Journals
  Publication Years
  Keywords
Search within results Open Search
Please wait a minute...
For Selected: Toggle Thumbnails
Terrace Sequences and Their Formation Ages in Pantang-Heiyukou Area, Northern Shanxi-Shaanxi Gorge, China
LIU Yunming, LI Youli, ZHOU Baohua
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (2): 257-264.   DOI: 10.13209/j.0479-8023.2015.139
Abstract1438)   HTML    PDF(pc) (797KB)(1687)       Save

Based on field work, four Quaternary terraces are found according to overlapped loess sequences at Pantang-Heiyukou area and its surroundings in northern Chinese Shanxi-Shaanxi Gorge. These four terraces, which are 12, 50, 80 and 130 m above present the Yellow River level respectively, are all rock-seated terraces. The thicknesses of overlapped loess from the lowest terrace to the highest Quaternary terrace are about 20, 33, 37 and 43 m respectively. ESR dating samples were collected from river sediments on T2, T3 and T4. ESR dating result reveals that the formation ages of these three terraces are 0.609, 0.876 and 0.97±0.107 Ma in turn from T2 to T4. In order to corroborate the dating results, powder samples and oriented samples were collected from sections on T3 and T4. Paleomagnetic result shows that section bottom on T3 does not reach the boundary of B/M (Brunhes/Matuyama), which means a formation age younger than 0.78 Ma. This age is younger than that gotten from ESR dating. The bottom age of T4 section reaches an age of 1.07 Ma, which is a bit older than ESR dating result but within its range. The formation ages of the terraces are in accord with other terraces in upper and lower reach of the Yellow River such as Lanzhou and Sanmenxia which suggests river terraces controlled by tectonic movement exist universally in the domain of the Yellow River. A Late Tertiary section was resampled and measured as an improvement to former works. The result is used to discuss the incision rate of different terraces in this region.

Related Articles | Metrics | Comments0
The Geochemical Characteristics of Hydrothermal Sediment for the Bedded Silicilith in the Meso Proterozoic Era and Their Sedimentary Environment Importance in Pingyin, Shandong Province
XU Yuetong,ZHOU Baohua,HUANG Fusheng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract643)            Save
There are bedded siliciliths which are conformity with the Mesoproterozoic Erathem stratum in Pingyin Area, Shandong Province. The siliciliths can be identified as hydrothermal sediment ones by the higher contents of Fe, Mn, As, Sb, Bi, Ga, and comparatively lower Al; lower total REE, negative Ce anomaly and comparatively enrichment in HREE, the δ30Si values range from -0.01% to 0.04%, the δ30O values range from 1.36% to 2.01%. The siliciliths all belong to hydrothermal sediment ones in Al-Fe-Mn and Fe-Mn-(Ni+Co+Cu) triangle diagrams. And the values of MnO/TiO2 ratioes, δCe and δ30Si in these siliciliths manifest that the siliciliths are deposited in the deep-sea environment.
Related Articles | Metrics | Comments0