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Analysis of morphological properties in the San men Gorges region of the Yellow River shows that four river terraces have been developed at the entrance to the gorges. Commonly, thick aeolian loess-paleosol sequence was deposited on the terraces, which makes it easy to date the terraces. The dating of paleomagnetic, loess-paleosol sequence matching and thermoluminescence show that terraces T2, T3 and T4 were formed 0.129 Ma, 0.625 Ma and 0.865 Ma ago, respectively. The formation of these terraces in this region indicates that the Yellow River has experienced four intensive downcutting events during the last 0.9 Ma. The Yellow River cut through the Sanmen Gorges and inpoured into the East China Sea no later than 0.865 Ma. [ABSTRACT FROM AUTHOR]

In the east of Xiaolangdi, many river terraces are developed at the exit of the Yellow River Gorges. Among them the terraces in Kouma, Yanshi of Henan Province are most typical, where the Yellow River developed three staircase terraces, among which the altitude of gravel stratum of the topmost terrace is 30-35 m higher than the river level. The top of the gravel stratum was covered by 60 m eolian loess deposits which have many brownish-red paleosol strips. And the paleosol S14 is at its bottom. Research on systematic magnetostratigraphy and paleosol-loess matching indicates that the bottom age of the loess on the topmost terrace is 1165 ka. Therefore, it can be concluded that the terrace develops no later than 1.165 Ma and the situation that the Yellow River runs through Sanmen Gorges and inpours into East China Sea happened at least before 1.165 Ma. [ABSTRACT FROM AUTHOR]

Abstract: The key to understanding the fluvial response to climate change and surface uplift is a thorough distinguishing between their roles in terrace formation. Previous studies have tended to attribute the fluvial behavior of deposit–incision alternation to climate cyclicity. A preliminary explanation is proposed here for terrace formation in the eastern part of the Fenwei Basin, China. The observed fluvial terrace sequence was developed by the Yellow River deeply downcutting into the Emei Platform, which was uplifted within the eastern Fenwei Basin, and therefore it probably records the tectonic history of this platform. On the basis of the magnetostratigraphy and optically stimulated luminescence (OSL) dating, a ca. 1.2Ma chronology was established for this terrace sequence. Pedostratigraphic analysis of the loess deposits accumulated on each tread reveals that the terrace deposits are overlain immediately by a paleosol bed, suggesting that the abandonment of these terraces due to fluvial incision occurred at the transitions from glacial to interglacial climates. The glacial–interglacial climate cycle probably has a temporal control on the fluvial behavior of deposit–incision alternation, even though the Yellow River develops in the subsiding Fenwei Basin. The terrace generation may be sporadic and in the form of unusual stacked pattern before the Emei Platform was uplifted within the eastern Fenwei Basin. The terrace staircases however, formed in synchrony with glacial–interglacial climate cycles since this platform began to uplift in the late Middle Pleistocene. This result indicates that uplift may be necessary in large terrace staircase genesis. It can force the river system to downcut deeply enough during climatic transitions to separate terrace levels adequately, favoring the generation and subsequent preservation of the terrace treads. The terrace sequence of the Yellow River in the eastern Fenwei Basin therefore can be considered as a combined archive of climate change and local tectonic activity. [Copyright &y& Elsevier]

Abstract: The Yellow River (Huang He) downstream of the Jinshaan Canyon displays well-preserved fluvial terrace sequences below an extensive planation surface at the northeastern Ordos Plateau. Despite a series of well developed geomorphic surfaces, the landscape evolution of the plateau is largely unconstrained. The Jinshaan Canyon, formed by the deeply incising Yellow River through the Ordos Plateau, provides keys to understanding the landscape evolution of this Plateau with respect to the nearby northeastern margin of the Tibetan Plateau. This paper presents two sets of magnetostratigraphic results derived from the aeolian deposits (Red Clay and loess) on the planation surface and the uppermost Yellow River terrace in the middle part of the Jinshaan Canyon. Magnetostratigraphic analysis reveals that the planation surface and the uppermost Yellow River terrace formed respectively at circa 3.7Ma and circa 1.2Ma ago. The Ordos Plateau is the product of a period of planation culminating just before circa 3.7Ma and then was interrupted by an episode of uplift, which may be correlated with the accelerated growth of the Tibetan Plateau in the Miocene–Pliocene. The drainage system in the Jinshaan Canyon was re-organized around 3.7Ma. No correlation seems to exist between an older drainage existing prior to circa 3.7Ma and the present Yellow River network in the Jinshaan Canyon, even though sedimentary and tectonic evidence suggests that the drainage in the middle reach of the Yellow River formed in the late Miocene-early Pliocene. The Yellow River has developed its rectangular course around the Ordos Plateau only since circa 3.7Ma. [Copyright &y& Elsevier]

Abstract: A continuous fluviolacustrine record provides the geochronological framework to reconstruct the fluvial landscape evolution of the middle reach of the Huanghe (Yellow River). Magnetostratigraphic records from six sections at the north of the Jinshaan Gorge indicate that an isolated fluviolacustrine system occupied this gorge from 8.3 to 3.7Ma. Local fluvial incision initiated at the lake margin around 5.3-4.9Ma, and concomitant fluvial deposits intruded laterally into fine lacustrine strata increasing the sedimentation rate (ca. 3.1cm/ky) within the isolated lake. The temporal coincidence of the onset of uplift-driven valley incision at 3.7Ma along the Yellow River and the onset of basin excavation suggest that uplift possibly played an important role in the late Pliocene-Quaternary drainage evolution. Consequently, incision of the Yellow River upstream in the Jinshaan Gorge initiated at 3.7Ma. [Copyright &y& Elsevier]

In North China, the Ordos block located northeast of the Tibetan Plateau is regarded as a stable craton surrounded by the Yinchuan graben to the west, the Hetao graben to the north, and the Fenwei graben to the southeast. The major tectonic structure around this block in the Cenozoic reflects intensive extension as a response to the eastward extrusion of the Tibetan Plateau. Intermittent downcutting by the Yellow River, starting from the planation surface level on the Ordos block and penetrating the bedrock, resulted in the formation of the Jinshaan gorge. A series of well-preserved fluvial terraces was identified along this gorge, providing new insight into the far-field effect of the eastward extrusion of the Tibetan Plateau. Magnetostratigraphic records from the planation surface and uppermost terrace suggest that this gorge has been entrenched over its total length in the period from 3.7 to 1.2 Ma. A preliminary explanation is proposed here for the morphological evolution of the Yellow River in the Jinshaan gorge. On the basis of terrace correlation between seventeen geomorphic sections, multiwave headward erosion initiated by the Yellow River along this gorge has been reconstructed. This process may be attributed to the lowering of the base level (the Fenwei graben). This graben has been formed during the Cenozoic as the Tibetan Plateau extruded eastwards resulting in accelerated ground subsidence. A combined approach of magnetostratigraphy, pedostratigraphy, and optically stimulated luminescence (OSL) was adopted to establish a new geochronology for terraces in the gorge at 1.2 Ma, 1.1 Ma, 787 ka, 412 ka, 245 ka, 128 ka, 29 ka, and 11 ka. These ages provide an excellent framework for calculating the extension within the Fenwei graben. The average incision rate appears to be enhanced significantly since 412 ka, indicating a rapid extension within the Fenwei graben during this time. [ABSTRACT FROM AUTHOR]