In 2001, the International Seabed Authority （ISBA） initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crust...In 2001, the International Seabed Authority （ISBA） initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crusts in the Area at its 7th session. Since then, the consideration of the Regulations has been mainly focused on the size of areas to be allocated for exploration and exploitation of the crusts. This paper, based on the investigation data and the analysis of the distribution characteristics of the crusts, suggests a model for determining the size of areas for exploration and exploitation of the crusts, taking into account various factors such as production scale, crust thickness and grade, mineable area proportion, recovery efficiency, exploration venture, and so on. Through the modeling, the paper suggests that the exploration area （the area covered by each application for approval of a plan of work for exploration of cobalt-rich crusts） shall be 4 856 km2 and the exploitation area （the mine site area） shall be 1 214 km2, for 20 years of 1 million wet tonnes annual production.展开更多
The Beikang Basin is located in the southern part of the South China Sea(SCS),which is one of most tectonically complex sea areas.It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era.O...The Beikang Basin is located in the southern part of the South China Sea(SCS),which is one of most tectonically complex sea areas.It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era.Owing to data restrictions,the research on carbonate platforms of this area is still in its infancy.High-resolution seismic data are analyzed to identify the Miocene carbonate platforms and reconstruct the architecture and growth history.The carbonate platforms of Beikang Basin began to develop in the Late Oligocene-Early Miocene,were extended in the Middle Miocene,and declined in the Late Miocene.The carbonate platform mainly developed during two periods:the Oligocene to the Early Miocene,and the Middle Miocene.The carbonate platforms that developed in the Middle Miocene were the most prosperous.The Middle Miocene carbonate platform in the Beikang Basin can be divided into three stages.In the first stage,the platforms had wide range which were thin.During the second stage,the platforms had a smaller range that was controlled by faults.In the third stage,the platforms were gradually submerged.The platform structure developed in the Middle Miocene at the Beikang Basin was controlled by the rate of rising/falling of the sea level and the carbonate growth rate.Based on an analysis of these changes and relationship,the platform can be divided into several patterns:retrogradation,submerged,aggradation,progradation,outward with up-stepping,outward with down-stepping,and down-stepping platforms.At the top of the carbonate platforms in the Beikang Basin a set of carbonate wings or mushrooms usually appeared.These were formed during a period of relative sea-level decline.It is believed that the Miocene carbonate platforms in the Beikang Basin are mainly controlled by tectonic and sedimentary environments,and are also affected by terrestrial detritus.展开更多
The CDE hydrothermal field was first discovered during a Chinese cruise to the East Lau Basin Spreading Centre in 2007.Apart from significant amounts of loose Fe-Si-Mn(oxyhydr) oxide(referred to as oxide below) precip...The CDE hydrothermal field was first discovered during a Chinese cruise to the East Lau Basin Spreading Centre in 2007.Apart from significant amounts of loose Fe-Si-Mn(oxyhydr) oxide(referred to as oxide below) precipitates,a small Si-rich oxide chimney was also recovered on this cruise.In this study,we report on the mineralogical and geochemical analyses of this chimney and a model for its growth that has been developed.Based on the mineralogy and O isotope results,the chimney walls can be divided into four growth generations(layers) from the inner to the outer layers:amorphous opal and barite layer(precipitation temperature 68.5°C based on oxygen isotope determinations),a rod-like amorphous layer(precipitation temperature 39.6°C),a filamentous Fe-Si oxide layer,and an outer Fe-Mn oxide layer.Investigations based on SEM and EDS showed that neutrophilic Fe-oxidizing bacteria play an important role in the formation of this chimney,particularly in the outer two generations.In the first stage,the metabolic activity of the microbes results in the pervasive precipitation of the filamentous Fe-rich oxides inside a ring formed by some amorphous opal and barite;therefore,a loose porous layer forms.In the second stage,amorphous opal then precipitates inside this wall as a result of conductive cooling and gradually controls the mixing between the hydrothermal fluids and ambient seawaters.In the third stage,barite and some amorphous opal form from the higher temperature fluids at the summit of the chimney growth history.In the last stage,the chimney wall becomes thicker and denser and the exchange of hydrothermal fluids and seawater ceases.As a result,a Fe-Mn oxide layer precipitates onto the outer surface of the chimney wall as neutrophilic Fe-oxidizing bacteria reoccupy the surface of the chimney.This mineral sequence and the resultant growth generations are confirmed by the chemical characteristics of the chimney wall.Sr isotopes extracted from the Fe oxides of the four-generation wall generally show a decreasing trend of the 87 Sr/86 Sr ratios from the second layer to the inner layer(from 0.707008 to 0.705877) except for the outer layer(0.706502).The Sr isotope and chondrite normalized REE patterns of the corresponding bulk samples from the chimney wall also display a similar trend.Our study shows that the biogenic filament network plays a key role in the formation of the chimney in contrast to previous growth models of higher temperature chimneys,which often ignore the influence of biogenic factors.展开更多
Microbial mats, several millimeters thick and brown-yellow to white in color, were collected in hollow inside of chimney structure from Edmond hydrothermal field on the Central Indian Ridge. Microbes with shapes of ro...Microbial mats, several millimeters thick and brown-yellow to white in color, were collected in hollow inside of chimney structure from Edmond hydrothermal field on the Central Indian Ridge. Microbes with shapes of rod and helical stalk-like filaments were observed in the microbial mats, and are com- monly characterized by their cells completely encrusted by thick mineralized layers, made up of large amounts of amorphous silica and minor amounts of iron oxides. Transmission Electron Microscope observation has demonstrated that the acicular Fe-bearing matter was not only heterogenously dis- tributed on the surface of the cell wall, but also deposited in the inside of cell, suggesting that bio-precipitation of Fe had occurred both on the surface and in the interior of cell. Microbial silicification was also commonly found in the mats. Silica usually precipitated homogeneously on the surface of the microbes and forms micro-laminated layers, which might be controlled by the inorganic process of precipitation in hydrothermal environment. The biomineralization phenomenon in the mi- crobial mats showed that the precipitation of Fe and Si was closely related to microbes in hydrothermal environment. Considering that hydrothermal activities provided required chemical elements for miner- alization, it is suggested that this biomineralization process also might be driven by hydrothermal ac- tivities at the sea floor to some extent.展开更多
As an important part of marine hydrothermal system, hydrothermal vent faunas live in hydrothermal inorganic environment and closely interact with hydrothermal inorganic environment. Sometimes, they can participate in ...As an important part of marine hydrothermal system, hydrothermal vent faunas live in hydrothermal inorganic environment and closely interact with hydrothermal inorganic environment. Sometimes, they can participate in the mineralization process of modern hydrothermal site. Hydrothermal vent faunas, particularly vestimentiferan and polychaete tubeworms, are occasionally preserved in the geological record. Study on the early mineralization process of hydrothermal vent fauna is significant for under- standing the interaction between mineral and organism, and also the formation and preservation mechanism of geological fossil in hydrothermal environment. In this paper, the early stage of miner- alization of Vestimentiferan Ridgeia piscesae tubes collected from Juan de Fuca Ridge is studied. The results showed that a lot of filamentous microorganisms were unevenly distributed on the surface of internal wall and in the interspace of the wall of tubeworm. In some cases, microorganisms aggregated as thin layers in or on the wall of tubeworm. The surfaces of microbial cells and the products of micro- bial degradation may play an important role in the early mineralization of tubeworm. Semitransparent thin layers of organic matter containing sulfur and sulfur granules were commonly found on the wall of tubeworm with lower degree of mineralization. The degradation production of these semitransparent thin layers may accelerate the mineralization of tube wall during the early stage. EDS results showed that on the tube walls some chemical elements such as Fe, P, Ca and Si are selectively enriched from ambient hydrothermal environment. Interestingly, P, Ca and Si covary with Fe content. Because element S originated from the bio-oxidation of H2S by symbiotic microorganism in the tissue of tubeworm, it can be considered as a biomarker when studying the mineralization process of tube wall. Based on the characteristics of tubeworms with different degrees of mineralization, we suggested that the early mineralization stage of tube wall was mainly controlled by microbial-induced mineralization and the degradation process of tube wall.展开更多
基金China International Seabed Area R & D Program under contract No.DYXM-115-01-1
文摘In 2001, the International Seabed Authority （ISBA） initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crusts in the Area at its 7th session. Since then, the consideration of the Regulations has been mainly focused on the size of areas to be allocated for exploration and exploitation of the crusts. This paper, based on the investigation data and the analysis of the distribution characteristics of the crusts, suggests a model for determining the size of areas for exploration and exploitation of the crusts, taking into account various factors such as production scale, crust thickness and grade, mineable area proportion, recovery efficiency, exploration venture, and so on. Through the modeling, the paper suggests that the exploration area （the area covered by each application for approval of a plan of work for exploration of cobalt-rich crusts） shall be 4 856 km2 and the exploitation area （the mine site area） shall be 1 214 km2, for 20 years of 1 million wet tonnes annual production.
基金supported by Geological Investigation Programs of China Geological Survey(Grant No.DD20190213 and No.DD20191009)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0208)the Open Fund of MLR Key Laboratory of Marine Mineral Resources(Grant No.KLMMR-2017-A-16)。
文摘The Beikang Basin is located in the southern part of the South China Sea(SCS),which is one of most tectonically complex sea areas.It is a deepwater sedimentary basin that was mainly deposited during the Cenozoic era.Owing to data restrictions,the research on carbonate platforms of this area is still in its infancy.High-resolution seismic data are analyzed to identify the Miocene carbonate platforms and reconstruct the architecture and growth history.The carbonate platforms of Beikang Basin began to develop in the Late Oligocene-Early Miocene,were extended in the Middle Miocene,and declined in the Late Miocene.The carbonate platform mainly developed during two periods:the Oligocene to the Early Miocene,and the Middle Miocene.The carbonate platforms that developed in the Middle Miocene were the most prosperous.The Middle Miocene carbonate platform in the Beikang Basin can be divided into three stages.In the first stage,the platforms had wide range which were thin.During the second stage,the platforms had a smaller range that was controlled by faults.In the third stage,the platforms were gradually submerged.The platform structure developed in the Middle Miocene at the Beikang Basin was controlled by the rate of rising/falling of the sea level and the carbonate growth rate.Based on an analysis of these changes and relationship,the platform can be divided into several patterns:retrogradation,submerged,aggradation,progradation,outward with up-stepping,outward with down-stepping,and down-stepping platforms.At the top of the carbonate platforms in the Beikang Basin a set of carbonate wings or mushrooms usually appeared.These were formed during a period of relative sea-level decline.It is believed that the Miocene carbonate platforms in the Beikang Basin are mainly controlled by tectonic and sedimentary environments,and are also affected by terrestrial detritus.
基金supported by National Natural Science Foundation of China(Grant Nos.40976045,40976025 and 41006072)
文摘The CDE hydrothermal field was first discovered during a Chinese cruise to the East Lau Basin Spreading Centre in 2007.Apart from significant amounts of loose Fe-Si-Mn(oxyhydr) oxide(referred to as oxide below) precipitates,a small Si-rich oxide chimney was also recovered on this cruise.In this study,we report on the mineralogical and geochemical analyses of this chimney and a model for its growth that has been developed.Based on the mineralogy and O isotope results,the chimney walls can be divided into four growth generations(layers) from the inner to the outer layers:amorphous opal and barite layer(precipitation temperature 68.5°C based on oxygen isotope determinations),a rod-like amorphous layer(precipitation temperature 39.6°C),a filamentous Fe-Si oxide layer,and an outer Fe-Mn oxide layer.Investigations based on SEM and EDS showed that neutrophilic Fe-oxidizing bacteria play an important role in the formation of this chimney,particularly in the outer two generations.In the first stage,the metabolic activity of the microbes results in the pervasive precipitation of the filamentous Fe-rich oxides inside a ring formed by some amorphous opal and barite;therefore,a loose porous layer forms.In the second stage,amorphous opal then precipitates inside this wall as a result of conductive cooling and gradually controls the mixing between the hydrothermal fluids and ambient seawaters.In the third stage,barite and some amorphous opal form from the higher temperature fluids at the summit of the chimney growth history.In the last stage,the chimney wall becomes thicker and denser and the exchange of hydrothermal fluids and seawater ceases.As a result,a Fe-Mn oxide layer precipitates onto the outer surface of the chimney wall as neutrophilic Fe-oxidizing bacteria reoccupy the surface of the chimney.This mineral sequence and the resultant growth generations are confirmed by the chemical characteristics of the chimney wall.Sr isotopes extracted from the Fe oxides of the four-generation wall generally show a decreasing trend of the 87 Sr/86 Sr ratios from the second layer to the inner layer(from 0.707008 to 0.705877) except for the outer layer(0.706502).The Sr isotope and chondrite normalized REE patterns of the corresponding bulk samples from the chimney wall also display a similar trend.Our study shows that the biogenic filament network plays a key role in the formation of the chimney in contrast to previous growth models of higher temperature chimneys,which often ignore the influence of biogenic factors.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40532011, 40403004 and 40473032)
文摘Microbial mats, several millimeters thick and brown-yellow to white in color, were collected in hollow inside of chimney structure from Edmond hydrothermal field on the Central Indian Ridge. Microbes with shapes of rod and helical stalk-like filaments were observed in the microbial mats, and are com- monly characterized by their cells completely encrusted by thick mineralized layers, made up of large amounts of amorphous silica and minor amounts of iron oxides. Transmission Electron Microscope observation has demonstrated that the acicular Fe-bearing matter was not only heterogenously dis- tributed on the surface of the cell wall, but also deposited in the inside of cell, suggesting that bio-precipitation of Fe had occurred both on the surface and in the interior of cell. Microbial silicification was also commonly found in the mats. Silica usually precipitated homogeneously on the surface of the microbes and forms micro-laminated layers, which might be controlled by the inorganic process of precipitation in hydrothermal environment. The biomineralization phenomenon in the mi- crobial mats showed that the precipitation of Fe and Si was closely related to microbes in hydrothermal environment. Considering that hydrothermal activities provided required chemical elements for miner- alization, it is suggested that this biomineralization process also might be driven by hydrothermal ac- tivities at the sea floor to some extent.
基金the National Natural Science Foundation of China (Grant Nos. 40532011, 40403004 and 40473032)
文摘As an important part of marine hydrothermal system, hydrothermal vent faunas live in hydrothermal inorganic environment and closely interact with hydrothermal inorganic environment. Sometimes, they can participate in the mineralization process of modern hydrothermal site. Hydrothermal vent faunas, particularly vestimentiferan and polychaete tubeworms, are occasionally preserved in the geological record. Study on the early mineralization process of hydrothermal vent fauna is significant for under- standing the interaction between mineral and organism, and also the formation and preservation mechanism of geological fossil in hydrothermal environment. In this paper, the early stage of miner- alization of Vestimentiferan Ridgeia piscesae tubes collected from Juan de Fuca Ridge is studied. The results showed that a lot of filamentous microorganisms were unevenly distributed on the surface of internal wall and in the interspace of the wall of tubeworm. In some cases, microorganisms aggregated as thin layers in or on the wall of tubeworm. The surfaces of microbial cells and the products of micro- bial degradation may play an important role in the early mineralization of tubeworm. Semitransparent thin layers of organic matter containing sulfur and sulfur granules were commonly found on the wall of tubeworm with lower degree of mineralization. The degradation production of these semitransparent thin layers may accelerate the mineralization of tube wall during the early stage. EDS results showed that on the tube walls some chemical elements such as Fe, P, Ca and Si are selectively enriched from ambient hydrothermal environment. Interestingly, P, Ca and Si covary with Fe content. Because element S originated from the bio-oxidation of H2S by symbiotic microorganism in the tissue of tubeworm, it can be considered as a biomarker when studying the mineralization process of tube wall. Based on the characteristics of tubeworms with different degrees of mineralization, we suggested that the early mineralization stage of tube wall was mainly controlled by microbial-induced mineralization and the degradation process of tube wall.
