| WANG Kunshan,SHI Xuefa,QIAO Shuqing,KORNKANITNAN Narumol,KHOKIATTIWONG Somkiat. 2015. Distribution and composition of authigenic minerals in surface sediments of the western Gulf of Thailand. Acta Oceanologica Sinica, 34(12):125－136 |
| Distribution and composition of authigenic minerals in surface sediments of the western Gulf of Thailand |
| 泰国湾西部表层沉积物自生矿物分布及组成 |
| Received:August 19, 2014 Revised:April 01, 2015 |
| DOI：10.1007/s13131-015-0772-y |
| Key words:Gulf of Thailand surface sediment authigenic minerals siderite glauconite composition of minerals |
| 中文关键词: 泰国湾 表层沉积物 自生矿物 菱铁矿 海绿石 矿物组成 |
| 基金项目:The National Programme on Global Change and Air-sea Interaction under contract No. GASI-02-SCS-CJ03; China Geological Survey:Continental Shelf Drilling Program under contract No. GZH201100202; China-Thailand Cooperation Project "Research on Vulnerability of Coastal Zones". |
| Author Name | Affiliation | E-mail | | WANG Kunshan | Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China
Function Laboratory for Marine Geology, National Oceanography Laboratory, Qingdao 266061, China | kunshwang@fio.org.cn | | SHI Xuefa | Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China
Function Laboratory for Marine Geology, National Oceanography Laboratory, Qingdao 266061, China | | | QIAO Shuqing | Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China
Function Laboratory for Marine Geology, National Oceanography Laboratory, Qingdao 266061, China | | | KORNKANITNAN Narumol | Marine and Coastal Resource Research Center, Samut Sakhon 74000, Thailand | | | KHOKIATTIWONG Somkiat | Phuket Marine Biological Center, Muaeng Phuket 83000, Thailand | |
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| Abstract: |
| Generation, morphology, and distribution of authigenic minerals directly reflect sedimentary environment and material sources. Surface sediments were collected from the western Gulf of Thailand during 2011-2012, and 159 samples were analyzed to determine detrital minerals. Authigenic minerals, including siderite, pyrite, and glauconite, are abundant whereas secondary minerals, such as chlorite and limonite, are distributed widely in the study area. Siderite has a maximum content of 19.98 g/kg and appears in three types from nearshore to continental shelf, showing the process of forming-maturity-oxidation. In this process, the MnO content in siderite decreases, but Fe2O3 and MgO content increase. Colorless or transparent siderite pellets are fresh grains generated within a short time and widely distributed throughout the region; high content appears in coastal area where river inputs are discharged. Translucent cemented double pellets appearing light yellow to red are mature grains; high content is observed in the central shelf. Red-brown opaque granular pellets are oxidized grains, which are concentrated in the eastern gulf. Pyrite is mostly distributed in the central continental shelf with an approximately north-south strip. Pyrite are mainly observed in foraminifera shell and distributed in clayey silt sediments, which is similar to that in the Yangtze River mouth and the Yellow Sea. The pyrite in the gulf is deduced from genetic types associated with sulfate reduction and organic matter decomposition. Majority of glauconite are granular with few laminar. Glauconite is concentrated in the northern and southern parts within the boundary of 9.5° to 10.5°N and is affected by river input diffusion. The distribution of glauconite is closely correlated with that of chlorite and plagioclase, indicating that glauconite is possibly derived from altered products of chlorite and plagioclase. The K2O content of glauconite is low or absent, indicating its short formation time. |
| 中文摘要: |
| 沉积物中自生矿物的生成、形态和分布是对沉积环境、物质来源的直接反映。本文所分析样品是2011年和2012年"中泰合作联合航次调查"获取的泰国湾西部表层沉积物,对其中的159站进行了碎屑矿物分析。结果表明,在表层沉积物中含有多种自生矿物和次生矿物。前者包括菱铁矿、黄铁矿和海绿石,后者为绿泥石和褐铁矿,这些矿物在研究区广泛分布,局部富集。菱铁矿最高含量达到19.98g/kg,主要形态为无色或浅色的透明小球粒(新鲜颗粒)、浅黄色到浅红色的半透明双球状颗粒(成熟颗粒)以及红褐色不透明颗粒(风化颗粒)。菱铁矿的新鲜小球粒几乎遍布全区,在近岸河流输入物影响区域内含量高,而成熟球粒在陆架中部含量高,在陆架东部区域菱铁矿多发生氧化。从近岸到陆架,菱铁矿表现出生成-成熟-氧化的过程,在此过程中MnO减少,而Fe2O3、MgO增加。黄铁矿主要为生物壳内生成,近似南北向条带分布在陆架中部,其成因与硫酸盐还原及有机质降解有关,主要分布在粘土质粉砂沉积物中,产出状态与长江口和黄海陆架表层沉积物中产出的黄铁矿相似。海绿石主要为颗粒状,壳生和书页状较少,含量分布以9.5-10.5°N为界,呈现南北分带性,表现出河流输入物质扩散对其生成的影响:北部分布同流入泰国湾上部的河流物质扩散方向关系密切,海绿石含量分布依扩散方向而展开;在南部近岸区特别是河流输入影响范围内含量高。海绿石的分布与绿泥石和斜长石分布具有较大的相关性,其成因与二者具有亲缘性,可能为斜长石和绿泥石的蚀变产物。海绿石化学成分中略含K2O或不含,表明形成年代新。 |
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