辽南滨海黄土粒度环境信息高分辨率研究

对辽南滨海黄土粒度研究证明 ,滨海黄土是在第四纪冰期寒冷气候下的产物 ,但是 ,由于滨海黄土所处靠近沿海的地理位置使得这种黄土的形成机制具有独特性。冰期时渤海湾西岸海面下降出露的冲洪积物和海底砂是滨海黄土除西北内陆地区以外的另一重要物源 ,搬运以风砂跃移方式进行。滨海黄土的粒度中包涵了丰富的有关渤海湾海面变化的信息。辽南滨海黄土剖面中的粒度拟合值、 2 - 3Ф粒级百分含量反映了渤海的海退、海侵过程和末次冰期蒙古高压的强弱 ,这种变化与滨海黄土 3个孢粉组合带所反映的古气候环境相吻合 ,同邻近地区的海面升降变化和深海岩芯氧同位素阶段也存在良好的对应关系 ,滨海黄土粒度的拟合度是本区古环境变化的重要的替代指标。

Research of high resolution on grain size of seashore loess and environmental information in south Liaoning Province

Research on grain size of seashore loess in Liaodong Peninsula indicates that kind of loess was the product of frigid climate in Quaternary ice age Due to geographical locations adjacent to coastal zone, the loess has distinctive formation process compared with loess in other areas Divulged alluvium and sands of Bohai seabed in the last glacial period constitute another important material source of this loess which are transported by sand saltation mode Grain size of this seashore loess bears a great deal of formation about changes of Bohai sea level Sedimentary process of this seashore loess is controlled by two factors, which are wind power and Bohai sea level's fluctuation in the last glacial period Wind deposits derived from adjacent source of materials make grain size distribution of this loess from normal to abnormal Goodness of fit of grain size distribution and 2 3Φ size percentage content reflect history of transgression and regression of Bohai Sea and strong and weak Mongolian high pressure of the last glaciation. These changes are identical with paleo environment reflected by sporo pollen assemblage, and also corresponding to sea leeventsl changes in the neighbouring areas and stage of δ 18 Ο/ 16 Ο Goodness of fit of seashore loess grain size distribution is a major substitutional index of paleo environmental changes Heinich events are recorded in Rosin's grain size distribution There are 5 high values of goodness of fit of Rosin's grain size distribution in profile of this seashore loess These events of high values occurred in transgression period of Bohai Sea during early and later phase of the last glacial period, and are records of extreme cool events which occurred during the last glacial period It is difficult to compare these events with Heinich events due to limitations of precision of chronological orders