The GOLD project - Drilling in the Western Mediterranean Sea

ECORD NEWSLETTER 16The "GOLD" IODP Project aims to recover the complete history of the Gulf of Lion (25-30 Ma) with a specific focus on Global Climate and Sea-level Changes, Extreme Events, Margin formation, Natural Resources and the Deep Biosphere using dedicated drilling Platform (MSP, Joides and Chikyu). It should be emphasized that no academic drillings dealing with pre-5million years exist in the Mediterranean Sea

Messinian erosional and salinity crises: View from the Provence Basin (Gulf of Lions, Western Mediterranean)

International audienceThough the late Miocene “Messinian Salinity Crisis” has been intensely researched along the circum-Mediterranean basins, few studies have focused on the central part of the Mediterranean Basin and, especially, the pre-salt deposits. To improve our knowledge of the Messinian events, it is imperative to better understand this domain. In this study, we provide a more complete understanding of this central domain in the Provence Basin. We were able to recognize: a) thick marine detrital series (up to 1000 m) derived from the Messinian subaerial erosion which is partly prolongated in the distal part by b) a thick unit of deep marine deposits (up to 800 m) prior to the evaporites; c) a thick presumed alternation of detritals and evaporites (1500 m) below the mobile halite; and d) a two-step transgression at the end of the Messinian. Spatially, we document the eroded shelf to the deep basin (and from the western to the eastern parts of the Gulf of Lions), and temporally, we extend the interpretations from the early deposition of detritic sediments to the final sea-level rise. The results provide a new basis for discussion not only for the development of the Messinian Salinity Crisis but also for the reconstruction of the subsidence history of the Provence Basin

Structure and evolution of the Gulf of Lions: The Sardinia seismic experiment and the GOLD (Gulf of Lions Drilling) project

International audienceThe study of the deep structure and evolution of passive continental margins is important for the understanding of rifting processes and the formation of associated sedimentary basins. Since the classical models of McKenzie (1978) and Wernicke (1985), understanding how passive continental margins form, that is to say mainly the way that continental lithosphere is thinned leading to subsidence, remains one of the main challenges in the Earth sciences. Many recent observations and discoveries have modified our basic views of margin formation. The conservational models paradigm (i.e., simple shear, pure shear, or polyphase models), which exclude exchanges between lower continental crust and upper mantle and which are usually proposed to explain lithospheric stretching and consequent crustal thinning of passive continental margins, fail to completely explain all these observations. Furthermore, these models imply a large amount of horizontal movement, movements not observed in the field. In consequence, new concepts need to be built and tested

Effects of Blended (Yellow) vs Forced Coagulation (Blue) Currents on Adverse Events, Complete Resection, or Polyp Recurrence After Polypectomy in a Large Randomized Trial

Background & aims: There is debate over the type of electrosurgical setting that should be used for polyp resection. Some endoscopists use a type of blended current (yellow), whereas others prefer coagulation (blue). We performed a single-blinded, randomized trial to determine whether type of electrosurgical setting affects risk of adverse events or recurrence. Methods: Patients undergoing endoscopic mucosal resection of nonpedunculated colorectal polyps 20 mm or larger (n = 928) were randomly assigned, in a 2 × 2 design, to groups that received clip closure or no clip closure of the resection defect (primary intervention) and then to either a blended current (Endocut Q) or coagulation current (forced coagulation) (Erbe Inc) (secondary intervention and focus of the study). The study was performed at multiple centers, from April 2013 through October 2017. Patients were evaluated 30 days after the procedure (n = 919), and 675 patients underwent a surveillance colonoscopy at a median of 6 months after the procedure. The primary outcome was any severe adverse event in a per patient analysis. Secondary outcomes were complete resection and recurrence at first surveillance colonoscopy in a per polyp analysis. Results: Serious adverse events occurred in 7.2% of patients in the Endocut group and 7.9% of patients in the forced coagulation group, with no significant differences in the occurrence of types of events. There were no significant differences between groups in proportions of polyps that were completely removed (96% in the Endocut group vs 95% in the forced coagulation group) or the proportion of polyps found to have recurred at surveillance colonoscopy (17% and 17%, respectively). Procedural characteristics were comparable, except that 17% of patients in the Endocut group had immediate bleeding that required an intervention, compared with 11% in the forced coagulation group (P = .006). Conclusions: In a randomized trial to compare 2 commonly used electrosurgical settings for the resection of large colorectal polyps (Endocut vs forced coagulation), we found no difference in risk of serious adverse events, complete resection rate, or polyp recurrence. Electrosurgical settings can therefore be selected based on endoscopist expertise and preference

Clip Closure Prevents Bleeding After Endoscopic Resection of Large Colon Polyps in a Randomized Trial

Background & aims: Bleeding is the most common severe complication after endoscopic mucosal resection of large colon polyps and is associated with significant morbidity and cost. We examined whether prophylactic closure of the mucosal defect with hemoclips after polyp resection reduces the risk of bleeding. Methods: We performed a multicenter, randomized trial of patients with a large nonpedunculated colon polyp (≥20 mm) at 18 medical centers in North America and Spain from April 2013 through October 2017. Patients were randomly assigned to groups that underwent endoscopic closure with a clip (clip group) or no closure (control group) and followed. The primary outcome, postprocedure bleeding, was defined as a severe bleeding event that required hospitalization, a blood transfusion, colonoscopy, surgery, or another invasive intervention within 30 days after completion of the colonoscopy. Subgroup analyses included postprocedure bleeding with polyp location, polyp size, or use of periprocedural antithrombotic medications. We also examined the risk of any serious adverse event. Results: A total of 919 patients were randomly assigned to groups and completed follow-up. Postprocedure bleeding occurred in 3.5% of patients in the clip group and 7.1% in the control group (absolute risk difference [ARD] 3.6%; 95% confidence interval [CI] 0.7%-6.5%). Among 615 patients (66.9%) with a proximal large polyp, the risk of bleeding in the clip group was 3.3% and in the control group was 9.6% (ARD 6.3%; 95% CI 2.5%-10.1%); among patients with a distal large polyp, the risks were 4.0% in the clip group and 1.4% in the control group (ARD -2.6%; 95% CI -6.3% to -1.1%). The effect of clip closure was independent of antithrombotic medications or polyp size. Serious adverse events occurred in 4.8% of patients in the clip group and 9.5% of patients in the control group (ARD 4.6%; 95% CI 1.3%-8.0%). Conclusions: In a randomized trial, we found that endoscopic clip closure of the mucosal defect following resection of large colon polyps reduces risk of postprocedure bleeding. The protective effect appeared to be restricted to large polyps located in the proximal colon

Percutaneous transhepatic vs. endoscopic retrograde biliary drainage for suspected malignant hilar obstruction: study protocol for a randomized controlled trial

Abstract Background The optimal approach to the drainage of malignant obstruction at the liver hilum remains uncertain. We aim to compare percutaneous transhepatic biliary drainage (PTBD) to endoscopic retrograde cholangiography (ERC) as the first intervention in patients with cholestasis due to suspected malignant hilar obstruction (MHO). Methods The INTERCPT trial is a multi-center, comparative effectiveness, randomized, superiority trial of PTBD vs. ERC for decompression of suspected MHO. One hundred and eighty-four eligible patients across medical centers in the United States, who provide informed consent, will be randomly assigned in 1:1 fashion via a web-based electronic randomization system to either ERC or PTBD as the initial drainage and, if indicated, diagnostic procedure. All subsequent clinical interventions, including crossover to the alternative procedure, will be dictated by treating physicians per usual clinical care. Enrolled subjects will be assessed for successful biliary drainage (primary outcome measure), adequate tissue diagnosis, adverse events, the need for additional procedures, hospitalizations, and oncological outcomes over a 6-month follow-up period. Subjects, treating clinicians and outcome assessors will not be blinded. Discussion The INTERCPT trial is designed to determine whether PTBD or ERC is the better initial approach when managing a patient with suspected MHO, a common clinical dilemma that has never been investigated in a randomized trial. Trial registration ClinicalTrials.gov, Identifier: NCT03172832 . Registered on 1 June 2017.https://deepblue.lib.umich.edu/bitstream/2027.42/142379/1/13063_2018_Article_2473.pd

Asymmetry of the mantle structure beneath the Mid-Atlantic Ridge

Altimetry data from repetitive orbits of the GEOSAT satellite are interpreted together with sea-floor depths over the Mid-Atlantic Ridge, South of Iceland and South of the Azores. Geoid / Topography ratios indicate a strong asymmetry of the upper mantle structure in oceanic areas created since 35 My, extending several hundreds kilometers from Iceland to the Azores. A model including interaction between the MAR and two layers of mantle convection seems adequate to produce the observed asymmetry

South and Equatorial Atlantic Margins

The margins of the North Atlantic Ocean, including the Newfoundland and Iberian Margins, present two distinct episodes of rifting: at Permian–Trias times and in the middle Cretaceous. In the South Atlantic Ocean, rifting occurred on the location of the Pan-African suture, more than 450 Ma after its formation, and the two events are clearly dissociated. At first order, the geodynamic segmentation of the South and Equatorial Atlantic Oceans leads to the formation of different types of passive margins, showing a relationship between the regional geodynamic context and the structural architecture of passive margins. The Central Segment of the South Atlantic Ocean is characterized by sedimentary basins with pre- and syn-break-up magmatism, and the presence of an approximately 1–2 km-thick salt layer in the so-called continent-ocean transition, overlying a mainly non-marine sequence

A comprehensive compilation of the seismic stratigraphy markers along the Adriatic Sea

Data base compilation, Adriatic sea (Seanoe document)The Mediterranean Sea is a natural laboratory for addressing questions on the formation and evolution of continental margins and the relationship between surface and deep processes. The evaporites deposited during the Messinian Salinity Crisis strongly impact its sedimentary and geomorphology evolution. We present here a compilation of the main regional seismic stratigraphic markers throughout the Central and South Adriatic Sea (CAB and SAB). The following original (uninterpolated) interpretations are provided in xyz format (z in second twt): i) Top of the Mesozoic formation, ii) Base and Top of the Gessoso Solfifera along the CAB, iii) Base and Top of the MSC detrital formation along the SAB, iv) Top of the Upper Unit, v) Base and Top of the middle Pliocene unit, vi) Seafloor. The available reflection seismic dataset the data set is compiled of processed vintage seismic profiles from the Videpi database