Processes influencing extreme As enrichment in shallow-sea hydrothermal fluids of Milos Island, Greece
Processes influencing extreme As enrichment in shallow-sea hydrothermal fluids of Milos Island, Greece
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影响希腊米洛斯岛浅海热液极端富集的过程
DOI：
10.1016/j.chemgeo.2012.06.007
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发表时间：
--
期刊：
影响因子：
3.9
通讯作者：
Pichler
中科院分区：
文献类型：
--
作者：
Planer-Friedrich;Bühring ;Pichler
砷 (As) 在大多数陆地和海洋热液系统中天然富集。它从浅海热液喷口排放到沿海海洋环境中可以极大地影响周围的生态系统。希腊米洛斯岛东南海岸的 Palaeochori 湾和 Spathi 湾出现酸性（pH~5）、高温（40-116°C）和高硫化物（高达 3.1mM H2S）流体的浅海热液喷发。从彼此相距几米的海底喷口收集到两种不同类型的流体，砷含量极高：(1) 高 Cl 流体（相对于海水，Cl 含量最高 47%），缺乏 Mg 和 SO4，富含主量元素（Na、Ca、K、B、Sr 和 Br）和微量/微量元素（Si、Li、Rb、Ce、As、Fe、Mn 和 Ba），以及 (2)低 Cl 流体（相对于海水，Cl 含量减少高达 66%）也减少了 Na、Mg、SO4 和 Br。高Cl 流体中As 的最大浓度达到39μM，低Cl 流体中As 的最大浓度达到78μM。这大约是海水中砷浓度的 3000 倍，远远超过洋中脊 (MOR) 和弧后盆地 (BAB) 流体中砷的浓度，通常分别 <0.7 和 <10μM。我们结合使用元素分析和稳定放射性同位素数据（氧、氘和锶）来了解砷富集的主要控制。这些参数都表明流体是海水和最初源自海水的热液的混合物，但由于水-岩相互作用、亚临界相分离（沸腾）和蒸汽/盐水分离而改变。由于砷在高氯和低氯热液中都极其富集，我们得出结论，该元素很容易在米洛斯热液系统中分配到气相中。砷的原始来源很可能是绿片岩相变质基岩的浸出，这些基岩被大量富含黄铁矿的次生石英和方解石脉穿透。这些矿脉可能是由富含砷的岩浆流体沉积而成，类似于一些浅成热液金矿床。当热液与上层海水混合时，结晶不良的雌黄会沉淀下来，并在排放前去除大部分溶解的砷。
Arsenic (As) is naturally enriched in most terrestrial and marine hydrothermal systems. Its discharge from shallow-sea hydrothermal vents into coastal marine environments can dramatically affect the surrounding ecosystems. Shallow-sea hydrothermal venting of acidic (pH~5), hot (40–116°C), and highly sulfidic (up to 3.1mM H2S) fluids occurs at Palaeochori and Spathi Bays, off the southeast coast of Milos Island, Greece. Two distinct types of fluids, both extremely As enriched, were collected from the submarine vents often within a few meters of each other: (1) a high-Cl fluid (enriched in Cl by up to 47% relative to seawater) depleted in Mg and SO4and enriched in major (Na, Ca, K, B, Sr, and Br) and minor/trace elements (Si, Li, Rb, Ce, As, Fe, Mn, and Ba), and (2) a low-Cl fluid (depleted in Cl by up to 66% relative to seawater) also depleted in Na, Mg, SO4, and Br. The maximum concentration of As reached 39μM in the high-Cl fluids and up to 78μM in the low-Cl fluids. This is approximately 3000 times the concentration of As in seawater and far exceeds the concentrations typically found in mid-ocean ridge (MOR) and back-arc basin (BAB) fluids, which are typically <0.7 and <10μM, respectively. We used a combination of elemental analyses and stable and radiogenic isotope data (oxygen, deuterium, and strontium) to understand the primary controls on As enrichment. Those parameters all indicated that the fluids were a mixture of seawater and a hydrothermal fluid originally derived from seawater but altered by water–rock interaction, subcritical phase separation (boiling), and vapor/brine segregation. Since As was extremely enriched in both the high-Cl and the low-Cl thermal fluids, we conclude that this element readily partitions into the vapor phase in the Milos hydrothermal system. The original source of As is most likely the leaching of the greenschist facies metamorphic basement rocks transpierced by an abundance of secondary quartz and calcite veins rich in pyrite. It is possible that these veins were deposited from As-rich magmatic fluids, similar to some epithermal Au deposits. A poorly-crystalline orpiment precipitates as hydrothermal fluids mix with overlying seawater, and removes much of the dissolved As prior to discharge.
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影响因子：
7.4
作者：
Planer-Friedrich, Britta;Suess, Elke;Wallschlaeger, Dirk
通讯作者：
Wallschlaeger, Dirk
自然环境中的砷
DOI：
--
发表时间：
2009
期刊：
影响因子：
--
作者：
K. Henke
通讯作者：
K. Henke
影响因子：
4.1
作者：
Dando, PR;Stüben, D;Varnavas, SP
通讯作者：
Varnavas, SP
改进的新近纪晚期海水年代地层参考曲线 87 Sr / 86 Sr : 评论和回复 COMMENT
DOI：
--
发表时间：
1996
期刊：
影响因子：
--
作者：
G. Friedman
通讯作者：
G. Friedman
影响因子：
11.4
作者：
Planer-Friedrich, Britta;London, Jacqueline;Wallschlaeger, Dirk
通讯作者：
Wallschlaeger, Dirk