Surface uplift of the Central Yunnan Plateau since the Pliocene

Abstract

The Central Yunnan Plateau (CYP) is located in the southeastern end of the Sichuan‐Yunnan rhombic block. CYP is surrounded by the South China Block to the east and the Indo‐China Block to the southwest. Stratigraphy and topography research shows the relative surface uplift of the CYP since the Pliocene. However, the widely accepted model of lower crustal flow is very difficult to fully explain the surface uplift of CYP, with faults and fold structures in the brittle shallow crust. The lower crust thickening led by the lower crustal flow only contributes 34–54% (600–950 m) of the total surface uplift. The wide‐angle seismic profiles and topography analysis show that the CYP surface uplift is predominately a consequence of isostatic compensation due to surface erosion, upper‐middle crustal shortening, and lower crustal thickening. The average isostatic adjustment caused by surface erosion of CYP is about 500 m, which is about 29% of the total surface uplift (1750 m). The GPS station velocities, focal mechanisms, and seismic anisotropy show the strong decoupling relationship between upper‐middle crust and lower crust. In detail, there is a movement with southeast‐directed and clockwise rotation around the Eastern Himalayan syntaxis in the upper‐middle crust, although south‐directed flow in the lower crust. The southeast motion of the upper‐middle crust could be resolved into two portions. The eastward component of upper‐middle crust motion is obstructed by the South China Block in the east. The result is the W‐E direction shortening of upper‐middle crust, shown by the S‐N trending CYP anticlinorium. The W‐E direction shortening of upper‐middle crust contributes 17–37% (300–650 m) of the total surface uplift. In contrast, the southward component of upper‐middle crust motion, shown by the sinistral strike‐slip displacement of the Xiaojiang fault zone, could pass through the Red River fault zone into the Indo‐China Block, where the left‐lateral Dien Bien Phu Fault would be the counterpart. The contribution of upper‐middle crustal shortening in a S‐N direction is very limited. The lower crustal flow could have been playing a prominent role in the growth of the whole southeast margin of the Tibetan Plateau, and the contribution from upper‐middle crustal shortening cannot be ignored in some local areas.

Genomic vulnerability to climate change in Quercus acutissima, a dominant tree species in East Asian deciduous forests

“…However, all three estimates indicated that the population demography of Q. acutissima most likely determined by major tectonic events and paleoclimate oscillations during Pliocene–Pleistocene. For example, the surface uplift of the Yunnan‐Guizhou Plateau during the Pliocene (Li et al, 2018) could have created physical barriers that prevented inter‐regional gene flow between mountainous West China and low‐lying East China, leading to east–west divergence in Q. acutissima . In addition, the intensification of monsoon in East Asia during the Pliocene (An et al, 2001; Ao et al, 2016; Yang et al, 2018) could have increased the climatic differences between West and East China, facilitating ecological selection‐driven genetic divergence.…”

Induction of callus in Cassia mimosoides

“…In the present study, Gln has no significant effect on callus induction, which may be due to the low concentration of the addition, no obvious effect was observed. Hydrolyzed casein (CH) is a kind of plant nutrition additive, which can promote the growth and differentiation of callus [17,18]. In this study, it was found that high concentration of CH could inhibit the growth of callus.…”

Quantifying the contribution of upper‐middle crustal shortening and lower crustal thickening to surface uplift in the south‐eastern Tibetan Plateau

“…However, the western branch of the LVZs shows a southward extrusion nearly along the ASRR, and further extends into the north-eastern corner of the ICB across the ASRR (Figure 6a; Bao et al, 2015). Considering the upper-middle crustal motion revealed by GPS station velocities and P axes, the uppermiddle crust and lower crust beneath the areas of the two LVZ branches in the CDB are strongly decoupled (Figure 6a; Li et al, 2018), which is also supported by the lithospheric rheological structures of a rather weak crème brûlée regime beneath the CDB (Figure 6e; Gong et al, 2018). The leading role of the two branches of the LVZs for tectonic uplift has been shown in profiles L1-2, L2-1, L4-3, and L5-1 nearly along a N-S direction (Figures 4 and 5).…”

“…The ASRR stands out as a remarkable boundary fault in morphology and geology, and involves two stages: the 500-700 km sinistral slip in the Tertiary (34-17 Ma), and the reactive 5.3-57 km dextral slip in the Quaternary (5 Ma;Harrison et al, 1996;Leloup et al, 1995;Searle, 2006). With the resistance of the SCP, part of the dextral displacement along the ASRR is converted to a large-scale S-N trending syncline and anticline, known as the Chuxiong Basin and CYP (Figure 1; Li et al, 2018;. The E-W extension occurring at the top of the S-N trending anticline is indicated by a series of grabens and horsts along the XJFZ (such as Dianchi Lake and Fuxian Lake in Figure 1), with Proterozoic fold basements and Palaeozoic rocks exposed in the central part, and Mesozoic continental strata in the east and west (Wang et al, 1998;.…”

“…However, with the south-eastward weakening of LVZs in the Chuandian Block (CDB), the upper-middle shortening structures become increasingly apparent, and play a non-negligible role in the topographic uplift (Li et al, 2018;Wang, Jiang, et al, 2012;Wen et al, 2011). Global Positioning System (GPS) measurements and focal mechanisms demonstrate the lateral extrusion and clockwise rotation of shallow crust around the Eastern Himalaya Syntaxis in the southeastern Tibetan Plateau, with a NW-SE motion in the CDB, but a small sudden counterclockwise turn in front of SCDB (Cui et al, 2006;Niu et al, 2005;Wang et al, 2001;Wang et al, 2008;Zhao, Luo, et al, 2013).…”