Xiangmin Zheng

PARTICLE SIZES, MAGNETIC PROPERTIES AND ORIGINS OF LOESS DEPOSITS FROM HUANGNISHAN HILL IN NANTONG, JIANGSU PROVINCE: PARTICLE SIZES, MAGNETIC PROPERTIES AND ORIGINS OF LOESS DEPOSITS FROM HUANGNISHAN HILL IN NANTONG, JIANGSU PROVINCE

Huangnishan hill is located in the southern area of Nantong City,Jiangsu Province. In this paper,we studied magnetic and granulometric characteristics of loess deposits from the Huangnishan hill and the origin of loess. The sediments are dominated by silty clay,and finer than those of both the Xiashu loess in Zhenjiang and the loess in the Chinese Loess Plateau. Huangnishan loess is similar to Xiashu loess in magnetic property,implying that the Huangnishan loess is the same as the Xiashu loess in Zhenjiang area,which is of aeolian origin. The fluctuation of magnetic parameters indicates that paleoenvironmental changes were recorded in the loess,too. The lower content of fine-grained ferrimagnetic minerals and higher S-100 values of the deposits in comparison to the Xiashu loess suggest that the Huangnishan loess experienced a lower degree of pedogenic alteration than that of the Xiashu loess in Zhenjiang.

Latest Miocene to Quaternary deformation in the southern Chaiwopu Basin, northern Chinese Tian Shan foreland

Basinward propagation of fold and thrust belts is a crucial geological process accommodating Cenozoic crustal shortening within the India-Eurasia collision zone. Anticlinal growth strata in the southern Chaiwopu Basin (a piggyback basin) of the northern Chinese Tian Shan foreland record basinward encroachment of the Tian Shan along the Junggar Frontal Thrust Fault. A new magnetostratigraphic section constrains the onset of syntectonic growth strata at circa 6.4Ma and suggests synchronous basinward thrusting and propagation of the Tian Shan. The intense alluviation in the southern Chaiwopu Basin ceased at circa 0.55Ma due to significant anticlinal growth and its resultant river incision. More recent anticlinal growth and deformation during the late Quaternary are revealed by folded river terraces developing across the anticline. The terrace height profile indicates that terrace T1 H has been vertically offset about 0.6m by thrust faulting since its formation at about 7 Ka. The stratigraphic and geomorphic data presented in this work are helpful to understand the initiation of thrust-related folding, as well as aggradation and subsequent incision, in foreland basins of the Tian Shan in relation to the India-Asia collision.