Since the consecutive discovery of several gas fields from 2004 to present,the Rakhine Basin has been an active area for petroleum exploration in the Bay of Bengal.High-resolution 3D seismic data and well data from bl...Since the consecutive discovery of several gas fields from 2004 to present,the Rakhine Basin has been an active area for petroleum exploration in the Bay of Bengal.High-resolution 3D seismic data and well data from blocks AD1,AD6 and AD8 offshore northwest Myanmar are used to study the Miocene–Pleistocene depositional architecture and sedimentary evolution in the Rakhine Basin.Analysis of seismic facies and seismic attributes indicates that deep-water architectural elements include submarine canyons,confined slope channel complex systems,aggradational channel–levee complexes,isolated channels,frontal splays and mass-transport complexes,which have variable characters(shape,dimension,sedimentary architecture)within predominantly background deep-water slope-basin floor facies.Most of the sediments are interpreted to be sourced from the Ganges–Brahmaputra fluvio-deltaic system to the north with only minor lateral input from the IndoMyanmar Ranges to the east.Investigation of the depositional evolution and architectural elements transformation during the filling history of the Rakhine Basin suggests the Rakhine Basin experienced rapid progradation during the Oligocene–Middle/Upper Miocene,gradual retrogradation during the Middle/Upper Miocene–Early Pliocene and gradual progradation during the Early Pliocene–Pleistocene.Published exploration results indicate that the main reservoirs of the discoveries in blocks A1 and A3 are Pliocene frontal splays and channel–levee fills,dominated by fine and very fine-grained sandstones,in structural and structural–stratigraphic traps.Analytic results from seismic characters and several exploration wells indicate that channel complexes and associated overbanks and frontal splays with fine-grained sandstones and siltstones trapped by the four-way closures are primary reservoir targets.展开更多
Supercritical flows are ubiquitous in natural environments;however,there is rare 3D anatomy of their deposits.This study uses high-quality 3D seismic datasets from the world’s largest submarine fan,Bengal Fan,to inte...Supercritical flows are ubiquitous in natural environments;however,there is rare 3D anatomy of their deposits.This study uses high-quality 3D seismic datasets from the world’s largest submarine fan,Bengal Fan,to interpret 3D architectures and flow processes of Pliocene undulating bedforms that were related to supercritical flows.Bengal undulating bedforms as documented in this study were developed in unconfined settings,and are seismically imaged as strike-elongated,crescentic bedforms in plan view and as rhythmically undulating,upstream migrating,erosive,discontinuous reflections in section view.Their lee sides are overall 3 to 4 times steeper(0.280 to 1.19°in slope)and 3 to 4 times shorter(117 to 419 m in length)than their stoss flanks and were ascribed to faster(high flow velocities of 2.70 to 3.98 m/s)supercritical flows(Froude numbers of 1.53 to 2.27).Their stoss sides,in contrast,are overall 3 to 4 times gentler(0.120 to 0.270 in slope)and 3 to 4 times longer(410 to 1139 m in length)than their lee flanks and were related to slower(low velocities of 2.35 to 3.05 m/s)subcritical flows(Froude numbers of 0.58 to 0.97).Bengal wave-like features were,thus,created by supercriticalto-subcritical flow transformations through internal hydraulic jumps(i.e.,cyclic steps).They have crests that are positive relative to the surrounding region of the seafloor,suggesting the predominant deposition of draping sediments associated with net-depositional cyclic steps.Turbidity currents forming Bengal wave-like features were,thus,dominated by deposition,resulting in net-depositional cyclic steps.Sandy deposits associated with Bengal net-depositional cyclic steps are imaged themselves as closely spaced,strike-elongated high RMS-attribute patches,thereby showing closely spaced,long and linear,strike-elongated distribution patterns.展开更多
The complex issues associated with marine delineation for the outer limit of continental shelf and the boundary delimitation have provoked considerable attention among researchers in a variety of academic circles, par...The complex issues associated with marine delineation for the outer limit of continental shelf and the boundary delimitation have provoked considerable attention among researchers in a variety of academic circles, particularly in the juristic filed and the geo-science field. In the present contribution, we start from an overview of submarine fans, as one of common types of sediment-deposit bodies in the ocean, and ex- plore the related geological features which may be of relevance to the marine delimitation in accordance with the 1982 United Nations Convention on the Law of the Sea. We carry out a comparative assessment of certain significant geological features of submarine fans, using the Bengal fan as an example, which is the biggest submarine fan in the world and represents an important factor in the maritime boundary dispute between the neighboring states currently. The relationship between the special geological bodies and the international principle in the 1982 United Nations Convention can be established by combining geological and juristic analyses. This preliminary observation on the effect of submarine bodies both on the marine entitlement and boundary delimitation indicates that it is important for the international society to appro- priately deal with this problem so that the marine right of any state can be protected.展开更多
Remnant ocean basin is a key to understand the plate suturing and subsequent uplift and erosion of orogen. The Bay of Bengal Basin （BOBB） provides a typical example to analyze the remnant ocean basin structures, evo...Remnant ocean basin is a key to understand the plate suturing and subsequent uplift and erosion of orogen. The Bay of Bengal Basin （BOBB） provides a typical example to analyze the remnant ocean basin structures, evolution, and relationships between depositional filling and uplifting of the Himalayan Orogen. Thirty-nine seismic profiles as well as interval velocities of well BODC3 were used to compile isopach maps of the basin. Among the seismic data, 26 seismic profiles were applied to estab- lish 8 cross sections. The cross sections suggest the basin is asymmetric, bounded to the west by the eastern continental margin of India （ECMI） with graben-horst and to the east by the Sunda conver- gence margin dominated by trench-arc system. The BOBB is characterized by a prominent down flex- ure structures caused by huge amount of Bengal fan turbidite sediments accumulation. Our isopach maps and chronology data collected from adjacent regions reveal the initial development and fast southward growth of the Bengal fan were related to the early and major stage uplift and erosion of the Himalayan Orogen, respectively. The BOBB has experienced a critical transition from an ocean basin to a remnant ocean basin at Late Oligocene. Such basin structures and evolution features indicate the BOBB provides whole records of oblique convergence of the India and Asia plates, and the early and major stage evolution of the Himalayan Orogen.展开更多
文摘Since the consecutive discovery of several gas fields from 2004 to present,the Rakhine Basin has been an active area for petroleum exploration in the Bay of Bengal.High-resolution 3D seismic data and well data from blocks AD1,AD6 and AD8 offshore northwest Myanmar are used to study the Miocene–Pleistocene depositional architecture and sedimentary evolution in the Rakhine Basin.Analysis of seismic facies and seismic attributes indicates that deep-water architectural elements include submarine canyons,confined slope channel complex systems,aggradational channel–levee complexes,isolated channels,frontal splays and mass-transport complexes,which have variable characters(shape,dimension,sedimentary architecture)within predominantly background deep-water slope-basin floor facies.Most of the sediments are interpreted to be sourced from the Ganges–Brahmaputra fluvio-deltaic system to the north with only minor lateral input from the IndoMyanmar Ranges to the east.Investigation of the depositional evolution and architectural elements transformation during the filling history of the Rakhine Basin suggests the Rakhine Basin experienced rapid progradation during the Oligocene–Middle/Upper Miocene,gradual retrogradation during the Middle/Upper Miocene–Early Pliocene and gradual progradation during the Early Pliocene–Pleistocene.Published exploration results indicate that the main reservoirs of the discoveries in blocks A1 and A3 are Pliocene frontal splays and channel–levee fills,dominated by fine and very fine-grained sandstones,in structural and structural–stratigraphic traps.Analytic results from seismic characters and several exploration wells indicate that channel complexes and associated overbanks and frontal splays with fine-grained sandstones and siltstones trapped by the four-way closures are primary reservoir targets.
基金jointly funded by PetroChina Hangzhou Research Institute of Geology(No.2019D-4309)。
文摘Supercritical flows are ubiquitous in natural environments;however,there is rare 3D anatomy of their deposits.This study uses high-quality 3D seismic datasets from the world’s largest submarine fan,Bengal Fan,to interpret 3D architectures and flow processes of Pliocene undulating bedforms that were related to supercritical flows.Bengal undulating bedforms as documented in this study were developed in unconfined settings,and are seismically imaged as strike-elongated,crescentic bedforms in plan view and as rhythmically undulating,upstream migrating,erosive,discontinuous reflections in section view.Their lee sides are overall 3 to 4 times steeper(0.280 to 1.19°in slope)and 3 to 4 times shorter(117 to 419 m in length)than their stoss flanks and were ascribed to faster(high flow velocities of 2.70 to 3.98 m/s)supercritical flows(Froude numbers of 1.53 to 2.27).Their stoss sides,in contrast,are overall 3 to 4 times gentler(0.120 to 0.270 in slope)and 3 to 4 times longer(410 to 1139 m in length)than their lee flanks and were related to slower(low velocities of 2.35 to 3.05 m/s)subcritical flows(Froude numbers of 0.58 to 0.97).Bengal wave-like features were,thus,created by supercriticalto-subcritical flow transformations through internal hydraulic jumps(i.e.,cyclic steps).They have crests that are positive relative to the surrounding region of the seafloor,suggesting the predominant deposition of draping sediments associated with net-depositional cyclic steps.Turbidity currents forming Bengal wave-like features were,thus,dominated by deposition,resulting in net-depositional cyclic steps.Sandy deposits associated with Bengal net-depositional cyclic steps are imaged themselves as closely spaced,strike-elongated high RMS-attribute patches,thereby showing closely spaced,long and linear,strike-elongated distribution patterns.
基金Public Science and Technology Research Funds Projects of Ocean under contract No.201205003Basic jurisprudence research of natural prolongation and historical territorial waters on the delimitation of outer continental shelf under contract No.JG1315Geological nature and delimitation influence of Kyushu-Palau ridge in Western Pacific Ocean under contract No.JT1306
文摘The complex issues associated with marine delineation for the outer limit of continental shelf and the boundary delimitation have provoked considerable attention among researchers in a variety of academic circles, particularly in the juristic filed and the geo-science field. In the present contribution, we start from an overview of submarine fans, as one of common types of sediment-deposit bodies in the ocean, and ex- plore the related geological features which may be of relevance to the marine delimitation in accordance with the 1982 United Nations Convention on the Law of the Sea. We carry out a comparative assessment of certain significant geological features of submarine fans, using the Bengal fan as an example, which is the biggest submarine fan in the world and represents an important factor in the maritime boundary dispute between the neighboring states currently. The relationship between the special geological bodies and the international principle in the 1982 United Nations Convention can be established by combining geological and juristic analyses. This preliminary observation on the effect of submarine bodies both on the marine entitlement and boundary delimitation indicates that it is important for the international society to appro- priately deal with this problem so that the marine right of any state can be protected.
基金financially supported by the National Science and Technology Major Project of China(No.2011ZX05030-002-003)
文摘Remnant ocean basin is a key to understand the plate suturing and subsequent uplift and erosion of orogen. The Bay of Bengal Basin （BOBB） provides a typical example to analyze the remnant ocean basin structures, evolution, and relationships between depositional filling and uplifting of the Himalayan Orogen. Thirty-nine seismic profiles as well as interval velocities of well BODC3 were used to compile isopach maps of the basin. Among the seismic data, 26 seismic profiles were applied to estab- lish 8 cross sections. The cross sections suggest the basin is asymmetric, bounded to the west by the eastern continental margin of India （ECMI） with graben-horst and to the east by the Sunda conver- gence margin dominated by trench-arc system. The BOBB is characterized by a prominent down flex- ure structures caused by huge amount of Bengal fan turbidite sediments accumulation. Our isopach maps and chronology data collected from adjacent regions reveal the initial development and fast southward growth of the Bengal fan were related to the early and major stage uplift and erosion of the Himalayan Orogen, respectively. The BOBB has experienced a critical transition from an ocean basin to a remnant ocean basin at Late Oligocene. Such basin structures and evolution features indicate the BOBB provides whole records of oblique convergence of the India and Asia plates, and the early and major stage evolution of the Himalayan Orogen.
