The circum-Pacific convergent margin is known as"the Ring of Fire",with abundant volcano eruptions.Large eruptions are rare but very disastrous.It remains obscure how are large explosive volcanos formed and ...The circum-Pacific convergent margin is known as"the Ring of Fire",with abundant volcano eruptions.Large eruptions are rare but very disastrous.It remains obscure how are large explosive volcanos formed and where are the danger zones.Three largest eruptions since 1900,the Hunga Tonga-Hunga Ha’apai,the Mt.Pinatubo,and the Novarupta were found to be associated with subductions of volatile-rich sediments and located close to slab windows.Among them,the Hunga Tonga-Hunga Ha’apai is close to subducting seamount chains;the Mt.Pinatubo is right next to subducting fossil ridges.Both seamount chains and fossil ridges have water depths much shallower than the carbonate compensation depths(CCD)in the Pacific Ocean.Seismic image shows that a seamount is subducting towards the Novarupta volcano.Subduction of volatile-rich sediments and a slab window nearby are the two most important favorable conditions for catastrophic eruptions.Slab windows expose the mantle wedge to the hot asthenosphere,which increases the temperature and dramatically promotes the partial melting of the carbonate-fluxed domains,forming volatile-rich magmas that powered explosive eruptions.展开更多
Nearly 80%of the seafloor extension has not been covered by high-resolution bathymetry,impeding direct observation of seamounts.Nevertheless,lists of seamount location and height at a global scale have been produced u...Nearly 80%of the seafloor extension has not been covered by high-resolution bathymetry,impeding direct observation of seamounts.Nevertheless,lists of seamount location and height at a global scale have been produced using different techniques.In this work four of such databases(publicly available)are compared with each other to assess their differences.Results identify large differences among databases that could have exerted strong influences on models of seamount production and associated geodynamic processes.Despite those differences,it is shown that all databases allow the identification of seamount lines both along the present-day Mid Ocean Ridge(MOR)system and on intraplate settings.Notably,those seamount lines do not coincide with the so-called hotspot tracks that commonly were defined by selectively focusing attention on the larger seamounts.Examination of all the databases also shows that distinction based only on seamount size between seamounts produced at Mid-Ocean Ridge(MOR)environments from those associated with mantle-plum fed-hotspot activity has been overestimated.This,combined with the fact that most seamount lines defined by the available databases can be traced back to past locations of MOR indicates that most of the present-day intraplate linear arrays of seamounts,which include some large seamounts,were not produced by the action of underlying mantle anomalies envisaged in the form of mantle plumes.The evidence presented here calls for a reassessment of the form in which volcanic and tectonic activities are conceptually related to each other.展开更多
The Philippine Basin,surrounded by a series of oceanic trenches,is an independent deep ocean basin in the West Pacific Ocean.Its middle part is divided into three marginal sea sub-basins by the Kyushu-Palau and West M...The Philippine Basin,surrounded by a series of oceanic trenches,is an independent deep ocean basin in the West Pacific Ocean.Its middle part is divided into three marginal sea sub-basins by the Kyushu-Palau and West Mariana Ridges,namely,the West Philippine Basin,the Shikoku and Parece Vela Basins and the Mariana Trough.This paper,through the analysis of the geomorphologic features and gravity and magnetic characteristics of the basin and identification of striped magnetic anomalies,suggests that the entire Philippine Basin developed magnetic lineation of oceanic nature,and therefore,the entire basin is of the nature of oceanic crust.The basin has developed a series of special geomorphic units with different shapes.The KPR runs through the entire Philippine Basin.From the view of geomorphologic features,the KPR is a discontinuous seamount chain （chain-shaped seamounts） and subduction beneath the Japanese Island arc at the Nankai Trough which is the natural boundary between the basin and the Japanese Island arc.At the positions of 25 N,24 N,23 N and 18 N,obvious discontinuity is shown,which belongs to natural topographic discontinuity.Therefore,the KPR is topographically discontinuous.展开更多
The tectonic evolution of the Caroline Plate during the Oligocene to Early Miocene was mainly controlled by two fulcrums.The west fulcrum at Palau Island remained fixed during 29-25 Ma as the Ayu Trough rifted and pro...The tectonic evolution of the Caroline Plate during the Oligocene to Early Miocene was mainly controlled by two fulcrums.The west fulcrum at Palau Island remained fixed during 29-25 Ma as the Ayu Trough rifted and produced the abyssal hills parallel to its boundaries,and the Pacific Plate and part of the Caroline Plate subducted to the north.At the northeast corner of the Caroline Plate,the east fulcrum is surrounded by a series of arc seamount chains.These chains resulted from the convergence between the Caroline Plate and the Pacific Plate and crustal softening of the northeastern Caroline Plate induced by the Caroline Hotspot at~25 Ma.This softening of the crust also led to the dysfunction of the east fulcrum,and the west fulcrum migrated south,which caused dextral motion along the Ayu Rift and the development of an en echelon structure.The Yap Trench was a part of the spreading center in the Parece-Vela Rift at~29 Ma.However,sinistral motion along the Parece-Vela Rift at around 20-15 Ma led to the exposure of the subducted Yap Trench and left a triangular region with distinctive geophysical characteristics in the surrounding area.展开更多
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22050103)the Taishan Scholar Program of Shandong(No.ts201712075)。
文摘The circum-Pacific convergent margin is known as"the Ring of Fire",with abundant volcano eruptions.Large eruptions are rare but very disastrous.It remains obscure how are large explosive volcanos formed and where are the danger zones.Three largest eruptions since 1900,the Hunga Tonga-Hunga Ha’apai,the Mt.Pinatubo,and the Novarupta were found to be associated with subductions of volatile-rich sediments and located close to slab windows.Among them,the Hunga Tonga-Hunga Ha’apai is close to subducting seamount chains;the Mt.Pinatubo is right next to subducting fossil ridges.Both seamount chains and fossil ridges have water depths much shallower than the carbonate compensation depths(CCD)in the Pacific Ocean.Seismic image shows that a seamount is subducting towards the Novarupta volcano.Subduction of volatile-rich sediments and a slab window nearby are the two most important favorable conditions for catastrophic eruptions.Slab windows expose the mantle wedge to the hot asthenosphere,which increases the temperature and dramatically promotes the partial melting of the carbonate-fluxed domains,forming volatile-rich magmas that powered explosive eruptions.
基金Funding for this work was provided by CONACYT Grant No.A1-S-23107。
文摘Nearly 80%of the seafloor extension has not been covered by high-resolution bathymetry,impeding direct observation of seamounts.Nevertheless,lists of seamount location and height at a global scale have been produced using different techniques.In this work four of such databases(publicly available)are compared with each other to assess their differences.Results identify large differences among databases that could have exerted strong influences on models of seamount production and associated geodynamic processes.Despite those differences,it is shown that all databases allow the identification of seamount lines both along the present-day Mid Ocean Ridge(MOR)system and on intraplate settings.Notably,those seamount lines do not coincide with the so-called hotspot tracks that commonly were defined by selectively focusing attention on the larger seamounts.Examination of all the databases also shows that distinction based only on seamount size between seamounts produced at Mid-Ocean Ridge(MOR)environments from those associated with mantle-plum fed-hotspot activity has been overestimated.This,combined with the fact that most seamount lines defined by the available databases can be traced back to past locations of MOR indicates that most of the present-day intraplate linear arrays of seamounts,which include some large seamounts,were not produced by the action of underlying mantle anomalies envisaged in the form of mantle plumes.The evidence presented here calls for a reassessment of the form in which volcanic and tectonic activities are conceptually related to each other.
基金973 Jointly funded by Cenozoic Sequence Stratigraphy and Sedimentary Evolution of Continental Margin of the East China Sea under contract No.2007CB41170301Research on Sedimentary Features and Sedimentary Filling of the Lower Slope Basin in the Deep Water Area of the Middle and Northern South China Sea of the Special Fund Program of Basic Scientific Research Expenses under contract No.JG1007Supporting Technologies for Delimitation of Continental Shelves and Exclusive Economic Zones under contract Nos 200805078,201205037 and 201205003
文摘The Philippine Basin,surrounded by a series of oceanic trenches,is an independent deep ocean basin in the West Pacific Ocean.Its middle part is divided into three marginal sea sub-basins by the Kyushu-Palau and West Mariana Ridges,namely,the West Philippine Basin,the Shikoku and Parece Vela Basins and the Mariana Trough.This paper,through the analysis of the geomorphologic features and gravity and magnetic characteristics of the basin and identification of striped magnetic anomalies,suggests that the entire Philippine Basin developed magnetic lineation of oceanic nature,and therefore,the entire basin is of the nature of oceanic crust.The basin has developed a series of special geomorphic units with different shapes.The KPR runs through the entire Philippine Basin.From the view of geomorphologic features,the KPR is a discontinuous seamount chain （chain-shaped seamounts） and subduction beneath the Japanese Island arc at the Nankai Trough which is the natural boundary between the basin and the Japanese Island arc.At the positions of 25 N,24 N,23 N and 18 N,obvious discontinuity is shown,which belongs to natural topographic discontinuity.Therefore,the KPR is topographically discontinuous.
基金supported financially by the Scientific and Technological Innovation Project of Pilot National Laboratory for Marine Science and Technology(Qingdao)(Grant No.2017ASKJ02)the Scientific Research Start Funds Project of the Fourth Institute of Oceanography,Ministry of Natural Resources(Grant No.202007)+3 种基金the National Natural Science Foundation of China(Grant No.U1606401)the National Ocean Bureau Program(Grant No.GASIGEOGE-1)the Aoshan Elite Scientist Plan(Grant No.2015ASTP-0S10)of Pilot National Laboratory for Marine Science and Technology(Qingdao)to Prof.Sanzhong LI and his research groupthe Taishan Scholor Program to Sanzhong LI。
文摘The tectonic evolution of the Caroline Plate during the Oligocene to Early Miocene was mainly controlled by two fulcrums.The west fulcrum at Palau Island remained fixed during 29-25 Ma as the Ayu Trough rifted and produced the abyssal hills parallel to its boundaries,and the Pacific Plate and part of the Caroline Plate subducted to the north.At the northeast corner of the Caroline Plate,the east fulcrum is surrounded by a series of arc seamount chains.These chains resulted from the convergence between the Caroline Plate and the Pacific Plate and crustal softening of the northeastern Caroline Plate induced by the Caroline Hotspot at~25 Ma.This softening of the crust also led to the dysfunction of the east fulcrum,and the west fulcrum migrated south,which caused dextral motion along the Ayu Rift and the development of an en echelon structure.The Yap Trench was a part of the spreading center in the Parece-Vela Rift at~29 Ma.However,sinistral motion along the Parece-Vela Rift at around 20-15 Ma led to the exposure of the subducted Yap Trench and left a triangular region with distinctive geophysical characteristics in the surrounding area.
