process, and 3) distinctive crustal layering and improved characterization of depth and sharpness of the crust-mantle transition. Our model sheds light on undercover mineral exploration and inspires future multi-disciplinary studies for a more comprehensive understanding of the mineral systems in Australia.
Publisher: American Geophysical Union (AGU)
Date: 08-2020
DOI: 10.1029/2019JB018559
Abstract: Seismic body‐wave tomography studies typically assume an isotropic upper mantle, possibly mapping anisotropy into artificial isotropic velocity anomalies in the resulting images. The Eastern Mediterranean with its oceanic, continental, and extinct subduction systems, as well as dense station coverage, provides an ideal setting to explore this issue. To examine the influence of seismic anisotropy, our study deals with both synthetic and real data inversions in which realistic seismic anisotropy models derived from 3D mantle convection simulations and shear wave splitting measurements are taken as a priori constraints. Spatial large‐scale velocity perturbations are mostly consistent between models derived with and without considering anisotropy. Small differences in the magnitude (up to 2%) and shape of velocity perturbations occur, and some structures are less diffuse when including anisotropy. Additionally, good backazimuthal coverage of teleseismic events and a larger data set improve the resolution of our model with respect to previous tomography studies and allow us to better interpret first‐order isotropic velocity anomalies. Key features, such as the half‐arc subducting oceanic plate in the southern Aegean and a wide and deep tear in the slab beneath southwestern Turkey, are clearly visible in all models. Our final tomography images also provide evidence for a shallow horizontal tear in the northern Hellenides and a vertical tear between two parts of the Cyprian slab. In eastern Anatolia, slab‐related high‐velocity anomalies are absent due to the continental collision and break‐off.
Publisher: Society of Exploration Geophysicists
Date: 11-2019
Abstract: Seismic full-waveform inversion (FWI) has become a popular tool for estimating subsurface models using the litude and phase of seismograms. Unlike the conventional gradient-based approach, Bayesian inference using Markov chain Monte Carlo (MCMC) s ling can remove dependence on starting models and can quantify uncertainty. We have developed a Bayesian transdimensional (trans-d) MCMC seismic FWI method for estimating dipping-layer velocity models, in which the number of layers is unknown. A time-domain staggered-grid finite-difference wave equation solver is used for forward modeling. The FWI and MCMC methods are known to be computationally expensive. Two strategies are used to get practical computational performance. A layer-stripping strategy is used to accelerate s ler convergence, and a parsimonious dipping layer parameterization is used so that the MCMC algorithm can search broadly with fewer iterations. The parameters for each layer are velocity, thickness, and lower interface dip angle. We find that this parameterization has sufficient flexibility to invert for narrow 2D velocity models using small offset data. Model stitching is then used to bring several such inversions together to create larger 2D models. In turn, these can be used as starting models for gradient-based adjoint FWI to image complicated geologic settings. Two synthetic 2D numerical ex les, including the Marmousi model, are considered, using seismic data dominated by reflections. Creation of good starting models traditionally requires significant human effort. We determine how much of that effort can be substituted with computation.
Publisher: Wiley
Date: 19-09-2020
Publisher: Wiley
Date: 19-09-2020
Publisher: American Geophysical Union (AGU)
Date: 10-2021
DOI: 10.1029/2020JB021001
Abstract: The sensitivity of seismic compressional and shear waves and their velocity ratios to rock lithology, pore fluids, and high‐temperature materials makes these parameters very useful for constraining the physical state of the crust. In this study, we develop a joint inversion approach utilizing both radial and vertical components’ autocorrelations of teleseismic P‐wave coda for imaging the crust by simultaneously characterizing the crustal , , and ratio. Autocorrelations of the radial and vertical components contain P and S waves that are reflected from the subsurface. Therefore, joint inversion of them can account for the variations of both and , and consequently, the ratio. Synthetic inversions show significant improvement in the estimation of these parameters compared to those from the inversion of either, P receiver functions or the autocorrelation of the vertical component. The velocity models inferred from the application of the approach to teleseismic data recorded along a north‐south passive seismic profile (BILBY experiment) in central Australia reveal a distinct pattern of the Moho and the variations across the crustal blocks/domains. The general trend of the Moho structure corresponds well with the change of the reflectivity that can normally be seen at the base of the crust and also with the Moho estimated from previous studies including the deep seismic reflection profiling method. The structure at depths greater than 10 km shows dominant high values beneath locations where the crustal domains interact (e.g., at transition from one domain to another).
Publisher: American Geophysical Union (AGU)
Date: 2012
DOI: 10.1029/2011JB008403
Publisher: Wiley
Date: 19-09-2020
Publisher: Elsevier BV
Date: 07-2013
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-8096
Abstract: & & Upper mantle dynamics (e.g. subduction processes, slab roll-back, slab tearing and mantle upwelling) impact eastern Mediterranean region tectonics but a detailed understanding of the acting forces has remained elusive. Further progress requires more accurate measurements not just of the surface kinematics (from GPS) but also of indirect indicators of kinematics throughout the lithosphere and convecting upper mantle from seismology. A robust quantification of the magnitude, location and orientation of seismic anisotropy is a primary source of information to provide constraints on tectonic processes of the formation and evolution of the Anatolian Peninsula and the surrounding regions. Direct shear-wave splitting measurements in the Aegean to revealed mostly NNE-SSW oriented fast polarization directions, perpendicular to the trench and parallel to the mantle flow induced by the roll-back and large time delays (1.15-1.62 s) in the upper mantle. In southwestern Turkey the FPDs are more confusing and probably related to the tearing of the slab in the upper mantle underneath this region. With complex non-steady state 3D geodynamic modelling, the plate movement, mantle flow, anisotropy and SKS splitting parameters for the last 20-30 Ma in the regional subduction system of the eastern Mediterranean and Anatolia were calculated. The model shows that tearing underneath southwestern Turkey, a break-off in the collitional regime of eastern Anatolia as well as the retreat of the slab in the Aegean influence on the strength and direction of the mantle flow and anisotropy. At last a P-wave tomography study of the Eastern Mediterranean region, focusing on the upper mantle with a large data set was done. Since anisotropy is present in the region especially due to the active subduction system, travel times were corrected by including anisotropy as an aprori constraint, from the numerical model and SKS splitting parameters. In isotropic inversions as well as the ones corrected for anisotropy, tears in the northern Hellenic slab, underneath southwestern Turkey and in the Cyprian slab can be seen. Spatially large first order velocity perturbations are stable and similar in isotropic and anisotropy corrected models. But differences up to 2% and small geometrical discrepancies beween the models show the importance of including anisotropy to P-wave tomographies.& &
Publisher: Elsevier BV
Date: 03-2013
Publisher: American Geophysical Union (AGU)
Date: 03-2019
DOI: 10.1029/2018JB016837
Publisher: Wiley
Date: 09-07-2022
Publisher: American Geophysical Union (AGU)
Date: 12-2022
DOI: 10.1029/2022JB024663
Abstract: Ambient noise seismic data are widely used by geophysicists to explore subsurface properties at crustal and exploration scales. Two‐step dispersion inversion schema is the dominant method used to invert the surface wave data generated by the cross‐correlation of ambient noise signals. However, the two‐step methods have a 1‐D layered model assumption, which does not account for the complex wave propagation. To overcome this limitation, we employ a 2‐D wave‐equation dispersion (WD) inversion method which reconstructs the subsurface shear ( S ) velocity model in one step, and elastic wave‐equation modeling is used to simulate the subsurface wave propagation. In the WD method, the optimal S velocity model is obtained by minimizing the dispersion curve differences between the observed and predicted surface wave data, which makes WD method less prone to getting stuck to local minima. In our study, the observed Scholte waves are generated by cross‐correlating continuous ambient noise signals recorded by each ocean bottom node (OBN) in the 3‐D Gorgon OBN survey, Western Australia. For every two OBN lines, the WD method is used to retrieve the 2‐D S velocity structure beneath the first line. We then use a robust neural network (NN)‐based method to interpolate the inverted 2‐D velocity slices to a continuous 3‐D velocity model and also generate a corresponding uncertainty model. Moreover, we compared the predicted dispersion curves and waveforms to the observed data, and a robust waveform and dispersion match are observed across all of the Gorgon OBN lines.
Publisher: Oxford University Press (OUP)
Date: 06-12-2013
DOI: 10.1093/GJI/GGS064
Publisher: Informa UK Limited
Date: 11-11-2019
Publisher: Research Square Platform LLC
Date: 02-04-2021
DOI: 10.21203/RS.3.RS-145281/V1
Abstract: Oceanic crust is formed at mid-ocean spreading centres by a combination of magmatic, tectonic and hydrothermal processes. The crust formed by magmatic process consists of an upper crust generally composed of basaltic dikes and lava flows and a lower crust presumed to mainly contain homogeneous gabbro whereas that by tectonic process can be very heterogeneous and may even contain mantle rocks. Although the formation and evolution of the upper crust are well known from geophysical and drilling results, those for the lower crust remain a matter of debate. Using a full waveform inversion method applied to wide-angle seismic data, here we report the presence of layering in the lower oceanic crust formed at the slow spreading Mid-Atlantic Ridge, ~7-12 Ma in age, revealing that the lower crust is formed mainly by in situ cooling and crystallisation of melt sills at different depths by the injection of magma from the mantle. These layers are 400-600 m thick with alternate high and low velocities, with ± 100-200 m/s velocity variation, and cover over a million-year old crust, suggesting that the crustal accretion by melt sill intrusions beneath the ridge axis is a stable process. We also find that the upper crust is ~400 m thinner than that from conventional travel-time analysis. Taken together, these discoveries suggest that the magmatism plays more important roles in the crustal accretion process at slow spreading ridges than previously realised, and that in-situ lower crustal accretion is the main process for the formation of lower oceanic crust.
Location: Australia
Start Date: 06-2020
End Date: 06-2021
Amount: $700,000.00
Funder: Australian Research Council
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