Late Quaternary active faulting on the inherited Baoertu basement fault within the eastern Tian Shan orogenic belt: Implications for regional tectonic deformation and slip partitioning, NW China

The deformation pattern and slip partitioning related to oblique underthrusting of the Tarim Basin in the eastern Tian Shan orogenic belt are not well understood because interior deformation images are lacking. The Baoertu fault is an E-W−striking, ∼350-km-long reactivated basement structure within the eastern Tian Shan. In this study, we quantify its late Quaternary activity based on interpretations of detailed high-resolution remote sensing images and field investigations. Three field observation sites along an ∼80-km-long fault segment indicate that the Baoertu fault is characterized by sinistral thrust faulting. Based on surveying of the displaced geomorphic surfaces with an unmanned drone and dating of the late Quaternary sediments using radiocarbon and optically stimulated luminescence (OSL) methods, we estimate a late Quaternary left-lateral, strike-slip rate of 1.87 ± 0.29 mm/yr and a N−S shortening rate of 0.26 ± 0.04 mm/yr for this fault. The lithospheric Baoertu fault acts as a decoupling zone and accommodates the left-lateral shearing caused by the oblique underthrusting of the Tarim Basin. In the eastern Tian Shan orogenic belt, the oblique convergence is partitioned into thrust faulting across the entire range and sinistral slip faulting on the high-dip basement structure within the orogen. This active faulting pattern in the eastern Tian Shan of sinistral shearing in the center and thrust faulting on both sides can be viewed as giant, crustal-scale positive flower structures.

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Supplemental Material: Late Quaternary active faulting on the inherited Baoertu basement fault within the eastern Tian Shan orogenic belt: Implications for regional tectonic deformation and slip partitioning, NW China

10.1130/gsab.s.16920046.v1 ◽

2021 ◽

Author(s):

Chuanyong Wu ◽

et al.

Keyword(s):

Late Quaternary ◽

Orogenic Belt ◽

Tectonic Deformation ◽

Active Faulting ◽

Nw China ◽

Basement Fault ◽

Regional Tectonic ◽

Slip Partitioning ◽

Tian Shan

Figure S1: Profile of velocity components normal to structure striking (E-W components) across the eastern Tian Shan (profile from (85.3°, 41.0°) to (85.3°, 45.0°) with a width of 240 km.

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Supplemental Material: Late Quaternary active faulting on the inherited Baoertu basement fault within the eastern Tian Shan orogenic belt: Implications for regional tectonic deformation and slip partitioning, NW China

10.1130/gsab.s.16920046 ◽

2021 ◽

Author(s):

Chuanyong Wu ◽

et al.

Keyword(s):

Late Quaternary ◽

Orogenic Belt ◽

Tectonic Deformation ◽

Active Faulting ◽

Nw China ◽

Basement Fault ◽

Regional Tectonic ◽

Slip Partitioning ◽

Tian Shan

Figure S1: Profile of velocity components normal to structure striking (E-W components) across the eastern Tian Shan (profile from (85.3°, 41.0°) to (85.3°, 45.0°) with a width of 240 km.

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Late Quaternary active faulting on the inherited Baoertu basement fault within the eastern Tian Shan: Implications for regional tectonic deformation and slip partitioning, NW China

10.1002/essoar.10503819.1 ◽

2020 ◽

Author(s):

Chuanyong Wu ◽

Guangxue Ren ◽

Siyu Wang ◽

Xue Yang ◽

Gan Chen ◽

...

Keyword(s):

Late Quaternary ◽

Tectonic Deformation ◽

Active Faulting ◽

Nw China ◽

Basement Fault ◽

Regional Tectonic ◽

Slip Partitioning ◽

Tian Shan

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Oblique Thrust of the Maidan Fault and Late Quaternary Tectonic Deformation in the Southwestern Tian Shan, Northwestern China

Tectonics ◽

10.1029/2018tc005248 ◽

2019 ◽

Vol 38 (8) ◽

pp. 2625-2645 ◽

Cited By ~ 3

Author(s):

Chuanyong Wu ◽

Wenjun Zheng ◽

Peizhen Zhang ◽

Zhuqi Zhang ◽

Qichao Jia ◽

...

Keyword(s):

Late Quaternary ◽

Northwestern China ◽

Tectonic Deformation ◽

Tian Shan

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Erosion rates of the New Zealand Southern Alps reflect long-term tectonics and transient climate

10.5194/egusphere-egu21-6571 ◽

2021 ◽

Author(s):

Duna Roda-Boluda ◽

Taylor Schildgen ◽

Hella Wittmann-Oelze ◽

Stefanie Tofelde ◽

Aaron Bufe ◽

...

Keyword(s):

New Zealand ◽

Strike Slip ◽

Southern Alps ◽

Fault System ◽

Tectonic Deformation ◽

Seismic Cycle ◽

Erosion Rates ◽

Alpine Fault ◽

Oblique Convergence

The Southern Alps of New Zealand are the expression of the oblique convergence between the Pacific and Australian plates, which move at a relative velocity of nearly 40 mm/yr. This convergence is accommodated by the range-bounding Alpine Fault, with a strike-slip component of ~30-40 mm/yr, and a shortening component normal to the fault of ~8-10 mm/yr. While strike-slip rates seem to be fairly constant along the Alpine Fault, throw rates appear to vary considerably, and whether the locus of maximum exhumation is located near the fault, at the main drainage divide, or part-way between, is still debated. These uncertainties stem from very limited data characterizing vertical deformation rates along and across the Southern Alps. Thermochronology has constrained the Southern Alps exhumation history since the Miocene, but Quaternary exhumation is hard to resolve precisely due to the very high exhumation rates. Likewise, GPS surveys estimate a vertical uplift of ~5 mm/yr, but integrate only over ~10 yr timescales and are restricted to one transect across the range.To obtain insights into the Quaternary distribution and rates of exhumation of the western Southern Alps, we use new 10Be catchment-averaged erosion rates from 20 catchments along the western side of the range. Catchment-averaged erosion rates span an order of magnitude, between ~0.8 and >10 mm/yr, but we find that erosion rates of >10 mm/yr, a value often quoted in the literature as representative for the entire range, are very localized. Moreover, erosion rates decrease sharply north of the intersection with the Marlborough Fault System, suggesting substantial slip partitioning. These 10Be catchment-averaged erosion rates integrate, on average, over the last ~300 yrs. Considering that the last earthquake on the Alpine Fault was in 1717, these rates are representative of inter-seismic erosion. Lake sedimentation rates and coseismic landslide modelling suggest that long-term (~103 yrs) erosion rates over a full seismic cycle could be ~40% greater than our inter-seismic erosion rates. If we assume steady state topography, such a scaling of our 10Be erosion rate estimates can be used to estimate rock uplift rates in the Southern Alps. Finally, we find that erosion, and hence potentially exhumation, does not seem to be localized at a particular distance from the fault, as some tectonic and provenance studies have suggested. Instead, we find that superimposed on the primary tectonic control, there is an elevation/temperature control on erosion rates, which is probably transient and related to frost-cracking and glacial retreat.Our results highlight the potential for 10Be catchment-averaged erosion rates to provide insights into the magnitude and distribution of tectonic deformation rates, and the limitations that arise from transient erosion controls related to the seismic cycle and climate-modulated surface processes.&#160;&#160;

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