The Yuhuang hydrothermal field(YHF)is located between the Indomed and Gallieni fracture zones near the top of the off-axis slope on the south rift wall of Segment 29 on the ultraslow Southwest Indian Ridge(SWIR).Previ...The Yuhuang hydrothermal field(YHF)is located between the Indomed and Gallieni fracture zones near the top of the off-axis slope on the south rift wall of Segment 29 on the ultraslow Southwest Indian Ridge(SWIR).Previous studies have shown that sulfides in the YHF formed during different mineralization episodes and the YHF has the greatest potential for the formation of large-scale seafloor massive sulfide deposits.However,the sulfide chronology and hydrothermal activity of the YHF remain poorly constrained.In this study,mineralogical analyses and 230Th/U dating were performed.Hydrothermal activity may start about(35.9±2.3)ka from the southwest part of the YHF and may cease about(708±81)a ago from the northeast part of the YHF.The 74 nonzero chronological data from hydrothermal sulfide samples provide the first quantitative characterization of the spatial and temporal history along the SWIR.Hydrothermal activity in the SWIR has been relatively active over the past20 ka.In contrast,between 40 ka and 100 ka,hydrothermal activity was relatively infrequently and short in duration.The maximum activity occurred at 15–11 ka,9–7 ka,6–0.2 ka.There was a slight positive correlation between the maximal age and estimated surface area or estimated tonnage.The minimum mass accumulation rate of YHF is about 278 t/a,which is higher than most HFs related to ultramafic systems.The ultraslow spreading SWIR has the greatest potential to form large-scale seafloor massive sulfides(SMS)deposits.The results of this study provide new insights into the metallogenic mechanism of hydrothermal sulfides along ultraslow-spreading ridges.展开更多
Besides being employed as an efficient plant growth retardant for field, garden and potted plants, paclobutrazol (PBZ) is also used in laboratory experiments, mainly in aseptic cultures, both in autoclaved and non-aut...Besides being employed as an efficient plant growth retardant for field, garden and potted plants, paclobutrazol (PBZ) is also used in laboratory experiments, mainly in aseptic cultures, both in autoclaved and non-autoclaved form. Therefore it is not known if autoclaving can partial or completely inactivates the product, thus decreasing its efficacy. Thus a simple experiment was carried out to assess to what extent the autoclaving process can affect some growth components and dry mass accumulation and partition in sunflower seedlings, by employing the techniques of plant Growth Analysis. Autoclaving did not modify either qualitative or quantitatively any of the plant responses to PBZ as well their reversions by gibberellic acid.展开更多
基金The National Key R&D Program of China under contract No.2022YFE0140200the National Natural Science Foundation of China under contract Nos 42127807 and 42006074+1 种基金the China Ocean Mineral Resources R&D Association Project under contract Nos DY135-S1-1-02 and DY135-S1-1-01the Macao Science and Technology Development Fund under contract No.FDCT-002/2018/A1。
文摘The Yuhuang hydrothermal field(YHF)is located between the Indomed and Gallieni fracture zones near the top of the off-axis slope on the south rift wall of Segment 29 on the ultraslow Southwest Indian Ridge(SWIR).Previous studies have shown that sulfides in the YHF formed during different mineralization episodes and the YHF has the greatest potential for the formation of large-scale seafloor massive sulfide deposits.However,the sulfide chronology and hydrothermal activity of the YHF remain poorly constrained.In this study,mineralogical analyses and 230Th/U dating were performed.Hydrothermal activity may start about(35.9±2.3)ka from the southwest part of the YHF and may cease about(708±81)a ago from the northeast part of the YHF.The 74 nonzero chronological data from hydrothermal sulfide samples provide the first quantitative characterization of the spatial and temporal history along the SWIR.Hydrothermal activity in the SWIR has been relatively active over the past20 ka.In contrast,between 40 ka and 100 ka,hydrothermal activity was relatively infrequently and short in duration.The maximum activity occurred at 15–11 ka,9–7 ka,6–0.2 ka.There was a slight positive correlation between the maximal age and estimated surface area or estimated tonnage.The minimum mass accumulation rate of YHF is about 278 t/a,which is higher than most HFs related to ultramafic systems.The ultraslow spreading SWIR has the greatest potential to form large-scale seafloor massive sulfides(SMS)deposits.The results of this study provide new insights into the metallogenic mechanism of hydrothermal sulfides along ultraslow-spreading ridges.
基金Thanks are due to FAPEMIG(Foundation for Research Sponsoring of Minas Gerais State)for the scholarships granted to DMR(Post-Doctoral training),JB and GBR(Scientific Initiation training)and for the financial support in several occasions.
文摘Besides being employed as an efficient plant growth retardant for field, garden and potted plants, paclobutrazol (PBZ) is also used in laboratory experiments, mainly in aseptic cultures, both in autoclaved and non-autoclaved form. Therefore it is not known if autoclaving can partial or completely inactivates the product, thus decreasing its efficacy. Thus a simple experiment was carried out to assess to what extent the autoclaving process can affect some growth components and dry mass accumulation and partition in sunflower seedlings, by employing the techniques of plant Growth Analysis. Autoclaving did not modify either qualitative or quantitatively any of the plant responses to PBZ as well their reversions by gibberellic acid.
