董铭, 苏怀, 史正涛, 明庆忠, 何回丽.
[DONG Ming, SU Huai, SHI Zhengtao, MING Qingzhong, HE Huili.
The age of river terraces in the Jinjiangjie reach of the Jinsha River and its implications for valley and drainage evolution[J]. Acta Geographica Sinica
The age of river terraces in the Jinjiangjie reach of the Jinsha River and its implications for valley and drainage evolution
DONG Ming1,, SU Huai1,, SHI Zhengtao1, MING Qingzhong2, HE Huili3
1. College of Tourism and Geography Sciences, Yunnan Normal University, Kunming 650500, China
2. Research Institute of Tourism and Culture Industry, Yunnan University of Finance and Economics, Kunming 650221, China
3. Kunming Institute of Botany, CAS, Kunming 650201, China
National Natural Science Foundation of China, No.41762014, No.41462007, No.41362010, No.41001010;
Applied Basic Research Project of Yunnan Province, No.2013FZ047;
The Jinsha River has attracted considerable attention for nearly a century due to its unusual drainage basin morphology. Most models describing its evolution suggest that the modern Jinsha River, draining the Tibetan Plateau margin, was once a tributary to a single, southward river system called "Paleo-Red River", which drained into the South China Sea and then its flow direction changed to east to join the Yangtze River due to river capture. The Red River submarine fan, considered to have been primarily fed by the Paleo-Red River system, suddenly disappeared at 5.5 Ma provides an important chronological constraint on this reorganization of drainage lines and reversal event. However, no geomorphic evidence has been found to agree with this hypothesized timeframe. Here, we present electron spin resonance (ESR) ages from eight terraces preserved in the Jinjiangjie reach of the Jinsha River together with their GPS altimetry data. Their ages from old to young are 1.07 Ma, 0.70 Ma, 0.65 Ma, 0.51 Ma, 0.47 Ma, 0.44 Ma, 0.30 Ma and 0.18 Ma, with a calculated average river incision rate of 147 mm/ka since 1.0 Ma. The paleo-topography, reconstructed by filling the deeply incised river gorges with digital elevation model (DEM) data, shows that the upper reach of the Paleo-Red River was captured by the Yangtze River and changed its flow direction eastward at the time of disruption of the 2000 m asl paleo-topographic surface in the Jinsha River drainage basin. The age of the paleo-topographic surface formation would be approximately 5.5 Ma using the average river incision rate extrapolation, suggesting that the present Jinsha River system was born after 5.5 Ma. This data support the chronological constraint from the Red River submarine fan, and hypothesized evolution of the Jinsha River.
Ancient drainage reconstruction scenarios created by filling the valley to different altitudes (a, b, c and d represent valleys filled to altitudes of 1600 m, 1800 m, 2000 m and 2200 m, respectively, to reconstruct ancient drainage)
KongPing, ZhengYong, Caffee MarcW.Provenance and time constraints on the formation of the first bend of the Yangtze River. , 2012, 13(6): 1-15.
Abstract Studies of the recent history of Earth's magnetic field have revealed a rich spatial and temporal structure, but face limitations by a lack of Southern Hemisphere archeomagnetic data. Studies of Iron Age (200-1850 AD) peoples of southern Africa have revealed a potentially rich source of archeomagnetic information in the form of ceramics (specifically pottery). Additionally, contemporary pottery made with traditional techniques and materials can still be found. Reported here is the first step in addressing whether ancient pottery from southern Africa might faithfully record the geomagnetic field. We analyze contemporary pottery made with traditional techniques and methods. Rock magnetic measurements, including magnetic susceptibility as a function of temperature and magnetic hysteresis behavior, are discussed. Intensity results generated by three common paleointensity methods: Thellier- Coe double heating experiments, the multi-specimen method of Dekkers and B hnel, and Shaw's method (with and without the corrections of Kono) are compared to the known field at the time of firing. The Thellier-Coe method reproduces the field (with an accuracy of 1.3 T), the Shaw technique with the correction approach of Kono overestimates the field by 3.7%. The multispecimen method overestimates the field by 20%, however improvement upon this could be expected given recent improvements to the technique. These values bound the accuracies we can expect when applying the methods to ideal samples, representing a best-case for dealing with archeological ceramics from southern Africa
HuZhenbo, PanBaotian, GuoLianyong, et al.Rapid fluvial incision and headward erosion by the Yellow River along the Jinshaan gorge during the past 1.2 Ma as a result of tectonic extension. , 2016, 133: 1-14.
WestawayRob, Bridgland DavidR, White TomS, et al.The use of uplift modelling in the reconstruction of drainage development and landscape evolution in the repeatedly glaciated Trent catchment, English Midlands, UK. Proceedings of the Geologists' , 2015, 126(4-5): 480-521.
ZhangYechun, LiJijun, ZhuJunjie, et al.Studies on development of Jinshajiang River during Late Cenozoic. , 1998, 10(2): 43-48.
After the research of sedimentology, geomorphology and chronology in the Sanduizi-Wudongde reach, we come to the conclusion that the geomorphic feature of the lower reaches of the Jinsha River was formed in the late middle Pleistocene. The ancient Jinsha River was jammed in Jingpingzi and it turned into a local base level of stream, which influences the incision rate along the Sanduizi-Wudongde reach of the Jinsha River. The average incision rate of Jinpingzi, Aoga, Longjie and Yuzha are 196-217 cm/ka, 145-172 cm/ka, 257-305 cm/ka, 82-97 cm/ka respectively. Because of the tectonic knickpoints and lithology knickpoints of the Jinsha River and the distinctions of the fluvial characters, there are some differences in the valley geomorphic feature and the TL datings of the terraces between Aoga reach and Yuzha reach,so the analysis of the terraces height relative to the Jinsha River do not make out. The Sanduizi-Wudongde reach of the Jinsha River contain many kinds of heavy minerals, such as magnetite, russet iron ore, epidote,garnet, and contain many steady minerals and degenerative heavy minerals, for example zircon,rutile, white-titanium, crossed-stone, cyanite, and so on.
PanBaotian, SuHuai, HuZhenbo, et al.Evaluating the role of climate and tectonics during non-steady incision of the Yellow River: Evidence from a 1.24 Ma terrace record near Lanzhou China. , 2009, 28(27/28): 3281-3290.
Gosse JohnC, Phillips FredM.Terrestrial in situ cosmogenic nuclides: Theory and application. , 2001, 20(14): 1475-1560.
The cosmogenic nuclide exposure history method is undergoing major developments in analytical, theoretical, and applied areas. The capability to routinely measure low concentrations of stable and radioactive cosmogenic nuclides has led to new methods for addressing long-standing geologic questions and has provided insights into rates and styles of surficial processes. The different physical and chemical properties of the six most widely used nuclides: 3He, 10Be, 14C, 21Ne, 26Al, and 36Cl, make it possible to apply the surface exposure dating methods on rock surfaces of virtually any lithology at any latitude and altitude, for exposures ranging from 10 2 to 10 7 years. The terrestrial in situ cosmogenic nuclide method is beginning to revolutionize the manner in which we study landscape evolution. Single or multiple nuclides can be measured in a single rock surface to obtain erosion rates on boulder and bedrock surfaces, fluvial incision rates, denudation rates of individual landforms or entire drainage basins, burial histories of rock surfaces and sediment, scarp retreat, fault slip rates, paleoseismology, and paleoaltimetry. Ages of climatic variations recorded by moraine and alluvium sediments are being directly determined. Advances in our understanding of how cosmic radiation interacts with the geomagnetic field and atmosphere will improve numerical simulations of cosmic-ray interactions over any exposure duration and complement additional empirical measurements of nuclide production rates. The total uncertainty in the exposure ages is continually improving. This article presents the theory necessary for interpreting cosmogenic nuclide data, reviews estimates of parameters, describes strategies and practical considerations in field applications, and assesses sources of error in interpreting cosmogenic nuclide measurements. TABLE OF CONTENTS 1. Introduction 1.1. Development of the TCN methods 1.2. Applications of TCN Exposure methods 1.3. Previous reviews 2. Glossary 2.1. Terminology 2.2. Notation 3. Principles 3.1. Introduction 3.1.1. Source of the primary radiation 3.1.2. Effects of the geomagnetic field on GCR 3.1.3. Trajectory models and models of secondary nuclide production rates 3.1.4. Recent numerical models of GCR particle production 3.1.5. Nuclide production from primary GCR 3.1.6. TCN production by energetic nucleons 3.1.7. TCN production by low-energy neutron 3.1.8. TCN production by muons 3.1.9. Factors limiting TCN applications 3.2. Numerical simulation of low-energy neutron behavior 3.3. Analytical equations for TCN production 3.3.1. Fast neutron (Spallation) production 3.3.2. Production by epithermal neutrons 3.3.3. Production by thermal neutrons 3.3.4. Production by muons and muon-derived neutrons 3.3.5. Total nuclide production 3.4. Energetic neutron attenuation length 3.5. Temporal variations in production rates 3.5.1. Variations in the primary GCR flux 3.5.2. Variations due to solar modulation of the magnetic field 3.5.3. Effects of the geomagnetic field 3.5.4. Variations in atmospheric shielding 3.5.5. Other sources of temporal variations in production 3.6. Estimation of production rates 3.6.1. Helium-3 3.6.2. Beryllium-10 3.6.3. Carbon-14 3.6.4. Neon-21 3.6.5. Aluminum-26 3.6.6. Chlorine-36 3.7. Scaling and correction factors for production rates 3.7.1. Spatial scaling 3.7.2. Topographic shielding 3.7.3. Surface coverage 3.7.4. Sample thickness 3.7.5. Thermal neutron leakage 3.8. Exposure dating with a single TCN 3.9. Exposure dating with multiple nuclides 3.10. Nuclide-specific considerations 3.10.1. Helium-3 3.10.2. Beryllium-10 3.10.3. Carbon-14 3.10.4. Neon-21 3.10.5. Aluminum-26 3.10.6. Chlorine-36 3.11. TCN dating of sediment 4. Sampling strategies 4.1. Field sampling considerations 4.1.1. Sample description 4.1.2. Sampling methodology 4.2. Other lithological considerations 4.3. How much sample is needed? 4.4. Strategies for concentration-depth profiles 5. Sample preparation and experimental data interpretation 5.1. TCN sample preparation 5.1.1. Preparation time 5.1.2. Physical and chemical pretreatment 5.1.3. Isotopic extraction 5.2. Experimental data interpretation 6. Uncertainty and sources of error 6.1. Sources of error 6.1.1. Sample characteristics 6.1.2. Sample preparation and elemental analyses 6.1.3. Mass spectrometry 6.1.4. Systematic errors 6.2. Reporting the uncertainty 6.2.1. Error propagation 6.2.2. Evaluating accuracy by intercomparison 6.2.3. Multiple sample measurements 6.2.4. Sensitivity analysis 7. Directions of future contributions Acknowledgements References
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The determination of the “clock zero” is the key as to whether sedimentary rock can be used for estimation of ages by ESR (Wintle and Huntley, 1979). This paper reports preliminary results revealing that the intensity of the E′ center signal of quartz in sedimentary loess increased with exposure to sunlight. Hence it is impossible to establish the clock zero using bleaching by light.
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 A new regional compilation of the drainage history in southeastern Tibet suggests that the modern rivers draining the plateau margin were once tributaries to a single, southward flowing system which drained into the South China Sea. Disruption of the paleo-drainage occurred by river capture and reversal prior to or coeval with the initiation of Miocene (?) uplift in eastern Tibet, including 芒聢录2000 m of surface uplift of the lower plateau margin since reversal of the flow direction of the Yangtze River. Despite lateral changes in course due to capture and reversal, the superposition of eastward and southward draining rivers that cross the southeastern plateau margin suggests that uplift has occurred over long wavelengths (>1000 km), mimicking the present low-gradient topographic slope. Thus reorganization of drainage lines by capture and reversal events explains most of the peculiar patterns of the eastern plateau rivers, without having to appeal to large-magnitude tectonic shear.
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In the present paper, we describe ductile and brittle deformation styles in western Yunnan and NE Myanmar, using field data and Landsat 7 imagery. We show that this complex area located at the northern termination of Sunda Plate (Three Rivers area) was wedged during the Tertiary between the left-lateral Ailao Shan/Chong Shan metamorphic belts to the east and the right-lateral Shan scarp/Gaoligong metamorphic belt in west. This triangular region therefore underwent the effects of these continental size ductile strike-slip faults separating major blocks with a dominant EW to ENE compression. Since the Late Miocene, date of the reversal of motion along the RRF, the incipient eastward motion of the Sunda block and the persisting right-lateral motion along its western boundary (Sagaing fault) created N–S compression and E–W to WNW extension underlined by left-lateral transtension along the Wanding/Nanting fault zones. At the same time, the Diangcan Shan, situated along strike the Ailao Shan metamorphic belt, was slightly impinged by the blocks extruded from the syntaxis and exhumed again from the Early Pliocene in accordance with this late and still active state of stress.
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Field observations and satellite geodesy indicate that little crustal shortening has occurred along the central to southern margin of the eastern Tibetan plateau since about 4 million years ago. Instead, central eastern Tibet has been nearly stationary relative to southeastern China, southeastern Tibet has rotated clockwise without major crustal shortening, and the crust along portions of the eastern plateau margin has been extended. Modeling suggests that these phenomena are the result of continental convergence where the lower crust is so weak that upper crustal deformation is decoupled from the motion of the underlying mantle. This model also predicts east-west extension on the high plateau without convective removal of Tibetan lithosphere and without eastward movement of the crust east of the plateau.