ORCID Profile
0000-0002-9843-7811
Current Organisation
University of Aberdeen
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-09-2020
Abstract: Seismic background noise dramatically decreased as a result of lockdown measures in place for mitigating the spread of COVID-19.
Publisher: American Geophysical Union (AGU)
Date: 11-2022
DOI: 10.1029/2022GC010564
Abstract: The relative paucity of recent post‐ subduction environments globally has meant that, so far, little is known about tectonic processes that occur during and after subduction termination, as previously convergent tectonic plates adjust to the new stress regime. The region of Southeast Asia that now encompasses northern Borneo has been host to two sequential episodes of subduction—both now terminated—since the mid‐Paleogene. It is expected that these processes will have left signatures in the fabric of the upper mantle, which are manifest in the form of seismic anisotropy. We investigate the evidence for, and alignment of, anisotropic fabrics by measuring the splitting of a family of teleseismic shear phases. These observations provide a measure of the orientation of the effective anisotropic elastic tensor, in the form of the orientation of the fast shear‐wave polarization, ϕ, and add constraints on the strength of the anisotropic fabric, in the form of the delay time, δt . We observe two principal trends across northern Borneo that appear to be confined to the lithosphere. These patterns are likely related to tectonic processes associated with subduction, continental collision, and oceanic basin formation, events that can exert primary influence on the formation of post‐subduction settings.
Publisher: American Geophysical Union (AGU)
Date: 04-02-2022
DOI: 10.1029/2021GL096117
Abstract: We use two‐plane‐wave tomography with a dense network of seismic stations across Sabah, northern Borneo, to image the shear wave velocity structure of the crust and upper mantle. Our model is used to estimate crustal thickness and the depth of the lithosphere‐asthenosphere boundary (LAB) beneath the region. Calculated crustal thickness ranges between 25 and 55 km and suggests extension in a NW‐SE direction, presumably due to back‐arc processes associated with subduction of the Celebes Sea. We estimate the β‐factor to be 1.3–2, well below the initiation of seafloor spreading. The LAB is, on average, at a depth of 100 km, which is inconsistent with models that ascribe Neogene uplift to wholescale removal of the mantle lithosphere. Instead, beneath a region of Plio‐Pleistocene volcanism in the southeast, we image a region 50–100 km across where the lithosphere has thinned to km, supporting recent suggestions of lower lithospheric removal through a Rayleigh‐Taylor instability.
Publisher: International Joint Conferences on Artificial Intelligence Organization
Date: 08-2019
Abstract: Trust evaluation of people and information on Twitter is critical for maintaining a healthy online social environment. How to evaluate the trustworthiness of users and tweets becomes a challenging question. In this demo, we show how our proposed CoTrRank approach deal with this problem. This approach models users and tweets in two coupled networks and calculate their trust values in different trust spaces. In particular, our solution provides a configurable way when mapping the calculated raw evidences to the trust values. The CoTrRank demo system has an interactive interface to show how our proposed approach produces more effective and adaptive trust evaluation results comparing with baseline methods.
Publisher: Elsevier BV
Date: 11-2017
Publisher: Research Square Platform LLC
Date: 08-09-2021
DOI: 10.21203/RS.3.RS-861968/V1
Abstract: Subduction is a key driver of plate tectonics on Earth1. A range of observations indicate that the termination of subduction leads to erse and unexplained tectonic and geological activity, including anomalous magmatism, exhumation and topographic subsidence, followed by rapid uplift. However, the mechanism driving this complex surface response remains enigmatic. A prime ex le of recent subduction termination can be found in northern Borneo (Malaysia), where subduction ceased in the late Miocene2 and was followed by a puzzling tectonic response3,4,5,6,7,8 that cannot be reconciled with our current understanding of post-subduction tectonics. Here, we use new passive-seismic data to image, in unprecedented detail, a sub-vertical lithospheric drip that developed as a Rayleigh-Taylor gravitational instability9 from the root of a volcanic arc. We use thermo-mechanical simulations to reconcile these images with time-dependent dynamical processes within the crust and underlying mantle following subduction termination. Our model predictions illustrate how significant extension from a downwelling lithospheric drip can thin the crust in an adjacent orogenic belt, facilitating lower crustal melting and possible exhumation of subcontinental material. Our study provides a new paradigm for core-complex formation in other areas of recent subduction termination.
Publisher: Elsevier BV
Date: 02-2019
Publisher: Elsevier BV
Date: 03-2023
Publisher: Elsevier BV
Date: 02-2017
Publisher: Wiley
Date: 15-03-2022
Publisher: Elsevier BV
Date: 04-2019
Publisher: Oxford University Press (OUP)
Date: 04-07-2019
DOI: 10.1093/GJI/GGZ057
Publisher: American Geophysical Union (AGU)
Date: 11-03-2017
DOI: 10.1002/2017GL072726
Publisher: American Geophysical Union (AGU)
Date: 11-10-2022
DOI: 10.1029/2022GL099123
Abstract: Subduction polarity reversal (SPR) is a key subduction initiation mechanism often associated with arc‐continent collision zones. Northern Borneo has long been recognized as a location where sequential but opposing subduction zones were present in the Miocene, but has not been examined in the context of SPR. Here, we exploit teleseismic data from northern Borneo to investigate crustal thickness variations using Virtual Deep Seismic Sounding (VDSS). Our results reveal a thick crustal root beneath the Crocker Range and an area of relatively thin crust in the southeast, which appears to extend northeast into the Sulu Sea, where back‐arc rifting behind the younger subduction zone developed. Overall, our findings are consistent with predictions from numerical models of SPR involving arc‐continent collision, but with several important differences—including a substantial mountain range and more limited back‐arc rifting that can be attributed to northern Borneo being an ex le of SPR involving continent‐continent collision.
Publisher: American Geophysical Union (AGU)
Date: 04-2018
DOI: 10.1002/2017JB015386
Publisher: Elsevier BV
Date: 09-2019
Publisher: Springer Science and Business Media LLC
Date: 19-06-2023
Publisher: Oxford University Press (OUP)
Date: 10-10-2020
DOI: 10.1093/GJI/GGAA475
Abstract: The deep crustal structure beneath the North Sea is poorly understood since it is constrained by only a few seismic reflection and refraction profiles. However, it is widely acknowledged that the mid to lower crust plays important roles in rift initiation and evolution, particularly when large-scale sutures and/or terrane boundaries are present, since these inherited features can focus strain or act as inhibitors to extensional deformation. Ancient tectonic features are known to exist beneath the iconic failed rift system of the North Sea, making it an ideal location to investigate the complex interplay between pre-existing regional heterogeneity and rifting. To this end, we produce a 3-D shear wave velocity model from transdimensional ambient seismic noise tomography to constrain crustal properties to ∼30 km depth beneath the North Sea and its surrounding landmasses. Major North Sea sedimentary basins appear as low shear wave velocity zones that are a good match to published sediment thickness maps. We constrain relatively thin crust (13–18 km) beneath the Central Graben depocentres that contrasts with crust elsewhere at least 25–30 km thick. Significant variations in crustal structure and rift symmetry are identified along the failed rift system that appears to be related to the locations of Laurentia–Avalonia–Baltica palaeoplate boundaries. We constrain first-order differences in structure between palaeoplates with strong lateral gradients in crustal velocity related to Laurentia–Avalonia–Baltica plate juxtaposition and reduced lower crustal velocities in the vicinity of the Thor suture, possibly representing the remnants of a Caledonian accretionary complex. Our results provide fresh insight into the pivotal roles that ancient terranes can play in the formation and failure of continental rifts and may help explain the characteristics of other similar continental rifts globally.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for David Cornwell.