南海北部陆坡沉积物中P-S-Fe的相互作用及其对划分硫酸盐-甲烷转换带的指示意义  

The interactions of P-S-Fe in sediment from the continental slope of northern South China Sea and their implication for the sulfate-methane transition zone

作　　者：张劼[1] 雷怀彦[1,2] 杨鸣[1] 陈勇[1] 孔媛 卢毅 ZHANG Jie;LEI Huaiyan;YANG Ming;CHEN Yong;KONG Yuan;LU Yi(College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China;State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China)

机构地区：[1]厦门大学海洋与地球学院,福建厦门361005 [2]厦门大学近海海洋环境科学国家重点实验室,福建厦门361005

出　　处：《地学前缘》2018年第3期285-293,共9页Earth Science Frontiers

基　　金：国家自然科学基金项目(41276046;41773078);国家重点基础研究发展计划"973"项目子课题(2009CB21951)

摘　　要：对南海北部陆坡台西南海域973-4岩心沉积物中自生磷灰石磷(P_(CAF))和铁氧化物结合态磷(P_(Fe))及4种活性Fe组分进行了分步提取测定。结果显示:沉积物自生磷灰石磷(P_(CFA))含量为0.34%~3.24%,是该站沉积物P的主要成分,其含量自海底向下反复波动;铁氧化物结合磷(P_(Fe))含量为0%~1.38%,总体上出现多次升降。Fe_(py)含量为0.05%~0.72%,平均含量为0.27%,Fecarb含量为0.14%~0.64%,平均含量为0.33%,在硫酸盐-甲烷转换带(SMTZ)上部Fe_(py)和Fe_(carb)均出现上升现象,在SMTZ下部Fe_(py)迅速下降而Fe_(carb)含量缓慢上升。Fe_(ox)含量为0.32%~0.73%,平均含量为0.46%;Fe_(mag)含量为0.18%~0.34%,平均含量为0.25%。Fe_(ox)和Fe_(mag)含量变化趋势基本一致。结合沉积物总硫(TS)、酸可挥发性硫(AVS)及孔隙水中硫酸根(SO_4^(2-))等指标分析可得出:973-4柱中两种SO_4^(2-)还原模式产生的CO_3^(2-)均会抑制磷灰石晶体的凝聚成核作用;可以利用Fe_(py)和Fe_(carb)含量的反向变化及Fe_(ox)和Fe_(mag)的迅速升高对SMTZ上下部进行判定划分;P_(CAF)和P_(Fe)含量在SMI界面以下的往复波动的现象为研究水合物不稳定分解影响的环境范围及古SMI界面提供了新的思路。P（CFA）,PFe） and four kinds of active Fe components in sediment core 973-4 from the continental slope of the northern South China Sea gas hydrate potential zone,near Jiulong Methane Reef,were extracted and analyzed.The results showed that the sedimental PCFA is the dominant P ingredient at this location,with its content fluctuating downwards from the seabed from 0.34% to 3.24%.PFe content was found to be 0-1.38%,displaying several up-and-down fluctuations.Similarly,Fepy and Fecarb contents fluctuated between 0.05%-0.72% and 0.14%-0.64%,with averages of 0.27% and 0.33%,respectively;both contents increased at the top of SMTZ,while Fepy content decreased sharply and Fecarb content increased slowly at the bottom of SMTZ.And Feox and Femag contents varied between 0.32%-0.73% and 0.18%-0.34%,with averages of 0.46% and 0.25%,respectively.The variation trends of Feox and Femag were similar.Combining with TS,AVS,SO_42- and other indicators,our analysis showed that CO_32-,produced by two types of reductive reactions in core 973-4,inhibited the formation of apatite core;and furthermore,SMTZ can be identified quickly from sharp increments of Feox and Femag contents and opposite variation trends of Fepy and Fecarb.Recurrent fluctuations of PCFAand PFe） under SMI,as observed in this study,shall provide us with new ideas in studying paleo-SMI and the range of effects from decomposition of methane hydrate.

关 键 词：硫酸盐-甲烷转换带 甲烷水合物 铁组分 磷形态 早期成岩作用 

分 类 号：P736.3[天文地球—海洋地质] P618.13[天文地球—海洋科学]