Marine Geology Research Articles

Generic Mapping Tools and Matplotlib Package of Python for Geospatial Data Analysis in Marine Geology

Understanding patterns of the correlation between the geomorphology and geology of the seafloor of the hadal trenches is important for the proper ocean modelling. Current paper focuses on the west Pacific Ocean region with a special case of Mariana Trench, the deepest hadal trench on the planet. Methodology of the research include combination of Generic Mapping Tools (GMT) and Quantum GIS based mapping of the geographic location, bathymetry, geodesy, sediment thickness, geomorphic shape, tectonic and geologic structure of the Mariana Trench area, and statistical analysis by means of Python. A GMT was selected for GIS visualization due to its powerful functionality and effective cartographic solutions. An object-oriented high-level programming language, Python was chosen for the data analysis and scientific plotting. The statistical analysis includes following steps: 1) Data distribution by the box plots; 2) Data sorting and grouping by stem plots; 3) Correlation analysis by 3D comparative plots referred to four tectonic plates; 4) Principal Component Analysis; 5) Analysis of Variance. The statistical analysis of the data set was performed in Matplotlib library and its dependencies: NumPy, SciPy and Pandas. A combination of the powerful methods by GMT with data analysis supported by Python programming language is an important method in geosciences aimed to increase the effectiveness of the data analysis by cartographic mapping, statistical computations and graph plotting. This paper illustrated usage of GMT, QGIS and Python for combined data analysis scheme. The results demonstrated correlation between the sediment thickness, slope steepness, depths and location of the bathymetric profiles crossing adjacent tectonic plates: Philippine, Pacific, Caroline and Mariana.

KAJIAN STATISTIK UKURAN BESAR BUTIR SEDIMEN DAN KAITANNYA DENGAN VARIABILITAS IKLIM MUSIMAN DAN TAHUNAN DI MUARA GEMBONG, TELUK JAKARTA

Variabilitas iklim dapat mempengaruhi sifat sedimen yang terendapkan di dasar laut. Salah satu sifat sedimen yang dipengaruhi oleh iklim adalah besar butir. Penelitian ini bertujuan untuk menguji hubungan antara besar butir dengan variabilitas iklim menggunakan sampel core GM01-2010-TJ22 dari Muara Gembong, Teluk Jakarta, muara sungai Citarum. Sampel core diambil pada tahun 2010 dengan menggunakan Kapal Riset Geomarin I oleh Pusat Penelitian dan Pengembangan Geologi Kelautan (P3GL). Pengukuran besar butir dilakukan dengan menggunakan Mastersizer 2000. Hasil pengukuran ditampilkan dalam seri waktu dari tahun 2001 sampai 2010. Hasil analisis besar butir sampel sedimen dikorelasikan secara statistik dengan fenomena musiman (monsun), tahunan dan antar tahun (El Niño/La Niña dan Dipole Mode). Verifikasi data dilakukan dengan menggunakan data sekunder temperatur permukaan laut dari citra satelit di sekitar lokasi sampel dan data curah hujan di Bekasi. Hasil verifikasi menunjukkan bahwa peningkatan curah hujan di sekitar daerah hilir Sungai Citarum diikuti dengan penurunan temperatur permukaan laut dan peningkatan ukuran rata-rata besar butir. Hasil yang didapat dalam uji statistika menunjukkan bahwa perubahan ukuran besar butir sampel sedimen di Muara Gembong memiliki korelasi signifikan dengan Multivariate ENSO (El Niño Southern Oscillation) Index (MEI), Ocean Niño Index (ONI), Dipole Mode Index (DMI) dan Australian Monsoon Index (AUSMI). Hasil tersebut menunjukkan bahwa besar butir sedimen dasar laut potensial digunakan untuk mengetahui variabilitas iklim di sekitar Teluk Jakarta.

Epibenthos Dynamics and Environmental Fluctuations in Two Contrasting Polar Carbonate Factories (Mosselbukta and Bjørnøy-Banken, Svalbard)

The Arctic Svalbard Archipelago hosts the world’s northernmost cold-water ‘carbonate factories’ thriving here despite of presumably unfavourable environmental conditions and extreme seasonality. Two contrasting sites of intense biogenic carbonate production, the rhodolith beds in Mosselbukta in the North of the archipelago and the barnacle-mollusc dominated carbonate sediments accumulating in the strong hydrodynamic regime of the Bjornoy-Banken south of Spitsbergen, were the targets of the RV Maria S. Merian cruise 55 in June 2016. By integrating data from physical oceanography, marine biology, and marine geology, the present contribution characterises the environmental setting and biosedimentary dynamics of these two polar carbonate factories. Repetitive CTD profiling in concert with autonomous temperature/salinity loggers on a long-term settlement platform identified spatiotemporal patterns in the involved Atlantic and Polar water masses, whereas short-term deployments of a lander revealed fluctuations of environmental variables in the rhodolith beds in Mosselbukta and at same depth (46 m) at Bjornoy-Banken. At both sites, dissolved inorganic nutrients in the water column were found depleted (except for elevated ammonium concentrations) and show an overall increase in concentration and N:P ratios towards deeper waters. This indicates that a recycling system was fuelling primary production after the phytoplankton spring bloom at the time of sampling in June 2016. Accordingly, oxygen levels were found elevated and carbon dioxide concentrations (pCO2) markedly reduced, on average only half the expected equilibrium values. Backed up by seawater stable carbon and oxygen isotope signatures, this is interpreted as an effect of limited air-sea gas exchange during seasonal ice cover in combination with a boost in community photosynthesis during the spring phytoplankton bloom. The observed trends are enhanced by the onset of rhodophyte photosynthesis in the rhodolith beds during the polar day upon retreat of sea-ice. Potential adverse effects of ocean acidification on the local calcifier community are thus predicted to be seasonally buffered by the marked drop in pCO2 during the phase of sea-ice cover and spring plankton bloom, but this effect will diminish should the seasonal sea-ice formation continue to decline. (Abstract truncated here - please see comments for our arrangement of excess word count)

ОСОБЕННОCТИ ФОРМИРОВАНИЯ ОТЛОЖЕНИЙ МАЙКОПСКОЙ СЕРИИ АЗЕРБАЙДЖАНА

ОСОБЕННОCТИ ФОРМИРОВАНИЯ ОТЛОЖЕНИЙ МАЙКОПСКОЙ СЕРИИ АЗЕРБАЙДЖАНА

What the marine geology of Table Bay, South Africa can inform about the western Saldania Belt, geological evolution and sedimentary dynamics of the region

Around the city of Cape Town, South Africa, the basal Neoproterozoic rocks are poorly exposed. There is however, historical evidence for good exposure of these rocks on the seafloor of Table Bay, although not mapped at sufficient resolution nor areal extent for significant conclusions. The Council for Geoscience therefore decided to commence their offshore mapping programme with this bay, mapping it at 1 m resolution using multibeam and sidescan sonar. The hope was that these data would help to unify the detailed sub-aerial investigations with offshore geological data.The seafloor outcrops are composed almost exclusively of rocks from the western branch of the Neoproterozoic Saldania Orogenic Belt and represent the largest exposure of the Tygerberg Formation regionally (~103 km2 under water compared to ~2 km2 exposed along the coastline). We demonstrate that the seafloor of Table Bay is an ideal locale to gain insight into the kinematics that have affected the rock mass on a regional scale. The outcrops display evidence of a shallow northwest-plunging anticline – syncline pair with associated smaller scale folds. The dip and strike of bedding planes delineate fold axial surface traces and fold type. The presence of lineaments and offset bedding suggest the presence of faults and/or fractures. The relative orientation of which is used to infer fault kinematics. Bedding truncation against a large northwest trending, linear, bathymetric low that is coincident with a weakly magnetic linear anomaly has led us to infer the presence of a regional Table Bay Fault zone. Lineaments interpreted as R1, R2 and P Riedel shears associated with this fault suggest sinistral strike-slip kinematics, similar to those recognised for other major fault zones on land with almost identical strike. The UNESCO world heritage site of Robben Island is located in the core of a syncline, its basal rocks composed of units marginally more arenaceous in character. The magnetic data acquired demonstrate the semi-continuous, anastomosing network of dolerite dykes within the Cretaceous False Bay Suite. Neogene features are absent in Table Bay, but as a result of Pleistocene sea level fluctuations, a complex palaeo-drainage network has incised into the seafloor during glacio-eustatically driven sea-level stillstands throughout the Quaternary Period.

Topographic surface modelling using raster grid datasets by GMT: example of the Kuril–Kamchatka Trench, Pacific Ocean

Abstract The study area is focused on the Kuril–Kamchatka Trench, North Pacific Ocean. This region is geologically complex, notable for the lithosphere activity, tectonic plates subduction and active volcanism. The submarine geomorphology is complicated through terraces, slopes, seamounts and erosional processes. Understanding geomorphic features of such a region requires precise modelling and effective visualization of the high-resolution data sets. Therefore, current research presents a Generic Mapping Tools (GMT) based algorithm proposing a solution for effective data processing and precise mapping: iterative module-based scripting for the automated digitizing and modelling. Methodology consists of the following steps: topographic mapping of the raster grids, marine gravity and geoid; semi-automatic digitizing of the orthogonal cross-section profiles; modelling geomorphic trends of the gradient slopes; computing raster surfaces from the xyz data sets by modules nearneighbor and XYZ2grd. Several types of the cartographic projections were used: oblique Mercator, Mercator cylindrical, conic equal-area Albers, conic equidistant. The cross-section geomorphic profiles in a perpendicular direction across the two selected segments of the trench were automatically digitized. Developed algorithm of the semi-automated digitizing of the profiles enabled to visualize gradients of the slope steepness of the trench. The data were then modelled to show gradient variations in its two segments. The results of the comparative geomorphic analysis of northern and southern transects revealed variations in different parts of the trench. Presented research provided more quantitative insights into the structure and settings of the submarine landforms of the hadal trench that still remains a question for the marine geology. The research demonstrated the effectiveness of the GMT: a variety of modules, approaches and tools that can be used to produce high-quality mapping and graphics. The GMT listings are provided for repeatability.

Institute of Marine Geology and Geophysics - 30 years for studying geology and geophysics in the marine zones of Vietnam and Eastern Sea

Geological and geophysical investigation and study in the marine zones of Vietnam and Eastern Sea, its application in the mineral exploration, for natural disaster and hazard prevention, environment and resource protection, for sea and island management, marine economic development, sea defence and security is the important, main and long-term tasks of the Institute of Marine Geology and Geophysics. For last 30 years, the institute has a leading role for conducting a numerous projects of national and international programs of marine research and investigation in the marine zones of Vietnam and Eastern Sea. The obtained results and achievements include big, abundant, up to date databases, newest and detailed schemes and maps, valuable published papers, books, and contributions on characteristics of geophysical fields, deep crustal structure, seabed sediment and environment, geological structure and tectonic evolution, seismotectonics and earthquake, tsunami hazard assessment, mineral potential and perspective evaluation. Results of study on geophysical fields, deep crustal structure, seabed topography and geomorphology have been used for determination of outer limits of continental shelf of Vietnam in the Eastern Sea. Big part of the results was gained from research and investigation projects conducted in the Truong Sa and Hoang Sa areas. On the basis of the obtained achievements, some special tasks are proposed to continue conducting the geological and geophysical research and investigation in the sea of Vietnam and adjacent areas.

Oceanic Plateau Formation Implied by Ontong Java Plateau, Kerguelen Plateau and Shatsky Rise

Oceanic plateaus are a significant type of large igneous provinces in the oceans, providing insights to regional tectonic events and mantle behavior. The three world’s largest oceanic plateaus, the Ontong Java Plateau, the Kerguelen Plateau and the Shatsky Rise, are representatives in displaying extraordinary fluxes of magma from mantle to lithosphere. Detailed description incorporating transdisciplinary observations on marine geology, geophysics and geochemistry allow us to test the two lively-debated oceanic plateau formation hypotheses (mantle plume and plate boundary models). Predictions from either hypothesis merely obtain partial support. It is therefore unclear to differentiate one model from another one regarding the oceanic plateau formation. Careful comparisons of the three oceanic plateaus show many commonalities and even more differences in their formation and evolution. This diversity signifies one may not be typical of all. Notably, several key common features, i.e ., massive and rapid eruption and near-ridge formation setting, imply that the lithospheric volcanic emplacement of oceanic plateaus was controlled by seafloor spreading despite a mantle plume exists peripherally. If a coincidence of mantle plume and spreading ridge occurs, it may indicate a plume-ridge interaction. One possible mechanism is that spreading ridge is dragged by a plume and migrates to the location of the plume. Another possibility is that the asthenosphere is fed by a plume nearby and generates melting anomalies along the spreading ridge.

Preface: Celebration of the Career of Robert Nathan Ginsburg

Preface: Celebration of the Career of Robert Nathan Ginsburg

Origin of natural gases and associated gas hydrates in the Shenhu area, northern South China Sea: Results from the China gas hydrate drilling expeditions

Geochemical data for hydrate gases acquired from the GMGS3 and GMGS4 gas hydrate drilling expeditions conducted by the Guangzhou Marine Geological Survey (GMGS) are used to explore the origin of hydrate gases and their relationship to deep hydrocarbon reservoirs, and to evaluate the contribution of different genetic types of gases to the formation and accumulation of gas hydrates in the Shenhu area of the northern part of the South China Sea (SCS). Compositionally, methane is the dominant gas (>90%) in the void gas and pressure core gas. In addition, as much as ~3% of the gas is composed of C2+ hydrocarbons, including ethane, propane, iso-butane, butane, iso-pentane, and n-pentane. The δ13C-CH4 and δD-CH4 values indicate a mixed biogenic-thermogenic origin for the hydrate-forming gas. The methane isotope correlation indicates that the source of the hydrate gas is closely related to the deep conventional gas reservoirs discovered in the Baiyun Sag-Panyu Low Uplift area. Both the hydrate gases and the deep reservoir gases are sourced from the hydrocarbon kitchens in the Baiyun Sag, revealing a paragenetic relationship within the same petroleum system. The composition of the hydrocarbons and the isotopic variation of methane with depth suggest that the thermogenic gas was likely affected by compositional and isotopic fractionation during the long-distance migration from the deep source rocks to the shallow gas hydrate stability zone (GHSZ). The impact of biodegradation on a solely thermogenic gas could also affect the final composition of the hydrate-forming gas. Analysis of the GHSZ based on gas hydrate compositions suggests that the occurrence of thermogenic gas could also indicate the coexistence of structure I (SI) and structure II (SII) gas hydrates in the Shenhu area, with the SII hydrates accumulating in or below the lower part of the SI GHSZ. The confirmed presence of SII hydrates in the Shenhu area relocated the base of the GHSZ deeper than was indicated by the bottom simulating reflector, which warrants further study in future explorations for gas hydrates in the Shenhu area.

Characteristics and dynamics of gas hydrate systems in the northwestern South China Sea - Results of the fifth gas hydrate drilling expedition

Abstract In 2018, Guangzhou Marine Geological Survey conducted the fifth gas hydrate drilling expedition (GMGS5) in the northwestern continental slope of South China Sea. We use pore water geochemistry, pressure core CT scanning, degassing quantification, seismic data and in situ temperature test at four drill sites (W01, W07, W08 and W09) to investigate the gas hydrate characteristics and discuss the dynamics of the gas hydrate system. Based on the CT scanning and pressure core degassing, we demonstrate the coexistence of pore-filling and vein-like gas hydrates. Gas hydrate saturation estimated based on the chloride concentration (0–92%) is higher than that based on the degassing quantification (0–52.9%). The saturation discrepancy is mainly resulted from the sampling discrimination. Based on the average gas hydrate saturation estimated using chloride concentration and degassing, the methane gas volume contained in the gas hydrate of one cubic meter sediment at drill sites W07, W08 and W09 are calculated to be 13.7 m3, 26.82 m3 and 22.24 m3 and 3.03 m3, 14.30 m3 and 16.25 m3. The geothermal gradients estimated based on the in situ temperature measurements at sites W07, W08 and W09 (102–111 °C/km) are more than 50% higher than that at the background site W01 (65 °C/km). It is inferred that the fractures and faults in the gas chimney at sites W07, W08 and W09 are the major contributors for the efficient fluid pathways and high geothermal gradients. The pore water sulfate profiles and inferred sulfate-reduction methane-oxidation interface (SMI) depths indicate that methane flux is lowest at site W01 and highest at site W08. The SMI depths and top of gas hydrate occurrence is linearly correlated which provides an experienced function for understanding the local gas hydrate distribution. Kick-type sulfate profiles at sites W07 and W09 indicate an ongoing increase of methane flux and corresponding shoaling SMI depths. In addition, chloride enrichment in the shallow sediment at site W08 indicates a recent fast gas hydrate formation process. The kick-type sulfate profiles, positive chloride anomalies and authigenic carbonates at multiple depths suggest that the system experienced dynamic changes in fluid flux and multi-stage gas hydrate evolution on time scale from months to thousands of years. Understanding the controlling mechanism and periodicity of the composite pressure system is important for evaluating the gas hydrate resource and carbon cycling.

Elements of oceanographic terminology in english and romanian

Oceanography is a vast domain dealing with various aspects of marine life, physical and chemical aspects of the seas and oceans of the world. Searching available oceanographic documents of the 19th, 20th and 21st century, the aim of the paper is to emphasize the specific terminology of at least one of the branches of oceanography. The branches of oceanography deal with marine biology, ocean chemistry, marine geology and marine physics. The differences between the Romanian and English terminology according to the etymology are brought into discussion and conclusions drawn according to the similarities and differences.

Chemical and structural characteristics of gas hydrates from the Haima cold seeps in the Qiongdongnan Basin of the South China Sea

Crystalline structure, cage occupancy, and gas composition are important gas hydrate characteristics, which can be used to calculate the gas hydrate’s stability and to estimate the energy potential. In May and October of 2015, a Guangzhou Marine Geological Survey team investigated two sites in the Haima cold seeps in the Qiongdongnan Basin, northern South China Sea. They recovered massive gas hydrate samples by conventional gravity coring. After the Shenhu Sea area and Dongsha Sea area, the Qiongdongnan Basin became a new area on the northern slope of the South China Sea where gas hydrates have been found. In order to reveal the structural and geochemical characteristics of the natural gas hydrates, samples were analyzed by micro-Raman spectroscopy and X-ray diffraction under ambient pressure and low-temperature conditions. The results indicate that the gas hydrate samples from the Haima cold seeps are typical structure I hydrates with a hydration number of 6.12–6.19. In addition, trace amounts of H2S trapped in the hydrate were identified based on its characteristic vibrational signature. The gas composition and δ13C-CH4 of the hydrate-bound gas samples were analyzed for gas-source correlation. All of the gas samples are dominated by methane with small amounts of ethane and propane and had relatively light δ13C-CH4, indicating that all of the hydrate-bound gases are mixtures of biogenic and thermogenic gas. The thermogenic gas is inferred to be mainly derived from the coal layers of the Late Miocene-Pliocene Yacheng Formation in the northern Lingshui sag.

Numerical Data Modelling and Classification in Marine Geology by the SPSS Statistics

The paper focuses on the geostatistical analysis of the data set on the Philippine archipelago. The research question is understanding variability in several geospatial parameters (geology, geomorphology, tectonics and bathymetry) in different segments of the study area. The initial data set was generated in QGIS by digitizing 25 cross-sectioning profiles. The data set contained information on the geospatial parameters in the samples by profiles. Modelling and statistical analysis were performed in SPSS IBM Statistics software. The analysis of the topography shows strong variability of the elevations in the samples with the extreme depths in the central part of the study area (profile 13 with -9,400 m) and highest elevations in its south-western part (profile 17 with 1950 m). The analysis of the geological classes and lithology shows maximal samples of the basic volcanic rocks (40,40%) followed by mixed sedimentary consolidated rocks (31,90 %). Pairwise analysis of the sediment thickness and slope aspect demonstrates correlation between these two variables with the maximal sediment layer in the profiles 1-4 crossing the Philippines. The hierarchical dendrogram clustering of the bathymetry by three approaches shown maximal correlation of 5 clusters containing profile groups: 12-18 (centre), 22-25 (south-west), 1-2 (north), 7-8 (north-east), 19-21 (south-west). Other profiles show lesser similarities in the bathymetric patterns. The forecasting models were computed for the geospatial variables showing gradual increase in the gradient angles southwards and increased values for the sediment thickness in the north. Technically, the results proved effectiveness of the SPSS application of the geological data modelling. The paper focuses on the geostatistical analysis of the data set on the Philippine archipelago. The research question is understanding variability in several geospatial parameters (geology, geomorphology, tectonics and bathymetry) in different segments of the study area. The initial data set was generated in QGIS by digitizing 25 cross-sectioning profiles. The data set contained information on the geospatial parameters in the samples by profiles. Modelling and statistical analysis were performed in SPSS IBM Statistics software. The analysis of the topography shows strong variability of the elevations in the samples with the extreme depths in the central part of the study area (profile 13 with -9,400 m) and highest elevations in its south-western part (profile 17 with 1950 m). The analysis of the geological classes and lithology shows maximal samples of the basic volcanic rocks (40,40%) followed by mixed sedimentary consolidated rocks (31,90 %). Pairwise analysis of the sediment thickness and slope aspect demonstrates correlation between these two variables with the maximal sediment layer in the profiles 1-4 crossing the Philippines. The hierarchical dendrogram clustering of the bathymetry by three approaches shown maximal correlation of 5 clusters containing profile groups: 12-18 (centre), 22-25 (south-west), 1-2 (north), 7-8 (north-east), 19-21 (south-west). Other profiles show lesser similarities in the bathymetric patterns. The forecasting models were computed for the geospatial variables showing gradual increase in the gradient angles southwards and increased values for the sediment thickness in the north. Technically, the results proved effectiveness of the SPSS application of the geological data modelling.

An Empirical Study of R Applications for Data Analysis in Marine Geology

The study focuses on the application of R programming language towards marine geological research with a case study of Mariana Trench. Due to its logical and straightforward syntax, multi–functional standard libraries, R is especially attractive to the geologists for the scientific computing. Using R libraries, the unevenness of various factors affecting Mariana Trench geomorphic structure has been studied. These include sediment thickness, slope steepness, angle aspect, depth at the basement and magmatism of the nearby areas. Methods includes using following R libraries: {ggplot2} for regression analysis, Kernel density curves, compositional charts; {ggalt} for Dumbbell charts for data comparison by tectonic plates, ranking dot plots for correlation analysis; {vcd} for mosaic plots, silhouette plots for compositional similarities among the bathymetric profiles, association plots; {car} for ANOVA. Bathymetric GIS data processing was done in QGIS and LaTeX. The innovativeness of the work consists in the multi–disciplinary approach combining GIS analysis and statistical methods of R which contributes towards studies of ocean trenches, aimed at geospatial analysis of big data.

일본 세이칸(青函)터널의 건설과 기술적 함의(含意)에 관한 연구 - 한일터널 건설논의에 대한 시사점 -

This study examines the construction process of the Seikan Tunnel. Through this, I have made suggestions for the future discussion on the construction of the Underwater tunnel between Korea and Japan. The following framework of analysis was used for this purpose: 1) Natural basic conditions of the Tsugaru Strait, 2) Limitations of construction and technology, and 3) Active development of tunnel construction technology. In particular, it was predicted that the construction of the Seikan Tunnel was a difficult construction. The rapid sea currents, deep seas, and the complicated submarine geology of the Tsugaru Strait made the construction very difficulte. Above all, fragile geology and complex geotechnical structures could not be resolved by civil engineering and equipment at that time. Nevertheless, Japan has developed a new tunnel construction technology and completed the Seikan Tunnel. As a result, Japan has established a relatively safe railway infrastructure. In particular, Japan has developed underwater tunnel excavation technology in the process of constructing the Seikan tunnel. As a result, Japan has the world's most advanced tunnel technology. These facts are expected to provide policy implications for discussions on the construction of the Underwater tunnels between Korea and Japan to be developed in the future.

Generating higher resolution regional seafloor maps from crowd-sourced bathymetry.

Seafloor mapping can offer important insights for marine management, spatial planning, and research in marine geology, ecology, and oceanography. Here, we present a method for generating regional bathymetry and geomorphometry maps from crowd-sourced depth soundings (Olex AS) for a small fraction of the cost of multibeam data collection over the same area. Empirical Bayesian Kriging was used to generate a continuous bathymetric surface from incomplete and, in some areas, sparse Olex coverage on the Newfoundland and Labrador shelves of eastern Canada. The result is a 75m bathymetric grid that provides over 100x finer spatial resolution than previously available for the majority of the 672,900 km2 study area. The interpolated bathymetry was tested for accuracy against independent depth data provided by Fisheries and Oceans Canada (Spearman correlation = 0.99, p<0.001). Quantitative terrain attributes were generated to better understand seascape characteristics at multiple spatial scales, including slope, rugosity, aspect, and bathymetric position index. Landform classification was carried out using the geomorphons algorithm and a novel method for the identification of previously unmapped tributary canyons at the continental shelf edge are also presented to illustrate some of many potential benefits of crowd-sourced regional seafloor mapping.

ЕФЕКТИВНІСТЬ ГИБКИХ З'ЄДНАНЬ (FC) МЕХАНІЗМІВ ПАЛИНИ

Statement of the problem in a general case and its connection with the important scientific or practical problems. The flexible connections (FC) of large length are used at towages, deep-water well-drilling and other works in the marine economy complex of Ukraine as a part of ship power plants. The solving of the problem for an estimation of oscillations in flexible working tools of large length will allow to reduce the terms and amount of the works related to their assembling, and, in turn, will bring down the expenses on acquisition and exploitation (FC). The deriving of the oscillations ’ equations (FC) is of undoubted interest, since they can be used for the study of the World ocean, investigation and exploitation of submarine mineral deposits, submarine geology and topography, choice of routes of submarine cable lines and pipelines, control of works’ quality on their laying, study of the sea ecology.

Features of the distribution of abnormal gas geochemical fields in the Red River rift (Gulf of Tonkin, South China Sea)

This paper reports the results of the third Russian–Vietnamese expedition (POI FEB RAS and the Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology) in the Gulf of Tonkin, South China Sea (April 2016) and field work outcomes from 2016-2017. The studies revealed new specific features of the distribution and origin of gas-geochemical fields in sediments within the rift zone of the Red River along a 150-km profile. Four zones with high amplitude anomalies of hydrocarbon gases, helium, hydrogen, carbon dioxide, and carbon monoxide were revealed. The distribution of the anomalies reflects the tectonic structure of the area and points to the presence of several lithospheric sources of gases including gases of deep origin. The studies were carried out within the scope of the Joint Vietnamese–Russian Laboratory for Marine Geosciences (POI FEB RAS and the Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology). The article is dedicated to the year of friendship between Russia and Vietnam.

Comment on “Holocene mass movements in west and mid-Norwegian fjords and lakes” by B. Bellwald, BO Hjelstuen, HP Sejrup, T. Stokowy and J. Kuvås [Marine Geology 407 (2019) 192–212

In their paper, Bellwald et al. (2019) present a frequency curve of mass movements from a total of 22 fjords and 6 lakes in west and mid-Norway. However, the time-series analysis that is used to create this frequency curve is somewhat flawed, as mass-transport deposits (MTDs) receive a weight that is positively correlated to their age uncertainty, instead of an equal weight. Here, I propose an alternative frequency curve in which the weight of each MTD is equal, independent of its age uncertainty. I conclude that this error in the frequency curve does not significantly impact the interpretations made by the authors, but that similar errors may lead to wrong interpretations when such a frequency curve would be used in a quantitative manner.