A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed basedon the quantitative census data of benthic f...A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed basedon the quantitative census data of benthic foraminiferal fauna, together with planktonic foraminiferal oxygen and carbon isotope, AMS14C dating, and the previous results achieved in thesouthern Okinawa Trough. The result shows that the benthic fauna was dominated by Buliminaaculeata (d′Orbigny), Uvigerina peregrina (Cushman), Hispid Uvigerina and Uvigerina dirupta(Todd) during the glaciation-deglaciation before 9.2 cal. ka BP, while Epistominella exigua(Brady), Pullenia bulloides (d′Orbigny), Cibicidoides hyalina (Hofker), Sphaeroidina bulloides(d’Orbigny) and Globocassidulina subglobosa (Brady) predominated the fauna in the post-glaciaperiod after 9.2 cal. ka BP. The benthic foraminifera accumulation rate (BFAR), paleoproductivityestimates and benthic foraminiferal assemblage conformably indicate that surface water paleoproductivity and organic matter flux during the glaciation-deglaciation were higher than those othe post-glacial period in the middle-southern Okinawa Trough, and gradually enhanced from thesouthern to the central Okinawa Trough during the glaciation-deglaciation, which could becaused by the discrepancy of the terrigenous nutrients supply. High abundances of E. exigua, anindicator of pulsed organic matter input, after 9.2 cal. ka BP may indicate that the intensity oseasonally riverine pulsed flux during the post-glacial period was stronger than that of the glaciation-deglaciation period, and the seasonal influx in the central trough might be stronger than inthe south. The temporal distributions of the typical species indicating bottom water oxygen content and ventilation condition show that the ventilation of the bottom water during the post-glaciaperiod is more active than the glaciation-deglaciation, which reflects that the evolution of the intermediate and deep waters of the northwestern Pacific during the last glacia展开更多
伊平屋北部热液区(Iheya North hydrothermal field)位于冲绳海槽中部地区。综合大洋钻探计划(IODP)331航次于2010年9月1日至10月4日在该区钻探了5个站位(C0013～C0017):C0016站位位于North Big Chimney(NBC)地区活跃的热液烟囱和硫化...伊平屋北部热液区(Iheya North hydrothermal field)位于冲绳海槽中部地区。综合大洋钻探计划(IODP)331航次于2010年9月1日至10月4日在该区钻探了5个站位(C0013～C0017):C0016站位位于North Big Chimney(NBC)地区活跃的热液烟囱和硫化物—硫酸盐丘状体上;在C0013、C0014、C0015、C0016站位发现了异常高热流值;在热液补给区C0017站位,实现最大钻探深度达到海底下151 m。在活跃的丘状热液喷口处的C0016站位,尽管取芯率只有4.7%,但首次在现代海底获得黑矿型(Kuroko-type)、富闪锌矿的黑色矿石样品。其他4个站位岩芯主要为具有不同热液蚀变和矿化程度(沸石相到绿片岩相)的互层状半深海和火山碎屑沉积物,及火山角砾和浮岩砾屑。钻孔中不规则的地温梯度剖面变化揭示出地下流体的横向运移趋势。现场数据表明,岩芯孔隙水和气体组成在垂向和横向上变化较大。海底作用主要包括通过相态分离而形成高盐水和富气体的流体,矿物蚀变释放Ca而吸附Mg和Na,高温下K释放而低温吸收,硬石膏形成,有机质的微生物氧化和甲烷利用硫酸盐的厌氧氧化,微生物作用下甲烷形成等。船上研究未证实研究区存在活跃的深部生物圈,细胞丰度明显低于以前的ODP/IODP在陆架边缘的钻探站位。展开更多
The melting of the West Antarctic Ice Shelf has increased since the 1990s,driven by the relatively warm Circumpolar Deep Water(CDW)that penetrates into the West Antarctic Ice Shelf cavities through submarine glacial t...The melting of the West Antarctic Ice Shelf has increased since the 1990s,driven by the relatively warm Circumpolar Deep Water(CDW)that penetrates into the West Antarctic Ice Shelf cavities through submarine glacial troughs across the continental shelf.In this study,temperature,salinity,and current velocity data obtained by the Chinese National Antarctic Research Expedition in the Dotson-Getz Trough(DGT)shows clear differences in distribution of modified Circumpolar Deep Water(mCDW)in the summers of 2020 and 2022.Combined with contemporaneous wind data and additional temperature and salinity data from instrumented seals,the processes and mechanisms responsible for this variation are discussed.Compared with 2020,there is a significant increase in mCDW thickness in 2022,with a doubling of total heat content as the mCDW inflow path across the DGT shifts towards the eastern bank.We propose that a southward shift in the westerly winds in the summer of 2022 moved the upper oceanic divergence zone southward towards the continental slope,promoting the upwelling of mCDW above 500 m.Concurrently,stronger westerly winds over the continental slope strengthened the eastward undercurrent,increasing the transport of this mCDW and its associated heat content to the DGT through Ekman dynamics.These observations show there is strong interannual variability in the strength,path and extent of mCDW inflows to the DGT and that care must be taken when planning observation programs for long-term monitoring of the oceanic heat input to the ice shelves of this globally significant region.展开更多
Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang-Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluate...Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang-Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluated. The results show that:(1) Dengying Formation in and around Deyang-Anyue erosion rift trough varies widely in sedimentary characteristics. The Dengying Formation in the northern part of the erosion rift trough developed deep-water sediments, the Dengying Formation in the northern part of the basin varied gradually from basin to slope, platform margin, and restricted platform, and the Dengying Formation in the middle and southern parts of the trough developed carbonate platform facies.(2) Deyang-Anyue erosion rift trough is formed by extensional rift and karst erosion jointly, the north section of the erosion rift trough is mainly the product of tensile rift, while the middle and south sections are formed by erosion in multi-episodes of Tongwan period.(3) Based on the segmented origins of the erosion rift trough, Dengying Formation in and around it is divided into three exploration fields: lithologic mound and beach bodies at the northern platform margin of the basin, karst mound and beach bodies in the central platform, and karst residual mounds in the central southern trough of the basin, among them, the karst residual mounds in the central southern trough of the basin are a new frontier for natural gas exploration in the basin, and the lithologic mound and beach bodies at the northern platform margin are a new position for increasing the reserves of trillions of cubic meters of natural gas resources in the basin.展开更多
Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach. The structure of the hurricane is examined using radar wind data made availab...Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach. The structure of the hurricane is examined using radar wind data made available from aircraft reconnaissance missions. This showed a dominant warm air advection configuration(winds turning in direction in an anticyclonic fashion with height) around the core of the hurricane. Conventional radiosonde data was also used to study the warm air advection environment east of a deep layered tough system which Michael moved into and which appeared to favour such strong intensification. The structure of this deep trough is also examined and compared with a situation where Hurricane Dennis in 2005 weakened as it approached the coast in much the same region. It appears that the thermal structure of the upper trough at low to middle levels is critical to whether the hurricane intensifies or weakens with the presence of strong cold air advection associated with weakening.展开更多
基金the CAS Pilot Project of the National Knowledge Innovation Program(Project No.KZCFX3-SW-220) the National Natural Science Foundation of China(Grant Nos.40176019 , 90411014) the National Major Fundamental Research and Development Project(Grant No.G20000467).
文摘A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed basedon the quantitative census data of benthic foraminiferal fauna, together with planktonic foraminiferal oxygen and carbon isotope, AMS14C dating, and the previous results achieved in thesouthern Okinawa Trough. The result shows that the benthic fauna was dominated by Buliminaaculeata (d′Orbigny), Uvigerina peregrina (Cushman), Hispid Uvigerina and Uvigerina dirupta(Todd) during the glaciation-deglaciation before 9.2 cal. ka BP, while Epistominella exigua(Brady), Pullenia bulloides (d′Orbigny), Cibicidoides hyalina (Hofker), Sphaeroidina bulloides(d’Orbigny) and Globocassidulina subglobosa (Brady) predominated the fauna in the post-glaciaperiod after 9.2 cal. ka BP. The benthic foraminifera accumulation rate (BFAR), paleoproductivityestimates and benthic foraminiferal assemblage conformably indicate that surface water paleoproductivity and organic matter flux during the glaciation-deglaciation were higher than those othe post-glacial period in the middle-southern Okinawa Trough, and gradually enhanced from thesouthern to the central Okinawa Trough during the glaciation-deglaciation, which could becaused by the discrepancy of the terrigenous nutrients supply. High abundances of E. exigua, anindicator of pulsed organic matter input, after 9.2 cal. ka BP may indicate that the intensity oseasonally riverine pulsed flux during the post-glacial period was stronger than that of the glaciation-deglaciation period, and the seasonal influx in the central trough might be stronger than inthe south. The temporal distributions of the typical species indicating bottom water oxygen content and ventilation condition show that the ventilation of the bottom water during the post-glaciaperiod is more active than the glaciation-deglaciation, which reflects that the evolution of the intermediate and deep waters of the northwestern Pacific during the last glacia
文摘伊平屋北部热液区(Iheya North hydrothermal field)位于冲绳海槽中部地区。综合大洋钻探计划(IODP)331航次于2010年9月1日至10月4日在该区钻探了5个站位(C0013～C0017):C0016站位位于North Big Chimney(NBC)地区活跃的热液烟囱和硫化物—硫酸盐丘状体上;在C0013、C0014、C0015、C0016站位发现了异常高热流值;在热液补给区C0017站位,实现最大钻探深度达到海底下151 m。在活跃的丘状热液喷口处的C0016站位,尽管取芯率只有4.7%,但首次在现代海底获得黑矿型(Kuroko-type)、富闪锌矿的黑色矿石样品。其他4个站位岩芯主要为具有不同热液蚀变和矿化程度(沸石相到绿片岩相)的互层状半深海和火山碎屑沉积物,及火山角砾和浮岩砾屑。钻孔中不规则的地温梯度剖面变化揭示出地下流体的横向运移趋势。现场数据表明,岩芯孔隙水和气体组成在垂向和横向上变化较大。海底作用主要包括通过相态分离而形成高盐水和富气体的流体,矿物蚀变释放Ca而吸附Mg和Na,高温下K释放而低温吸收,硬石膏形成,有机质的微生物氧化和甲烷利用硫酸盐的厌氧氧化,微生物作用下甲烷形成等。船上研究未证实研究区存在活跃的深部生物圈,细胞丰度明显低于以前的ODP/IODP在陆架边缘的钻探站位。
基金This work is supported by Chinese Arctic and Antarctic Administration(Grant no.IRASCC2020-2022)National Key R&D Program of China(Grant no.2018YFA0605701).
文摘The melting of the West Antarctic Ice Shelf has increased since the 1990s,driven by the relatively warm Circumpolar Deep Water(CDW)that penetrates into the West Antarctic Ice Shelf cavities through submarine glacial troughs across the continental shelf.In this study,temperature,salinity,and current velocity data obtained by the Chinese National Antarctic Research Expedition in the Dotson-Getz Trough(DGT)shows clear differences in distribution of modified Circumpolar Deep Water(mCDW)in the summers of 2020 and 2022.Combined with contemporaneous wind data and additional temperature and salinity data from instrumented seals,the processes and mechanisms responsible for this variation are discussed.Compared with 2020,there is a significant increase in mCDW thickness in 2022,with a doubling of total heat content as the mCDW inflow path across the DGT shifts towards the eastern bank.We propose that a southward shift in the westerly winds in the summer of 2022 moved the upper oceanic divergence zone southward towards the continental slope,promoting the upwelling of mCDW above 500 m.Concurrently,stronger westerly winds over the continental slope strengthened the eastward undercurrent,increasing the transport of this mCDW and its associated heat content to the DGT through Ekman dynamics.These observations show there is strong interannual variability in the strength,path and extent of mCDW inflows to the DGT and that care must be taken when planning observation programs for long-term monitoring of the oceanic heat input to the ice shelves of this globally significant region.
基金Supported by the National Key Research and Development Program of China (2017YFC0603106)Project of Science and Technology Department of PetroChina Southwest Oil and Gas Field Company (20200301-01)。
文摘Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang-Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluated. The results show that:(1) Dengying Formation in and around Deyang-Anyue erosion rift trough varies widely in sedimentary characteristics. The Dengying Formation in the northern part of the erosion rift trough developed deep-water sediments, the Dengying Formation in the northern part of the basin varied gradually from basin to slope, platform margin, and restricted platform, and the Dengying Formation in the middle and southern parts of the trough developed carbonate platform facies.(2) Deyang-Anyue erosion rift trough is formed by extensional rift and karst erosion jointly, the north section of the erosion rift trough is mainly the product of tensile rift, while the middle and south sections are formed by erosion in multi-episodes of Tongwan period.(3) Based on the segmented origins of the erosion rift trough, Dengying Formation in and around it is divided into three exploration fields: lithologic mound and beach bodies at the northern platform margin of the basin, karst mound and beach bodies in the central platform, and karst residual mounds in the central southern trough of the basin, among them, the karst residual mounds in the central southern trough of the basin are a new frontier for natural gas exploration in the basin, and the lithologic mound and beach bodies at the northern platform margin are a new position for increasing the reserves of trillions of cubic meters of natural gas resources in the basin.
文摘Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach. The structure of the hurricane is examined using radar wind data made available from aircraft reconnaissance missions. This showed a dominant warm air advection configuration(winds turning in direction in an anticyclonic fashion with height) around the core of the hurricane. Conventional radiosonde data was also used to study the warm air advection environment east of a deep layered tough system which Michael moved into and which appeared to favour such strong intensification. The structure of this deep trough is also examined and compared with a situation where Hurricane Dennis in 2005 weakened as it approached the coast in much the same region. It appears that the thermal structure of the upper trough at low to middle levels is critical to whether the hurricane intensifies or weakens with the presence of strong cold air advection associated with weakening.
