Seismic evidence of small-scale lacustrine drifts in Lake Baikal (Russia)

High resolution, single-channel seismic sparker profiles across the Akademichesky Ridge, an intra-basin structural high in Lake Baikal (Russia), reveal the presence of small sediment mounds and intervening moats in the upper part of the sedimentary cover. Such features interrupt the generally uniform and even acoustic facies and are not consistent with the hemipelagic sedimentation expected on such an isolated high, which would produce a uniform sediment drape over bottom irregularities. The influence of turbidity currents is excluded since the ridge is an isolated high, elevated more than 600-1000 m above adjacent basins. The mounded seismic facies includes migrating sediment waves and non-depositional/erosional incisions that strongly suggest sediment accumulation was controlled by bottom-current activity. We interpret the mounds as small-scale (few tens of km2 in area) lacustrine drifts. Four basic types of geometry are identified: 1) slope-plastered patch sheets; 2) patch drifts; 3) confined drifts; 4) fault-controlled drifts. The general asymmetry in the sedimentary cover of the ridge, showing thicker deposits on the NW flank, and the common location of patch drifts on the northeast side of small basement knolls, indicate that deposition preferentially took place on the lee sides of obstacles to a current flowing northward or sub-parallel to the main contours. Deep-water circulation in the ridge area is not known in detail, but there are indications that relatively cold saline water masses are presently flowing out of the Central Basin and plunging into the deep parts of the North Basin across the ridge, a process that appears to be driven mainly by small differences in salinity. We infer that the process responsible for the observed bottom-current-controlled sedimentary features has to be sought in these large-scale water-mass movements and their past equivalents. The age of the onset of the bottom-current-controlled sedimentation, based on an average sedimentation rate of 4.0 cm/ky, is roughly estimated to be at least 3.5 Ma, which is generally regarded as the age of the onset of the last major tectonic pulse of rift basin development in the Baikal region

Mega debris flow deposits on the western Wilkes Land margin, East Antarctica

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Rewiring Neural Interactions by Micro-Stimulation

Plasticity is a crucial component of normal brain function and a critical mechanism for recovery from injury. In vitro, associative pairing of presynaptic spiking and stimulus-induced postsynaptic depolarization causes changes in the synaptic efficacy of the presynaptic neuron, when activated by extrinsic stimulation. In vivo, such paradigms can alter the responses of whole groups of neurons to stimulation. Here, we used in vivo spike-triggered stimulation to drive plastic changes in rat forelimb sensorimotor cortex, which we monitored using a statistical measure of functional connectivity inferred from the spiking statistics of the neurons during normal, spontaneous behavior. These induced plastic changes in inferred functional connectivity depended on the latency between trigger spike and stimulation, and appear to reflect a robust reorganization of the network. Such targeted connectivity changes might provide a tool for rerouting the flow of information through a network, with implications for both rehabilitation and brain–machine interface applications

Geomorphology and development of a high-latitude channel system: the INBIS channel case (NW Barents Sea, Arctic)

This is a post-peer-review, pre-copyedit version of an article published in Arktos. The final authenticated version is available online at: http://dx.doi.org/https://doi.org/10.1007/s41063-019-00065-9 .The INBIS (Interfan Bear Island and Storfjorden) channel system is a rare example of a deep-sea channel on a glaciated margin. The system is located between two trough mouth fans (TMFs) on the continental slope of the NW Barents Sea: the Bear Island and the Storfjorden–Kveithola TMFs. New bathymetric data in the upper part of this channel system show a series of gullies that incise the shelf break and minor tributary channels on the upper part of the continental slope. These gullies and channels appear far more developed than those on the rest of the NW Barents Sea margin, increasing in size downslope and eventually merging into the INBIS channel. Morphological evidence suggests that the Northern part of the INBIS channel system preserved its original morphology over the last glacial maximum (LGM), whereas the Southern part experienced the emplacement of mass transport glacigenic debris that obliterated the original morphology. Radiometric analyses were applied on two sediment cores to estimate the recent (~ 110 years) sedimentation rates. Furthermore, analysis of grain size characteristics and sediment composition of two cores shows evidence of turbidity currents. We associate these turbidity currents with density-driven plumes, linked to the release of meltwater at the ice-sheet grounding line, cascading down the slope. This type of density current would contribute to the erosion and/ or preservation of the gullies’ morphologies during the present interglacial. We infer that Bear Island and the shallow morphology around it prevented the flow of ice streams to the shelf edge in this area, working as a pin (fastener) for the surrounding ice and allowing for the development of the INBIS channel system on the inter-ice stream part of the slope. The INBIS channel system was protected from the burial by high rates of ice-stream derived sedimentation and only partially affected by the local emplacement of glacial debris, which instead dominated on the neighbouring TMF systems

Санитарно-эпидемиологическая экспертиза импортной пищевой продукции и продовольственного сырья как составляющая профилактического направления транспортной медицины

Санітарно епідеміологічна експертиза імпортної харчової продукції й продовольчої сировини (далі експертиза) є одним з пріоритетних напрямів діяльності транспортних підрозділів санепідслужби. Здійснюючи функцію по контролю, виявленню та попередженню впливу небезпечних факторів, пов’язаних з перевезенням вантажів, вона є однією зі складових частин профілактичного напряму транспортної медицини. Експертиза імпортованої продукції харчового призначення нерозривно пов’язана та базується на загальних принципах всієї державної політики у сфері безпеки харчової продукції та продовольчої сировини. Основою для проведення усього комплексу робіт санітарно епідеміологічного направлення є нормативна база, яка була сформована в нашій країні кілька десятиліть назад. Механізм визначення безпеки продукції та ті критерії оцінки, які були закладені в її основі, вимагають перегляду у відповідності з вимогами сьогодення та враховуючи розвиток міжнародних відносин. Зроблені деякі кроки у цьому напрямку. Наприклад, визначення експертизи у законі «Про внесення змін до закону України «Про якість та безпеку харчових продуктів та продовольчої сировини» поряд зі встановленням відповідності продукції нормативним вимогам передбачає оцінку ризику дії шкідливих факторів у процесі обігу харчових продуктів, що відповідає сучас ним вимогам до вирішення задач профілактичного напрямку, запобігання шкідливого впливу факторів, керування санітарно-епідеміологічною ситуацією взагалі та на етапі транспортування харчових грузів зокрема. Такий підхід потрібно враховувати при подальшому необхідному перегляді та формуванні нової нормативної бази.Sanіtarу epidemiological examination of imported foodstuffs and edible raw materials (then «examination») is one of the priority directions of transport sanіtarу epidemiological servise. Examination controls, discovers and prevents an influence of dangerous factors while in transportation of loads. So it’s one of the component of the transport medicine preventive activity. Examination of import foodstuffs and edible raw materials inseparably linked with and based on general principles of the food safety state policy. The foundation of the sanitary service work is the normative base, that was formed in our country about twenty years ago. It is necessary to review the mechanism of the food safety determination and its criteria in accordance with requirements of present day time and with account of the development of the international relations. One of taken steps in this direction is a characteristic of examination in law «About contributing the modification to law of the Ukraine «About quality and safety of foodstuffs and foodraw materials» where along with determination of the products correspondence to the normative requirements is provided forrisk assessment of the harmful factors in process of the turn of the food stuffs. Such approach corresponds with modern requests to decision of the prophylactic problems, prevention bad influence dangerous factors, management sanіtarу epidemiological situation in general and in step of transportation food cargo in particular. And it should be taken into account during the further necessary process of revision and forming the new normative base

The depositional record of the Odyssea drift (Ross Sea, Antarctica)

The Ross Sea is one of the major areas for Antarctic Bottom Water formation (the Ross Sea Bottom Water, RSBW), representing the densest ocean water mass, filling the deepest ocean basins connected to the southern ocean. Peri- odic refill of the RSBW occurs through formation of dense, cold and saline water masses (brine) forming on the shelf at the Ross Sea permanent polynya by freezing and salt rejection (high-salinity shelf water, HSSW). The HSSW periodically overspills the shelf area and descends along the slope. This mechanism represents the engine of the global ocean circulation regulating the climate. The Hillary Canyon, crossing the Ross Sea continental slope, represents one of the main conducts through which the HSSW descends the slope to reach the deeper ocean. On its western levee, there is a mounded depocen- tre that was mapped and ground-sampled during the Italian ITRS17-ODYSSEA expedition on board the RV OGS-Explora (January-February 2017). Geophysical data allowed interpreting such feature as a sediment drift (ODYSSEA Drift), generated by along-slope, contour currents sediment transport and accumulation through sev- eral hundred-thousands years. It was inferred that contour currents transported and deposited the sediments that descent the Hillary Canyon by means of the HSSW. Therefore, the depositional sequence of the ODYSSEA Drift potentially contains the record of the variability of HSSW formation, the along slope current intensity in associa- tion to climate change, and the interplay between the two bottom currents. A multidisciplinary investigation was applied to six gravity cores collected in the proximal and distal area of the ODYSSEA Drift. The cores were analysed to reconstruct the age model combining AMS radiocarbon dating on foraminifera tests, biostratigraphy, and the sediment palaeomagnetic record; the sediment physical properties (wet bulk density, water content and grain size); and compositional characteristics (XRF core scan and geochemistry). Three main lithofacies were distinguished and associated to depositional processes and climatic conditions: 1) finely laminated and bioturbated sediments characterized by a relatively high Ca content with common presence of biogenic component. Such facies was associated to contour current deposition during relatively warm conditions. 2) Bioturbated sediments with abundant, sparse and/or layered Ice Rafted Debris, and high Ca content. The onset of this facies is characterized by a prominent Mn peak that was associated to bottom ocean oxygenation through ice sheet melting/decay. 3) Laminated, barren sediments associated to steady strong bottom currents under harsh climate conditions. Further preliminary data interpretations are discussed

The International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 3.0

[1] The International Bathymetric Chart of the Arctic Ocean (IBCAO) released its first gridded bathymetric compilation in 1999. The IBCAO bathymetric portrayals have since supported a wide range of Arctic science activities, for example, by providing constraint for ocean circulation models and the means to define and formulate hypotheses about the geologic origin of Arctic undersea features. IBCAO Version 3.0 represents the largest improvement since 1999 taking advantage of new data sets collected by the circum-Arctic nations, opportunistic data collected from fishing vessels, data acquired from US Navy submarines and from research ships of various nations. Built using an improved gridding algorithm, this new grid is on a 500 meter spacing, revealing much greater details of the Arctic seafloor than IBCAO Version 1.0 (2.5 km) and Version 2.0 (2.0 km). The area covered by multibeam surveys has increased from ∼6% in Version 2.0 to ∼11% in Version 3.0

The Baiyun Slide Complex, South China Sea: a modern example of slope instability controlling submarine-channel incision on continental slopes

The Baiyun Slide Complex is one of the largest submarine landslides on the northern margin of the South China Sea. Newly acquired high-resolution bathymetric data, 2D and 3D seismic data permitted the systematic investigation of the Baiyun Slide Complex in terms of its seafloor morphology and associated sedimentary processes. The headwall region of the Baiyun Slide Complex, located at a water depth between 1000 m and 1700 m, is U-shaped and opens towards the east. It was efficiently and almost completely evacuated, generating pronounced headwall and sidewall scarps. Submarine channels, sediment waves, migrating channels, sediment drifts and moats are observed within and around the headwall region, illustrating the effects of both downslope and along-slope sedimentary processes. Submarine channels are 16–37 km-long 800-1500 m-wide, and 20 to 50 m-deep. As a modern example of the interplay between slope instability and subsequent incision, submarine channels were generated after the formation of the Baiyun Slide scar to suggest intensified downslope sedimentary processes after the slope collapsed. The initiation and formation of these submarine channels result from the evacuation of the Baiyun Slide scar, which provided the necessary space of the continental slope to accommodate subsequent turbidity and mass wasting flows. Our results are an important example of how submarine landslides can influence erosional and depositional processes on continental margins

The discovery of the southernmost ultra-high-resolution Holocene paleoclimate sedimentary record in Antarctica

The response of the Antarctic ice sheet to climate warming is the main source of uncertainty regarding future global sea level rise, since little is known about its present and past dynamics. The last deglaciation is the most recent interval of large-scale climate warming, during which the Northern and Southern Hemisphere ice sheets retreated, and sea level rose globally, although at a non-uniform rate. Geologic records from the polar regions are fundamental in determining the factors that caused the major changes in ice sheets during the last deglacial under different boundary conditions. Here, we combine morpho-bathymetric and seismic data with sediment cores and oceanographic measurements to reconstruct the processes that influenced the deposition of the southernmost, most extensive, ultrahigh-resolution record of the Holocene in Edisto Inlet fjord (Ross Sea, Antarctica). We find that post-glacial sedimentation resulted in a layered diatom mud up to 110 m thick that was locally redistributed by bottom currents over confined drifts-moats in the central part of the fjord. After the Holocene climatic optimum, the fjord was not carved by ground ice, and there continued to be internal fjord water circulation associated with Ross Sea circulation. These results support a retreat of coastal glaciers by about 11 kiloyears ago (ka) from the continental shelf of North Victoria Land

Architecture of North Atlantic contourite drifts modified by transient circulation of the Icelandic mantle plume

Overflow of Northern Component Water, the precursor of North Atlantic Deep Water, appears to have varied during Neogene times. It has been suggested that this variation is moderated by transient behavior of the Icelandic mantle plume, which has influenced North Atlantic bathymetry through time. Thus pathways and intensities of bottom currents that control deposition of contourite drifts could be affected by mantle processes. Here, we present regional seismic reflection profiles that cross sedimentary accumulations (Björn, Gardar, Eirik and Hatton Drifts). Prominent reflections were mapped and calibrated using a combination of boreholes and legacy seismic profiles. Interpreted seismic profiles were used to reconstruct solid sedimentation rates. Björn Drift began to accumulate in late Miocene times. Its average sedimentation rate decreased at ∼2.5 Ma and increased again at ∼0.75 Ma. In contrast, Eirik Drift started to accumulate in early Miocene times. Its average sedimentation rate increased at ∼5.5 Ma and decreased at ∼2.2 Ma. In both cases, there is a good correlation between sedimentation rates, inferred Northern Component Water overflow, and the variation of Icelandic plume temperature independently obtained from the geometry of diachronous V-shaped ridges. Between 5.5 and 2.5 Ma, the plume cooled, which probably caused subsidence of the Greenland-Iceland-Scotland Ridge, allowing drift accumulation to increase. When the plume became hotter at 2.5 Ma, drift accumulation rate fell. We infer that deep-water current strength is modulated by fluctuating dynamic support of the Greenland-Scotland Ridge. Our results highlight the potential link between mantle convective processes and ocean circulationThis work is partly supported by Natural Environment Research Council Grant NE/G007632/1. RPT was supported by the University of Cambridge Girdler Fund and by BP Exploration.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/2015GC00594