黄土沉积物中次生细粒强磁性矿物记录的古气候信息

Implication of pedogenic fine-grained magnetic material in loess sediment

伊犁地区位于我国新疆地区西北部,为天山山脉环绕。区内降水自西向东递增,而温度则由于海拔高度的抬升而逐渐降低。上述地理环境有利于分析和探讨温度和降水与黄土沉积物中次生细粒强磁性颗粒数量之间关系。本研究在伊犁河谷西部地区,对不同海拔高度黄土表层沉积物进行样品采集。环境磁学分析结果显示:黄土沉积物中次生细粒强磁性矿物含量与降水量之间存在很好的正相关关系,而与温度之间存在反相关关系。结合黄土高原的研究结果可以发现:温度对黄土沉积物中次生细粒强磁性矿物的数量影响微弱,降水是控制其含量的主要因素;即:在黄土古气候研究中,次生细粒强磁性矿物的磁化率可以作为古降水量的代用指标,但对温度变化不敏感。

Ili region is in the northwestern XinJiang prefecture of China, which is surrounded by TianshanMountains. In this area, precipitation is increasing from west to east, contrasting, the temperature isgradually reduced, due to the uplift of the altitude. The superior geographical environment backgroundis very conducive to analysis and probe into how temperature and precipitation influence on quantityof pedogenic fine-grained magnetic particles of the loess sediments. So as to further illustrate what ishierarchical background gave birth to the main control factors of magnetic mineral content. This research isin the western region of Ili river valley, we collected loess surface sediment samples as altitude increasing.According to environmental magnetism analysis the results is pedogenic fine-grained magnetic mineralof loess sediments have positive correlation with precipitation and inverse correlation with temperature.Contrasting with the investigation results in Chinese Loess Plateau, it can be determined： the precipitationhas much closer link with increase magnetic mineral rather than temperature of loess sediments. That is tosay： Magnetic susceptibility of pedogenic fine-grained magnetic particles in loess sediments can be used asthe substitute of the precipitation index, but not temperature.