Analyse And Study On The Granulity And Microstructure Of The Sediments From SO177 In The North Of South China Sea

The latest study shows that South China Sea have quite good geologicalenvironments for the forming of gas hydrate. There are also many abnormalcharacteristics in this area, for example, the BSR abnormal, thedecreasing of pore water and chlorite ion concentration, the temperatureincreasing of thermal infrared of satellite, the different methaneconcentration and thermaloluinescence abnormal. This area is expected agood prospect for forming the gas hydrate.The researching material were provided by the internationalcorporation project, which named SiGer, was cooperated between marineresearch institute, Kirel University and Gongzhou marine geologicalsurvey.Based on the data from S0177 leg core, which were collected in SouthChina Sea by German scientific investigation ship – SONNE, our study canbe divided into three parts. The first part is the grain size analysisand data-processing. Then we decided the 14C isotopic age. We summarizedcore characteristic through observing the sample with scan electronicmicroscope.In this study, the core is divided into three lithologic members.Member Ⅰ is mainly composed of silty clay which belongs to the mid-lateHolocene deposit environment. Member Ⅰ includes 10% sand, 70% silt and20% clay and all the components have stable concentration in differentgrade and the average deposit rate is approximately 20.83/ka. Thepercentage in member Ⅱ has large fluctuation margine. The percentage ofdifferent grades in member Ⅱ are large fluctuation margine, 0～80%approximately. There are very good matching between the high sandconcentration layers and the four turbidite layers (Y < 9.8433). MemberⅡbelongs to the age range from the last glacial epoch since 50,000 yearsto the early Holocene deposit. Member Ⅲ have small fluctuation marginein different grades percentage which includes 10% sand, 65% silt and 25%clay. But there are still some layers, for example the layers in depthGC10-643-652cm,GC10-760-771cm and GC11-522-547cm with more than 50%sand, more than 30% silt. The average deposit rate is more than 7.83cm/ka.The age can not be decided since the absence of the core time data. Itscalculated by the age of 50,000.We generalized the classical microstructure style through contactrelation, pore-size and the cementation status. For example: aggregativesupported large aperture microcosmic cement texture, bracket large aperture loosentexture, mosaic large aperture microcosmic cement texture, wadding cement texture,oriented structure, ellipse – round interstitial texture, and so on.The sedimentary analysis provided the relative data for realizing thegas hydrate deposits in profundal zone, South China Sea.