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Evolution and diagenetic implications of framboids in the methane-related carbonates of the northern Okinawa Trough

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Acta Oceanologica Sinica 2021年第12期40卷 114-124页

作者： Kehong Yang Zhimin Zhu Yanhui Dong Fengyou Chu Weiyan Zhang key laboratory of submarine geosciences Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China

Authigenic carbonate samples were collected from the northern Okinawa *** on their carbon and oxygen isotopes,these samples were found to be methane-related carbonates precipitated by the anaerobic oxidation of methane(AOM).Petrological analysis revealed numerous framboidal pyrites that had been partly *** order to trace the variation and diagenetic information of these framboidal pyrites,their diameters and geochemical components were studied using an electron *** results showed that their diameters varied from 4μm to 17μm(n=60;geometric mean of 9.9μm)and were of a normal *** diameters of single pyrite that formed the framboidal pyrites varied from 1μm to 2μ*** framboidal pyrites with diameters of 6–14μm accounted for~80%of the *** geometric mean of 9.9μm indicates that they are probably diagenetic pyrites that were precipitated in a lower dysoxic environment(weakly oxygenated bottom waters).The S/Fe ratio of the framboidal minerals ranged from 0 to 1.67,and the pyrite content of single framboid varied between 0%and 86.4%.Therefore,numerous pyrites were oxygenated to iron oxides or oxyhydroxides,and were retained as pseudomorphism *** size of framboidal pyrites precipitated in cold seeps can be used to trace the redox environment;however,acquisition of additional data via investigation of different cold seeps is necessary to obtain more persuasive results.

关键词： framboidal pyrite grain size S/Fe ratio methane-related carbonate

Major and trace element composition of surface sediments from the Southwest Indian Ridge:evidence for the incorporation of a hydrothermal component

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Acta Oceanologica Sinica 2016年第2期35卷 101-108页

作者： LI Zhenggang CHU Fengyou JIN Lu LI Xiaohu DONG Yanhui CHEN Ling ZHU Jihao key laboratory of submarine Geoscience Second Institute of OceanographyState Oceanic Administration (SOA) Department of Earth Sciences Zhejiang University

Hydrothermal materials in deep-sea sediments provide a robust tracer to the localized hydrothermal activity at mid-ocean ridges. Major, trace and rare earth element（REE） data for surface sediments collected from the ultraslow spreading Southwest Indian Ridge are presented to examine the existence of hydrothermal *** carbonate oozes dominate all the sediment samples, with CaO content varying from 85.5% to 89.9% on a volatile-free basis. The leaching residue of bulk sediments by ~5% HCl is compositionally comparable to the Upper Continental Crust（UCC） in SiO_2, Al_2O_3, CaO, MgO, alkali elements（Rb, Cs） and high field strength elements（Nb, Ta, Zr, Hf, Ti）. These detritus-hosted elements are inferred to be prominently derived from the Australian continent by means of eolian dust, while the contribution of local volcaniclastics is insignificant. In addition, the residual fraction shows a clear enrichment in Fe, Mn, and Ba compared with the UCC. Combining the positive Eu anomaly of residual fraction which is opposed to the UCC but the characteristic of hydrothermal fluids and associated precipitates occurred at mid-ocean ridges, the incorporation of localized hydrothermal component can be constrained. REE mixing calculations indicate that more than half REE within the residual fraction（~55%–60%） are derived from a hydrothermal component, which is inferred to be resulted from a diffuse fluid mineralization. The low-temperature diffuse flow may be widely distributed along the slow-ultraslow spreading ridges where crustal faults and fissures abound, and probably have a great mineralization potential.

关键词： deep-sea sediments hydrothermal component diffuse fluid eolian dust Southwest Indian Ridge

Magma Evolution Processes in the Southern Okinawa Trough:Insights from Melt Inclusions

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Journal of Ocean University of China 2021年第6期20卷 1383-1397页

作者： ZHANG Yujiao ZHAI Shikui key laboratory of submarine geosciences and Prospection of Ministry of Education Ocean University of ChinaQingdao 266100China

The Okinawa Trough is an initial back-arc basin that is influenced by the subduction of the Philippine Sea Plate and develops on the continental *** Okinawa Trough is a natural laboratory for the study of basin evolution,magmatism,and crustmantle processes in the early stage of back-arc *** inclusions are small droplets of magma that are captured during the mineral crystallization process and can record the geochemical composition changes during magma *** this study,the geochemical compositions of melt inclusions in host plagioclases of two volcanic rock samples at Station nos.9-1 and 9-2 from the southern Okinawa Trough are systematically *** on previous studies,the origin and evolution of magma and the introduction of subducting materials in the study area are *** show that melt inclusions are characterized by the relative enrichment of large-ion lithophile elements,depletion of high-field-strength elements,and slight enrichment of rare earth ***,the subduction of the Philippine Sea Plate introduced sediment-derived melts and fluids into the magma source area of the southern Okinawa ***,4%to 5%partial melting of the hydrated mantle produces basaltic *** melt inclusions of andesite and dacite investigated in this study were formed by fractional crystallization of basaltic ***,the crystallization of plagioclase,pyroxene,and magnetite occurred during the late stage of magma *** temperature-pressure data show that the melt inclusions in plagioclase have two capture periods:one is at temperatures above 1250℃and the other is at temperatures between 1180℃and 1200℃.The capture pressure of the inclusions at temperatures between 1180℃and 1200℃is between 5.6 kPa and 6.1 kPa,corresponding to the depth of 15–17 km below the *** geochemical characteristics of major and trace elements in inclusions show that the samples from two stations(i.e.,9-1 and 9-2)have similar

关键词： melt inclusions magma evolution processes contamination of crustal materials introduction of subducting materials the southern Okinawa Trough

Resolving the hydrothermal signature by sequential leaching studies of sediments from the middle of the Okinawa Trough

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Science China Earth Sciences 2012年第3期55卷 665-674页

作者： YU ZengHui GAO YuHua ZHAI ShiKui LIU FeiFei key laboratory of submarine geosciences and Prospecting Techniques College of Marine GeosciencesOcean University of ChinaQingdao 266100China Shandong Institute of Geophysical and Geochemical Exploration Jinan 250013China

A sediment core H9 collected from the middle of the Okinawa Trough was studied by sequential leaching to indentify the hydrothermal component from the various other components such as detrital,biogenic,and so *** elements were partitioned into five fractions:exchangeable,bound to carbonates,bound to iron and manganese oxides,bound to organic matter,and *** contents of elements Al,Ti,K,Fe,Mn,Pb,Co,Cu,Ni,and V in each fraction were determined and their percentages were *** fraction is a dominant speciation for most studied elements except for Mn and Pb in the core *** the elements Al,Ti,and K,residual fraction accounts for more than 95% of the total metal *** concentrations of all studied elements in the exchangeable fraction,carbonate fraction,and organic fraction are relatively *** metal levels in the iron and manganese oxide fraction are relatively high and this fraction represents another prevalent *** in this fraction,the metal concentrations and percentages are higher in the core section above 80 cm than those below 80 *** for Mn and Pb,the fractions bound to iron and manganese oxides account for more than 50% of the total metal concentration for the upper 80 cm *** components mainly occur in this *** the downcore variations of metal contents and percentages reflect the variations of hydrothermal inputs to the *** high metal levels in the upper core indicate the enhancing influence of hydrothermal activities around on the core H9 during its late stage of *** accumulation rates of hydrothermally derived Fe,Mn,Pb,Co,Cu,Ni,and V were evaluated based on their concentrations in the iron and manganese oxide fractions in this *** results show that the accumulation rate of hydrothermally derived Mn is similar to those obtained from the Mid-ocean Ridges and Lau ***,hydrothermally derived Fe and Cu present a relatively lower level

关键词：热液活动冲绳海槽沉积物碳酸盐结合态金属离子浓度锰氧化物金属含量签名

Source and nature of ore-forming fluids of the Edmond hydrothermal field,Central Indian Ridge:evidence from He-Ar isotope composition and fluid inclusion study

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Acta Oceanologica Sinica 2017年第1期36卷 101-108页

作者： WANG Yejian HAN Xiqiu QIU Zhongyan key laboratory of submarine geosciences Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012China

To understand the source and nature of the ore-forming fluids of the Edmond hydrothermal field on the Central Indian Ridge, we studied the He-Ar isotope composition and fluid inclusions of the hydrothermal *** results show that the sulfide samples contain noble gases He, Ne, Kr, and Xe with their abundances in between those of air-saturated water（ASW） and mid-ocean ridge basalt（MORB）. The ^3He/^4He ratio varies from1.3 to 8.7 Ra（n=10, average： 5.1 Ra）, whereas the ^40Ar/^36Ar ratio is from 285.3 to 314.7（n=10, average： 294.8）. These results suggest that the He was derived from a mixture of MORB with variable amounts of seawater, but the Ar in the ore-forming fluids trapped in the sulfides is predominantly derived from seawater. The fluid inclusions of barite have a wide range of homogenization temperatures and salinities varying from 163℃ to 260℃ and 2.6 wt%to 8.5 wt% Na Cl equiv., respectively. It is suggested that the ore-forming fluids were produced by phase separation, which agreed with the present-day vent fluid study.

关键词： fluid inclusion helium and argon isotopes phase separation massive sulfides Central Indian Ridge

Correction for Depth Biases to Shallow Water Multibeam Bathymetric Data

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China Ocean Engineering 2013年第2期27卷 245-254页

作者：阳凡林李家彪刘智敏韩李涛 Geomatics College Shandong University of Science and Technology key laboratory of Surveying and Mapping Technology on Island and Reef NASG key laboratory of submarine geosciences of State Oceanic Administration

Vertical errors often present in multibeam swath bathymetric data. They are mainly sourced by sound refraction, internal wave disturbance, imperfect tide correction, transducer mounting, long period heave, static draft change, dynamic squat and dynamic motion residuals, etc. Although they can be partly removed or reduced by specific algorithms, the synthesized depth biases are unavoidable and sometimes have an important influence on high precise utilization of the final bathymetric data. In order to. confidently identify the decimeter-level changes in seabed morphology by MBES, we must remove or weaken depth biases and improve the precision of multibeam bathymetry further. The fixed-interval profiles that are perpendicular to the vessel track are generated to adjust depth biases between swaths. We present a kind of postprocessing method to minimize the depth biases by the histogram of cumulative depth biases. The datum line in each profile can be obtained by the maximum value of histogram. The corrections of depth biases can be calculated according to the datum line. And then the quality of final bathymetry can be improved by the corrections. The method is verified by a field test.

关键词： Multibeam Echosounder System depth biases correction shallow water

Shallow Water Body Data Processing Based on the Seismic Oceanography

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Journal of Ocean University of China 2013年第3期12卷 319-326页

作者： LIU Huaishan HU Yi YIN Yanxin WANG Linfei TONG Siyou MA Hai key laboratory of submarine geosciences and Prospecting Techniques Ministry of EducationOcean University of China

Physical properties of sea water,such as salinity,temperature,density and acoustic velocity,could be demarcated through degradation of energy caused by water absorption,attenuation and other *** overcome the challenging difficulties in the quick monitoring of these physical properties,we have explored the high resolution marine seismic survey to instantly characterize *** on the unique wavefield propagating in the sea water,we have developed a new approach to suppress the noise caused by the shallow sea water disturbance and obtain useful information for estimating the sea water *** approach improves seismic data with high signal-to-noise ratio and *** seismic reflection imaging can map the sea water structure *** with the knowledge of local water body structure profile over years,the instant model for predicting the sea water properties could be built using the seismic data acquired from the specially designed high precision marine seismic *** model can also be updated with instant observation and the complete data processing *** present study has the potential value to many applications,such as 3D sea water monitoring,engineering evaluation,geological disaster assessment and environmental assessment.

关键词：数据处理系统地震勘测海洋学水体地震数据采集海水结构浅层高分辨率

Origin of submarine canyon-channel systems along the middle segment of West Mariana Ridge,Philippine Sea

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Journal of Oceanology and Limnology 2023年第3期41卷 881-896页

作者： Guangxu ZHANG Shuang LI Wei LI Xiujuan WANG Duanxin CHEN Dongdong DONG Wenlong WANG key laboratory of Marine Geology and Environment&Center for Ocean Mega-Science Institute of OceanologyChinese Academy of SciencesQingdao 266071China laboratory for Marine Mineral Resources National Laboratory for Marine Science and TechnologyQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China CAS key laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Frontiers Science Center for Deep Ocean Multispheres and Earth System Key Lab of Submarine Geosciences and Prospecting TechniquesMOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China

submarine canyon-channel systems have been documented in the Parece Vela Basin,West Mariana Ridge;however,the mechanism of the formation and controlling factors remain poorly *** on high-resolution multibeam bathymetric data and two-dimensional(2D)seismic profiles,we identified and mapped the submarine canyon-channel system along the middle segment of West Mariana Ridge in the Philippine *** submarine canyon-channels show a main W-E orientation at depth of 2000–4500 *** are approximately 72–128 km in length and 1.3–15 km in width,and their canyon heads are adjacent to the seamounts with several *** upper reaches of submarine canyon-channels are characterized by deeply incised,narrow,V-shaped thalwegs,suggesting the powerful erosion of gravity *** distinguished sediment waves are suggested to be resulted from the interaction of turbidity currents and *** observations demonstrate that gravity flows originated from the collapses of seamount flanks plays a vital role in developing the submarine canyonchannel system along the West Mariana *** work provides better understanding of erosion,transport,and deposition of sediments from subducting ridges to deep-water basins,and also new insights into the origin and evolution of submarine canyon-channel systems along subducting ridges.

关键词： submarine canyon-channel system gravity flow subducting ridges West Mariana Ridge

Effects of Uncertainties in the Position and Orientation of Both the Transmitter and Receivers on Marine Controlled-Source Electromagnetic Data

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Journal of Ocean University of China 2016年第1期15卷 83-92页

作者： XU Zhenhuan LIU Ying LI Yuguo key laboratory of submarine geosciences and Prospecting Techniques of Ministry of Education Ocean University of China

Simulation and interpretation of marine controlled-source electromagnetic(CSEM) data often approximate the transmitter source as an ideal horizontal electric dipole(HED) and assume that the receivers are located on a flat ***,however,the transmitter dipole source will be rotated,tilted and deviated from the survey profile due to ocean *** free-fall receivers may be also rotated to some arbitrary horizontal orientation and located on sloping *** this paper,we investigate the effects of uncertainties in the transmitter tilt,transmitter rotation and transmitter deviation from the survey profile as well as in the receiver's location and orientation on marine CSEM *** model study shows that the uncertainties of all position and orientation parameters of both the transmitter and receivers can propagate into observed data uncertainties,but to a different *** interpreting marine data,field data uncertainties caused by the position and orientation uncertainties of both the transmitter and receivers need to be taken into account.

关键词：不确定性接收机发射机位置电磁数据水平电偶极子海洋数据 CSEM