Mud extrusion dynamics constrained from 3D seismics in the Mercator Mud Volcano. El Arraiche mud volcano field, Gulf of Cadiz

Located on the western Moroccan continental shelf of the Gulf of Cadiz, the Mercator Mud Volcano (MMV) is one of a total of eight mud volcanoes which compose the El Arraiche mud volcano field. We collected a high-resolution P-cable 3D seismic cube during the Charles Darwin cruise 178 in April 2006, covering an area of 25 km2. The data image the upper 500-1000 m of the MMV. El Arraiche mud volcano field is located in the top of the Tortonian accretionary wedge in the Gulf of Cadiz, between 200 and 700 m water deep. Despite of the general compressive trend of the Gulf of Cadiz due to the westward movement of the Gibraltar arc, the local regimen of the western Moroccan margin is extensional in the study area. The MMV is a 2.5 km diameter positive conical structure at 350 m water deep that rises from the flank of a salt diapir. The high-resolution 3D cube shows the main internal structure in the southern flank of an anticline and a secondary structure southwest of it. Parallel and continuous reflections onlapping the anticline structure define the seismic character outside the mud volcano. The body of the main structure shows the typical "Christmas tree" features related to mud flow deposits. The preliminary interpretation of the 3D seismic cube shows four main mud flows southwestward oriented from the main structure and interfingered into the hemipelagic regional sedimentation. From deeper to shallower, the flows are located approximately at 0.870 s, 0.838 s, 0.774 s, and 0.685 s travel time, respectively. The extrusions correlate with the main seismic sequences observed in the surrounding hemipelagic deposits. The maximum run-out distance for the mud flows is approximately 1 km southwestward from the main structure, which corresponds to the third youngest mud flow described. The secondary "Christmas tree" structure penetrates the hemipelagic sediments almost to the seabed. Its seismic character is defined by low amplitude and chaotic signal. Several mud flows are interfingered with the surrounding sediments and, in some cases, overlap the mud flows from the main structure but they are less extensive and thinner but more frequent than those from the main structure. The MMV is an active mud volcano and depends on complex fluid and mud dynamics. The existence of a secondary and apparently "abandoned" structure indicates the variation of mud pathways during the evolution of its plumbing system

The Postglacial response of Arctic Ocean gas hydrates to climatic amelioration

Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been argued that a gas hydrate gun could trigger abrupt climate change, the processes and rates of subsurface/atmospheric natural gas exchange remain uncertain. Here we investigate the dynamics between gas hydrate stability and environmental changes from the height of the last glaciation through to the present day. Using geophysical observations from offshore Svalbard to constrain a coupled ice sheet/gas hydrate model, we identify distinct phases of subglacial methane sequestration and subsequent release on ice sheet retreat that led to the formation of a suite of seafloor domes. Reconstructing the evolution of this dome field, we find that incursions of warm Atlantic bottom water forced rapid gas hydrate dissociation and enhanced methane emissions during the penultimate Heinrich event, the B?lling and Aller?d interstadials, and the Holocene optimum. Our results highlight the complex interplay between the cryosphere, geosphere, and atmosphere over the last 30,000 y that led to extensive changes in subseafloor carbon storage that forced distinct episodes of methane release due to natural climate variability well before recent anthropogenic warmingauthorsversionPeer reviewe

Организация самостоятельных физкультурно-оздоровительных занятий "Программа 100 минут"

Подготовлено в помощь студентам, осваивающим теоретический курс дисциплины «Физическое воспитание», в том числе и студентам, освобожденным от практических занятий по «Физическому воспитанию». Назначение учебного пособия заключается в том, чтобы представить сведения, необходимые для разработки студентами индивидуальных физкультурно- оздоровительных программ.Содержит знания об использовании различных средств рекреационной физической культуры, самомассажа, а также психологических средств восстановления и самоконтроля за своим функциональным состоянием. Усвоив их, студенты могут под контролем преподавателя разрабатывать такие оздоровительные программы занятий, которые будут учитывать исходное состояние здоровья и способствовать достижению стойкой ремиссии в ходе преодоления имеющихся заболеваний

Research perspectives of sediment waves and drifts: Monitors of global change in deepwater circulation

The purpose of this special section in Paleoceanography is to present interdisciplinary approaches for contributing to the reconstruction of ocean circulation and its response to climate changes. A high-priority objective for understanding the causes and mechanisms of climate change is the monitoring of past ocean circulation and oceanic heat and nutrient transport. Lehman and Keigwin [1992] have shown that cooling, for example, during the younger Dryas event, may have culminated in a cessation of the oceans conveyor circulation. The cooling in the North Atlantic was apparently the result of reduced northward heat transport in the upper water masses of the North Atlantic conveyor belt. In contrast, intervals with a strong surface and deepwater circulation were marked by a high northward heat transport. For the understanding of the causes and the timing of such rapid,highfrequency events, marine records of high deposition ratecores are needed. These cores should provide evidence for changes in abyssal circulation and heat transport, as well as arecord of surface and deepwater characteristics. The sediment drifts of the North Atlantic and in other ocean basins are one of the major targets for the recovery of sediments with high deposition rates (>10 cm/kyr) and for reconstructing the role of both intermediate and deepwater production in the conveyor belt, that is drawing low-latitude heat northward. We stress the need for international programs targeting high deposition rate areas on sediment drifts and sediment waves in order to understand (1) the evolution of the conveyor belt and (2) its dynamics and variability. The North Atlantic, where sediment drifts are concentrated, will provide ideal study areas with time resolutions comparable to those of ice core records but with records linked directly to the record of changing bottom water flow. Therefore one can address the changes in circulation, heat and carbon budget on high and ultrahigh resolution records

КЛАВИАТУРНЫЕ ШПИОНЫ

В данной работе приводится обзор клавиатурного шпионажа как одного из главных видов электронного мошенничества. Описана его «легальная» сторона и рассмотрены способы распространения. Так же приведены некоторые рекомендации защиты как от программных, так и от аппаратных клавиатурных шпионов

Triggering mechanism and tsunamogenic potential of the Cape Fear Slide complex, U.S. Atlantic margin

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 8 (2007): Q12008, doi:10.1029/2007GC001722.Analysis of new multibeam bathymetry data and seismic Chirp data acquired over the Cape Fear Slide complex on the U.S. Atlantic margin suggests that at least 5 major submarine slides have likely occurred there within the past 30,000 years, indicating that repetitive, large-scale mass wasting and associated tsunamis may be more common in this area than previously believed. Gas hydrate deposits and associated free gas as well as salt tectonics have been implicated in previous studies as triggers for the major Cape Fear slide events. Analysis of the interaction of the gas hydrate phase boundary and the various generations of slides indicates that only the most landward slide likely intersected the phase boundary and inferred high gas pressures below it. For much of the region, we believe that displacement along a newly recognized normal fault led to upward migration of salt, oversteepening of slopes, and repeated slope failures. Using new constraints on slide morphology, we develop the first tsunami model for the Cape Fear Slide complex. Our results indicate that if the most seaward Cape Fear slide event occurred today, it could produce waves in excess of 2 m at the present-day 100 m bathymetric contour.Acquisition of new data was funded by NOAA Ocean Exploration grant NA03OAR4600100 to C.R., and we thank the National Science Foundation for contributing to transit costs for the ship

Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere

© 2016. American Geophysical Union. All Rights Reserved. We find that summer methane (CH4) release from seabed sediments west of Svalbard substantially increases CH4 concentrations in the ocean but has limited influence on the atmospheric CH4 levels. Our conclusion stems from complementary measurements at the seafloor, in the ocean, and in the atmosphere from land-based, ship and aircraft platforms during a summer campaign in 2014. We detected high concentrations of dissolved CH4 in the ocean above the seafloor with a sharp decrease above the pycnocline. Model approaches taking potential CH4 emissions from both dissolved and bubble-released CH4 from a larger region into account reveal a maximum flux compatible with the observed atmospheric CH4 mixing ratios of 2.4-3.8 nmol m-2 s-1. This is too low to have an impact on the atmospheric summer CH4 budget in the year 2014. Long-term ocean observatories may shed light on the complex variations of Arctic CH4 cycles throughout the year.The project MOCA- Methane Emissions from the Arctic OCean to the Atmosphere: Present and Future Climate Effects is funded by the Research Council of Norway, grant no.225814 CAGE – Centre for Arctic Gas Hydrate, Environment and Climate research work was supported by the Research Council of Norway through its Centres of Excellence funding scheme grant no. 223259. Nordic Center of Excellence eSTICC (eScience Tool for Investigating Climate Change in northern high latitudes) funded by Nordforsk, grant no. 57001