Crustal structure and evolution of the outer Møre Margin, NE Atlantic

Five regional Ocean Bottom Seismic profiles from the northwestern part of the Møre Margin, NE Atlantic, have been modeled with regard to crustal structure, and the interpretations have been supported by the use of multi-channel seismic and potential field data. The chi-squared values (uncertainty) for the studied profiles are generally in the range 1-3, and the uncertainty in the Moho depth is estimated to +/- 1 km. The Continent-Ocean-Transition is found to be relatively sharp (10-40 km wide) expressing a change in physical properties corresponding to felsic continental crust along the landward part of the marginal high (Vp=6.2-6.5 km/s), and thick, mafic oceanic crust further northwestwards. The Early Eocene breakup was associated with excessive magmatism, and the models document direct continuity between this magmatism and a lower crustal high-velocity layer in the Møre Basin (Vp=7.1-7.3 km/s), suggesting a genetic link. The Jan Mayen Lineament is observed across the entire study area as northeastward termination of the lower crustal body, as well as structuring in the top of the crystalline basement and the Moho. We present a speculative model involving lower crustal bodies of eclogites (Vp > 8 km/s) inferred in the easternmost part of the Møre Basin linking the Jan Mayen Lineament to the post-Caledonian Nordfjord-Sogn Detachment

Doppler-guided transanal hemorrhoidal dearterilization versus conventional hemorrhoidectomy for treatment of hemorrhoids – early and long-term postoperative results

Abstract Background A variety of effective methods for treatment of hemorrhoids has been proposed. In recent years, there has been an increasing number of studies comparing transanal hemorrhoidal dearterilization (THD) and conventional hemorrhoidectomy (CH), but the focus of most studies has been about the early postoperative results. The data about long-term outcomes is still limited. We aimed to compare Doppler-guided THD and CH with regard to early and long-term postoperative results. Methods The conducted prospective research included 287 patients who underwent CH (167 cases) or Doppler-guided THD with mycopexy (120 patients) between November 2010 and December 2015. Information on hemorrhoidal stage, demographic data, presenting symptoms, complications, duration of hospital stay, postoperative pain, patients’ satisfaction and follow-up were obtained. Statistical tests were performed by SPSS 19.0. Results There was no significant difference between the studied groups according to gender, mean age, preoperative prolapse, pain and pruritus, hemorrhoidal stage and postoperative complications. Preoperative bleeding was more frequent in THD group (p = 0,002). The mean visual analog scale (VAS) pain scores in CH and THD groups on days 1, 2 and 7 were 7.01 vs 5.03, 5.07 vs 2.98, 2.39 vs 0,57 (p = 0,000). Practically, there was no difference in VAS on day 30 and patients’ satisfaction at the 18th month. Mean hospital stay was 5,13 (CH) and 3,38 days (THD), p = 0,000. The postoperative follow-up was between 18 and 78 months (mean 46 ± 16 months). During this stage, 5 patients (2,99%) in CH group required surgery for recurrence. In THD group, 3 patients (2,5%), all with 4th-degree hemorrhoids underwent additional procedures (p 0,802). Conclusions Doppler-guided THD seems to be an efficient and safe option for treatment of hemorrhoids, related to lower postoperative pain and excellent, similar long-term outcomes compared to CH. For advanced grades of hemorrhoids, Doppler-guided THD could be a valuable alternative, but there is a need for patients’ selection. Trial registration (retrospectively registered) researchregistry3090

Deep structure of the central Lesser Antilles Island Arc : relevance for the formation of continental crust

Oceanic island arcs are sites of high magma production and contribute to the formation of continental crust. Geophysical studies may provide information on the configuration and composition of island arc crust, however, to date only few seismic profiles exist across active island arcs, limiting our knowledge on the deep structure and processes related to the production of arc crust. We acquired active-source wide-angle seismic data crossing the central Lesser Antilles island arc north of Dominica where the oceanic Tiburon Ridge subducts obliquely beneath the forearc. A combined analysis of wide-angle seismics and pre-stack depth migrated reflection data images the complex structure of the backstop and its segmentation into two individual ridges, suggesting an intricate relation between subducted basement relief and forearc deformation. Tomographic imaging reveals three distinct layers composing the island arc crust. A three kilometer thick upper crust of volcanogenic sedimentary rocks and volcaniclastics is underlain by intermediate to felsic middle crust and plutonic lower crust. The island arc crust may comprise inherited elements of oceanic plateau material contributing to the observed crustal thickness. A high density ultramafic cumulates layer is not detected, which is an important observation for models of continental crust formation. The upper plate Moho is found at a depth of 24 km below the sea floor. Upper mantle velocities are close to the global average. Our study provides important information on the composition of the island arc crust and its deep structure, ranging from intermediate to felsic and mafic conditions. In this study we model the deep structure of the Lesser Antilles Island Arc. We use a hybrid analysis of refraction and reflection seismic data. We image the complex structure of two ridges forming the backstop. Island arc crust composition ranges from intermediate to felsic to mafic conditions. We discuss the formation of island arc and continental crust