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以2~4 cm为间隔,对冲绳海槽北部的CSH1孔岩心(17.36 m)进行了岩石磁学研究.根据岩心上部的两个特征火山灰层和浮游有孔虫组合分析建立了钻孔的时间框架,沉积物底部年龄可能为50 ka.除了在三个火山灰层和近表层向下的快速降低外,整个钻孔磁学参数的变化甚小,未能反映出50 ka来的气候变化.与大多数沉积物不同,该钻孔大多数层位的S值(S=-IRM-0.3T/SIRM,它代表了低矫顽力磁性矿物的含量)小于0.9,指示钻孔沉积物中存在相当比例的高矫顽力磁性矿物.代表性沉积物样品的磁化率-温度(K-T)曲线除了存在580℃磁铁矿的居里温度之外,还显示200~350℃的居里温度,指示样品中存在铁硫化物(胶黄铁矿-磁黄铁矿).这与加热过程中有刺鼻的臭味、加热后的沉积物变黑对铁硫化物的指示相吻合.自生成因的铁硫化物的存在以及表层磁性参数的快速降低,都明确表明沉积物遭受了早期成岩作用.除了三个火山灰层以外钻孔的其他层位无特征磁学变化,表明沉积物后来受到的改造作用强烈,磁学参数所蕴含的原始气候信号被破坏.在这一系列氧化-还原过程中消耗了沉积物中的有机质和水溶液中的硫酸盐,造成了沉积物中铁、锰元素的重新溶解和沉淀等.
Rock magnetism was performed on the CSH1 pore core (17.36 m) in the northern Okinawa Trough at intervals of 2 ~ 4 cm.Based on the combination of two characteristic volcanic ash layers and planktonic foraminifera in the upper part of the core, the drilling time Framework, the bottom of the sediment may be 50 ka in age. Except for the rapid descending of the three volcanic ash layers and the subsurface, the variation of the magnetic parameters of the whole borehole is very small, which can not reflect the climate change of 50 ka. Most sediments are different and S values (S = -IRM-0.3T / SIRM, which represent low-coercivity magnetic minerals) at most of the horizon of the boreholes are less than 0.9, indicating that there is a comparable presence in borehole sediments Coefficient High Coercivity Magnetic Minerals The magnetic susceptibility-temperature (KT) curve of a representative sediment sample shows, in addition to the Curie temperature of 580 ° C magnetite, a Curie temperature of 200-350 ° C, indicating that the sample Iron pyrite (pyrrhotite-pyrrhotite) is present in the flue gas, which has a pungent smell during heating and darkening of the heated sediment to coincide with the indication of iron sulphides. The presence of matter and the rapid reduction of surface magnetic parameters clearly indicate that the sediments suffered early Rock features. Except for the three volcanic ash layers, there is no characteristic magnetism change in the other layers of the boreholes, which indicates that the later reformation of the sediments is strong and the original climatic signals implied by the magnetic parameters are destroyed.In this series of oxidation-reduction During the process, the organic matter in the sediments and the sulfate in the aqueous solution are consumed, resulting in the redissolution and precipitation of iron and manganese elements in the sediments.