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Rifting characteristics of eastern subbasin of South China Sea and its spreading pattern

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Acta Oceanologica Sinica 2002年第1期21卷 77-85页

作者： Li Jiabiao Jin Xianglong gao jinyao Key Laboratory of Submarine Geosciences of State Oceanic Administration Hangzhou 310012China Second Institute of Oceanography State Oceanic AdministrationHangzhou 310012China

With processing and interpretation of 25 000 km full-coverage multibeam swath data fromthe eastern South China Sea, it is found that NE-trending and NW-trending linear morphological features such as scarps, horsts and grabens, govern the central part (14°-17° N) of eastern subbasin. Compared with reflection seismic profiles, these NE-trending linear morpho-structures are considered to be the representation of basement structures on seabed and can be divided into three linear structural zones. The trend of the central zone is NE45°-50° occurring around extinct spreading center, the trend of the second zone is NE70° - 78° on both sides of the central one and the trend of the third zone is about NE60° just on the north of the second one. These three NE-trending linear zones are formed in late-stage NW - SE-trending seafloor spreading of the eastern subbasin along NW-trending linear faults, and respectively correspond to three spreading episodes: 17.0- 19.0 Ma (5d-5e), 19.0 - 21.0 Ma (5e-6a) and 21.0 - 24.2 Ma (6a-6c) based on the contrast of morpho-structures to magnetic lineation anomalies.

关键词： Multibeam echosounding swath topography morpho-structures spreading pattern

Glacial bedforms in the Northwind Abyssal Plain,Chukchi Borderland

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Acta Oceanologica Sinica 2021年第5期40卷 114-119页

作者： Zhongyan Shen Tao Zhang jinyao gao Chunguo Yang Qingsheng Guan Key Laboratory of Submarine Geosciences Ministry of Natural ResourcesHangzhou 310012China Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China School of Geographic and Oceanographic Sciences Nanjing UniversityNanjing 210023China

A series of sub-parallel linear glacial scours are identified on the crest of the Baoshi Seamount in the Northwind Abyssal Plain by compiling new multibeam data acquired during the 9 th Chinese Arctic Research Expedition(CHINARE-Arc9)in 2018 and previously published *** new data reveal scours that developed at water depths of 850–1030 m with an orientation of about 75°/255°.The maximum water depth occurs in the southernmost scour and is deeper than that from previous investigations,which showed a maximum scouring depth of about 900 m on the *** topographic and geomorphological characteristics suggest that these scours resulted from erosion by the ice shelf extending from the Chukchi margin and/or Laurentide Ice Sheet that grounded on the crest of the seamount and moved in a NE–SW *** possibilities of their genesis include armadas of large icebergs/multi-keel icebergs calved from the Chukchi Shelf or the Laurentide Ice *** new data provide new constraints for assessing the extent and volume of the ice sheet in the Chukchi area during glacial maxima.

关键词： Chukchi Borderland Northwind Abyssal Plain glacial bedforms mega-scale glacial lineations ice shelf

Estimation of annual variation of water vapor in the Arctic Ocean between 80°–87°N using shipborne GPS data based on kinematic precise point positioning

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Acta Oceanologica Sinica 2015年第6期34卷 1-4页

作者： LUO Xiaowen ZHANG Tao gao jinyao YANG Chunguo WU Zaocai The Second Institute of Oceanography State Oceanic Administration Key Laboratory of Submarine Geosciences State Oceanic Administration

The measurement of atmospheric water vapor （WV） content and variability is important for meteorological and climatological research. A technique for the remote sensing of atmospheric WV content using ground-based Global Positioning System （GPS） has become available, which can routinely achieve accuracies for integrated WV content of 1-2 kg/m2. Some experimental work has shown that the accuracy of WV measurements from a moving platform is comparable to that of （static） land-based receivers. Extending this technique into the marine environment on a moving platform would be greatly beneficial for many aspects of meteorological research, such as the calibration of satellite data, investigation of the air-sea interface, as well as forecasting and climatological studies. In this study, kinematic precise point positioning has been developed to investigate WV in the Arctic Ocean （80°-87°N） and annual variations are obtained for 2008 and 2012 that are identical to those related to the enhanced greenhouse effect.

关键词： annual variation estimation water vapor Arctic Ocean kinematic precise point positioning

Bedrock samples from the Chukchi Borderland, Arctic Ocean——First Chinese dredge in the polar regions

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Acta Oceanologica Sinica 2019年第11期38卷 162-164页

作者： Tao Zhang Yanhui Dong Chunguo Yang Qingsheng Guan jinyao gao Key Laboratory of Submarine Geosciences State Oceanic AdministrationHangzhou 310012China Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China Collaborative Innovation Center of South China Sea Studies/School of Geographic and Oceanographic Sciences Nanjing UniversityNanjing 210023China

The Chukchi Borderland is a relict continental block in the Arctic *** origin and tectonic processes are of great significance for understanding the formation model of the Amerasia Basin and the configurations of the Mesozoic Arctic *** to the harsh environment and rare geological and geophysical data,the evolution of the Chukchi Borderland is still unclear(e.g.,Grantz et al.,1998,2011).We conducted two rock dredges and a multibeam full coverage survey of 830 km2 in the Northwind Abyssal Plain of the Chukchi Borderland during the Chinese ninth Arctic scientific expedition in *** is the first rock dredge survey of China in the polar regions with floating ice,and is just after the HLY0905 dredge at the Northwind Abyssal Plain in 2009(Mayer and Armstrong,2011).The retrieved samples will provide new information for understanding the origin and tectonic evolution of the Chukchi Borderland.

关键词： Arctic rock tectonic

Magmatism and tectonic processes in Area A hydrothermal vent on the Southwest Indian Ridge

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Science China Earth Sciences 2013年第12期56卷 2186-2197页

作者： ZHANG Tao LIN Jian gao jinyao Second Institute of Oceanography State Oceanic Administration Key Laboratory of Submarine Geosciences State Oceanic Administration Department of Geology and Geophysics Woods Hole Oceanographic InstitutionWoods HoleMA 02543USA

The hydrothermal vent in Area A （37.78°S, 49.65°E） is the first active hydrothermal vent discovered on the Southwest Indian Ridge （SWlR）. Heat source and adequate bulk permeability are two necessary factors for the formation of a hydrothermal vent. Along the SWIR 49.3°E to 51.2°E, the gravity-derived crustal thickness is up to 9.0 km, much thicker than the average thick- ness of the global oceanic crust. This characteristic indicates that the magma supply in this area is robust, which is possibly af- fected by a hotspot. The large-scale residual mantle Bouguer anomalies （RMBA） reveal prominent negative-gravity anomalies between the first-order ridge segment （from Indomed to Gallieni, 46.0°E to 52.0°E） and the Marion-Del Cano-Crozet region. These anomalies indicate the channel of the hotspot-ridge interaction. The tomography data corrected with theoretical thermal model indicate that the low-velocity anomalies corresponding to this channel can reach the base of the lithosphere. Near the hydrothermal vent area, the topography and crustal thickness at the off-axis area are extremely asymmetrical. South of the SWIR, the high topography corresponds to the thinning crustal thickness. The residual isostatic topography anomalies indicate that Area A is a deviation from the local isostatic equilibrium, similar to the characteristics of the transform fault inside corner. The forward profiles of the magnetic data indicate that the thinning magnetic layer at the south side of Area A corresponds to the shallow, high-velocity area revealed by the OBS, which is the result of tectonic extension of a detachment fault. The active tectonic processes in Area A can provide sufficient crustal permeability to the hydrothermal circulation and may form massive sulfide deposits.

关键词： ultra-slow spreading ridge Area A hydrothermal vent RMBA hotspot-ridge interaction detachment fault

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Mantle melting factors and amagmatic crustal accretion of the Gakkel ridge, Arctic Ocean

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Acta Oceanologica Sinica 2015年第6期34卷 42-48页

作者： ZHANG Tao gao jinyao CHEN Mei YANG Chunguo SHEN Zhongyan ZHOU Zhiyuan WU Zhaocai SUN Yunfan Key Laboratory of Submarine Geosciences State Oceanic Administration Second Institute of Oceanography State Oceanic Administration East China Construction Engineering Corporation of Zhejiang School of Ocean and Earth Science Tongji University

Spreading rate is a primary factor of mantle melting and tectonic behavior of the global mid-ocean ridges. The spreading rate of the Gakkel ridge decreases gradually from west to east. However, the Gakkel ridge can be divided into four thick-and-thin zones with varying crustal thicknesses along ridge axis. This phenomenon indicates that mantle melting of the Gakkel ridge is not a simple function of spreading rate. Mantle temperature, water content, mantle composition, and other factors are important in crustal accretion processes. Based on gravity-derived crustal thickness and wet melting model, we estimate that the mantle potential temperatures of the four zones are 1 270, 1 220, 1 280, and 1 280℃ （assuming that mantle water content equals to global average value）, with corresponding mantle water contents of 210, 0, 340, and 280 mg/kg （assuming that mantle potential temperature is 1 260℃）, respectivly. The western thinned crust zone is best modeled with low mantle temperature, whereas the other zones are mainly controlled by the enhanced conduction caused by the slower spreading rate. Along the Gakkel ridge, the crustal thickness is consistent with rock samples types. Predominated serpentinized peridotite and basalt are found in the area with crustal thickness 〈1.5 km and 〉2.5 km, respectively. The rock samples are including from basalt to peridotite in the area with crustal thickness between 1.5 and 2.5 km. Based on this consistency, the traditional magmatic accretion zone accounted for only 44% and amagmatic accretion accounted for 29% of the Gakkel ridge. The amagmatic accretion is a significant characteristic of the ultra-slow spreading ridge.

关键词： Gakkel ridge residual mantle bouguer anomaly crustal thickness wet melting amagmatic accretion

Neogene faulting and volcanism in the Victoria Land Basin of the Ross Sea, Antarctica

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Earth and Planetary Physics 2022年第3期6卷 248-258页

作者： Mei Yue jinyao gao ChunFeng Li Chao Zhu XinZhi Fan Guochao Wu ZhongYan Shen Han Shi XiaoXian Cai YiDong Guo Ocean College Zhejiang UniversityZhoushan 316021China Key Laboratory of Submarine Sciences Second Institute of OceanographyMNRHangzhou 310012China Key Laboratory of Environmental Survey Technology and Application MNRGuangzhou 528200China Sanya Institute Zhejiang UniversitySanya 572000China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China

The Neogene Terror Rift in the Antarctic Victoria Land Basin(VLB)of the Ross Sea,Antarctica,is composed of the Discovery Graben and the Lee *** Neogene volcanoes are aligned in the north-south direction in the southern VLB,belonging to the McMurdo Volcanic ***,due to multiple glaciations and limited seismic data,the volcanic processes are still unclear in the northern VLB,especially in the Terror *** seismic profiles were collected at the VLB from the 32nd Chinese National Antarctic Research Expedition(CHINARE).We utilized four seismic profiles from the CHINARE and additional historical profiles,along with gravity and magnetic anomalies,to analyze faults and stratigraphic characteristics in the northern Terror Rift and volcanism in the *** flower structures found in the northern Terror Rift suggest that the Terror Rift was affected by dextral strike-slip faults extending from the northern Victoria Land(NVL).After the initial orthogonal tension,the rift transited into an oblique extension,forming a set of downward concaving normal faults and accommodation zones in the Terror *** the Lee Arch,several imbricated normal faults formed and converged into a detachment *** gravitational forces,the strata bent upward and formed a rollover *** deep faults and thin strata subjected to erosion facilitated volcanic activity.A brittle volcanic region in the VLB was affected by dextral strike-slip movements and east-west extension,resulting in two Neogene volcanic chains that connect three igneous provinces in the VLB:the Hallett,Melbourne,and Erebus *** two chains contain mud volcanoes with magnetic nuclei,volcanic intrusions,and late-stage volcanic *** have brought about opposite polarities of magnetic anomalies in Antarctica,indicating the occurrence of multiple volcanic activities.

关键词： Victoria Land Basin Terror Rift seismic stratigraphy gravity and magnetic modeling faulting Neogene volcanic intrusion

Erosion-Dominated Modern Submarine Gully–Canyon–Channel Systems in Offshore Northwest Palawan， Southern South China Sea

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Journal of Earth Science 2023年

作者： Han Shi Weifeng Ding Shaoru Yin jinyao gao Jiabiao Li College of Marine Science and Technology， China University of Geosciences Key Laboratory of Submarine Geosciences， Second Institute of Oceanography， Ministry of Natural Resources

We investigated the morphology and sedimentary state of an extensive modern canyon system on the northwest continental slope of Palawan Island in the southern South China Sea using multibeam bathymetry data and chirp sub-bottom profiles. The canyon system in northwest Palawan consists of a fairly large dendritic canyon， a braided canyon， and a set of short， straight， and slope-confined gullies. The erosion state covers 71% of the system. Sediment accumulates downstream of the bend’s inner side in the proximal main stem of the dendritic canyon and is eroded in its outer side. In the distal main stem， sediment is deposited inside and outside the bend. In most of the system’s tributaries， decreasing slope gradients result in more sediment deposition. There is thick aggradation of sediment waves in the interfluve throughout the system， which exhibit increasing levels of stratification as the slope decreases. The lack of slump scars and headward erosion at the canyon heads， as well as the presence of regular gullies and sediment wave fields， suggest that large areas of unconfined downslope turbidity currents formed the system. We propose that frequent storms in northwestern Palawan triggered these currents by resuspending sediments on the shelf.

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On tectonic movement in the South China Sea during the Cenozoic

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Acta Oceanologica Sinica 2009年第1期28卷 25-36页

作者： LIN Changsong CHU Fengyou gao jinyao TAN Yonghua Key Laboratory of Submarine Geosciences of State Oceanic Administration Second Institute Oceanography State Oceanic Administration Hangzhou 310012 China Second institute of Oeeanography State Oceanic Administration Hangzhou 310012 China

The tectonic movement taking place at the end of Cretaceous and the beginning of Cenozoic had opened the Cenozoic phase of polycyclic tectonic movements,then the whole crust of the South China Sea had been mainly subjected to the regional stress field of tectonic tension,which was characterized by rifting *** times of regional tectonic movement and sedimentation had been assembled into a geological development history of polycyclic ***,the tectonic movements were strongly intensified at the end of Cretacious and the beginning of Paleagene,between Late Eocene and Mid-Oligocene,during Mid-and Late *** three times of tectonic movement had built the most important regional tectonic interfaces in the South China *** movements of the South China Sea were the result and epitome of interaction of the Eurasia,Pacific and Indo-Australia plates,that is,they were introduced by polycyclic changes of directions,rates and strengths of lithospheric movements and asthenospheric flows across the Pacific and Indo-Australia plates.

关键词： South China Sea Cenozoic tectonic movement