Variable Thrust Rates of the Eastern Qilianshan Mountain Front, Northeastern Margin of the Tibet Plateau and Its Implication to the Topography of the Yongchangnan Shan

It is commonly assumed a thrust has a constant slip and uplifting rate along strike, however, this simplified model cannot always be consistent with field observations. The along strike slip patterns with variable offsets and rates contain plenty of information about the characteristics of the faulting behavior and its relationship with adjacent faults. The east Qilian Shan, located at the northeastern margin of the Tibetan Plateau, provides us an excellent opportunity to study the faulting behavior in a thrust-bounded range area. Besides the previously reported slip rates of the N-W trending tectonics across the region, we augmented the data by surveying the Fengle fault (FF), one of the north bounding thrusts of the Yongchangnan Shan. Another north bounding fault is the Kangningqiao Fault (KNF), east of the FF. Based on the vertical offsets and rates along the fault, we constructed the slip pattern along strike. The results show the vertical slip rate of the FF ranges from 0.7 ± 0.1 mm/a to 2.8 ± 1.3 mm/a across three surveyed sites. The slip rate decreases from the east to the west. The FF and KNF might be inferred as two segments of a single segmented thrust controlling the uplift of the Yongchangnan Shan. By comparing the uplift onsets in the study region, we discuss the northeastward propagated deformation along the northeastern margin of the Tibet plateau.

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Effects of Erosion and Deposition on Constraining Vertical Slip Rates of Thrust Faults: A Case Study of the Minle–Damaying Fault in the North Qilian Shan, NE Tibetan Plateau

Frontiers in Earth Science ◽

10.3389/feart.2021.635702 ◽

2021 ◽

Vol 9 ◽

Author(s):

Qingri Liu ◽

Huiping Zhang ◽

Youli Li ◽

Feipeng Huang ◽

Xudong Zhao ◽

...

Keyword(s):

Tibetan Plateau ◽

Slip Rate ◽

Simulation Method ◽

The Tibetan Plateau ◽

Stratigraphic Sequence ◽

Erosion And Deposition ◽

Slip Rates ◽

The North ◽

Vertical Fault ◽

Fault Displacement

The height of a thrust-fault scarp on a fluvial terrace would be modified due to erosion and deposition, and these surface processes can also influence the dating of terraces. Under such circumstances, the vertical slip rate of a fault can be misestimated due to the inaccurate displacement and/or abandonment age of the terrace. In this contribution, considering the effect of erosion and deposition on fault scarps, we re-constrained the vertical slip rate of the west end of the Minle–Damaying Fault (MDF), one of the thrusts in the north margin of the Qilian Shan that marks the northeastern edge of the Tibetan Plateau. In addition, we tried to explore a more reliable method for obtaining the vertical fault displacement and the abandonment age of terraces with AMS 14C dating. The heights of the surface scarps and the displacements of the fluvial gravel layers exposed on the Yudai River terraces were precisely measured with the Structure from Motion (SfM) photogrammetry and the real-time kinematic (RTK) GPS. The Monte Carlo simulation method was used to estimate the uncertainties of fault displacements and vertical slip rates. Based on comparative analysis, the dating sample from the fluvial sand layer underlying the thickest loess in the footwall was suggested to best represent the abandonment age of the terrace, and the fluvial gravel layer could better preserve the original vertical fault displacement compared with the surface layer. Using the most reliable ages and vertical offsets, the vertical slip rate of the MDF was estimated to be 0.25–0.28 mm/a since 42.3 ± 0.5 ka (T10) and 0.14–0.24 mm/a since 16.1 ± 0.2 ka (T7). The difference between the wrong vertical slip rate and the right one can even reach an order of magnitude. We also suggest that if the built measuring profile is long enough, the uncertainties in the height of a surface scarp would be better constrained and the result can also be taken as the vertical fault displacement. Furthermore, the consistency of chronology with stratigraphic sequence or with terrace sequence are also key to constraining the abandonment ages of terraces. The fault activity at the study site is weaker than that in the middle and east segments of the MDF, which is likely due to its end position.

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OSL dating of the late Quaternary slip rate on the Gyaring co Fault in central Tibet

Geochronometria ◽

10.1515/geochr-2015-0040 ◽

2016 ◽

Vol 43 (1) ◽

pp. 162-173 ◽

Cited By ~ 1

Author(s):

Duo Wang ◽

Gong-Ming Yin ◽

Xu-Long Wang ◽

Chun-Ru Liu ◽

Fei Han ◽

...

Keyword(s):

Tibetan Plateau ◽

Late Quaternary ◽

Slip Rate ◽

Strike Slip ◽

Alluvial Fan ◽

Osl Dating ◽

The Tibetan Plateau ◽

Slip Rates ◽

Absolute Age ◽

Central Tibet

Abstract The Gyaring Co Fault (GCF) is an active right-lateral strike-slip fault in central Tibet that accommodates convergence between India and Asia in the interior of the Tibetan Plateau. The average long-term slip rate of the fault remains controversial, given the absence of absolute age data of faulted geomorphic features. We have applied optically stimulated luminescence (OSL) dating to the northern segment of the GCF, revealing that the GCF has displaced alluvial fans at Aerqingsang by 500 ± 100 m since their deposition at ~109 ka, yielding a slip rate of 4.6 ± 1.0 mm/yr. A slip rate of 3.4 ± 0.4 mm/yr is inferred from analysis of an alluvial fan with an offset of 65 ± 5 m (~19 ka) at Quba site 1. The Holocene slip rate is estimated to be 1.9 ± 0.3 mm/yr, as inferred from the basal age (~8.3 ka) of terrace T1 that has a gully displacement of 16 ± 2 m at Quba site 2. These slip rates are generally lower early estimates (10–20 mm/yr), but are consistent with more recent results (2.2–4.5 mm/yr) and GPS data for other strike-slip faults in this region, indicating that deformation may be distributed across the entire Tibetan Plateau. Moreover, we suggest that the slip rate along the GCF may have decreased slightly during the late Quaternary.

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Three-dimensional structural model of the Qaidam basin: Implications for crustal shortening and growth of the northeast Tibet

Open Geosciences ◽

10.1515/geo-2017-0015 ◽

2017 ◽

Vol 9 (1) ◽

Author(s):

Jianming Guo ◽

Xuebing Wei ◽

Guohui Long ◽

Bo Wang ◽

Hailong Fan ◽

...

Keyword(s):

Tibetan Plateau ◽

Qaidam Basin ◽

Strike Slip ◽

Crustal Thickening ◽

Tibet Plateau ◽

The Tibetan Plateau ◽

Altyn Tagh Fault ◽

Altyn Tagh ◽

History Of ◽

The Tibet Plateau

AbstractThe Qaidam basin, bounded by the Altyn Tagh fault in the north, is located in the northeast of the Tibet plateau, and it has important implications for understanding the history and mechanism of Tibetan plateau formation during the Cenozoic Indo-Eurasia collision. In this study, we constructed the main geological structures and surfaces in three dimensions through the interpolation of regularly spaced 2D seismic sections, constrained by wells data and surface geology of the Qaidam basin in northeast Tibet. Meanwhile the Cenozoic tectonic history of the Qaidam basin was reconstructed and the uplift mechanism of the Tibetan plateau was discussed. This study presents the subsurface data in conjunction with observations and analysis of the stratigraphic and sedimentary evolution. The Cenozoic deformation history of the Qaidam basin shows geologic synchroneity with uplifting history of the Tibet Plateau. It is therefore proposed that the deformation and uplifting in the south and north edges of the Tibet Plateau was almost synchronous. The total shortening and shortening rate during Cenozoic reached 25.5 km and 11.2% respectively across the Qaidam basin, indicating that the loss of the left-lateral strike slip rates of the Altyn Tagh fault has been structurally transformed into local crustal thickening across NW-trending folds and thrust faults. Meanwhile there is an about 11° vertical component along the strike-slip Altyn Tagh fault, the block oblique slip shows one more growth mechanism of the northeast Tibet.

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Three-dimensional structural model of the Qaidam basin: Implications for crustal shortening and growth of the northeast Tibet

10.5194/se-2016-74 ◽

2016 ◽

Author(s):

Jianming Guo ◽

Xuebing Wei ◽

Guohui Long ◽

Bo Wang ◽

Shiyang Xu

Keyword(s):

Qaidam Basin ◽

Vertical Component ◽

Strike Slip ◽

Crustal Thickening ◽

Tibet Plateau ◽

The Tibetan Plateau ◽

Altyn Tagh Fault ◽

Altyn Tagh ◽

History Of ◽

The Tibet Plateau

Abstract. We reconstruct the main geological structures and surfaces in three dimensions through the interpolation of regularly spaced 2D seismic sections, constrained by wells data and surface geology of the Qaidam basin to reconstruct Cenozoic tectonic history of the Qaidam basin and decipher how the Tibetan plateau was formed. This study presents the subsurface data in conjunction with observations and analysis of the stratigraphic and sedimentary evolution. The Cenozoic deformation history of the Qaidam basin shows geologic synchroneity with uplifting history of the Tibet Plateau. It is therefore proposed that the deformation and uplifting in the south and north edges of the Tibet Plateau was almost synchronous. The total shortening and shortening rate during Cenozoic reached 25.5 km and 11.2 % respectively across the Qaidam basin, indicating that the loss of the left-lateral strike slip rates of the Altyn Tagh fault has been structurally transformed into local crustal thickening across NW-trending folds and thrust faults. Meanwhile there is an about 10° vertical component along the strike-slip Altyn Tagh fault, the block oblique slip shows one more growth mechanism of the northeast Tibet.

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Extension of the Upper Yellow River into the Tibet Plateau: Review and New Data

Quaternary ◽

10.3390/quat4020014 ◽

2021 ◽

Vol 4 (2) ◽

pp. 14

Author(s):

Zhengchen Li ◽

Xianyan Wang ◽

Jef Vandenberghe ◽

Huayu Lu

Keyword(s):

Tibetan Plateau ◽

Yellow River ◽

Google Earth ◽

Tibet Plateau ◽

The Yellow River ◽

Published Data ◽

The Tibetan Plateau ◽

Large Lakes ◽

River Terraces ◽

The Tibet Plateau

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.

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A physics-based approach of deep interseismic creep for viscoelastic strike-slip earthquake cycle models

Geophysical Journal International ◽

10.1093/gji/ggz426 ◽

2019 ◽

Vol 220 (1) ◽

pp. 79-95

Author(s):

Lucile Bruhat

Keyword(s):

Surface Deformation ◽

Slip Rate ◽

Strike Slip ◽

Dynamic Rupture ◽

Crust And Upper Mantle ◽

Slip Rates ◽

Region I ◽

Best Fitting ◽

Time Invariant ◽

Analytical Expressions

SUMMARY Most geodetic inversions of surface deformation rates consider the depth distribution of interseismic fault slip-rate to be time invariant. However, some numerical simulations show downdip penetration of dynamic rupture into regions with velocity-strengthening friction, with subsequent updip propagation of the locked-to-creeping transition. Recently, Bruhat and Segall developed a new method to characterize interseismic slip rates, that allows slip to penetrate up dip into the locked region. This simple model considered deep interseismic slip as a crack loaded at its downdip end, and provided analytical expressions for stress drop within the crack, slip and slip rate along the fault. This study extends this approach to strike-slip fault environments, and includes coupling of creep to viscoelastic flow in the lower crust and upper mantle. I use this model to investigate interseismic deformation rates along the Carrizo Plain section of the San Andreas fault. This study reviews possible models, elastic and viscoelastic, for fitting horizontal surface rates. Using this updated approach, I develop a physics-based solution for deep interseismic creep which accounts for possible slow vertical propagation, and investigate how it improves the fit of the horizontal deformation rates in the Carrizo Plain region. I found solutions for fitting the surface deformation rates that allow for reasonable estimates for earthquake rupture depth and coseismic displacement and improves the overall fit to the data. Best-fitting solutions present half-space relaxation time around 70 yr, and very low propagation speeds, less than a metre per year, suggesting a lack of creep propagation.

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North-South variation in tectonic activity along left-stepping extensional basins revealed by morphometric analysis: Gofa province, southwestern Ethiopia, East Africa

10.5194/egusphere-egu2020-6770 ◽

2020 ◽

Author(s):

Asfaw Erbello ◽

Gerold Zeilinger ◽

Manfred R. Strecker

Keyword(s):

Strain Localization ◽

Tectonic Activity ◽

Southern Ethiopia ◽

Climatic Data ◽

Long Term Effects ◽

Study Region ◽

The North ◽

Hypsometric Integral ◽

Mountain Front ◽

Channel Steepness

<p>We report on the morphotectonic characteristics in the tectonically active Southern Ethiopia Rift (SER) based on the analysis of high-resolution topographic data (12m TanDemX) and satellite imagery. The study region is a wide zone of distributed extension at the transition from the SER and the Northern Kenyan Rift and reflects the long-term effects of episodic tectonic events in the landscape. &#160;The uplifted footwall margins of the north-south trending and left stepping &#275;n &#275;chelon basins of the SER constitute Pan-African basement rocks in the southern and central part (Chew Bahir, Mali-Dancha and part of Beto) and tectonized Miocene basalts in the north (Sawula). As such this region is an ideal location to record the tectonic characteristics of a major transition zone between two rift systems. Some of the unsolved problems in this area concern the degree of tectonic activity, spatiotemporal variations in the amount of extension, and the nature of kinematic linkage between different faults. To examine these issues, we calculated morphometric indices of river catchments along major fault-bounded blocks as proxies for tectonic activity and combined this information with structural, seismicity, and climatic data.&#160;<br>We determined basin asymmetry, hypsometric integral, mountain-front sinuosity, valley floor to valley-width-height ratio, basin shape, the range of basin form and mean slope; additionally, we calculated knickpoint distributions and channel-steepness index values from 89 sub-basins. Combined, the data suggest a significant north-south variation in extensional processes. For example, in the northern basins knickpoints are generally located in upstream areas near the channel heads. They are rare in the Mali-Dancha basin, whereas in the Chew Bahir basin a distinct distribution along the main channel is recognized from basin head to the mountain front. In the south the knickpoints are closest to the mountain front. This unique spatial arrangement of knickpoints in rivers draining the footwalls of extensional blocks in the north-south transect suggests a gradual, southward-directed shift in extensional deformation and recent tectonic activity. The normalized channel-steepness index value is generally small; however, it also exhibits a significant southward trend with higher values (i.e., tectonic activity). Additionally, the normalized channel steepness indices are higher at orthogonally interacting faults compared to neighbouring areas, suggesting strain localization.&#160;<br>Our new results suggest a northward increase in the geomorphic maturity of the analyzed sub-basins from Chew Bahir (juvenile) to Sawula (mature), which is compatible with a northward decrease in tectonic activity and a dominance of erosional processes. This is consistent with published, northward-decreasing extension rates and the degree of regional seismicity. Furthermore, strain localization at interacting faults suggests kinematic linkage of the left-stepping bounding faults of the sub-basins.</p>

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Dextral strike-slip of Sanguankou-Niushoushan fault zone and extension of arc tectonic belt in the northeastern margin of the Tibet Plateau

Science China Earth Sciences ◽

10.1007/s11430-016-5272-1 ◽

2016 ◽

Vol 59 (5) ◽

pp. 1025-1040 ◽

Cited By ~ 16

Author(s):

QiYun Lei ◽

PeiZhen Zhang ◽

WenJun Zheng ◽

ChiZhang Chai ◽

WeiTao Wang ◽

...

Keyword(s):

Fault Zone ◽

Strike Slip ◽

Tibet Plateau ◽

Tectonic Belt ◽

Dextral Strike Slip ◽

The Tibet Plateau

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Geomorphic expression and slip rate of the Fairweather fault, southeast Alaska, and evidence for predecessors of the 1958 rupture

Geosphere ◽

10.1130/ges02299.1 ◽

2021 ◽

Author(s):

Robert C. Witter ◽

Adrian M. Bender ◽

Katherine M. Scharer ◽

Christopher B. DuRoss ◽

Peter J. Haeussler ◽

...

Keyword(s):

Active Faults ◽

Plate Boundary ◽

Slip Rate ◽

Strike Slip ◽

Tectonic Deformation ◽

Plate Boundaries ◽

Slip Rates ◽

Southeast Alaska ◽

The Past ◽

Show Evidence

Active traces of the southern Fairweather fault were revealed by light detection and ranging (lidar) and show evidence for transpressional deformation between North America and the Yakutat block in southeast Alaska. We map the Holocene geomorphic expression of tectonic deformation along the southern 30 km of the Fairweather fault, which ruptured in the 1958 moment magnitude 7.8 earthquake. Digital maps of surficial geology, geomorphology, and active faults illustrate both strike-slip and dip-slip deformation styles within a 10°–30° double restraining bend where the southern Fairweather fault steps offshore to the Queen Charlotte fault. We measure offset landforms along the fault and calibrate legacy 14C data to reassess the rate of Holocene strike-slip motion (≥49 mm/yr), which corroborates published estimates that place most of the plate boundary motion on the Fairweather fault. Our slip-rate estimates allow a component of oblique-reverse motion to be accommodated by contractional structures west of the Fairweather fault consistent with geodetic block models. Stratigraphic and structural relations in hand-dug excavations across two active fault strands provide an incomplete paleoseismic record including evidence for up to six surface ruptures in the past 5600 years, and at least two to four events in the past 810 years. The incomplete record suggests an earthquake recurrence interval of ≥270 years—much longer than intervals <100 years implied by published slip rates and expected earthquake displacements. Our paleoseismic observations and map of active traces of the southern Fairweather fault illustrate the complexity of transpressional deformation and seismic potential along one of Earth’s fastest strike-slip plate boundaries.

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Integrated Geophysical Evidence for the Middle-Lower Crust Melting of the Songpan-Aba Terrain, NE Tibetan Plateau

Frontiers in Earth Science ◽

10.3389/feart.2021.752693 ◽

2021 ◽

Vol 9 ◽

Author(s):

Chongjin Zhao ◽

Luolei Zhang ◽

Peng Yu ◽

Xi Xu

Keyword(s):

Tibetan Plateau ◽

Magnetic Layer ◽

Orogenic Belt ◽

The Tibetan Plateau ◽

The West ◽

Magnetotelluric Data ◽

West Qinling ◽

The North ◽

Weakly Magnetic ◽

Surrounding Areas

The Songpan−Aba region is located on the northeastern edge of the Tibetan Plateau. Tectonically, the area is surrounded by the West Qinling orogenic belt in the north, the Longmenshan orogenic belt in the southeast, and the East Kunlun and Sanjiang orogenic belts in the west and southwest, forming a triangle that provides an ideal location to study the crust-mantle structure and deep tectonics of the eastward extrusion of the Tibetan Plateau. In this study, the magnetic and electrical structures of the Songpan−Aba area were investigated by inversion using high-precision magnetic anomaly and magnetotelluric data to obtain the subsurface magnetization inversion intensity and resistivity of Songpan–Aba and adjacent areas. The results revealed a continuous magnetic layer up to 20 km below Songpan–Aba and its surrounding areas in the south, possibly originating from a magma root southwest of the Longmenshan massif. In the West Qinling, Songpan–Aba, and Longmenshan areas, pervasive low-resistance, weakly magnetic, or magnetic layers were identified below 20 km that might be formed from the molten mantle material extruded from the eastern edge of the Tibetan Plateau.

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