摘要
为了探索海洋天然气水合物背景下有孔虫特征的响应,对综合大洋钻探计划(IODP)311航次岩芯沉积物中底栖有孔虫Uvigerina peregrina和Bulimina mexicana进行了初步研究。通过对冷泉站位U1328和毗邻的非冷泉站位U1327沉积物中底栖有孔虫Uvigerina peregrina和Buliminamexicana的显微形貌特征和碳、氧稳定同位素测试等,证实有孔虫壳体未受到后期成岩作用的改造和自生碳酸盐岩的交代影响,有孔虫壳体的碳稳定同位素呈现明显的负偏。其中U1327站位中U.peregrinaδ13C为-0.67‰^-2.75‰(PDB),B.mexicanaδ13C为-0.51‰^-1.52‰(PDB);U1328站位中U.peregrinaδ13C为-0.72‰^-2.71‰(PDB),B.mexicanaδ13C为-0.58‰^-1.45‰(PDB)。底栖有孔虫壳体的碳稳定同位素负偏成因可能与水合物不稳定分解释放的甲烷厌氧氧化作用和食物源有关,因而可较好地指示海底天然气水合物系统地质背景。
A preliminary research of the benthic Foraminifera from Integrated Ocean Drilling Program IODP） Expedition 311 has been carried out for the purpose of better understanding their stable carbon isotopic response to the marine gas hydrate geo-system. SEM photographs and stable oxygen isotopes of the species Uvigerina peregrina and Bulimina mexicana indicated that diagenesis and authigenic carbonate precipitation had little effect on Foramin- ifera. Uvigerina peregrina and Bulimina mexicana collected from the sediments in seepage Site U1328 and in adjacent non-seepage Site U1327 exhibited a distinct negative δ^13C excursion with values of U. peregrina -0. 67‰～ -2.75‰ PDB, B. mexicana -0.51‰ ～ - 1.52‰ PDB in Site U1327 and U. peregrina -0. 72‰ ～ -2.71‰ PDB, B. mexicana -0. 58‰ ～ - 1.45‰ PDB in Site U1328 respectively. The formation of distinct stable carbon isotopic excursions of benthic Foraminifera could be most likely interpreted by the involvement of both anaerobic oxidation of methane （AOM） and food sources in sediments. The distinct negative carbon isotopic excursion of benthic Foraminifera thus could be believed as one of indicators to recognize the marine gas hydrate geo-system.
出处
《地球科学进展》
CAS
CSCD
北大核心
2008年第11期1161-1166,共6页
Advances in Earth Science
基金
国家自然科学基金项目"海洋天然气水合物地质系统的沉积物粒度制约
自生矿物和有孔虫响应"(编号:40772073)
中国综合大洋钻探计划(IODP-China)
中石化海相油气勘探前瞻性项目"海相优质烃源岩形成的地球生物学过程"(编号:G0800-06-ZS-319)联合资助
