• Digital Humanities and Cultural Heritage
• CN close
• IE close
• NEANIAS Underwater Research Communi... close

Abstract The Plio-Quaternary unidirectionally migrating channels (UMCs) and contourites in the northern slope of the South China Sea were investigated in this paper using seismic data. The UMCs include thalweg deposits (TDs) and laterally migrating deposits (LMDs), which result from the interaction between gravity flow and contour current. The LMDs migrating directions are northeast (NE) and west-southwest (WSW) and also display weak seismic reflection and obvious multi-stages. By contrast, the TDs show high seismic reflection and lateral aggradation. Giant elongated, confined, and slope sheeted drifts, as well as sediment waves are widespread in the northern slope of the South China Sea. Helicoidal contour currents can generate giant elongated and confined drifts associated with moats. By contrast, tabular contour currents can develop slope sheeted drifts with rare moats. NE-migrating channels, giant elongated drifts, and a number of sediment waves are exclusively formed at water depths of 200 m–1200 m. Drifts, sediment waves, and few WSW-migrating channels are developed at water depths of 1200 m–3000 m. The intermediate water contour current circulates clockwise, moving from Xisha Islands to Dongsha Islands and extending into the eastern part of Dongsha Islands because of the bathymetry. Deep water contour current may circulate counterclockwise and be transported northeastward through Dongsha Islands to Xisha Islands, bifurcating in the Xisha Islands because of topographical prominences.

ABSTRACTThe Songliao Basin is a large Mesozoic nonmarine petroliferous basin in northeastern China. Based on an analysis of high‐resolution three‐dimensional seismic data, a large‐scale lacustrine turbidite channel and fan system is identified within the lacustrine mudstone of the Nenjiang Formation in the central depression. The system was fed by a delta complex and extends to the south along the Daqing anticline. This system is composed of three trunk channels and four tributary channels, with a maximum length of about 71 km. Changes in channel patterns, specifically bifurcations and terminations into fans, are associated with gradient changes along the palaeoslope, which vary from 0.13 to 0.02°. Interpretation of geophysical well logs and core indicate that channel sand bodies are oil charged. The widest channel sandstone body is about 600 m with an average around 300 m, and the maximum thickness of sandstone is more than 6 m with an average of about 3 m. The sandstone bodies of the turbidite system, which are encased within organic‐rich source rocks, provide a new target for hydrocarbon exploration and development.

Abstract The shoreline is the boundary between land and sea. The shoreline has an irregular nature and change due to tidal conditions. Shoreline changes occur due to human activity and natural environment that results in eradication of erosion and sediment in the shoreline. UAV as a tool used to identify the shoreline change. However, the measurement of large-size reclaimed land using terrestrial survey methods, such as total station and GPS requires a huge number of efforts in terms of time and labour spending. Although, the current method is good in airborne sampling, however it is quite expensive and more complicated to handle. The objectives of this study is to identify the shoreline change from the image taken by using Unmanned Aerial Vehicle (UAV) and to analyse the data using pix4Dmapper and Global Mapper. Planning flight plans for UAV is necessary in this study. The shoreline changes are visibly clear during low tide from July to October 2018. Total length of erosion for three months from July to October 2018 is 8.428 m. Since the aim of this study was successfully achieved, using UAV photogrammetry could be applied in many fields and in determining and identifying the shoreline change.

AbstractHigh‐resolution multibeam bathymetric and multichannel seismic data are used to investigate the morphology of a submarine canyon (Taiwan Canyon), and its surrounding strata, in the north‐east South China Sea. This submarine canyon shows two main branches at its head, and changes its orientation from north‐west/south‐east to east–west due to the effect of a tectonically active seamount. The asymmetry of the submarine canyon’s banks in its middle reach is due to the combined action of recurrent slope instability and turbidity currents. In addition, two fields of sediment waves were identified in the study area. Field 1 is located on the south‐west levée of the canyon and is fed by turbidity currents from one of its branches, being also associated with marked hydraulic jumps. Field 2 is observed in the southern bank of the lower canyon reach and was formed by the overspill of turbidity currents within the Taiwan Canyon due to the effect of inertial centrifugal forces. Turbidity currents sourced from Dongsha Channel also contributed to forming Field 2. Importantly, trains of plunge pools have been identified along the thalweg of the lower canyon reach, generated by turbidity currents deriving from the submarine canyons in the north of the Taiwan Canyon. These results not only provide a very detailed account of submarine bedforms within and around a large submarine canyon, but also contribute to a better understanding of their origin and development. The high‐resolution bathymetric and seismic data in this work reveal how gravity flows can drive erosion and deposition in submarine canyons.

Abstract Partially-avulsed, leveed channels from the continental slope of the western Niger delta are studied using 3D seismic and well data. Four channel complexes (BC1– BC4), two ridges (A and B) and two mud volcanoes (MV1 and MV2) were identified. The morphology, internal architecture, and evolution of the channels changed in response to variations in slope gradient promoted by diapirism, faulting, and mud volcanism. The influence of local tectonics on the mapped channels is marked by channel blocking, migration, and diversion. The relative position of the channel to tectonic structures also interferes with channel morphology. Preserved cross-sectional profiles of BC3 varied between dish, U and V shapes with channel width increased in sections overlying the ridges A and B. Similar variations in morphology were also recorded for thalweg depth, channel fill thickness, levee width, and depth ratio. Abandonment fill is nearly even in BC3 except at the terminal end. MV2 was active at least twice during the evolution of BC3 and may have contributed some fine-grained sediments to BC3. Channel fill is mainly turbidity prone with alternating waxing and waning cycles; lithology consists of sandstone shale and silt in varying grain sizes and thicknesses. Tectonic activity such as diapirism, growth and listric faulting as well as mud volcanism influenced the channel evolution and internal architecture of BC3. In summary, the simple, straight BC3 as imaged by seafloor bathymetry is underlain by a complex, older geomorphology that favor the generation of structural traps and enhance reservoir properties in the western Niger Delta.

International audience; Subaqueous sand dunes are common bedforms on continental shelves dominated by tidal and geostrophic currents. However, much less is known about sand dunes in deep-marine settings that are affected by strong bottom currents. In this study, dune fields were identified on drowned isolated carbonate platforms in the Mozambique Channel (south-west Indian Ocean). The acquired data include multibeam bathymetry, multi-channel high-resolution seismic reflection data, sea floor imagery, a sediment sample and current measurements from a moored current meter and hull-mounted acoustic Doppler current profiler. The dunes are located at water depths ranging from 200 to 600 m on the slope terraces of a modern atoll (Bassas da India Atoll) and within small depressions formed during tectonic deformation of drowned carbonate platforms (Sakalaves Seamount and Jaguar Bank). Dunes are composed of bioclastic medium size sand, and are large to very large, with wavelengths of 40 to 350 m and heights of 0·9 to 9·0 m. Dune migration seems to be unidirectional in each dune field, suggesting a continuous import and export of bioclastic sand, with little sand being recycled. Oceanic currents are very intense in the Mozambique Channel and may be able to erode submerged carbonates, generating carbonate sand at great depths. A mooring located at 463 m water depth on the Hall Bank (30 km west of the Jaguar Bank) showed vigorous bottom currents, with mean speeds of 14 cm sec−1 and maximum speeds of 57 cm sec−1, compatible with sand dune formation. The intensity of currents is highly variable and is related to tidal processes (high-frequency variability) and to anticyclonic eddies near the seamounts (low-frequency variability). This study contributes to a better understanding of the formation of dunes in deep-marine settings and provides valuable information about carbonate preservation after drowning, and the impact of bottom currents on sediment distribution and sea floor morphology. © 2018 The Authors. Sedimentology © 2018 International Association of Sedimentologists

Launched in 1981,the journal "Marine Geology and Quaternary Geology" published thirty volumes,and like tree rings the thirty volumes have recorded the development of marine geology over the 30 years of China's reform and opening-up.Today the Chinese marine science community is on the march to the deep open ocean,getting active on the ocean science frontiers.As shown by recent discoveries,the deep sea floor provides a passageway between the surface and interior parts of the Earth system,and its understanding has become a bottleneck in the Earth system studies.On the other hand,the marine science is now at the transition from "expedition" to "observation",and the sea-floor observatories are building up the third platform for the Earth system observation.Looking forward to the 30 years ahead,the "Marine Geology and Quaternary Geology" will mirror the progress of marine geology in China,keeping track of its growth in the international scientific arena.

Abstract Understanding the societal impacts of past climate changes may deepen our insight into human adaptation and resilience against potential climate changes in the future. However, the degree and nature of climate-civilization link are still a matter of debate. Fluvial deposits preserved within a cultural stratigraphical context at archaeological sites in the lower Yellow River area may offer an exceptional framework for evaluating the role of climate changes in the rise and fall of ancient civilizations. Here we show evidence for great lower Yellow River floods during the Neolithic-Bronze Age transition about 4000–3500 years ago. Comparing with existing terrestrial and marine records suggests that they were a downstream manifestation of flooding in the middle reaches of the Yellow River, most likely triggered by excessive summer precipitation while a weak El Nino condition prevailed. The floods substantially modified the preexisting landscape and altered the agricultural conditions, thereby driving people dwelling on the higher mounds to move upward. Our results provide a past analogue of the linked climatic, environmental, and societal changes at a time when large and rapid climate changes occurred.

Harvesting the commercially significant lobster, Nephrops norvegicus, is a multimillion dollar industry in Europe. Stock assessment is essential for maintaining this activity but it is conducted by manually inspecting hours of underwater surveillance videos. To improve this tedious process, we propose an automated procedure. This procedure uses mosaics for detecting the Nephrops, which improves visibility and reduces the tedious video inspection process to the browsing of a single image. In addition to this novel application approach, key contributions are made for handling the difficult lighting conditions in these kinds of videos. Mosaics are built using 1-10 minutes of footage and candidate Nephrops regions are selected using image segmentation based on local image contrast and colour features. A K-Nearest Neighbour classifier is then used to select the respective Nephrops from these candidate regions. Our final decision accuracy at 87.5% recall and precision shows a corresponding 31.5% and 79.4% improvement compared with previous work [1].