HYDROTHERMAL OXIDE AND NONTRONITE DEPOSITS ON SEAMOUNTS IN THE EASTERN PACIFIC
HYDROTHERMAL OXIDE AND NONTRONITE DEPOSITS ON SEAMOUNTS IN THE EASTERN PACIFIC
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DOI：
10.1016/0025-3227(88)90029-1
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发表时间：
1988-06-01
期刊：
影响因子：
2.9
通讯作者：
ALT, JC
中科院分区：
文献类型：
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作者：
ALT, JC
在东太平洋的两座海山的山顶上采集了氧化铁泥、非铁土和铁锰结壳的沉积物。在低温（0 ~ 15℃）热液作用下，矿床由x射线无定形氧化铁组成，富Fe (43 wt.%)，含少量Si和P（分别为4%和3.5%），Mn（< 0.01%）和其他微量元素含量极低。其他没有观察到当前热液活动的矿床由泥浆和由无定形物质和结晶性差的赤铁矿、针铁矿和蒙脱石组成的结壳组成。这些矿床的锰含量略高（可达2%）和其他微量元素含量。活性和非活性矿床和地壳之间的矿物学和化学差异被解释为由于碎屑、生物源、氢和可能的热液硫化物物质的再结晶和污染。由铁锰氧化物覆盖的非长石矿床从其中一个海底山取样。这些矿床的成分与其他海底非润土矿床相似，是在低温（30℃）下由低温热液流体与海水混合形成的。氧化沉积物几乎完全由长而纤细的细丝组成，在形态上与铁氧化菌属非常相似。这些细菌可能在催化海底山热液中铁的氧化和沉淀中起重要作用。在两个相隔很远的海山上发现了几乎相同的富细丝氧化物矿床，这表明这种矿床可能在海山上很常见，但以前未被发现。
Deposits of Fe oxide mud, nontronite, and Fe-Mn crusts were sampled from the summits of two seamounts in the eastern Pacific. Where low temperature (0–15° C) hydrothermal fluids are issuing, the deposits consist of X-ray amorphous Fe oxyhydroxide and are rich in Fe (43 wt.%), contain minor Si and P (4% and 3.5%, respectively), and have very low Mn (< 0.01%) and other trace element contents. Other deposits, where no current hydrothermal activity was observed, consist of mud and crusts composed of amorphous material and poorly crystalline hematite, goethite, and smectite. These deposits have slightly higher Mn (up to 2%) and other trace element contents. The mineralogical and chemical differences between the active and inactive deposits and crusts are interpreted to be due to recrystallization and contamination with detrital, biogenic, hydrogenous, and possibly hydrothermal sulfide material. Nontronite deposits, capped by Fe-Mn oxides, were sampled from one of the seamounts. These deposits have compositions similar to other seafloor nontronite deposits, and formed at low temperatures (30° C) during mixing of low temperature hydrothermal fluids with seawater. The oxide deposits consist almost entirely of long, delicate filaments, remarkably similar in morphology to genera of Fe oxidizing bacteria. Such bacteria were probably important in catalyzing the oxidation and precipitation of iron from hydrothermal fluids on the seamounts. The occurrence of nearly identical filament-rich oxide deposits on two widely separated seamounts suggests that this type of deposit may be common on seamounts, but previously unrecognized.