Synchronous reorientation of the Woodlark Basin spreading center

Abstract A sidescan and multibeam bathymetry survey of the Woodlark Basin reveals that its 500-km-long spreading center reoriented synchronously, without propagation, about 80 ka. There is no evidence of the V-shaped pseudofault geometry typical of spreading center propagation, nor of the progressive fanning of seafloor fabric characteristic of spreading center rotation. The reorientation is recognized by a sharp contact between two seafloor fabric trends, and ruptured off-axis lithosphere formed up to 0.7 m.y. previously. The length of the reoriented spreading segments and the tendency to fault pre-reorientation seafloor fabric are controlled by the strength of the lithosphere, the angle of the reorientation, and the length of preexisting spreading and transform segments. We document the process of synchronous reorientation in the Woodlark Basin and propose that it may occur in other ocean basins

The Impact of Falls: A Qualitative Study of the Experiences of People Receiving Haemodialysis

The prevalence of falls is high in people receiving haemodialysis (HD). This study aimed to explore the experiences of people receiving HD who had fallen in the last six months. A qualitative study, informed by constructivist grounded theory, used semi-structured interviews in combination with falls diaries. Twenty-five adults (mean age of 69 ± 10 years, 13 female, 13 White British) receiving HD with a history of at least one fall in the last six months (median 3, IQR 2−4) participated. Data were organised within three themes: (a) participants’ perceptions of the cause of their fall(s): poor balance, weakness, and dizziness, exacerbated by environmental causes, (b) the consequences of the fall: injuries were disproportionate to the severity of the fall leading to loss of confidence, function and disruptions to HD, (c) reporting and coping with falls: most did not receive any specific care regarding falls. Those who attended falls services reported access barriers. In response, personal coping strategies included avoidance, vigilance, and resignation. These findings indicate that a greater focus on proactively identifying falls, comprehensive assessment, and timely access to appropriate falls prevention programmes is required to improve care and outcomes

Rapid spatiotemporal variations in rift structure during development of the Corinth Rift, central Greece

The Corinth Rift, central Greece, enables analysis of early rift development as it is young (<5Ma) and highly active and its full history is recorded at high resolution by sedimentary systems. A complete compilation of marine geophysical data, complemented by onshore data, is used to develop a high-resolution chronostratigraphy and detailed fault history for the offshore Corinth Rift, integrating interpretations and reconciling previous discrepancies. Rift migration and localization of deformation have been significant within the rift since inception. Over the last circa 2Myr the rift transitioned from a spatially complex rift to a uniform asymmetric rift, but this transition did not occur synchronously along strike. Isochore maps at circa 100kyr intervals illustrate a change in fault polarity within the short interval circa 620-340ka, characterized by progressive transfer of activity from major south dipping faults to north dipping faults and southward migration of discrete depocenters at ~30m/kyr. Since circa 340ka there has been localization and linkage of the dominant north dipping border fault system along the southern rift margin, demonstrated by lateral growth of discrete depocenters at ~40m/kyr. A single central depocenter formed by circa 130ka, indicating full fault linkage. These results indicate that rift localization is progressive (not instantaneous) and can be synchronous once a rift border fault system is established. This study illustrates that development processes within young rifts occur at 100kyr timescales, including rapid changes in rift symmetry and growth and linkage of major rift faults

26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15–20 July 2017

This work was produced as part of the activities of FAPESP Research,\ud Disseminations and Innovation Center for Neuromathematics (grant\ud 2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud supported by a CNPq fellowship (grant 306251/2014-0)

Ages and two-way travel times of ODP Sites 180-1109, 180-1115 and 180-1118

Synthetic seismograms are constructed from check shot-corrected velocity and density measurements collected during Ocean Drilling Program (ODP) Leg 180 at Sites 1109, 1115, and 1118. The synthetic seismograms facilitate direct correlation of a coincident multichannel seismic (MCS) profile with borehole data collected at the three sites. The MCS data and the synthetic seismograms correlate very well, with most major reflectors successfully reproduced in the synthetics. Our results enable a direct calibration of the MCS data in terms of age, paleoenvironment, and subsidence history. Seismic reflectors are time correlative within stratigraphic resolution but are often observed to result from different lithologies across strike. Our results facilitate the extrapolation of the sedimentation history into an unsampled section of Site 1118 and enable a full correlation between the three sites using all the data collected during ODP Leg 180. This study forms the foundation for regionalizing the site data to the northern margin of the Woodlark Basin, where the transition from continental rifting to seafloor spreading is taking place

Reconciling Extension from Brittle Faulting, Subsidence, and Kinematic Reconstructions: Lessons from the Woodlark Basin*

In contrast to ancient rift margins where many of the mechanisms vital to the formation of the margin have long since been hidden, the Woodlark Basin of Papua New Guinea offers the opportunity to study active rift processes. Near the rifting-to-seafloor spreading transition the asymmetric rift system comprises large tilted fault blocks on the southern margin and a principally unfaulted northern margin that has subsided more than 3 km. As is often the case, estimates of extension derived by examining brittle faulting fall short of those calculated through subsidence. However, by including multiple phases of faulting and sub-resolution faulting, this gap can be closed- resulting in a total of 111+/-23km of extension. Assuming Airy isostasy, the extension calculated from subsidence along the same profile is 115+/-45 km. Though these estimates are in close agreement, it remains that locally a mechanism such as lower-crustal flow must be important. Extension can also be estimated by fitting Euler poles to fracture zones and magnetic chrons in the oceanic lithosphere. This gives an estimate of more than 200 km of extension since 6 Ma. Given that the basin has been opening since at least 8.4 Ma, this estimate far exceeds those predicted by brittle extension and subsidence. Can these extension estimates be reconciled? Estimates of brittle extension have so far ignored the potential role of metamorphic core complexes (MCC). At an MCC the upper crust has been removed- a 30 km wide MCC represents 30 km of extension. MCCs have not yet been identified along the study profile, but an MCC that has been dissected by normal faults may not be visible. The extension discrepancy may also be explained by a detachment between the mantle lithosphere and the upper crust. In this case, estimates of extension from Euler pole kinematics should not agree with othe

Subduction of Submarine Arc Volcanoes Beneath the Solomon Islands Arc

In the Solomon Islands, arc magmas are erupting on the subducting Australia Plate. These island (Simbo) and submarine arc volcanoes (Kana Keoki, Coleman and Pavuvu) are about to be recycled by rapid subduction. We identify eight of their former equivalents beneath the forearc by the morphologies and deformation structures that are characteristic of seamount subduction. Tsunamigenic earthquakes recently nucleated just ahead of two of the subducting seamounts. A third (Pavuvu), that has indented the subduction front and uplifted the lower forearc, is associated with a historic earthquake gap. It is positioned such that a rupture there has the potential for tsunami waves to impact the capital, Honiara