晚新生代中国北方风尘沉积的可能物源及变化

中国北方风尘沉积是晚新生代中纬西风和冬季风输送的粉尘相互加积的结果。对北方风尘沉积物来源和搬运动力的分析表明,风尘沉积的物质来源具有多样性,物源类型和分布、传输路径随时间变化。认为亚洲中部山地古风化壳可能是中国北方早期风尘沉积,尤其是第三纪红粘土的重要物源之一;晚新生代的粉尘源区类型由山地因干旱化被风蚀的红色风化壳逐渐向盆地周边被抬升的中、新生代砂泥岩过渡,再由盆地周边过渡到盆地内部的中生代与新生代的河湖沉积物和沙漠。同时大气环流格局的变化相应地导致了粉尘源区分布和传输路径的迁移。

Possible provenances and their change of aeolian deposits in north China in late Cenozoic

Many studies have proved that aeolian deposits in north China since the late Cenozoic are jointly transported by both westerly air current and winter monsoon in East Asia in the Northern Hemisphere,but there are lots of uncertainties in the sand-dust source areas.The analyzed results of the provenances and transport processes of aeolian deposits reveal that the sand-dust sources are various,and the dust transport paths,types and spatial distribution vary with the time.It is considered that the paleo-weathering crust in the mountainous regions in Central Asia is possibly an important source of aeolian deposits,especially is one of the important sources of Cenozoic red clay.Because of aridification,the late-Cenozoic sand-dust source areas shifted from the wind-eroded reddish weathering crust in the mountainous regions to the Mesozoic and Cenozoic sandstone or mudstone in the peripheral regions of the basins,and then to the Mesozoic and Cenozoic fluvial and lacustrine deposits as well as the deserts in the basins.Moreover,the distribution of sand-dust source areas and the dust transport paths were correspondingly changed with the change of the general circulation patterns.