The Tianxiu hydrothermal field(TXHF) located on Carlsberg Ridge is one of the few active ultramafic-hosted venting systems known in the Indian Ocean. Despite numerous investigations, there is limited understanding of ...The Tianxiu hydrothermal field(TXHF) located on Carlsberg Ridge is one of the few active ultramafic-hosted venting systems known in the Indian Ocean. Despite numerous investigations, there is limited understanding of its sulfide structure morphology, and the factors controlling the formation of TXHF are poorly understood. In this study, we conducted detailed seafloor mapping using visual data obtained by dives using the human-occupied vehicle(HOV) Jiaolong. The TXHF is found to be an active, off-axis, ultramafic-hosted, high-temperature hydrothermal area in which serpentine peridotite is exposed. Two main hydrothermal sites were identified, i.e., P and Y, both of which feature a complex of chimneys and beehive diffusers constituting a “chimney jungle” and isolated large steep-sided structures developed on flat-lying sulfide mounds. In addition, some sporadic inactive chimneys and outcrops of hydrothermal deposits were noted. The chimneys are rich in Fe and Zn sulfide, and lack the central fluid channel formed by focused high-temperature fluid flow. Hydrothermal venting at TXHF is likely related to low-angle detachment faults that focus and transport hydrothermal fluids away from a heat source along the valley wall. Our results complement and expand upon previous works concerning sulfide chimney morphology and their corresponding mineral paragenesis in ultramafic-hosted hydrothermal systems in the Indian Ocean and further our understanding of modern seafloor hydrothermal systems.展开更多
The 26th Chinese COMRA （China Ocean Mineral Resources Research ＆ Development Association） cruise was an important cruise. The Carlsberg Ridge （CR） of the Northwest Indian Ocean and the North Atlantic Ridge （NAR...The 26th Chinese COMRA （China Ocean Mineral Resources Research ＆ Development Association） cruise was an important cruise. The Carlsberg Ridge （CR） of the Northwest Indian Ocean and the North Atlantic Ridge （NAR）, in which less investigation has been carried out for hydrothermal activities, were investigated and studied during the first two legs of the 26th COMRA cruise. During the first leg, we found one hydrother- mal activity field located in the CR at 3.5^-3.8~ N on the Northwest Indian Ocean Ridge （NWIR）, and sampled seafloor polymetallic sulfide deposits where only abnormalities were found before. During the second leg, we found a new hydrothermal anomaly field located in the NAR at 4^-7~N. The discovery of two hydrother- real and anomaly fields filled in the gap of hydrothermal investigation and study in the corresponding re- ~ions for China.展开更多
Fractional crystallization of basaltic magma at variable depths influences strongly the geochemical compositions of mid-ocean ridge basalts(MORBs),especially at slow-spreading mid-ocean ridges.The Carlsberg Ridge is a...Fractional crystallization of basaltic magma at variable depths influences strongly the geochemical compositions of mid-ocean ridge basalts(MORBs),especially at slow-spreading mid-ocean ridges.The Carlsberg Ridge is a typical slow-spreading ridge located in the northwestern Indian Ocean.In this study,we conducted petrological,geochemical and modelling studies of MORBs collected along the Carlsberg Ridge from 57°-65°E to understand the fractional crystallization processes of magma and the controls on variations in MORB geochemistry.Our results show that the mantle sources beneath the Carlsberg Ridge are heterogeneous even on the local scale of a segment;such heterogeneity may be ubiquitous beneath the Carlsberg Ridge.Mantle heterogeneity may be caused by the enriched components resulting in the"DUPAL"anomaly,whereas the effect of pyroxenite on mantle heterogeneity is negligible.The parental melts experienced crystallization of olivine,plagioclase and clinopyroxene prior to eruption,which played a significant role in the major and trace element variations in MORBs from the Carlsberg Ridge.The liquid lines of descent(LLDs),deduced from the forward modelling of three parental magma compositions using the Petrolog3 program at pressures between 1 atm and 10 kbar,demonstrate that clinopyroxene joined the olivine and plagioclase cotectic.The over-enrichment in highly incompatible elements relative to LLDs may be caused by the processes of replenishment-tapping-crystallization in magma chambers.The calculated crystallization pressures suggest that parental magmas beneath the Carlsberg Ridge experienced moderateto high-pressure crystallization and that crystallization beneath the slow-spreading Carlsberg Ridge may start at upper mantle depths.展开更多
Hydrothermal venting has a profound effect on the chemical and biological properties of local and distal seawater and sediments. In this study, lipid biomarkers were analyzed to examine the potential influence of hydr...Hydrothermal venting has a profound effect on the chemical and biological properties of local and distal seawater and sediments. In this study, lipid biomarkers were analyzed to examine the potential influence of hydrothermal activity on the fate of organic matter(OM) in surface sediments around Tianxiu Hydrothermal Field in the Carlsberg Ridge(CR), Northwest Indian Ocean. By comparing the biomarker distributions of the samples with that of other typical hydrothermal sediments in the mid ocean ridge, it is shown that the location of the samples is not affected by the hydrothermal activity. The relatively low abundances of terrestrial n-alkyl lipids and riverine1,15-C_(32) diol suggested a minor contribution of terrigenous OM to the study area. The bacteria contributed predominantly to sedimentary marine OM;however, other marine source organisms, e.g., eukaryotes(i.e.,phytoplankton and fungi) could not be completely neglected. The marine-originated biomarkers showed significantly variable distributions between the two sediments, suggesting different dynamic physical and biogeochemical processes controlling the fate of marine OM. This study identified various diagnostic biomarkers(5,5-diethyl alkanes, diols and β-OH FAs), which may have significant environmental implications for future works in this region.展开更多
Serpentinization and calcite precipitation of mantle peridotites exhumed along detachment faults at the slow-to ultraslow-spreading centers can provide important clues to the hydrothermal alteration processes.The Tian...Serpentinization and calcite precipitation of mantle peridotites exhumed along detachment faults at the slow-to ultraslow-spreading centers can provide important clues to the hydrothermal alteration processes.The Tianxiu hydrothermal field is a new-found active and ultramafichosted hydrothermal vent site along the Carlsberg Ridge,Northwest Indian Ocean.Two types of calcite veins are recognized in serpentinized harzburgite samples collected from the seafloor at the water depth of 3 500 m(3.67°N/63.83°E) and 400 m north of Tianxiu hydrothermal field.Calcite veins Ⅰ occur in the fractures that cut through mesh texture in the highly serpentinized harzburgite,while calcite veins Ⅱ precipitate within the mesh texture in the relatively weaker serpentinized harzburgite.Both veins show similar δ13CPDB(+0.54‰ and +0.58‰) but different δ18OPDB(-16.67‰ and +4.46‰) values,suggesting that they were derived from the same carbon source but precipitated at different temperatures.Taking the deep seawater temperature of 2℃as the precipitation temperature of the calcite veins I,the equilibrium δ18OV-SMOW of calcite-precipitating fluid was calculated to be 1.78‰,which is close to the average δ18OV-SMOW value(1.74‰) of vent fluid samples from the ultramafic-hosted hydrothermal systems worldwide.The formation temperature of calcite veins Ⅱ is inferred to be approximately 134℃,based on the calculated δ18OV-SMOW above.The temperature differences of calcite precipitation probably resulted from the fluid cooling conductively and mixing with seawater along the presumed fractures during slow upflow.The low-temperature calcite postdates the mesh texture,while the high-temperature calcite may precipitate under relatively low water/rock ratios,alkaline and reduced conditions among the mesh texture,which is revealed by the geochemical models.Therefore,it is suggested that they both have been influenced by hydrothermal fluids and the sampling site is near the discharge zone of hydrothermal circulation.展开更多
Nattokinase is a novel fibrinolytic en- zyme, which is homologous to Subtilisin Carlsberg. In this paper, Subtilisin Carlsberg was taken as a model protein of nattokinase. Effects of pH, ionic strength, concentration ...Nattokinase is a novel fibrinolytic en- zyme, which is homologous to Subtilisin Carlsberg. In this paper, Subtilisin Carlsberg was taken as a model protein of nattokinase. Effects of pH, ionic strength, concentration of isopropanol on the extraction of Subtilisin Carlsberg with AOT/isooctane reverse mi- celles system were investigated. Further, the process of reverse micelles extraction of nattokinase from fermentation broth was studied. By taking the reverse micelles of AOT/isooctane as extractant to perform a full extraction cycle, it was found that about eighty percent of the total activity of nattokinase in the fer- mentation broth could be recovered and the purifica- tion factor was about 2.5. Homologous protein could be reasonably used as model protein of a target protein.展开更多
基金The National Key Research and Development Program of China under contract No. 2017YFC0306603the National Key Research and Development Program of China under contract No. 2021YFC2801705+2 种基金the Scientific Research Fund of the Second Institute of OceanographyMinistry of Natural Resources under contract Nos JG1905 and SZ2201the National Natural Science Foundation of China under contract No. 41806076。
文摘The Tianxiu hydrothermal field(TXHF) located on Carlsberg Ridge is one of the few active ultramafic-hosted venting systems known in the Indian Ocean. Despite numerous investigations, there is limited understanding of its sulfide structure morphology, and the factors controlling the formation of TXHF are poorly understood. In this study, we conducted detailed seafloor mapping using visual data obtained by dives using the human-occupied vehicle(HOV) Jiaolong. The TXHF is found to be an active, off-axis, ultramafic-hosted, high-temperature hydrothermal area in which serpentine peridotite is exposed. Two main hydrothermal sites were identified, i.e., P and Y, both of which feature a complex of chimneys and beehive diffusers constituting a “chimney jungle” and isolated large steep-sided structures developed on flat-lying sulfide mounds. In addition, some sporadic inactive chimneys and outcrops of hydrothermal deposits were noted. The chimneys are rich in Fe and Zn sulfide, and lack the central fluid channel formed by focused high-temperature fluid flow. Hydrothermal venting at TXHF is likely related to low-angle detachment faults that focus and transport hydrothermal fluids away from a heat source along the valley wall. Our results complement and expand upon previous works concerning sulfide chimney morphology and their corresponding mineral paragenesis in ultramafic-hosted hydrothermal systems in the Indian Ocean and further our understanding of modern seafloor hydrothermal systems.
基金the National Basic Research Program of China under contract No. 2012CB417305China Ocean Mineral Resources Research & Development Association Project under contract No. DY125-11Endowment Fund of International Seabed Authority (the International Cooperative Study on Hydrothermal System at Ultraslow Spreading SWIR)
文摘The 26th Chinese COMRA （China Ocean Mineral Resources Research ＆ Development Association） cruise was an important cruise. The Carlsberg Ridge （CR） of the Northwest Indian Ocean and the North Atlantic Ridge （NAR）, in which less investigation has been carried out for hydrothermal activities, were investigated and studied during the first two legs of the 26th COMRA cruise. During the first leg, we found one hydrother- mal activity field located in the CR at 3.5^-3.8~ N on the Northwest Indian Ocean Ridge （NWIR）, and sampled seafloor polymetallic sulfide deposits where only abnormalities were found before. During the second leg, we found a new hydrothermal anomaly field located in the NAR at 4^-7~N. The discovery of two hydrother- real and anomaly fields filled in the gap of hydrothermal investigation and study in the corresponding re- ~ions for China.
基金Supported by the National Key R&D Program of China(No.2018YFC0309903)the China Ocean Mineral Resources R&D Association Project(No.DY135-S2-1-2,5&7)+1 种基金the National Natural Science Foundation of China(Nos.91228101,41872242)the Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,China(Nos.JG1410,JG1405,QNYC1701,JZ1901)
文摘Fractional crystallization of basaltic magma at variable depths influences strongly the geochemical compositions of mid-ocean ridge basalts(MORBs),especially at slow-spreading mid-ocean ridges.The Carlsberg Ridge is a typical slow-spreading ridge located in the northwestern Indian Ocean.In this study,we conducted petrological,geochemical and modelling studies of MORBs collected along the Carlsberg Ridge from 57°-65°E to understand the fractional crystallization processes of magma and the controls on variations in MORB geochemistry.Our results show that the mantle sources beneath the Carlsberg Ridge are heterogeneous even on the local scale of a segment;such heterogeneity may be ubiquitous beneath the Carlsberg Ridge.Mantle heterogeneity may be caused by the enriched components resulting in the"DUPAL"anomaly,whereas the effect of pyroxenite on mantle heterogeneity is negligible.The parental melts experienced crystallization of olivine,plagioclase and clinopyroxene prior to eruption,which played a significant role in the major and trace element variations in MORBs from the Carlsberg Ridge.The liquid lines of descent(LLDs),deduced from the forward modelling of three parental magma compositions using the Petrolog3 program at pressures between 1 atm and 10 kbar,demonstrate that clinopyroxene joined the olivine and plagioclase cotectic.The over-enrichment in highly incompatible elements relative to LLDs may be caused by the processes of replenishment-tapping-crystallization in magma chambers.The calculated crystallization pressures suggest that parental magmas beneath the Carlsberg Ridge experienced moderateto high-pressure crystallization and that crystallization beneath the slow-spreading Carlsberg Ridge may start at upper mantle depths.
基金The Key-Area Research and Development Program of Guangdong Province under contract No.2020B1111010004the Science and Technology Program of Guangzhou,China under contract Nos 201804010264 and 201804010372+2 种基金the Guangdong MEPP Fund under contract No.GDOE[2019]A41the National Natural Science Foundation of China under contract No.91951201the China Ocean Mineral Resources R&D Association Project under contract No.DY135-S2-1-05。
文摘Hydrothermal venting has a profound effect on the chemical and biological properties of local and distal seawater and sediments. In this study, lipid biomarkers were analyzed to examine the potential influence of hydrothermal activity on the fate of organic matter(OM) in surface sediments around Tianxiu Hydrothermal Field in the Carlsberg Ridge(CR), Northwest Indian Ocean. By comparing the biomarker distributions of the samples with that of other typical hydrothermal sediments in the mid ocean ridge, it is shown that the location of the samples is not affected by the hydrothermal activity. The relatively low abundances of terrestrial n-alkyl lipids and riverine1,15-C_(32) diol suggested a minor contribution of terrigenous OM to the study area. The bacteria contributed predominantly to sedimentary marine OM;however, other marine source organisms, e.g., eukaryotes(i.e.,phytoplankton and fungi) could not be completely neglected. The marine-originated biomarkers showed significantly variable distributions between the two sediments, suggesting different dynamic physical and biogeochemical processes controlling the fate of marine OM. This study identified various diagnostic biomarkers(5,5-diethyl alkanes, diols and β-OH FAs), which may have significant environmental implications for future works in this region.
基金funded by the National Key Research and Development Program of China(No.2018YFC0309903)the Scientific Research Fund of the Second Institute of Oceanography,MNR(No.QNYC1701)+1 种基金the China Ocean Mineral Resources R&D Association Project(No.DY135-S2-1-02&05)the National Science Foundation of China(No.41976076)
文摘Serpentinization and calcite precipitation of mantle peridotites exhumed along detachment faults at the slow-to ultraslow-spreading centers can provide important clues to the hydrothermal alteration processes.The Tianxiu hydrothermal field is a new-found active and ultramafichosted hydrothermal vent site along the Carlsberg Ridge,Northwest Indian Ocean.Two types of calcite veins are recognized in serpentinized harzburgite samples collected from the seafloor at the water depth of 3 500 m(3.67°N/63.83°E) and 400 m north of Tianxiu hydrothermal field.Calcite veins Ⅰ occur in the fractures that cut through mesh texture in the highly serpentinized harzburgite,while calcite veins Ⅱ precipitate within the mesh texture in the relatively weaker serpentinized harzburgite.Both veins show similar δ13CPDB(+0.54‰ and +0.58‰) but different δ18OPDB(-16.67‰ and +4.46‰) values,suggesting that they were derived from the same carbon source but precipitated at different temperatures.Taking the deep seawater temperature of 2℃as the precipitation temperature of the calcite veins I,the equilibrium δ18OV-SMOW of calcite-precipitating fluid was calculated to be 1.78‰,which is close to the average δ18OV-SMOW value(1.74‰) of vent fluid samples from the ultramafic-hosted hydrothermal systems worldwide.The formation temperature of calcite veins Ⅱ is inferred to be approximately 134℃,based on the calculated δ18OV-SMOW above.The temperature differences of calcite precipitation probably resulted from the fluid cooling conductively and mixing with seawater along the presumed fractures during slow upflow.The low-temperature calcite postdates the mesh texture,while the high-temperature calcite may precipitate under relatively low water/rock ratios,alkaline and reduced conditions among the mesh texture,which is revealed by the geochemical models.Therefore,it is suggested that they both have been influenced by hydrothermal fluids and the sampling site is near the discharge zone of hydrothermal circulation.
基金supported by the Creative Research Group of the National Natural Science Foundation of China(Grant No.20221603).
文摘Nattokinase is a novel fibrinolytic en- zyme, which is homologous to Subtilisin Carlsberg. In this paper, Subtilisin Carlsberg was taken as a model protein of nattokinase. Effects of pH, ionic strength, concentration of isopropanol on the extraction of Subtilisin Carlsberg with AOT/isooctane reverse mi- celles system were investigated. Further, the process of reverse micelles extraction of nattokinase from fermentation broth was studied. By taking the reverse micelles of AOT/isooctane as extractant to perform a full extraction cycle, it was found that about eighty percent of the total activity of nattokinase in the fer- mentation broth could be recovered and the purifica- tion factor was about 2.5. Homologous protein could be reasonably used as model protein of a target protein.
