Manganese nodules in areas CP and CC of the central Pacific are rich in REE. Comparatively speaking,the REE contents of nodules in area CP are hihger than those in area CC; and the REE contents of nodulesfrom seamount...Manganese nodules in areas CP and CC of the central Pacific are rich in REE. Comparatively speaking,the REE contents of nodules in area CP are hihger than those in area CC; and the REE contents of nodulesfrom seamounts are higher than those of nodules from sea-floor plains and hills. Within the nodules, the REEshow a zonal distribution. The REE distribution patterns of the nodules are similar to those of the sedimentsand have a mirror image relationship with those of the sea water. Trivalent REE were not obviously differenti-ated when they entered into the nodules from the sea water.A major factor causing the difference of REE abundances between nodules and sediments is the redoxconditions. The redox intensity of the ocean floor of the Pacific is controlled mainly by Antarctic Bottom Wat-er(AABW), The iron-bearing facies in the nodules is the main carrier of REE.展开更多
Water column turbidity and temperature were investigated along the Central Indian Ridge (CIR) from 25°19′S to 23°48′S during a December 2005 cruise on board Chinese R/V DayangYihao. Measurements were made ...Water column turbidity and temperature were investigated along the Central Indian Ridge (CIR) from 25°19′S to 23°48′S during a December 2005 cruise on board Chinese R/V DayangYihao. Measurements were made using NOAA’s MAPR (Miniature Autonomous Plume Recorder) sensors during CTD casts, TV grabber operations, and tow-yo profiles, yielding the following results on hydrothermal plume anomalies: (1) Strong hydrothermal turbidity and temperature anomalies were recorded over the pre- viously discovered Kairei (25°19.2′S, 70°02.4′E) and Edmond (23°52.7′S, 69°35.8′E) vent fields, with the plume anomalies concentrated at depths of 2150―2300 m and 2700―2900 m, respectively. The maxi- mum height of the turbidity anomalies near the Kairei vent field recorded in December 2005 was slightly below 2100 m, which is consistent with the plume depth measured in June 2001, indicating that the Kairei plume may have maintained its buoyancy flux in the intervening 4.5 years. (2) The water column beneath the Kairei plume has background anomalies of about 0.005△NTU, whereas no such back- ground turbidity anomalies were observed below the Edmond hydrothermal plume. (3) No visible tur- bidity anomalies were detected from 24°42′S to 24°12′S including the Knorr Seamount. Thus 24°12′S marks the southern end of the hydrothermal plume. (4) Significant turbidity anomalies were observed at four individual sections from 24°12′S to 23°56′S at the depth of 2500―3000 m along the eastern rift valley wall. Whether the individual sections of anomalies are connected is still unknown due to the absence of data at the intervening gaps. If the four sections are connected with each other and are linked to the Edmond vent field farther to the north, the total along-axis length of the plume anomaly would be more than 37 km, implying a plume incidence value ph of 0.38, greater than the predicted ph of 0.21―0.25 based on the spreading rate of the Central Indian Ridge.展开更多
文摘Manganese nodules in areas CP and CC of the central Pacific are rich in REE. Comparatively speaking,the REE contents of nodules in area CP are hihger than those in area CC; and the REE contents of nodulesfrom seamounts are higher than those of nodules from sea-floor plains and hills. Within the nodules, the REEshow a zonal distribution. The REE distribution patterns of the nodules are similar to those of the sedimentsand have a mirror image relationship with those of the sea water. Trivalent REE were not obviously differenti-ated when they entered into the nodules from the sea water.A major factor causing the difference of REE abundances between nodules and sediments is the redoxconditions. The redox intensity of the ocean floor of the Pacific is controlled mainly by Antarctic Bottom Wat-er(AABW), The iron-bearing facies in the nodules is the main carrier of REE.
基金WHOI Deep Ocean Exploration Institute and Cecil H. and Ida M. Green Technology Innovation Awards (J. Lin) and the Chinese Ocean Mineral Re-sources R&D Association (J. Chen)
文摘Water column turbidity and temperature were investigated along the Central Indian Ridge (CIR) from 25°19′S to 23°48′S during a December 2005 cruise on board Chinese R/V DayangYihao. Measurements were made using NOAA’s MAPR (Miniature Autonomous Plume Recorder) sensors during CTD casts, TV grabber operations, and tow-yo profiles, yielding the following results on hydrothermal plume anomalies: (1) Strong hydrothermal turbidity and temperature anomalies were recorded over the pre- viously discovered Kairei (25°19.2′S, 70°02.4′E) and Edmond (23°52.7′S, 69°35.8′E) vent fields, with the plume anomalies concentrated at depths of 2150―2300 m and 2700―2900 m, respectively. The maxi- mum height of the turbidity anomalies near the Kairei vent field recorded in December 2005 was slightly below 2100 m, which is consistent with the plume depth measured in June 2001, indicating that the Kairei plume may have maintained its buoyancy flux in the intervening 4.5 years. (2) The water column beneath the Kairei plume has background anomalies of about 0.005△NTU, whereas no such back- ground turbidity anomalies were observed below the Edmond hydrothermal plume. (3) No visible tur- bidity anomalies were detected from 24°42′S to 24°12′S including the Knorr Seamount. Thus 24°12′S marks the southern end of the hydrothermal plume. (4) Significant turbidity anomalies were observed at four individual sections from 24°12′S to 23°56′S at the depth of 2500―3000 m along the eastern rift valley wall. Whether the individual sections of anomalies are connected is still unknown due to the absence of data at the intervening gaps. If the four sections are connected with each other and are linked to the Edmond vent field farther to the north, the total along-axis length of the plume anomaly would be more than 37 km, implying a plume incidence value ph of 0.38, greater than the predicted ph of 0.21―0.25 based on the spreading rate of the Central Indian Ridge.
