摘要
54 sediments were sampled at 5 sites, 1244, 1245, 1246,1250 and 1251 from ODPLeg 204, Hydrate Ridge, Cascadia Margin. The stable carbon and nitrogen isotopic composition,δ^(13)C of organic matter and δ^(15)N, have been used to characterize the depositional variationof sediments with gas hydrate bearing. Values of δ^(13)C of bulk organic matter range between-22.37 per thousand and -24.72 per thousand PDB, with a mean value of -23.54 ± 1.17 per thousandPDB; δ^(15)N of the same sedimentary samples range from 3.30 per thousand to 5.68 per thousand,with a mean value of 4.49 ± 1.19 per thousand; Values of C/N ratio range from 4.53 to 9.26, with amean value of 6.90 ± 2.37. The occurrence of gas hydrate changed the diagenetic evolution trend ofthe carbon and nitrogen in organic matter. The δ^(15)N and C/N ratio depletion suggest that thenitrogen fixation related with the bacteria/archaea maybe occurred in the sediments near thehydrate. The stable carbon and nitrogen isotopic composition could be used to evaluate thedepositional environment in the study area.
54 sediments were sampled at 5 sites, 1244, 1245, 1246, 1250 and 1251 from ODP Leg 204, Hydrate Ridge, Cascadia Margin. The stable carbon and nitrogen isotopic composition, δ C of 13 organic matter and δ N, have been used to characterize the depositional variation of sediments with 15 gas hydrate bearing. Values of δ C of bulk organic matter range between ?22.37‰ and ?24.72‰ 13 PDB, with a mean value of ?23.54±1.17‰ PDB; δ N of the same sedimentary samples range from 15 3.30‰ to 5.68‰, with a mean value of 4.49±1.19‰; Values of C/N ratio range from 4.53 to 9.26, with a mean value of 6.90±2.37. The occurrence of gas hydrate changed the diagenetic evolution trend of the carbon and nitrogen in organic matter. The δ N and C/N ratio depletion suggest that the nitrogen 15 fixation related with the bacteria/archaea maybe occurred in the sediments near the hydrate. The stable carbon and nitrogen isotopic composition could be used to evaluate the depositional environ- ment in the study area.
基金
This work was supported by the National Major Fundamental Research and Development Project of China(Grant No.G2000046704)
the National Natural Science Foundation of China(Grant No.40576059).
