The Relation Of Distribution Characteristic Of Pyrite From The Core Sediments Of The South China Sea And Its Significance To Gas Hydrate And Environment

This article through the analysis of geological tectonic and sedimentary environment of the South China Sea North of the study area, hydrodynamic conditions, as well as background information on sea-level change, and experimental analysis the colμmnar sediment samples taken fromTaixinan basin, Baiyun SAG, Pearl River mouth basin of the Fox God waters. Identification of the change of characteristics in vertical direction in gas hydrate occurrence area. Also studied the Crystal form of pyrite and its causes, and discussed the formation and development of pyrite and interaction between methane gas in the early diagenetic processes. Get on the following major known:(1)2B,3B,5A,6B, the plane distribution change characteristics of total flat of pyrite in the four stations is that5A station whicd is located in the Pearl River mouth basin of the Fox God waters is the highest,3B station followed by. Vertical distribution characteristics of total flat of pyrite:Pyrite is mostly concentrated in the300cm-700cm layer; the Peak District of pyrite in3B station is in the350cm layer, the followed peak district is in the560cm layer; the Peak District of pyrite in2B station is in the405cm layer; the Peak District of pyrite in5A station is in the360cm layer; the followed peak district in2B and5A station are both in the705cm-710cm layer.(2)2B,3B,5A,6B, the total content of organic carbon in the colμmnar sediment which taken from shallow surficial sediments in these four stations is0.37%-1.18%, the average content is0.71, the total content of sulphur is0.04%-0.81%, the average content is0.30%; the content of Pyrite is0-0.71%, the average content is0.23%. TOC, TS and contents of pyrite with depth changes, increasing, decreasing after reaching the peak. Distribution trends of these Three characteristics are almost the same. Deposits of pyrite is the main sulphide, anaerobic oxidation of methane play the role of a main contribution to the formation of pyrite. (3) Scanning electron microscope to pyrite most berry spherical aggregates and octahedral microcrystals morphology output, regular octahedron monomer larger particle size, aggregate particle size is also larger, local layers found the tubular biological endometrial-like and cube-shaped pyrite crystals. Organic matter content to a large extent affected the the pyrite content distribution, high values in the TS content, pyrite content is at its peak, part of the layer is not significant for other sulfide TS content.3B,5A,6B stations are located in northern South China Sea gas hydrate prospects, the development of the deep fracture in the formation, shallow environment of extreme reducing environment, active AOM role, the terrigenous material source of iron and sulfur in the environment source easy to form authigenic pyrite. Pyrite framboid output, indicating a pneμmatic oxygen-rich with background and local hypoxic microenvironment.