THERE are four submarine hydrothermal activity areas in the Middle Okinawa Trough. They are Izena hole(127°05’E, 27°16’N), Iheya Deep (126°58’E, 27°33’N). Natsushima 84-1 Mound (127°08.6’...THERE are four submarine hydrothermal activity areas in the Middle Okinawa Trough. They are Izena hole(127°05’E, 27°16’N), Iheya Deep (126°58’E, 27°33’N). Natsushima 84-1 Mound (127°08.6’E, 27°34.4’N), Western mount of Tokunoshima island (127°39’E, 37°52’N), respectively. In an attemptto determine the influence of the Middle Okinawa Trough area hydrothermal activity on copper distributionin the surrounding sediments, 8 surface samples and 6 core samples collected from this area were analyzedfor sequential extraction procedure and bulk analyses. 1 Samples and method Sediment samples were collected at 8 stations by dredger or piston corer (table 1). The sampleswere stored at【4℃, dried at【110℃, and finely ground to pass 200 meshes in an agate mortar.Sequential leaching procedures developed by Tessler were modified as follows: Cu (1) was ex-展开更多
The Okinawa Trough is located between the shelf-sea area of the East China Sea and the deep-sea area of western Pacific Ocean.More than 60 chemical elements in the sediments from the shelf area of the East China Sea,t...The Okinawa Trough is located between the shelf-sea area of the East China Sea and the deep-sea area of western Pacific Ocean.More than 60 chemical elements in the sediments from the shelf area of the East China Sea,the Okinawa Trough and western Pacific Ocean were determined by advanced techniques including neutron acti-vation analysis,X-ray fluorescence spectrometry,atomic fluorescence spectrometry and atomic absorption spectrometry.Quantitative comparisons of the element abundances of the sediments were made in terms of the enrichment coefficients(K) of the elements.K>1.5 indicates enrichment (K=1.5-2, weak enrichment;K=2-4,strong enrichment) and K>4,anomalous enrichment.The results show that the Okinawa Trough sediments are characterized by Hg anomaly and the enrichment of such elements as Au,Ag,Se,Te,Sb,Cd,Mn,Mo,etc.Detailed studies show that the excess Hg comes from hydrothermal solutions rather than from the continent,sea water ,marine organisms,cosmic dust or vol-canic rocks.Attributed to modern hydrothermal activities on the sea floor ,Hg anomaly can be used as a geochemical indicator of modern seafloor hydrothermal activity.展开更多
THE hydrothermal activity area investigated is located at the middle of the trough (126°50′—127°30′E; 27°20′—27°50′N). Some surface sediment samples and core samples were collected, with othe...THE hydrothermal activity area investigated is located at the middle of the trough (126°50′—127°30′E; 27°20′—27°50′N). Some surface sediment samples and core samples were collected, with other samples from non-hydrothermal activity area (128°20′—129°10′E; 30°30′—31°40′N) in the north of the trough for comparison. Analyses for elements and展开更多
The major and minor element contents in the sediment core H9 from the hydrothermal fields of the Okinawa Trough show a sharp change at the depth of 80 cm. The elements enriched in the upper 80 cm core are those enrich...The major and minor element contents in the sediment core H9 from the hydrothermal fields of the Okinawa Trough show a sharp change at the depth of 80 cm. The elements enriched in the upper 80 cm core are those enriched in the hydrothermal deposits and in the surface sediments recovered from the hydrothermal fields in the trough, which indicates the input of hydrothermal materials. Comparing with other hydrothermal sediments from Mid-ocean Ridges or the Lau Basin, the degree of the enrichment of elements iron, copper,cobah, and nickel is relatively low. However, the enrichment of elements manganese, lead, arsenic, antimony and mercury is remarkable. The average contents of these elements in the upper 80 cm core sediments are three to six times those in the lower section, and 3 - 12 times those in the surface sediments which are not influenced by hydrothermal activities. Hydrothermal activities have contributed significant manganese, lead, arsenic, antimony and mercury to the sediments, and these elements are distinct indicators for the hydrothermal activity in the Okinawa Trough. The significant enrichment of these elements in Core H9 upward from the depth 80 cm indicates the start or the significant enhancing of the hydrothermal activity in this area at about 5 740 aB. P. The average accumulation rate of manganese during this period is about 40 461μg/（ cm^2·ka） , which is similar to the hydrothermal sediments in the Lau Basin or the East Pacific Rise.展开更多
文摘THERE are four submarine hydrothermal activity areas in the Middle Okinawa Trough. They are Izena hole(127°05’E, 27°16’N), Iheya Deep (126°58’E, 27°33’N). Natsushima 84-1 Mound (127°08.6’E, 27°34.4’N), Western mount of Tokunoshima island (127°39’E, 37°52’N), respectively. In an attemptto determine the influence of the Middle Okinawa Trough area hydrothermal activity on copper distributionin the surrounding sediments, 8 surface samples and 6 core samples collected from this area were analyzedfor sequential extraction procedure and bulk analyses. 1 Samples and method Sediment samples were collected at 8 stations by dredger or piston corer (table 1). The sampleswere stored at【4℃, dried at【110℃, and finely ground to pass 200 meshes in an agate mortar.Sequential leaching procedures developed by Tessler were modified as follows: Cu (1) was ex-
文摘The Okinawa Trough is located between the shelf-sea area of the East China Sea and the deep-sea area of western Pacific Ocean.More than 60 chemical elements in the sediments from the shelf area of the East China Sea,the Okinawa Trough and western Pacific Ocean were determined by advanced techniques including neutron acti-vation analysis,X-ray fluorescence spectrometry,atomic fluorescence spectrometry and atomic absorption spectrometry.Quantitative comparisons of the element abundances of the sediments were made in terms of the enrichment coefficients(K) of the elements.K>1.5 indicates enrichment (K=1.5-2, weak enrichment;K=2-4,strong enrichment) and K>4,anomalous enrichment.The results show that the Okinawa Trough sediments are characterized by Hg anomaly and the enrichment of such elements as Au,Ag,Se,Te,Sb,Cd,Mn,Mo,etc.Detailed studies show that the excess Hg comes from hydrothermal solutions rather than from the continent,sea water ,marine organisms,cosmic dust or vol-canic rocks.Attributed to modern hydrothermal activities on the sea floor ,Hg anomaly can be used as a geochemical indicator of modern seafloor hydrothermal activity.
文摘THE hydrothermal activity area investigated is located at the middle of the trough (126°50′—127°30′E; 27°20′—27°50′N). Some surface sediment samples and core samples were collected, with other samples from non-hydrothermal activity area (128°20′—129°10′E; 30°30′—31°40′N) in the north of the trough for comparison. Analyses for elements and
基金This work was supported by the Major State Basic Research Program of China under contract No. G2000078503 the National Natural Science Foundation of China under contract No. 40306009.
文摘The major and minor element contents in the sediment core H9 from the hydrothermal fields of the Okinawa Trough show a sharp change at the depth of 80 cm. The elements enriched in the upper 80 cm core are those enriched in the hydrothermal deposits and in the surface sediments recovered from the hydrothermal fields in the trough, which indicates the input of hydrothermal materials. Comparing with other hydrothermal sediments from Mid-ocean Ridges or the Lau Basin, the degree of the enrichment of elements iron, copper,cobah, and nickel is relatively low. However, the enrichment of elements manganese, lead, arsenic, antimony and mercury is remarkable. The average contents of these elements in the upper 80 cm core sediments are three to six times those in the lower section, and 3 - 12 times those in the surface sediments which are not influenced by hydrothermal activities. Hydrothermal activities have contributed significant manganese, lead, arsenic, antimony and mercury to the sediments, and these elements are distinct indicators for the hydrothermal activity in the Okinawa Trough. The significant enrichment of these elements in Core H9 upward from the depth 80 cm indicates the start or the significant enhancing of the hydrothermal activity in this area at about 5 740 aB. P. The average accumulation rate of manganese during this period is about 40 461μg/（ cm^2·ka） , which is similar to the hydrothermal sediments in the Lau Basin or the East Pacific Rise.
