The Devonian hydrotyermal sedimentation and mineralization are widespread and typical in Maizi、Kelang and Chonghuer basins of southern Altay margin, and have their respective signs in occurrence, fabric and geochemis...The Devonian hydrotyermal sedimentation and mineralization are widespread and typical in Maizi、Kelang and Chonghuer basins of southern Altay margin, and have their respective signs in occurrence, fabric and geochemistry.Hydr)thermal sedimentary rocks mainly occur in the intermittent period between volcanic sub(?)ycles. They are thin-midium-bedded, lenticular and basically uniform to the occurrences of the overlying and underlying strata. The classification of the hydrothermal sedimentary rocks is proposed based on the mineral compositions. The detailed descriptions are given to the five types of hydrothermal sedimentary rocks: silicates, feldspar-rich rocks,展开更多
Six hydrothermal sediment samples were collected from the Xunmei and Tongguan hydrothermal fields along the southern Mid-Atlantic Ridge during the China Ocean Cruise DY46 in 2017.Sulfides and oxides in the samples wer...Six hydrothermal sediment samples were collected from the Xunmei and Tongguan hydrothermal fields along the southern Mid-Atlantic Ridge during the China Ocean Cruise DY46 in 2017.Sulfides and oxides in the samples were separated,and Cu and Zn isotope compositions were analyzed.Results show that the ranges ofδ^(65)Cu values of the bulk sediments,sulfides,and oxides were 0.36‰-2.46‰,-0.21‰-1.10‰,and 0.68‰-1.52‰,respectively.Theδ^(65)Cu values of sulfides in four samples(46II-14,46II-30,46III-06,and 46II-09)were relatively low(-0.21‰-0.50‰),corresponding to theδ^(65)Cu values of sulfides from inactive old hydrothermal chimneys in northern Mid-Atlantic Ridge(n MAR),suggesting that the sulfides in the sediments were originated from collapsed dead chimney mainly.While theδ^(65)Cu values of the other two samples(46III-02 and 46III-08)were relatively high(1.10‰-0.96‰),corresponding to theδ^(65)Cu values for active hydrothermal chimneys sulfides in n MAR,which indicated that the sulfides in these two samples might mainly come from sulfide particles settled from active hydrothermal plume.Because of the high density of sulfide particles,they tended to settle near the hydrothermal vents first.Therefore,highδ^(65)Cu values of sulfides in 46III-02 and 46III-08 implied that undiscovered active hydrothermal vents near the sampling positions of 46III-02 in the Xunmei hydrothermal field and 46III-08 in the Tongguan hydrothermal field.Theδ^(66)Zn values of hydrothermal sediments and sulfides ranged 0.11‰-0.43‰and 0.29‰-0.67‰,respectively.In the four samples from the Xunmei hydrothermal field,a positive correlation was found between the distance of the sampling position from sulfide mineralized spot and the Zn isotopic ratio,showing that the greater the distance from the mineralized spot,the heavier the Zn isotope composition as seen in two samples(46II-30 and 46II-14)of the Xunmei-3 spot.This result aligned with the findings of Wilkinson et al.(2005)and Baumgartner et al.(2023),suggesting that the lower the Zn isotope composition,the closer it is to the hydrothermal vent.However,in the Xunmei hydrothermal field,the Zn isotope composition in the other two samples(46III-02and 46III-06)showed the opposite trend.This indicated that there might be an active hydrothermal vent near the sampling location of sample 46III-02.This observation aligned with the Cu isotope analysis results.This study showed that Cu-Zn isotopes are good indicators for understanding the formation mechanisms of hydrothermal sediments and for locating active hydrothermal vents.展开更多
Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and precipitated from the alka...Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and precipitated from the alkaline hot brine under the conditions of the Mesozoic faulted lake basin. The main rock-forming mineral of this dolostone is ferruginous dolomite with a micritic structure. This dolomite mostly exhibits laminae of 0.1-1 mm thick and is often discovered with other minerals, such as albite, analcite, barite and dickite, which have at least two types of interbedded laminae. Petrogeochemistry reveals that this dolostone contains a large number of typomorphic elements of hydrothermal sedimentation, including Sb, Ba, Sr, Mn, and V. In addition, the LREE is in relatively high concentrations and possesses the typical REE distribution pattern with negative Eu anomaly. Oxygen isotope values （C^ISOpDB） range from 5.89%~ to 14.15%o with an average of 9.69%0. The ratio of 87Sr/86Sr is between 0.711648 and 0.719546, with an average of 0.714718. These data indicate that the depositional environment is a stable, blocked, anoxic low-lying hot brine pool in the bottom of deep lake controlled by basement faults. The hydrothermal fluid is the alkaline hot brine formed by the combination of the infiltration lake water and mantle-derived magmatic water, consisting of many ions, including Ca2＋, Mg2＋ and Fe2＋. Under the driving flow power of magmatic heat, gravity and compaction, the hy- drothermal fluid overcame the overburden pressure and hydrostatic pressure of the lake water body, and boiled to explosion, and then the explosion shattered the original laminated micritic ferruginous primary dolostone near the vent and then formed a new type of dolostone called shattered ＂hydroexplosion breccias＂. In the low-lying, unperturbed hot brine pool, far from the vent, the laminated micritic ferruginous primary dolostone was quickly crystallized and chemicals precipitated from the hy- drotherm. This study of special rocks contributes to research into the causes of the formation of lacustrine carbonate rocks and dolostone. In particular, it provides new examples and research insights for future studies of the lacustrine dolomite from the similar Mesozoic and Cenozoic basins in China.展开更多
The molybdenum-nickel deposits in Shuidong District of Nayong County （Guizhou Province, Southwest China） are found mainly in black shale series of Lower Cambrian Niutitang Formation, which is another Mo-Ni-rich regi...The molybdenum-nickel deposits in Shuidong District of Nayong County （Guizhou Province, Southwest China） are found mainly in black shale series of Lower Cambrian Niutitang Formation, which is another Mo-Ni-rich region besides Zunyi District （Guizhou province）. Our systematic study on the Mo-Ni deposits in Tangjiaba of Nayong reveals that layered coarse-grained limestones, spherical beaded limestones concretions are hosted at the lower seam of the Mo-Ni deposits. Its strong negative carbon isotope anomaly （the carbon isotope value of the coarse-grained limestones varies from -2.148‰ to 8.223‰） is similar to that in the modern submarine black smoker chimney. The carbon in the coarse-grained limestones from black rock series of Nayong County might be deep source inorganic carbon. The seams, coarse-grained limestones, ore-bearing coarse-grained limestones and the roof and floor of the deposits are characterized by co-variation on the trace element spider diagram, showing good homology. The extraordinary enrichment of Ag, As and Sb resembles hydrothermal sedimentation. Pro-Earth＇s core elements Se is strongly enriched in Ni-Mo ore-bearing coarse-grained limestones. The ore-bearing rock series has an extremely low Th/U value （0.012-0.19）; in the logU-logTh Cartesian Coordinates, the samples of the roof and floor of the deposits and ore-bearing coarse-grained limestones are found in the East Pacific tise; and the samples of coarse-grained limestones are found between the paleo-hydrothermal dedimentary area and the East Pacific tise. The chondrite-normalized rare earth element patterns of the Ni-Mo deposits show LREE enrichment, Ce negative anomaly, and Eu negative anomaly （which is supposed to be influenced by the deep magmatic processes in an extensional environment） resembles the rare earth element distribution patterns of the fluid and its sediments in modern submarine hydrothermal system. It proves that coarse-grained limestones is characterized by typical hydrothermal limestones, being closely related with the genesis of Mo-Ni deposits in Nayong County, which provides new evidence for hydrothermal sedimentary genesis of Mo-Ni deposit and negative carbon anomaly in the basal Cambrian on a global scale.展开更多
The Bamianshan fluorite deposit is a super-large one recently discovered in Zhejiang Province of China. This paper presents an analysis of its geological background, orebody and ore characteristics, petrochemical char...The Bamianshan fluorite deposit is a super-large one recently discovered in Zhejiang Province of China. This paper presents an analysis of its geological background, orebody and ore characteristics, petrochemical characteristics of host rocks, rare earth elements （REE） of rocks and ores, fluid inclusions in fluorite and Sm-Nd isotopic features in an effort to study its sedimentary mineralization. The result shows that the super-large Bamianshan fluorite deposit is of hydrothermal sedimentation genesis, deformed by the later hydrothermal fluid. Integrated with host rocks and orebody characteristics, it is inferred that the deposit originates from the Cambrian sedimentary rocks. And the later magmatic activities deformed some orebodies in different degrees, forming steeply dipping vein orebodies in the tectonic belts regionally.展开更多
In 2008-2009, hydrothermal barnacle and sediment samples were collected from the Southwest Indian Ridge during a survey of the China Ocean Mineral Resources R＆D Association （COMRA）. Samples were ana- lyzed by gas c...In 2008-2009, hydrothermal barnacle and sediment samples were collected from the Southwest Indian Ridge during a survey of the China Ocean Mineral Resources R＆D Association （COMRA）. Samples were ana- lyzed by gas chromatography-mass spectrometer （GC-MS）, revealing the main organic constituents of hy- drothermal barnacle and sediment to be fatty acids and alkylbenzenes. N-alkanes which possessed obvious even carbon advantage were also detected in hydrothermal sediment. The high concentrations of aromatic compounds might be the result of macromolecular thermal alteration. Microorganism in the submarine hydrothermal ecosystem, especially those related to sulfur metabolism, might be the source of the high con- centrations of fatty acids detected in these samples. In high temperature and high pressure hydrothermal environments, n-alkanes which possessed obvious even carbon advantage might originate from thermal alteration of carboxylic acids and other lipid compounds.展开更多
Eighteen samples of hydrothermal sediments from the Jade hydrothermal field in the central Okinawa Trough have been analyzed. Sulfur isotopic values for 10 sulfide samples vary from 5.2× 10^(-3)to 7.2× 10^(-...Eighteen samples of hydrothermal sediments from the Jade hydrothermal field in the central Okinawa Trough have been analyzed. Sulfur isotopic values for 10 sulfide samples vary from 5.2× 10^(-3)to 7.2× 10^(-3), δ^(34)S values for 7 sulfate samples vary from 16.3 × 10^(-3) to 22.3 × 10^(-3), and 1 native sulphur sample has a δ^(34)S value of 8.2 × 10^(-3). The major sources of sulfur for hydrothermal sediment are intermediate to acid volcanic rocks and sea water sulfate, and it is possible that the partial sulfur of hydrothermal sediment is from the pelagic sediment by the interaction between hydrothermal fluid and sediment. The reasons of causing the distinct differences in sulfur isotopic values for sulfide samples from hydrothermal sediment ( compared with other hydrothermal fields), are the differences in the sources of sulfur, the magmatic activity and the tectonic evolution in different hydrothermal fields. The sulfur evolution is a long and complex process in the seafloor hydrothermal system, involving the ascending of heating sea water, the interaction between fluid and volcanic rocks, the mixing of sea water sulfate and sulfur from intermediate to acid volcanic rocks, and the fluid/pelagic-sediment interaction. And the interaction between sea water and intermediate to acid volcanic rocks is an important mechanism for the sulfur evolution in the Jade hydrothermal field.展开更多
Thirty sediment subsamples were recovered from the Iheya North hydrothermal field （with an average of 38 m away from the hydrothermal vent） in the middle Okinawa Trough. Samples were obtained by the ROV （Remote Ope...Thirty sediment subsamples were recovered from the Iheya North hydrothermal field （with an average of 38 m away from the hydrothermal vent） in the middle Okinawa Trough. Samples were obtained by the ROV （Remote Operated Vehicle） Faxian during the virgin cruise of the R/V Kexue in 2014 with the application of push cores. The chemical compositions of the sediments show that the hydrothermal sediments near the hydrothermal vent are mainly composed of SO3, ZnO and Fe203. Moreover, the hydrothermal sediments are also highly enriched in Pb, As, Sb, Hg, Se, Ag, Ba, Mo and Cd comparing with previous analysis results. On the other hand, the concentrations of St, Hg andAg in studied sediments are strongly and positively correlated, these elements can be used as an hydrothermal indicator. In addition, a factor analysis of the sediments suggested that the sediments were mainly influenced by hydrothermal origin, and terrestrial and biogenic input are limited in studied area. It is also suggested that different stages of crystallization were involved in the formation of hydrothermal chimney from factor analysis.展开更多
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...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 component.Biogenic 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.展开更多
Hydrothermal plumes released from the eruption of sea floor hydrothermal fluids contain large amounts of oreforming materials. They precipitate within certain distances from the hydrothermal vent. Six surficial sedime...Hydrothermal plumes released from the eruption of sea floor hydrothermal fluids contain large amounts of oreforming materials. They precipitate within certain distances from the hydrothermal vent. Six surficial sediment samples from the Southwest Indian Ridge（SWIR） were analyzed by a portable X-ray fluorescence（PXRF） analyzer on board to find a favorable method fast and efficient enough for sea floor sulfide sediment geochemical exploration. These sediments were sampled near, at a moderate distance from, or far away from hydrothermal vents. The results demonstrate that the PXRF is effective in determining the enrichment characteristics of the oreforming elements in the calcareous sediments from the mid-ocean ridge. Sediment samples（〉40 mesh） have high levels of elemental copper, zinc, iron, and manganese, and levels of these elements in sediments finer than 40 mesh are lower and relatively stable. This may be due to relatively high levels of basalt debris/glass in the coarse sediments, which are consistent with the results obtained by microscopic observation. The results also show clear zoning of elements copper, zinc, arsenic, iron, and manganese in the surficial sediments around the hydrothermal vent. Sediments near the vent show relatively high content of the ore-forming elements and either high ratios of copper to iron content and zinc to iron content or high ratios of copper to manganese content and zinc to manganese content. These findings show that the content of the ore-forming elements in the sediments around hydrothermal vents are mainly influenced by the distance of sediments to the vent, rather than grain size. In this way, the PXRF analysis of surface sediment geochemistry is found to satisfy the requirements of recognition geochemical anomaly in mid-ocean ridge sediments. Sediments with diameters finer than 40 mesh should be used as analytical samples in the geochemical exploration for hydrothermal vents on mid-oceanic ridges. The results concerning copper, zinc, arsenic, iron, and manganese and their ratio features can be used as indicators in sediment geochemical exploration of seafloor sulfides.展开更多
Sediment samples obtained from the South Mid-Atlantic Ridge were analyzed for the major and trace elements by inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry. R...Sediment samples obtained from the South Mid-Atlantic Ridge were analyzed for the major and trace elements by inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry. Results revealed that the contents of elements(e.g., Fe, Mn, Cu, Zn, V, Co) were high in samples 22V-TVG10 and 26V-TVG05 from the sites near the hydrothermal areas, and low in sample 22V-TVG14, which was collected far from the hydrothermal areas. The contents of Ca, Sr and Ba in the samples showed opposite trends. A positive correlation between the concentrations of metallic elements(Cu, Zn, Co, Ni, Pb, V) and Fe in the samples were observed. These results are consistent with chemical evolution of the dispersing hydrothermal plume.展开更多
A total of 1 264 sulfur isotopic values for modern seafloor hydrothermel sediments from different hydrothermal fields have been collected.On this basis,combining our sulfur isotpic data for surface hydrothermal sedime...A total of 1 264 sulfur isotopic values for modern seafloor hydrothermel sediments from different hydrothermal fields have been collected.On this basis,combining our sulfur isotpic data for surface hydrothermal sediments from the Jade hydrohtermal field in the Okinawa Trough and the TAG hydrothermal field in the Mid-Atlantic Ridge,respectively,and comparing the sulfur isotopic compositions and analyzing their sources of sulfur in seafloor hydrothermal sediments from different geologic-tectonic setting,the results show that:(1) sulfur isotopic values of sulfides and sulfates in modern seafloor hydrothermal sediments are concentrated in a narrow range,δ 34S values of sulfides vary from 1×10 -3 to 9×10 -3,with a mean of 4.5×10 -3 (n=1042),δ 34S values of sulfates vary from 19×10 -3 to 24×10 -3,with a mean of 21.3×10 -3(n=217);(2) comparing the sulfur isotopic compositions of hydrothermal sediments from the sediment-hosted hydrothermal fields,the range of sulfur isotopic values for hydrothermal sediments from the sediment-free hydrothermal fields is narrow relatively;(3) the differences of sulfur isotopic compositions in sulfides from different hydrothermal fields show the differences in the sources of sulfur.The sulfur of hydrothermal sulfides in the sediment-free mid-ocean ridges is mainly from mid- ocean ridge basalt,and partially from the reduced seawater sulfate,and it is the result of partially reduced seawater sulfate mixed with basaltic sulfur.In the sediment-hosted mid-ocean ridges and the back-arc basins,the volcanics,the sediments and the organic matters also can offer their sulfur for forming hydrothermal sulfides;(4)the variations of sulfur isotopic compositions and the different sources of sulfur for hydrothermal sediments may be attributed to the various physical-chemical characteristics of hydrothermal fluids,the magmatic evolution and the different geologic-tectonic settings of seafloor hydrothermal systems.展开更多
There occur abundant cherts in the Mesozoic and Cenozoic strata in southern Tibet. Some of them possess characteristic hydrothermal structures such as layered, laminated, massive and breccia structures. Ratios of Al/...There occur abundant cherts in the Mesozoic and Cenozoic strata in southern Tibet. Some of them possess characteristic hydrothermal structures such as layered, laminated, massive and breccia structures. Ratios of Al/（Al＋Fe＋Mn）, Co/Ni, Fe/Ti and TiO2-A1203 demonstrate that their origin is related to hydrothermal sedimentation. The chert formations have close relationship with Sb, Au and poly-metallic mineralization, and the ore-forming fluid show strong correlation with fossil hydrothermal water. There occur abundant cherts in the Mesozoic and Cenozoic strata in southern Tibet. Some of them possess characteristic hydrothermal structures such as layered, laminated, massive and breccia structures. Ratios of A1/（AI＋Fe＋Mn）, Co/Ni, Fe/Ti and TiO2-A1203 demonstrate that their origin is related to hydrothermal sedimentation. The chert formations have close relationship with Sb, Au and poly-metallic mineralization, and the ore-forming fluid show strong correlation with fossil hvdrothermal water.展开更多
A sediment core H9 collected from the middle of the Okinawa Trough was studied by sequential leaching to indentify the hy- drothermal component from the various other components such as detrital, biogenic, and so on. ...A sediment core H9 collected from the middle of the Okinawa Trough was studied by sequential leaching to indentify the hy- drothermal component from the various other components such as detrital, biogenic, and so on. The elements were partitioned into five fractions： exchangeable, bound to carbonates, bound to iron and manganese oxides, bound to organic matter, and re- sidual. The contents of elements A1, Ti, K, Fe, Mn, Pb, Co, Cu, Ni, and V in each fraction were determined and their percent- ages were calculated. Residual fraction is a dominant speciation for most studied elements except for Mn and Pb in the core sediments. For the elements A1, Ti, and K, residual fraction accounts for more than 95% of the total metal concentration. The concentrations of all studied elements in the exchangeable fraction, carbonate fraction, and organic fraction are relatively low. The metal levels in the iron and manganese oxide fraction are relatively high and this fraction represents another prevalent speciation. Also in this fraction, the metal concentrations and percentages are higher in the core section above 80 cm than those below 80 cm. Especially 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 section. Hydrothermal components mainly occur in this fraction. And the downcore variations of metal contents and percentages reflect the variations of hydrothermal inputs to the sediments. 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 sedimentation. The 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 study. The results show that the accumulation rate of hydrothermally derived Mn is similar to those obtained from the Mid-ocean Ridges and Lau Basin. However, hydrothermally derived Fe and Cu present a relatively lower level.展开更多
文摘The Devonian hydrotyermal sedimentation and mineralization are widespread and typical in Maizi、Kelang and Chonghuer basins of southern Altay margin, and have their respective signs in occurrence, fabric and geochemistry.Hydr)thermal sedimentary rocks mainly occur in the intermittent period between volcanic sub(?)ycles. They are thin-midium-bedded, lenticular and basically uniform to the occurrences of the overlying and underlying strata. The classification of the hydrothermal sedimentary rocks is proposed based on the mineral compositions. The detailed descriptions are given to the five types of hydrothermal sedimentary rocks: silicates, feldspar-rich rocks,
基金Supported by the National Natural Science Foundation of China(No.42106080)the Laboratory for Marine Geology+2 种基金China Ocean Mineral Resources R&D Association Project(No.DY135-S2-2-03)the Natural Science Foundation of Shandong Province(No.ZR2020QD074)the Talents Research Start-up Funding Project of Ludong University。
文摘Six hydrothermal sediment samples were collected from the Xunmei and Tongguan hydrothermal fields along the southern Mid-Atlantic Ridge during the China Ocean Cruise DY46 in 2017.Sulfides and oxides in the samples were separated,and Cu and Zn isotope compositions were analyzed.Results show that the ranges ofδ^(65)Cu values of the bulk sediments,sulfides,and oxides were 0.36‰-2.46‰,-0.21‰-1.10‰,and 0.68‰-1.52‰,respectively.Theδ^(65)Cu values of sulfides in four samples(46II-14,46II-30,46III-06,and 46II-09)were relatively low(-0.21‰-0.50‰),corresponding to theδ^(65)Cu values of sulfides from inactive old hydrothermal chimneys in northern Mid-Atlantic Ridge(n MAR),suggesting that the sulfides in the sediments were originated from collapsed dead chimney mainly.While theδ^(65)Cu values of the other two samples(46III-02 and 46III-08)were relatively high(1.10‰-0.96‰),corresponding to theδ^(65)Cu values for active hydrothermal chimneys sulfides in n MAR,which indicated that the sulfides in these two samples might mainly come from sulfide particles settled from active hydrothermal plume.Because of the high density of sulfide particles,they tended to settle near the hydrothermal vents first.Therefore,highδ^(65)Cu values of sulfides in 46III-02 and 46III-08 implied that undiscovered active hydrothermal vents near the sampling positions of 46III-02 in the Xunmei hydrothermal field and 46III-08 in the Tongguan hydrothermal field.Theδ^(66)Zn values of hydrothermal sediments and sulfides ranged 0.11‰-0.43‰and 0.29‰-0.67‰,respectively.In the four samples from the Xunmei hydrothermal field,a positive correlation was found between the distance of the sampling position from sulfide mineralized spot and the Zn isotopic ratio,showing that the greater the distance from the mineralized spot,the heavier the Zn isotope composition as seen in two samples(46II-30 and 46II-14)of the Xunmei-3 spot.This result aligned with the findings of Wilkinson et al.(2005)and Baumgartner et al.(2023),suggesting that the lower the Zn isotope composition,the closer it is to the hydrothermal vent.However,in the Xunmei hydrothermal field,the Zn isotope composition in the other two samples(46III-02and 46III-06)showed the opposite trend.This indicated that there might be an active hydrothermal vent near the sampling location of sample 46III-02.This observation aligned with the Cu isotope analysis results.This study showed that Cu-Zn isotopes are good indicators for understanding the formation mechanisms of hydrothermal sediments and for locating active hydrothermal vents.
基金supported by National Natural Science Foundation of China(Grant No.41002033)National Science and Technology Major Project(Grant No.2011ZX05030-003-02)Foundation for Fostering Middleaged and Young Key Teachers of Chengdu University of Technology
文摘Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and precipitated from the alkaline hot brine under the conditions of the Mesozoic faulted lake basin. The main rock-forming mineral of this dolostone is ferruginous dolomite with a micritic structure. This dolomite mostly exhibits laminae of 0.1-1 mm thick and is often discovered with other minerals, such as albite, analcite, barite and dickite, which have at least two types of interbedded laminae. Petrogeochemistry reveals that this dolostone contains a large number of typomorphic elements of hydrothermal sedimentation, including Sb, Ba, Sr, Mn, and V. In addition, the LREE is in relatively high concentrations and possesses the typical REE distribution pattern with negative Eu anomaly. Oxygen isotope values （C^ISOpDB） range from 5.89%~ to 14.15%o with an average of 9.69%0. The ratio of 87Sr/86Sr is between 0.711648 and 0.719546, with an average of 0.714718. These data indicate that the depositional environment is a stable, blocked, anoxic low-lying hot brine pool in the bottom of deep lake controlled by basement faults. The hydrothermal fluid is the alkaline hot brine formed by the combination of the infiltration lake water and mantle-derived magmatic water, consisting of many ions, including Ca2＋, Mg2＋ and Fe2＋. Under the driving flow power of magmatic heat, gravity and compaction, the hy- drothermal fluid overcame the overburden pressure and hydrostatic pressure of the lake water body, and boiled to explosion, and then the explosion shattered the original laminated micritic ferruginous primary dolostone near the vent and then formed a new type of dolostone called shattered ＂hydroexplosion breccias＂. In the low-lying, unperturbed hot brine pool, far from the vent, the laminated micritic ferruginous primary dolostone was quickly crystallized and chemicals precipitated from the hy- drotherm. This study of special rocks contributes to research into the causes of the formation of lacustrine carbonate rocks and dolostone. In particular, it provides new examples and research insights for future studies of the lacustrine dolomite from the similar Mesozoic and Cenozoic basins in China.
基金sponsored by the Doctoral Fund of Ministry of Education of China (Grant no.20105201110002)Research Fund of Guizhou Province and Doctoral Programme Fund of Guizhou University
文摘The molybdenum-nickel deposits in Shuidong District of Nayong County （Guizhou Province, Southwest China） are found mainly in black shale series of Lower Cambrian Niutitang Formation, which is another Mo-Ni-rich region besides Zunyi District （Guizhou province）. Our systematic study on the Mo-Ni deposits in Tangjiaba of Nayong reveals that layered coarse-grained limestones, spherical beaded limestones concretions are hosted at the lower seam of the Mo-Ni deposits. Its strong negative carbon isotope anomaly （the carbon isotope value of the coarse-grained limestones varies from -2.148‰ to 8.223‰） is similar to that in the modern submarine black smoker chimney. The carbon in the coarse-grained limestones from black rock series of Nayong County might be deep source inorganic carbon. The seams, coarse-grained limestones, ore-bearing coarse-grained limestones and the roof and floor of the deposits are characterized by co-variation on the trace element spider diagram, showing good homology. The extraordinary enrichment of Ag, As and Sb resembles hydrothermal sedimentation. Pro-Earth＇s core elements Se is strongly enriched in Ni-Mo ore-bearing coarse-grained limestones. The ore-bearing rock series has an extremely low Th/U value （0.012-0.19）; in the logU-logTh Cartesian Coordinates, the samples of the roof and floor of the deposits and ore-bearing coarse-grained limestones are found in the East Pacific tise; and the samples of coarse-grained limestones are found between the paleo-hydrothermal dedimentary area and the East Pacific tise. The chondrite-normalized rare earth element patterns of the Ni-Mo deposits show LREE enrichment, Ce negative anomaly, and Eu negative anomaly （which is supposed to be influenced by the deep magmatic processes in an extensional environment） resembles the rare earth element distribution patterns of the fluid and its sediments in modern submarine hydrothermal system. It proves that coarse-grained limestones is characterized by typical hydrothermal limestones, being closely related with the genesis of Mo-Ni deposits in Nayong County, which provides new evidence for hydrothermal sedimentary genesis of Mo-Ni deposit and negative carbon anomaly in the basal Cambrian on a global scale.
基金financially supported by the Excellent Chemical Nonmetal Resource Evaluation Program (Grant 200310300002) from China Geological Survey
文摘The Bamianshan fluorite deposit is a super-large one recently discovered in Zhejiang Province of China. This paper presents an analysis of its geological background, orebody and ore characteristics, petrochemical characteristics of host rocks, rare earth elements （REE） of rocks and ores, fluid inclusions in fluorite and Sm-Nd isotopic features in an effort to study its sedimentary mineralization. The result shows that the super-large Bamianshan fluorite deposit is of hydrothermal sedimentation genesis, deformed by the later hydrothermal fluid. Integrated with host rocks and orebody characteristics, it is inferred that the deposit originates from the Cambrian sedimentary rocks. And the later magmatic activities deformed some orebodies in different degrees, forming steeply dipping vein orebodies in the tectonic belts regionally.
基金The National Key Basic Research Program of China under contract No.2013CB429700National Special Fund for the 12th Five Year Plan of COMRA under contract Nos DY125-12-R-02 and DY125-11-R-05+1 种基金Shandong Province Natural Science Foundation of China for Distinguished Young Scholars under contract No.JQ200913the National Natural Science Foundation of China under contract Nos 40830849,40976027and 40906029
文摘In 2008-2009, hydrothermal barnacle and sediment samples were collected from the Southwest Indian Ridge during a survey of the China Ocean Mineral Resources R＆D Association （COMRA）. Samples were ana- lyzed by gas chromatography-mass spectrometer （GC-MS）, revealing the main organic constituents of hy- drothermal barnacle and sediment to be fatty acids and alkylbenzenes. N-alkanes which possessed obvious even carbon advantage were also detected in hydrothermal sediment. The high concentrations of aromatic compounds might be the result of macromolecular thermal alteration. Microorganism in the submarine hydrothermal ecosystem, especially those related to sulfur metabolism, might be the source of the high con- centrations of fatty acids detected in these samples. In high temperature and high pressure hydrothermal environments, n-alkanes which possessed obvious even carbon advantage might originate from thermal alteration of carboxylic acids and other lipid compounds.
基金This work was financially supported in part by the National Natural Science Foundation of China under contract No. 40176020 the National Major Fundamental Research Development Project of China under contract No. G2000046703.
文摘Eighteen samples of hydrothermal sediments from the Jade hydrothermal field in the central Okinawa Trough have been analyzed. Sulfur isotopic values for 10 sulfide samples vary from 5.2× 10^(-3)to 7.2× 10^(-3), δ^(34)S values for 7 sulfate samples vary from 16.3 × 10^(-3) to 22.3 × 10^(-3), and 1 native sulphur sample has a δ^(34)S value of 8.2 × 10^(-3). The major sources of sulfur for hydrothermal sediment are intermediate to acid volcanic rocks and sea water sulfate, and it is possible that the partial sulfur of hydrothermal sediment is from the pelagic sediment by the interaction between hydrothermal fluid and sediment. The reasons of causing the distinct differences in sulfur isotopic values for sulfide samples from hydrothermal sediment ( compared with other hydrothermal fields), are the differences in the sources of sulfur, the magmatic activity and the tectonic evolution in different hydrothermal fields. The sulfur evolution is a long and complex process in the seafloor hydrothermal system, involving the ascending of heating sea water, the interaction between fluid and volcanic rocks, the mixing of sea water sulfate and sulfur from intermediate to acid volcanic rocks, and the fluid/pelagic-sediment interaction. And the interaction between sea water and intermediate to acid volcanic rocks is an important mechanism for the sulfur evolution in the Jade hydrothermal field.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDA11030301,XDA11040301)
文摘Thirty sediment subsamples were recovered from the Iheya North hydrothermal field （with an average of 38 m away from the hydrothermal vent） in the middle Okinawa Trough. Samples were obtained by the ROV （Remote Operated Vehicle） Faxian during the virgin cruise of the R/V Kexue in 2014 with the application of push cores. The chemical compositions of the sediments show that the hydrothermal sediments near the hydrothermal vent are mainly composed of SO3, ZnO and Fe203. Moreover, the hydrothermal sediments are also highly enriched in Pb, As, Sb, Hg, Se, Ag, Ba, Mo and Cd comparing with previous analysis results. On the other hand, the concentrations of St, Hg andAg in studied sediments are strongly and positively correlated, these elements can be used as an hydrothermal indicator. In addition, a factor analysis of the sediments suggested that the sediments were mainly influenced by hydrothermal origin, and terrestrial and biogenic input are limited in studied area. It is also suggested that different stages of crystallization were involved in the formation of hydrothermal chimney from factor analysis.
基金The National Key Basic Research Program of China under contract Nos 2013CB429705 and 2013CB429701the National Natural Science Foundation of China under contract Nos 41176045 and 41376067+1 种基金the Scientific Research Fund of the Second Institute of Oceanographythe SOA of China under contract Nos JG1403 and JT1304
文摘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 component.Biogenic 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.
基金The Open Fund of Key Laboratory of Marine Mineral Resources,Ministry of Land and Resources under contract No.KLMMR-2015-B-03the China Ocean Mineral Resources Research and Development Association Project under contract Nos DY125-11-R-01 and DY125-11-R-05the National Basic Research Program(973 program)of China under contract No.2012CB417305
文摘Hydrothermal plumes released from the eruption of sea floor hydrothermal fluids contain large amounts of oreforming materials. They precipitate within certain distances from the hydrothermal vent. Six surficial sediment samples from the Southwest Indian Ridge（SWIR） were analyzed by a portable X-ray fluorescence（PXRF） analyzer on board to find a favorable method fast and efficient enough for sea floor sulfide sediment geochemical exploration. These sediments were sampled near, at a moderate distance from, or far away from hydrothermal vents. The results demonstrate that the PXRF is effective in determining the enrichment characteristics of the oreforming elements in the calcareous sediments from the mid-ocean ridge. Sediment samples（〉40 mesh） have high levels of elemental copper, zinc, iron, and manganese, and levels of these elements in sediments finer than 40 mesh are lower and relatively stable. This may be due to relatively high levels of basalt debris/glass in the coarse sediments, which are consistent with the results obtained by microscopic observation. The results also show clear zoning of elements copper, zinc, arsenic, iron, and manganese in the surficial sediments around the hydrothermal vent. Sediments near the vent show relatively high content of the ore-forming elements and either high ratios of copper to iron content and zinc to iron content or high ratios of copper to manganese content and zinc to manganese content. These findings show that the content of the ore-forming elements in the sediments around hydrothermal vents are mainly influenced by the distance of sediments to the vent, rather than grain size. In this way, the PXRF analysis of surface sediment geochemistry is found to satisfy the requirements of recognition geochemical anomaly in mid-ocean ridge sediments. Sediments with diameters finer than 40 mesh should be used as analytical samples in the geochemical exploration for hydrothermal vents on mid-oceanic ridges. The results concerning copper, zinc, arsenic, iron, and manganese and their ratio features can be used as indicators in sediment geochemical exploration of seafloor sulfides.
基金the National Natural Science Foundation of China (No. 41306053)the Open Fund of the Key Laboratory of Marine Geology and Environment, Chinese Academy of Sciences (Nos. MGE 2015KG04 and MGE2015KG01)+2 种基金the Open Fund of the Key Laboratory of Submarine Geosciences, State Oceanic Administration, People’s Republic of China (No. KSLG 1503)the Special Fund for the Taishan Scholar Program of Shandong Province (No. ts201511061)The authors would like to thank the crews of the COMRA cruises (DY115-22 and DY115-26)
文摘Sediment samples obtained from the South Mid-Atlantic Ridge were analyzed for the major and trace elements by inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry. Results revealed that the contents of elements(e.g., Fe, Mn, Cu, Zn, V, Co) were high in samples 22V-TVG10 and 26V-TVG05 from the sites near the hydrothermal areas, and low in sample 22V-TVG14, which was collected far from the hydrothermal areas. The contents of Ca, Sr and Ba in the samples showed opposite trends. A positive correlation between the concentrations of metallic elements(Cu, Zn, Co, Ni, Pb, V) and Fe in the samples were observed. These results are consistent with chemical evolution of the dispersing hydrothermal plume.
文摘A total of 1 264 sulfur isotopic values for modern seafloor hydrothermel sediments from different hydrothermal fields have been collected.On this basis,combining our sulfur isotpic data for surface hydrothermal sediments from the Jade hydrohtermal field in the Okinawa Trough and the TAG hydrothermal field in the Mid-Atlantic Ridge,respectively,and comparing the sulfur isotopic compositions and analyzing their sources of sulfur in seafloor hydrothermal sediments from different geologic-tectonic setting,the results show that:(1) sulfur isotopic values of sulfides and sulfates in modern seafloor hydrothermal sediments are concentrated in a narrow range,δ 34S values of sulfides vary from 1×10 -3 to 9×10 -3,with a mean of 4.5×10 -3 (n=1042),δ 34S values of sulfates vary from 19×10 -3 to 24×10 -3,with a mean of 21.3×10 -3(n=217);(2) comparing the sulfur isotopic compositions of hydrothermal sediments from the sediment-hosted hydrothermal fields,the range of sulfur isotopic values for hydrothermal sediments from the sediment-free hydrothermal fields is narrow relatively;(3) the differences of sulfur isotopic compositions in sulfides from different hydrothermal fields show the differences in the sources of sulfur.The sulfur of hydrothermal sulfides in the sediment-free mid-ocean ridges is mainly from mid- ocean ridge basalt,and partially from the reduced seawater sulfate,and it is the result of partially reduced seawater sulfate mixed with basaltic sulfur.In the sediment-hosted mid-ocean ridges and the back-arc basins,the volcanics,the sediments and the organic matters also can offer their sulfur for forming hydrothermal sulfides;(4)the variations of sulfur isotopic compositions and the different sources of sulfur for hydrothermal sediments may be attributed to the various physical-chemical characteristics of hydrothermal fluids,the magmatic evolution and the different geologic-tectonic settings of seafloor hydrothermal systems.
基金Ministry of Science and Technology 973 Program(Grant No.2002CB412600-VI)NSFC(Grant No.40073010)the Ph.D.Training Base Fund the National Education Ministry of China(Grant Nos.20040558050,20000099815)
文摘There occur abundant cherts in the Mesozoic and Cenozoic strata in southern Tibet. Some of them possess characteristic hydrothermal structures such as layered, laminated, massive and breccia structures. Ratios of Al/（Al＋Fe＋Mn）, Co/Ni, Fe/Ti and TiO2-A1203 demonstrate that their origin is related to hydrothermal sedimentation. The chert formations have close relationship with Sb, Au and poly-metallic mineralization, and the ore-forming fluid show strong correlation with fossil hydrothermal water. There occur abundant cherts in the Mesozoic and Cenozoic strata in southern Tibet. Some of them possess characteristic hydrothermal structures such as layered, laminated, massive and breccia structures. Ratios of A1/（AI＋Fe＋Mn）, Co/Ni, Fe/Ti and TiO2-A1203 demonstrate that their origin is related to hydrothermal sedimentation. The chert formations have close relationship with Sb, Au and poly-metallic mineralization, and the ore-forming fluid show strong correlation with fossil hvdrothermal water.
基金supported by National Natural Science Foundation of China (Grant No.40306009)
文摘A sediment core H9 collected from the middle of the Okinawa Trough was studied by sequential leaching to indentify the hy- drothermal component from the various other components such as detrital, biogenic, and so on. The elements were partitioned into five fractions： exchangeable, bound to carbonates, bound to iron and manganese oxides, bound to organic matter, and re- sidual. The contents of elements A1, Ti, K, Fe, Mn, Pb, Co, Cu, Ni, and V in each fraction were determined and their percent- ages were calculated. Residual fraction is a dominant speciation for most studied elements except for Mn and Pb in the core sediments. For the elements A1, Ti, and K, residual fraction accounts for more than 95% of the total metal concentration. The concentrations of all studied elements in the exchangeable fraction, carbonate fraction, and organic fraction are relatively low. The metal levels in the iron and manganese oxide fraction are relatively high and this fraction represents another prevalent speciation. Also in this fraction, the metal concentrations and percentages are higher in the core section above 80 cm than those below 80 cm. Especially 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 section. Hydrothermal components mainly occur in this fraction. And the downcore variations of metal contents and percentages reflect the variations of hydrothermal inputs to the sediments. 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 sedimentation. The 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 study. The results show that the accumulation rate of hydrothermally derived Mn is similar to those obtained from the Mid-ocean Ridges and Lau Basin. However, hydrothermally derived Fe and Cu present a relatively lower level.
