Major Element Geochemistry of LongShan Loess Profile in the Central Shandong Mountainous regions, Northern China

Abstract

In this paper, the major elements of the Longshan loess profile on the northern piedmont zones and intermountain valleys of mountainous regions in central Shandong Province in northern China, have been systematically tested and been compared with the YHC loess in the Loess Plateau to reveal the geochemical characteristics and material sources of LS loess. It is found that the average chemical composition of Shandong LS profile is similar to that of typical loess at YHC profile. The CIA, Na2O/K2O and Al2O3-CaO+Na2O-K2O triangles show that the LS loess is in moderate weathering stage and the chemical weathering degree is higher than that of the YHC profile in the Loess Plateau, but it is still in the Na, Ca removal of stage. Element activity sequence at the LS profile is Ca> Na> Mg> Si> Al> K> Fe, and Element activity capacity at LS profile is higher than that of at YHC profile. The ratio of TiO2/ Al2O3 and K2O /Al2O3 of the material source index clearly distinguishes LS loess and YHC loess, and it is concluded that the LS loess has different source from the loess plateau loess. It is not the result of dust storm direct from the northwest of China; otherwise, the Yellow River sediments and the North China Plain Material nearby may be its main sources when it was colder and drier during the glacial period. CIA and K2O/Na2O, and the migration rate of Fe, Al, K and Na is restored to the depositional environment of research. The winter monsoon in the late glaciation is strong and the chemical weathering is weak. In the early Holocene winter monsoon is weakened and the chemical weathering is enhanced. In the middle of Holocene, the summer monsoon dominated and the chemical weathering is strongest; in late Holocene, the climate deteriorated again, the chemical weathering is weakened.