Structural and stratigraphic controls on subsurface fluid flow at the Veslemøy High,SW Barents Sea

Subsurface and seafloor fluid flow anomalies are gaining large interest after the finding of five new hydrocarbon discoveries and observation of large gas flares in the SW Barents Sea. In the present study, we have analysed structural and stratigraphic controls on fluid flow towards the seafloor using gravity cores selected based on subsurface gas anomalies observed on seismic data from the Veslemøy High, SW Barents Sea. The subsurface fluid flow at the Veslemøy High is observed to be controlled by 1) the morphology and orientation of regional faults, structural highs and sedimentary basins, 2) the presence of Paleocene silica ooze deposits that changes microstructure with temperature thereby controlling fluid flow and 3) the location of regional and local open faults formed by glacial loading and unloading. Analysis of extractable organic matter in subsurface Holocene sediments corroborates the active migration pathways inferred from seismic data. Micropalaeontological studies on benthic foraminifera reveal methane seep associated assemblages that confirm the interpretation of subsurface gas anomalies in seismic data. We ultimately link these new results to the geological evolution history of the region to give a comprehensive model for the fluid flow system within the study area.     

Coincidence or not? Interconnected gas/fluid migration and ocean–atmosphere oscillations in the Levant Basin

A growing number of studies on shallow marine gas/fluid systems from across the globe indicate their abundance throughout geological epochs. However, these episodic events have not been fully integrated into the fundamental concepts of continental margin development, which are thought to be dictated by three elements: tectonics, sedimentation and eustasy. The current study focuses on the passive sector of the Levant Basin on the eastern Mediterranean continental margin where these elements are well constrained, in order to isolate the contribution of gas/fluid systems. Single-channel, multichannel and 3D seismic reflection data are interpreted in terms of variance, chaos, envelope and sweetness attributes. Correlation with the Romi-1 borehole and sequence boundaries constrains interpretation of seismic stratigraphy. Results show a variety of fluid- or gas-related features such as seafloor and subsurface pockmarks, volumes of acoustic blanking, bright spots, conic pinnacle mounds, gas chimneys and high sweetness zones that represent possible secondary reservoirs. It is suggested that gas/fluid migrate upwards along lithological conduits such as falling-stage systems tracts and sequence boundaries during both highstands and lowstands. In all, 13 mid-late Pleistocene sequence boundaries are accompanied by independent evidence of 13 eustatic sea-level drops. Whether this connection is coincidental or not requires further research. These findings fill gaps between previously reported sporadic appearances throughout the Levant Basin and margin and throughout geological time from the Messinian until the present day, and create a unified framework for understanding the system as a whole. Repetitive appearance of these features suggests that their role in the morphodynamics of continental margins is more important than previously thought and thus may constitute one of the key elements of continental margin development.     

Paleotemperatures and paleofluids recorded in fluid inclusions from calcite veins from the northern flank of the Ponta Grossa dyke swarm: Implications for hydrocarbon generation and migration in the Paraná Basin

The Paraná Basin, southern Brazil, has an atypical thermal and fluid history due to the occurrence of an episodic continental flood volcanism during the Early Cretaceous. So far, there are few data about the influence of this volcanic event on the paleotemperatures and paleofluids of the Paraná Basin sedimentary rocks. The Teresina Formation in the northern flank of the Ponta Grossa dyke swarm hosts high concentration of subsurface igneous rock bodies (sills and dykes), besides its covering by a hundreds meter thick volcanic rock cap. In this study, we used fluid inclusion analysis performed in horizontal and vertical calcite veins from the Teresina Formation and from a Late Cretaceous basic dyke to estimate paleotemperatures and to characterize the composition of diagenetic paleofluids. Homogenization temperatures of requilibrated fluid inclusions show that the Teresina Formation reached temperatures above 200 °C. Horizontal parallel bedding calcite veins from the Teresina Formation record low to high salinity (2–26 wt.% NaCl eq.) aqueous paleofluids. The prevalence of high salinity fluid inclusions associated with light hydrocarbon fluid inclusions indicates deep buried fluids. Fluid inclusions in vertical calcite vein from basic dyke comprise only low salinity aqueous fluids (0–3 wt.% eq.NaCl) interpreted as dominated by meteoric water. The recorded paleotemperatures are attributed to the heating by the Paraná volcanic event during the Early Cretaceous, with the thermal effect of the volcanic rock cap surpassing the effect of nearby sills and dykes. Estimated paleotemperatures higher than 200 °C would allow the generation of light liquid and gaseous hydrocarbons. Overpressured compartments in the Teresina Formation allowed the expulsion of buried pore fluids (high salinity aqueous fluids and hydrocarbons) to fracture systems, where they mixed with meteoric water. The input of meteoric water through fracture systems connected with the surface favored hydrocarbons degradation in the early stages of source rock maturation during the Early Cretaceous.     

‘Bulls-eye’ pockmarks and polygonal faulting in the Lower Congo Basin: Relative timing and implications for fluid expulsion during shallow burial

This study describes a new type of pockmark association from the Lower Congo Basin offshore West Africa, consisting of up to 8 stacked paleopockmarks separated by intervals of drape and onlap fill. The stacked paleopockmarks occur within the depocentres of polygonally-faulted Plio-Pleistocene sediments and are distributed evenly in the downslope parts of two salt mini-basins. The majority of the stacked pockmarks initiated synchronously in the late Pliocene (~ 3 Ma) with a subordinate initiation phase in the mid Pliocene (~ 4 Ma). The primary agents in pockmark formation are interpreted to be pore water expelled during early-stage compaction together with biogenic methane. Bottom simulating reflections (BSRs) associated with free gas overlain by gas hydrates are currently found in the area. It is speculated that biogenic methane accumulated within and below a clathrate cap, which was repeatedly breached, forming pockmarks at discrete horizons separated by intervals of draping sedimentation. The mid and late Pliocene pockmark initiations appear to coincide with sea-level falls following periods of relatively stable highstand conditions. Several subsequent pockmark horizons may similarly correlate with subsequent sea-level falls during the late Pliocene and early Pleistocene. The stacked paleopockmarks are completely surrounded by polygonal faults and consistently occur within polygonal fault cells that crosscut the succession containing the stacked pockmarks. Early-stage compaction and dewatering of the Pliocene sediments thus preceded polygonal faulting, providing a constraint on the conditions leading to polygonal faulting of the fine-grained host sediments. The relationship documented here is interpreted as due to the presence of a hydrate cap in the Plio-Pleistocene mini-basins which may have retarded the normal compaction processes and facilitated pockmark formation by allowing the build up of gas hydrate and free gas in the basin centres. The relative timing and spatial relationships implies that fluids expelled due to polygonal faulting were not implicated in pockmark formation in this area.     

Main Tendency and Results ol the Investigation of the Kuroshie in the East ol Taiwan and the East China Sea

In this paper, the main tendency and results of the investigation of the Kuroshio in the east of Taiwan and the East China Sea are reviewed briefly since the beginning of the Cooperative Study of the Kuroshio and Adjacent Regions (CSK). The emphases are laid upon the following four aspects, i.e., (1) the variability of the Kuroshio, (2) the hydrography of the Kuroshio, (3) the air-sea interaction in the Kuroshio area and (4) the fisheries oceanography.     

A study on the polyculture of the algae, the shrimp and the crab

A study was made on the polyculture of the red algae Gracilaria tenuistipitata Chang et Xia f. Liui Zhang et Xia, f. nov. , the shrimp Penaeus penicillatus Alcock and the mud crab Scylla serrata (Forskal) . The photosynthesis of the algae produces the oxygen on which the shrimp and the crab breathe. The algae are the reproductive place of the organism for the food of the shrimp and the carb, also is the shelter of the shrimp and the crab. The shrimp and the crab regard the algae as the vegetable     

Liftboat Fixty with the Interaction Between the Soil Foundation and the Structure

A liftboat has big independent spuncans. The interaction between the liftboat structure and the foundation can provide significant fixity. Both methods of numerical simulation and experimental test are adopted to study the fixity. An experimental model to the scale of 1：40 ofa liftboat was mounted on a sand box in the laboratory, and also a three-dimensional FEM model was established in the numerical simulation. The variation of the fixity and the maximum stress in the legs are studied. On the basis of the fact that the experimental data are in good agreement with the numerical simulation results, the fixity is further studied by numerical simulation with different soil foundation parameters and different sizes of spuncans.     

El Nino and the Southern Oscillation

Using the Comprehensive Ocean-Atmosphere Data Set (COADS), wind, surface pressure and SST fields in the Equatorial Eastern Pacific and the Equatorial South Indian Ocean were analysed comprehensively.lt is pointed out that the seesaw between surface pressure in the Equatorial South Indian Ocean and the Equatorial Southeast Pacific causes the seesaw between the wind fields in the two areas, and the seesaw of wind fields results in the seesaw of SST between Indonesia and the Equatorial Eastern Pacific. El Nino is the response of ocean to the forcing of monsoon system in the Indian Ocean and the trade system in the Pacific.     

Function and Characteristics of the Alginases

In crude enzymes extracted from the Lunella cornata coreensis there are two algi- nases with different functions. One of the alginases can cleave the middle bond of the algin molecular chains in the reactive condition of 30 μM pH 7.5 Tris-HCl buffer and 50 μM KCl per ml of reactive mixture Ⅰ. This enzyme can readily decrease the viscosity, but the reducing groups increase slowly in the algin reactive mixture Ⅰ. Thus, it is defined as alginase Ⅰ.     

Size fractionated biomass and productivity of phytoplankton and new production in the Prydz Bay and the adjacent Indian sector of the Southern Ocean during the austral summer 1998/1999

INTRODUCTIONComparedwithotheroceansintheworld ,thereisrelativelyhigherlevelofnutrients (ni trate ,phosphate ,silicate)intheSouthernOcean .Butprimaryproductivitiesarelow ,andnewproductionisalsoonlyinthemiddlelevelthere .Itiscommonlyconsideredthatthelowerpro ductivitiesintheSouthernOceaniscausedbylowtemperature ,lowlight,lowstabilityofwa ter,scarcityoftraceelementsuchasironandgrazingbyzooplankton (Burkilletal.,1 995) ,etc.ThemostexistedstudiesconcentratedontheAtlanticSectoroftheSouthernO…     

The evolution of the coral reefs in the middle and north parts of the South China Sea and its relation with tectonic and eustatic movements

In this paper, the morphogenesis, stratigraphic sequences and dates of the coral reefs in the middle and north parts of the South China Sea are discussed, the position of the distributary regions of Cenozoic coral reefs in plate tectonics, the relationships of coral-reef evolutionary characteristics and dates with sea-basin spreading. Neogene sea-water transgression and Quaternary global climate-eustatic fluctuation are expounded and proved, and the latitudinal variation of the distribution of coral reefs in various geologic times are summed up.     

Coupled SPHS–BEM method for transient fluid–structure interaction and applications in underwater impacts

Coupled SPHS–BEM method is proposed for transient fluid–structure interaction problems: SPH shell (SPHS) is selected to discretize shell structures, the second-order doubly asymptotic approximations (DAA₂) of boundary element method (BEM) is chosen to analyze flow-field. BEM can remedy the expensive costs for three-dimensional SPH (smoothed particle hydrodynamics), yet SPHS provides a structural solver for BEM. The coupled method is attractive, since only a layer of SPHS particles and a piece of flow-field boundary elements are needed to be modeled; the compatibility conditions of the coupled surface are performed with moving least square (MLS) function. The final two benchmarks on underwater impacts prove the feasibility, stability and accuracy of the proposed method.     

Biochemical Mechanism of the Eutrophication and Its Prevention—the Deep Treatment of Waste Water and Its Denitrification and Dephosphorization

Biochemical mechanism of forming the red tide is discussed in this paper.The existence of a large number of nitrates and phosphates in the eutrophic water is the prerequisite of explosive increase of algae and the forming of red tide.Reduction of eutrophication is an important approach to preventing the red tide.The method of deep treatment of the waste water and its denitrification and dephosphorization are introduced,and a new opinion on the red tide formation and fundamental prevention is put forward.     

Ecological studies on the Hydromedusae, Siphonophores and Ctenophores in the Xiamen Harbour and adjacent waters

- This paper deals with species composition, seasonal change and horizontal distribution of the Hydromedusae (Hyd.), Siphonophores (Sip.) and Ctenophores (Cte.) and their relationship to the environmental factors. Materials from 17 stations in the Xiamen Harbour and adjacent waters were taken once monthly for the period from Sep. 1980 to Aug. 1981. The results indicate that for the dominant species of Phialidium folleatum, Lensia subtiloides and Pleurobrachia globosa , the total annual number of species has one peak and the total annual number of individual has one peak and two secondary peaks. On the basis of their ecological characteristice, the Hydromedusae, Siphonophores and Ctenophores found in the region investigated may be divided into the following ecological groups: estuarine group, neritic group and oceanic group. Their seasonal succession is correlated with the relative intensity of several water systems.     

Kuroshio warm filament and the source of the warm water of the Tsushima Current

Characteristics and evolution of the Kuroshio frontal eddies and warm filaments are analyzed according to two series of satellite images (March 5 to 7, 1986 and April 14 to 16, 1988). The results show that the frontal eddies in the East China Sea are generated at the shelf break and move along the continental slope at a speed of 15 cm/s with the Kuroshio. The frontal eddies occur about every 10 d and evolve to be warm filaments a few hundred km in length and 30-40 km in width in the area west of the Yaku-shima. Meanwhile, the existence of the warm filament was also found in the area by analysing the hydrographic data in the area west of Kyushu during May 24-June 5, 1988.The Kuroshio warm filaments move westward opposite to the Kuroshio and then turn northward at the shelf break and become the main source of the warm water of the Tsushima Warm Current. A simple dynamic explanation for the process is presented in this paper.     

Transgressions and the sea-level changes of the western Taiwan Strait since the Late Pleistocene

The sedimentary sequences since the Late Pleistocene can be divided into Layers E, D, C, B, A from old to young according to systematic analysis of grain-size, pollen and spore, diatom, foraminifera, radiocarbon dating and paleogeomagnetism of 16 sedimentary cores from the sea area of the western Taiwan Strait. The results proved the existences of the Langqi transgression (upper section of Layer D) formed in middle and late stages of early Wurm glacial period, Fuzhou transgression (Layer C) formed in Wurm sub-interglacial period and Changle transgression (Layer A) formed in postglacial period. It was also the first time to discover the Jinmen transgression (Layer E) formed in Riss -Wurm interglacial period. In this paper it is proposed that most part of the Taiwan Strait emerged as land in the early stage of early Wurm glacial period, and was still under sublittoral environment in late Wurm glacial period, as well as the existence of Dongshan Continental Bridge was in 8×103 a BP.     

Recreational fishing and boating: Are the determinants the same?

The research uses household survey data collected from 656 people in Townsville (adjacent to the Great Barrier Reef, Australia) within a hurdle model to investigate key factors influencing both the probability of participating and the frequency of (a) boating trips which involve fishing; (b) boating trips which do not involve fishing; and (c) land-based fishing trips. The findings suggest that there are differences in determinants, highlighting the importance of disaggregating the fishing/boating and boat/land-based experience (an uncommon practice in the literature) if wishing to obtain information for use in the design of monitoring programs, policy and/or for developing monitoring and enforcement strategies relating to fishing and boating.     

The effect of unstable inertia-gravity wave on the occurrence and the development of typhoon and tropical cyclone

In this paper,the analysis of the occurrence and the development of typhoon and tropical cyclone is made with the unstable theory of wave. The result indicates that the primary wave is the unstable inertia-gravity wave in the process of the occurrence and the deveJopmant of typhoon and tropical cyclone: The existence of the deep moist layer and the heating by moisture condensation can impel and intensify the unstability of the wave and is favourable for the reduction of the wave energy dispersion, therefore, it is good for the formation and the development of typhoon and tropical cyclone, and also can slow down the wave speed. Besides, the condition that the change of the specific volume of the basic state with pressure is less than that of adiabatic state may also lead to the wave unstability, thus may have certain effect on the occurrence and the development of typhoon and tropical cyclone.     

Wind speed scaling and the drag coefficient

[1]Banner M L, Chen W, Walsh E J, et al.     

The relationship between tidal current field and sediment transport in the Huanghai Sea and the Bohai Sea

-Based on a two-dimensional numerical M2 tidal model of the Huanghai and Bohai Seas, sediment transport of particles with different sizes in the computational area is given. It is concluded that tidal currents play an important role in sediment transport and deposition in the Huanghai and Bohai Seas.