本文選題：自生黃鐵礦 + 掃描電鏡�。� 參考：《廈門大學(xué)》2014年碩士論文

【摘要】：本論文通過(guò)對(duì)采自南海北部的柱狀沉積物樣品的總硫含量、總有機(jī)碳含量進(jìn)行實(shí)驗(yàn)分析以及借助帶能譜儀的掃描電鏡(SEM)對(duì)保存在沉積物中的黃鐵礦的亞微結(jié)構(gòu)特征,進(jìn)行初步探討研究。查明在天然氣水合物賦存區(qū)的黃鐵礦的垂向分布特征以及在平面上的變化特征,同時(shí)對(duì)黃體礦的晶體形貌特征和成因機(jī)制進(jìn)行了研究,并對(duì)早期成巖過(guò)程中黃鐵礦的發(fā)育與甲烷氣體之間的相互作用進(jìn)行了有益探討。得到了以下幾個(gè)方面的主要認(rèn)識(shí)： (1)2B、3B、5A、6B4個(gè)站位在平面上黃鐵礦總量的變化特征為神狐海域的5A站位含量最高,東沙海域的3B、2B站位黃鐵礦含量次之。4個(gè)站位的黃鐵礦垂向上的分布特征為,多數(shù)集中在300cm～700cm層段處。3B站位的黃鐵礦含量的最大值區(qū)域位于350cm層段,次峰值區(qū)位于560cm層段；2B站位的黃鐵礦峰值區(qū)在405cm層位,5A站位的黃鐵礦峰值區(qū)在360cm層位,2B站位和5A站位次峰值區(qū)都分布在705cm～710cm層位。 (2)2B、3B、5A、6B站位淺表層柱狀沉積物中的總有機(jī)碳(TOC)含量為0.37%～1.18%,平均值為0.71,總硫(TS)含量為0.04%～0.81%,平均值為0.30%,黃鐵礦(FeS2)含量為0～0.71%,平均含量為0.23%,TOC、TS和黃鐵礦含量隨著沉積物埋藏深度增加逐漸增大,達(dá)到峰值后逐漸減少,三者的分布趨勢(shì)基本一致。黃鐵礦是沉積物中硫化物的主要形式,甲烷的厭氧氧化作用(AOM作用)對(duì)黃鐵礦的形成起主要的貢獻(xiàn)作用。 (3)在掃描電鏡(SEM)下觀察到黃鐵礦,其產(chǎn)出形式大部分為莓球狀集合體和八面體微晶形貌。正八面體的單體黃鐵礦粒徑較大,形成的集合體粒徑也較大,在局部層位還發(fā)現(xiàn)少量的管狀的、生物內(nèi)膜狀的以及立方體狀的黃鐵礦晶體。有機(jī)質(zhì)含量在很大程度上影響了黃鐵礦的含量分布,在TS含量的高值區(qū),黃鐵礦含量亦處于峰值,少部分層位的相關(guān)性不明顯,為其他硫化物對(duì)TS含量的影響。3B、5A、6B站位均位于南海北部陸坡天然氣水合物遠(yuǎn)景區(qū),地層中深大斷裂發(fā)育,淺表層環(huán)境為極端還原環(huán)境,甲烷厭氧氧化作用活躍,陸源物質(zhì)帶來(lái)的鐵源與該環(huán)境中的硫源易形成自生黃鐵礦。黃鐵礦的莓球狀產(chǎn)出,亦指示該背景為充氣富氧和局部的缺氧環(huán)境。
[Abstract]:In this paper, the total sulfur content and total organic carbon content of the columnar sediments collected from the northern part of the South China Sea were analyzed experimentally, and the submicrostructural characteristics of pyrite preserved in the sediments were studied by means of scanning electron microscope (SEM) with energy spectrometer. A preliminary study was carried out. The vertical distribution of pyrite in the gas hydrate region and its variation on the plane are investigated. The crystal morphology and genetic mechanism of the luteinite are also studied. The interaction between the development of pyrite and methane gas during the early diagenesis is also discussed. The following key aspects were recognized: The variation characteristics of the total amount of pyrite in the plane are that the content of pyrite at 5A station is the highest in Shenhu area, followed by the pyrite content at 3BX 2B station in Dongsha Sea area. The vertical distribution characteristics of pyrite in 4 stations are as follows. Most of the pyrite content at station. 3B of 300cm~700cm is located in the 350cm layer. The sub-peak area is located in the pyrite peak area of the 560cm section and the pyrite peak area at the 405cm level and 5A station. The pyrite peak area in the 360cm layer is located at the 360cm layer and the sub-peak area at the 5A station is located in the 705cm~710cm layer. The total organic carbon (TOC) content in the shallow surface columnar sediments at the station No. 2B2B2BC5A5A6B was 0.370.18 with an average value of 0.71, the total sulfur content was 0.040.81, the average value was 0.30, the content of pyrite FeS2 was 0.0.71, and the average content of 0.23TOCnTS and pyrite gradually increased with the increase of the depth of burial of the sediments, and the total organic carbon (TOC) in the columnar sediments of the shallow surface was 0.371.The average content of TOC was 0.371.The average value of TOC was 0.71, and the content of TSC was 0.040.81, the average was 0.30. After reaching the peak value, the distribution trend of the three is basically the same. Pyrite is the main form of sulfides in sediments, and the anaerobic oxidation of methane (AOM) plays a major role in the formation of pyrite. (3) Pyrite was observed under scanning electron microscope (SEM), and most of the pyrite was produced in the form of globular aggregate and octahedral microcrystalline morphology. The size of pyrite monomers of octahedron is larger and the particle size of formed aggregates is larger. A small number of tubular, biofilm and cubic pyrite crystals are also found in local layers. The content of organic matter affects the distribution of pyrite content to a great extent. In the high value region of TS content, the content of pyrite is also at the peak, and the correlation of a few layers is not obvious. For the influence of other sulfides on TS content. The stations. 3B- 5AY6B are located in the natural gas hydrate area on the northern slope of the South China Sea. The deep faults in the strata are developed, the shallow surface environment is an extreme reduction environment, and the anaerobic oxidation of methane is active. Tie Yuan from land-based sources and sulfur sources from the environment are prone to form authigenic pyrite. The raspberry globular production of pyrite also indicates that the background is aerated oxygen-rich and partially anoxic.
【學(xué)位授予單位】：廈門大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P744;P618.31

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