摘要
麦哲伦海山区 MD、ME、MF海山具有三层构造的结壳特征 ,研究表明 ,结壳可分为上部较致密层、中部疏松层、下部致密层。致密层构造单一 ,含很少脉石矿物 ;疏松层构造杂乱 ,含有大量脉石矿物 ;较致密层介于两者之间 ,壳层矿物有锰相矿物 (主要为水羟锰矿 )、铁相矿物和次要矿物 (粘土矿物、钙十字沸石、石英、方解石、磷灰石等 )。不同壳层地球化学特征具有明显差异性 ,Ce异常表明在结壳从下层到上层的生长过程中 ,环境的氧化性逐渐减弱。结壳 1 0 Be测年结果表明 ,疏松层的生长速率最大 ,其次为致密层 ,较致密层的生长速率最小。推测区内最老的结壳的生长年代为中新世晚期 ,在 4Ma以前 ,区内水动力条件很弱 ,氧化性较强 ;4～ 3.1Ma BP水动力条件较强 ,氧化性较弱 ;2 .6 Ma BP以来 ,水动力条件为强—弱波动期 。
The study of the cobalt rich ferromanganese crusts which have three layer structure from the MA,ME and MF seamounts of the Magellan Seamounts gives the following results:(1)the typical three layer structure crust can be divided into dense layer in the upper part,loose layer in the middle,and dense layer in the lower.The lower dense layer has a simple structure and few gangue minerals,the loose layer has a mixed structure and many gangue minerals,and the upper dense layer has an intermediate nature.The crust contains manganese minerals(mainly vernadite),ferro phase minerals and secondary minerals(clay mineral,phillipsite,quartz,calcite and fluorapatite).(2)There are clear geochemical differences among the three layers.It is indicated that the oxidation in the paleo oceanographical environment is decreased from lower to upper layer by Ce anomaly.(3)It is inferred that growth age of the oldest crust is late Miocene in this area, and there were weakest water dynamic condition and stronger oxidation before 4Ma,stronger water dynamic condition and weaker oxidation from 4Ma to 3.1Ma,and strong weak undulating water dynamic condition and weaker oxidation after 2.6Ma in this area.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2001年第1期33-38,共6页
Marine Geology & Quaternary Geology
基金
中国大洋协会 DY95 -9航次勘查资助项目
关键词
富钴钻壳
壳层构造
壳层矿物
地球化学
生长速率
麦哲伦海山
铍同位素
cobalt rich ferromanganese crust
crust structure
crust mineral
geochemical
10 Be
growth rate
Magellan seamounts
