Asymmetrical valleys created by the geomorphic response of rivers to strike-slip fault

2004 ◽  
Vol 62 (3) ◽  
pp. 310-315 ◽  
Author(s):  
Ke Zhang ◽  
Kaiyu Liu ◽  
Jinchun Yang

Offset fluvial valleys, including rivers beheaded and deflected by strike-slip faults, have long been used to estimate horizontal displacements on the faults. Larger rivers crossing such faults, however, sometimes show either no offset or only a small amount of offset compared to smaller rivers crossing the same faults. The larger rivers with higher erosional rates may widen their valleys asymmetrically downstream of strike-slip faults, rather than being beheaded or deflected. Examples are described from the Yellow River near the NE margin of the Tibetan Plateau. River beheading and asymmetrical widening are two end-members of a fluvial valley's response to strike-slip faulting, whereas deflection is a combination of both. Recognition of the formation of such asymmetrical valleys related to strike-slip faulting will help to understand fault activity better over longer time spans and enable a re-evaluation of many fault histories worldwide.

Quaternary ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 14
Author(s):  
Zhengchen Li ◽  
Xianyan Wang ◽  
Jef Vandenberghe ◽  
Huayu Lu

The Wufo Basin at the margin of the northeastern Tibet Plateau connects the upstream reaches of the Yellow River with the lowland catchment downstream, and the fluvial terrace sequence in this basin provides crucial clues to understand the evolution history of the Yellow River drainage system in relation to the uplift and outgrowth of the Tibetan Plateau. Using field survey and analysis of Digital Elevation Model/Google Earth imagery, we found at least eight Yellow River terraces in this area. The overlying loess of the highest terrace was dated at 1.2 Ma based on paleomagnetic stratigraphy (two normal and two reversal polarities) and the loess-paleosol sequence (12 loess-paleosol cycles). This terrace shows the connections of drainage parts in and outside the Tibetan Plateau through its NE margin. In addition, we review the previously published data on the Yellow River terraces and ancient large lakes in the basins. Based on our new data and previous researches, we conclude that the modern Yellow River, with headwaters in the Tibet Plateau and debouching in the Bohai Sea, should date from at least 1.2 Ma. Ancient large lakes (such as the Hetao and Sanmen Lakes) developed as exorheic systems and flowed through the modern Yellow River at that time.


2020 ◽  
Vol 33 (4) ◽  
pp. 531-538
Author(s):  
Qianyun Ge ◽  
Caixia Gao ◽  
Yuan Cai ◽  
Ting Jiao ◽  
Jinqiang Quan ◽  
...  

Objective: Evidence from previous reports indicates that pig domestication in East Asia mainly occurred in the Mekong region and the middle and downstream regions of the Yangtze River. Further research identified two new origin centers for domestic pigs in the Tibetan Plateau and the islands of Southeast Asia. However, due to the small sample size of Tibetan pigs, details of the origin and spread of Tibetan pigs has not yet been established.Methods: We analyzed mitochondrial DNA control region (D-loop) variation in 1,201 individuals from nine Tibetan pig populations across five provinces. Comprehensive Tibetan pig samples were taken to perform the most detailed analysis of Tibetan pigs to date.Results: The result indicate that Rkaze pigs had the lowest level of diversity, while Changdu pigs had the highest diversity. Interestingly, these two populations were both in the Tibetan Plateau area. If we calculate diversity in terms of each province, the Tibetan Plateau area had the lowest diversity, while the Chinese province of Gansu had the highest diversity. Diversity gradient analysis of major haplotypes suggested three domestication centers of Tibetan pigs in the Tibetan Plateau and the Chinese provinces of Gansu and Yunnan.Conclusion: We found two new domestication centers for Tibetan pigs. One is in the Chinese province of Gansu, which lies in the upstream region of the Yellow River, and the other is in the Chinese province of Yunnan.


2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Lijuan Wen ◽  
Shihua Lv ◽  
Zhaoguo Li ◽  
Lin Zhao ◽  
Nidhi Nagabhatla

The Tibetan Plateau harbors thousands of lakes; however few studies focus on impacts of lakes on local climate in the region. To investigate and quantify impacts of the two biggest lakes (Ngoring Lake and Gyaring Lake) of the Yellow River source region in the Tibetan Plateau on local climate, two simulations (with and without the two large lakes) from May 2010 to July 2011 are performed and analyzed using the WRF-CLM model (the weather research and forecasting model coupled with the community land model). Differences between simulated results show that the WRF-CLM model could provide realistic reproduction of surface observations and has better simulation after considering lakes. Lakes mostly reduce the maximum temperature all year round and increase the minimum temperature except in March due to the large heat capacity that makes lakes absorb (release) more energy for the same temperature change compared to land. Lakes increase precipitation over the lake area and in the nearby region, mostly during 02–14 BT (Beijing Time) of July to October when the warm lake surface induces the low level horizontal convergence and updraft over lake and provides energy and vapor to benefit the development of the convection for precipitation.


2006 ◽  
Vol 43 ◽  
pp. 86-90 ◽  
Author(s):  
Xiaohua Gou ◽  
Fahu Chen ◽  
Meixue Yang ◽  
Gordon Jacoby ◽  
Jianfeng Peng ◽  
...  

AbstractThe ecological environment of the headwater area of the Yellow River, west China, is seriously deteriorating because of the harsh natural environment, weakened ecological systems and intensified human activities as well as regional climate changes. Forests and glaciers coexist in this area. Glaciers in the area have retreated over the last decade because of climate change. Most glaciers on the Tibetan Plateau (TP) tend to retreat during warm intervals and advance during cold intervals. Tree-ring records provide an important index for examining past climate changes. A total of 139 core samples from 97 living cypresses (Juniperus przewalskii) in the central region of the Yellow River headwater area, the Animaqin mountains, northeastern TP, were sampled from three sites that are close to each other. The chronologies were developed using the ARSTAN program. Analyses indicate that these tree-ring width records reflect the summer maximum temperature of the study area over the past 700 years. The tree-ring records and the glacier advances recorded by terminal moraines are compared. Inferred summer maximum temperatures suggest three cold periods during the Little Ice Age, around AD1500, 1700 and 1850. These cold intervals are consistent with the glacier moraine record from the region.


2021 ◽  
Vol 13 (10) ◽  
pp. 4727-4757
Author(s):  
Mengna Li ◽  
Yijian Zeng ◽  
Maciek W. Lubczynski ◽  
Jean Roy ◽  
Lianyu Yu ◽  
...  

Abstract. The Tibetan Plateau is the source of most of Asia's major rivers and has been called the Asian Water Tower. Detailed knowledge of its hydrogeology is paramount to enable the understanding of groundwater dynamics, which plays a vital role in headwater areas like the Tibetan Plateau. Nevertheless, due to its remoteness and the harsh environment, there is a lack of field survey data to investigate its hydrogeology. In this study, borehole core lithology analysis, soil thickness measurement, an altitude survey, hydrogeological surveys, and hydrogeophysical surveys (e.g. magnetic resonance sounding – MRS, electrical resistivity tomography – ERT, and transient electromagnetic – TEM) were conducted in the Maqu catchment within the Yellow River source region (YRSR). The hydrogeological surveys reveal that groundwater flows from the west to the east, recharging the Yellow River. The hydraulic conductivity ranges from 0.2 to 12.4 m d−1. The MRS sounding results, i.e. water content and hydraulic conductivity, confirmed the presence of an unconfined aquifer in the flat eastern area. Based on TEM results, the depth of the Yellow River deposits was derived at several places in the flat eastern area, ranging from 50 to 208 m. The soil thickness measurements were done in the western mountainous area of the catchment, where hydrogeophysical and hydrogeological surveys were difficult to be carried out. The results indicate that most soil thicknesses, except on the valley floor, are within 1.2 m in the western mountainous area of the catchment, and the soil thickness decreases as the slope increases. These survey data and results can contribute to integrated hydrological modelling and water cycle analysis to improve a full-picture understanding of the water cycle at the Maqu catchment in the YRSR. The raw dataset is freely available at https://doi.org/10.17026/dans-z6t-zpn7 (Li et al., 2020a), and the dataset containing the processed ERT, MRS, and TEM data is also available at the National Tibetan Plateau Data Center with the link https://doi.org/10.11888/Hydro.tpdc.271221 (Li et al., 2020b).


RSC Advances ◽  
2016 ◽  
Vol 6 (99) ◽  
pp. 96853-96860 ◽  
Author(s):  
Hong Zhang ◽  
Pei Lei ◽  
Baoqing Shan ◽  
Wenzhong Tang ◽  
Liang Ao

A complete record derived from a core dated by both210Pb and137Cs chronologies from Lake Ngoring at the key headwater areas of the Yellow River provides new insight into the increase of primary production induced by aeolian input of phosphorus.


2014 ◽  
Vol 81 (3) ◽  
pp. 538-544 ◽  
Author(s):  
Yibo Wang ◽  
Fujun Niu ◽  
Qingbai Wu ◽  
Zeyong Gao

AbstractMeasurements of 137Cs concentration in soils were made in a representative catchment to quantify erosion rates and identify the main factors involved in the erosion in the source region of the Yellow River in the Tibetan Plateau. In order to estimate erosion rates in terms of the main factors affecting soil loss, samples were collected taking into account the slope and vegetation cover along six selected transects within the Dari County catchment. The reference inventory for the area was established at a stable, well-preserved, site of small thickness (value of 2324 Bq·m− 2). All the sampling sites had been eroded and 137Cs inventories varied widely in the topsoil (14.87–25.56 Bq·kg− 1). The effective soil loss values were also highly variable (11.03–28.35 t·km− 1·yr− 1) in line with the vegetation cover change. The radiometric approach was useful in quantifying soil erosion rates and examining patterns of soil movement.


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