東馬努斯海盆PACMANUS熱液區(qū)Si-Fe-Mn氧化物的形成機(jī)制及其對(duì)熱液活動(dòng)的指示
發(fā)布時(shí)間：2018-11-02 18:38
【摘要】：在東馬努斯海盆PACMANUS(巴布亞新幾內(nèi)亞 澳大利亞 加拿大 馬努斯)熱液區(qū)拖網(wǎng)取得了部分Si-Fe-Mn氧化物樣品。通過(guò)分析Si-Fe-Mn氧化物的主量、微量和稀土元素含量,Sr、Nd、Pb同位素組成,探討了Si-Fe-Mn氧化物的成因及元素含量的限制因素,研究了熱液區(qū)Si-Fe-Mn氧化物的物質(zhì)來(lái)源。利用PACMANUS熱液流體端元組分的Si、Fe、Mn含量,分別繪制了300°C和25°C的Si-Fe-Mn-H2O系統(tǒng)熱力學(xué)圖解——布拜圖。闡明了隨溫度降低,噴口流體中沉淀的Si-Fe-Mn氧化物種類和沉淀順序,以及各類產(chǎn)物穩(wěn)定存在的區(qū)域。根據(jù)光學(xué)顯微鏡下觀察、掃描電鏡、電子探針?lè)治鲎R(shí)別了樣品中細(xì)菌作用形成的典型細(xì)絲結(jié)構(gòu),并探討了生物作用與非生物作用在Si-Fe-Mn氧化物形成過(guò)程中的競(jìng)爭(zhēng)機(jī)制、分析了無(wú)定形硅的沉淀作用。樣品具有復(fù)雜的成因,以熱液成因?yàn)橹?受海水的影響較小。幾乎沒(méi)有深海遠(yuǎn)洋沉積物和火山碎屑物質(zhì)的貢獻(xiàn)。Sr和Nd同位素組成具有兩個(gè)端元的物質(zhì)來(lái)源。海水對(duì)樣品貢獻(xiàn)的Sr含量占總量的76.7%~83.1%。所有樣品的Nd主要來(lái)自熱液流體并保存了熱液的信息。Pb同位素組成變化范圍較小,主要來(lái)自東馬努斯海盆的基底巖石。熱力學(xué)圖解布拜圖顯示當(dāng)溫度降低到25°C時(shí),從熱液流體中形成的Si、Fe、Mn氧化物種類主要為SiO2、Fe(OH)3、Fe3(OH)8、Mn3O4、Mn2O3。在熱液流體與海水的混合過(guò)程中,由于SiO2的穩(wěn)定區(qū)邊界較低,因此SiO2會(huì)在Fe-Mn氧化物形成之前沉淀。然后Fe(OH)2先沉淀,Fe3(OH)8和Fe(OH)3隨后沉淀,Mn3O4和Mn2O3最后沉淀。計(jì)算得到PACMANUS熱液區(qū)Fe2+氧化為Fe3+的無(wú)機(jī)氧化速率為0.012 g/min,噴口周圍一年內(nèi)將形成約3.2 kg鐵氧化物。網(wǎng)狀細(xì)絲結(jié)構(gòu)是生物作用的結(jié)果,這種疏松的結(jié)構(gòu)既保證了充足的Fe2+供應(yīng),又阻止了海水中過(guò)量氧氣的侵害,為嗜中性鐵氧化細(xì)菌的生存提供了良好環(huán)境。同時(shí),生物作用與非生物作用之間保持著既互相競(jìng)爭(zhēng),又互相促進(jìn)的作用。樣品中二氧化硅的沉淀過(guò)程主要分為兩個(gè)階段。第一個(gè)階段是二氧化硅在富Fe的細(xì)絲狀結(jié)構(gòu)中生長(zhǎng),此時(shí)形態(tài)上基本由細(xì)絲狀結(jié)構(gòu)組成。當(dāng)富Fe和Si的細(xì)絲結(jié)構(gòu)成殼時(shí),才會(huì)出現(xiàn)第二階段的二氧化硅。此階段細(xì)絲的尺寸增大,并且在細(xì)絲周圍開(kāi)始大量沉淀富Fe、Si的球狀結(jié)構(gòu)的集合體。
[Abstract]:Some samples of Si-Fe-Mn oxides were obtained by trawl in the PACMANUS (Papua New Guinea Australia) hydrothermal zone of the East Manus Basin. By analyzing the main amount of Si-Fe-Mn oxide, trace and rare earth element content and Sr,Nd,Pb isotopic composition, the origin of Si-Fe-Mn oxide and the limiting factors of element content are discussed. The source of Si-Fe-Mn oxides in hydrothermal region was studied. Based on the Si,Fe,Mn content of the end component of the PACMANUS hydrothermal fluid, the thermodynamic diagrams of the Si-Fe-Mn-H2O system of 300 擄C and 25 擄C have been drawn respectively. The species and order of Si-Fe-Mn oxides precipitated in nozzle fluid with the decrease of temperature, and the regions where the products exist stably are explained. According to the observation under optical microscope, scanning electron microscope and electron probe analysis, the typical filaments formed by bacterial interaction in the sample were identified, and the competitive mechanism between biological and abiotic interactions in the formation of Si-Fe-Mn oxide was discussed. The precipitation of amorphous silicon was analyzed. The samples are of complex origin, mainly hydrothermal origin, but less affected by seawater. There are almost no contributions from deep-sea pelagic sediments and pyroclastic materials. Sr and Nd isotopic compositions have two end-member material sources. The content of Sr contributed by seawater to the sample was 76.7% and 83.1% of the total. The Nd of all samples was mainly from hydrothermal fluid and kept hydrothermal information. The variation range of Pb isotopic composition was relatively small, mainly from the basement rocks of the East Manus basin. The thermodynamic diagram shows that when the temperature is reduced to 25 擄C, the main types of Si,Fe,Mn oxides formed from hydrothermal fluids are SiO2,Fe (OH) _ 3 Fe _ 3, (OH) _ 8, mn _ 3O _ 4 and mn _ 2O _ 3. In the process of mixing hydrothermal fluid with seawater, SiO2 precipitates before the formation of Fe-Mn oxides due to the lower boundary of the stable region of SiO2. Then Fe (OH) 2 precipitated, Fe3 (OH) 8 and Fe (OH) 3 precipitated, and Mn3O4 and Mn2O3 finally precipitated. The inorganic oxidation rate of Fe2 to Fe3 in the PACMANUS hydrothermal region is calculated to be 0.012 g / min, and about 3.2 kg iron oxides will be formed around the nozzle within one year. The reticular filament structure is the result of biological action. This loose structure not only guarantees sufficient supply of Fe2, but also prevents the damage of excessive oxygen in seawater, and provides a good environment for the survival of neutral iron oxidizing bacteria. At the same time, biological action and abiotic action maintain the role of competition and mutual promotion. The precipitation process of silica in the sample is divided into two stages. The first stage is the growth of silica in the filamentous structure rich in Fe, which is basically composed of filamentous structures. When the filaments rich in Fe and Si are formed into shells, the second stage silica will appear. At this stage, the size of the filaments increases and a large number of aggregates of Fe,Si rich spherical structures begin to precipitate around the filaments.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院(海洋研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P736.3
本文編號(hào)：2306631
[Abstract]:Some samples of Si-Fe-Mn oxides were obtained by trawl in the PACMANUS (Papua New Guinea Australia) hydrothermal zone of the East Manus Basin. By analyzing the main amount of Si-Fe-Mn oxide, trace and rare earth element content and Sr,Nd,Pb isotopic composition, the origin of Si-Fe-Mn oxide and the limiting factors of element content are discussed. The source of Si-Fe-Mn oxides in hydrothermal region was studied. Based on the Si,Fe,Mn content of the end component of the PACMANUS hydrothermal fluid, the thermodynamic diagrams of the Si-Fe-Mn-H2O system of 300 擄C and 25 擄C have been drawn respectively. The species and order of Si-Fe-Mn oxides precipitated in nozzle fluid with the decrease of temperature, and the regions where the products exist stably are explained. According to the observation under optical microscope, scanning electron microscope and electron probe analysis, the typical filaments formed by bacterial interaction in the sample were identified, and the competitive mechanism between biological and abiotic interactions in the formation of Si-Fe-Mn oxide was discussed. The precipitation of amorphous silicon was analyzed. The samples are of complex origin, mainly hydrothermal origin, but less affected by seawater. There are almost no contributions from deep-sea pelagic sediments and pyroclastic materials. Sr and Nd isotopic compositions have two end-member material sources. The content of Sr contributed by seawater to the sample was 76.7% and 83.1% of the total. The Nd of all samples was mainly from hydrothermal fluid and kept hydrothermal information. The variation range of Pb isotopic composition was relatively small, mainly from the basement rocks of the East Manus basin. The thermodynamic diagram shows that when the temperature is reduced to 25 擄C, the main types of Si,Fe,Mn oxides formed from hydrothermal fluids are SiO2,Fe (OH) _ 3 Fe _ 3, (OH) _ 8, mn _ 3O _ 4 and mn _ 2O _ 3. In the process of mixing hydrothermal fluid with seawater, SiO2 precipitates before the formation of Fe-Mn oxides due to the lower boundary of the stable region of SiO2. Then Fe (OH) 2 precipitated, Fe3 (OH) 8 and Fe (OH) 3 precipitated, and Mn3O4 and Mn2O3 finally precipitated. The inorganic oxidation rate of Fe2 to Fe3 in the PACMANUS hydrothermal region is calculated to be 0.012 g / min, and about 3.2 kg iron oxides will be formed around the nozzle within one year. The reticular filament structure is the result of biological action. This loose structure not only guarantees sufficient supply of Fe2, but also prevents the damage of excessive oxygen in seawater, and provides a good environment for the survival of neutral iron oxidizing bacteria. At the same time, biological action and abiotic action maintain the role of competition and mutual promotion. The precipitation process of silica in the sample is divided into two stages. The first stage is the growth of silica in the filamentous structure rich in Fe, which is basically composed of filamentous structures. When the filaments rich in Fe and Si are formed into shells, the second stage silica will appear. At this stage, the size of the filaments increases and a large number of aggregates of Fe,Si rich spherical structures begin to precipitate around the filaments.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院(海洋研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P736.3
【參考文獻(xiàn)】
相關(guān)期刊論文 前2條
1 姜學(xué)鈞;林學(xué)輝;姚德;郭衛(wèi)東;;稀土元素在水成型海洋鐵錳結(jié)殼中的富集特征及機(jī)制[J];中國(guó)科學(xué):地球科學(xué);2011年02期
2 曾志剛;陳帥;王曉媛;歐陽(yáng)荷根;殷學(xué)博;李兆學(xué);;東馬努斯海盆PACMANUS熱液區(qū)Si-Fe-Mn羥基氧化物的礦物學(xué)和微形貌特征[J];中國(guó)科學(xué):地球科學(xué);2013年01期
，本文編號(hào)：2306631
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