Ductile deformation and regional strain field in the southern segment of the Tancheng-Lujiang fault zone, eastern China

Deliang

Acta Geologica Sinica (Eng)

et al. 1998

On the basis of field geology, three typical ductile shear zones in the southern part of the Tancheng-Lujiang fault belt have been chosen for a detailed study. Altogether ten samples of the tectonites have been collected for this study. The paper is focused on a comprehensive study of the tectonites in the medium-lower horizons of the ductile shear zones. The mineral compositions of the rocks are analyzed with EPMA and some typical whole-rock samples analyzed by chemical and ICP methods. Based on the comprehensive study of the characteristics of the deformation, the mineral assemblages and the changes of chemical composition of the bulk rocks, this paper presents a discussion on the relationship between the volume loss, the fluid flow and compositional changes during mylonitization of the ductile shear zones in this region. Our study shows that there are a large amount of fluids flowing through the shear zones during the process of mylonhtion, accompanied by the loss of rock volume and migration of elements and components. Modelling calculation results under different saturation conditions of fluids show that the maximum volume loss of the tectonites is about 60% relative to their protolith, while the fluid/ rock ratio ranges from 10 to lo3 in different ductile shear zones. and Technology of China (USTC) in 1992 and 1996 respectively, He is presently engaged in research and teaching work as a lecturer in USTC, and particularly interested in the study of fault systems, orogenic belt geology and economic geology.

Section: Geological Setting and Samplingmentioning

confidence: 99%

Section: Geological Setting and Samplingmentioning

confidence: 99%

Characteristics of Compositional Migration in Mylonites from the Ductile Shear Zones of the Southern Tancheng‐Lujiang Fault Belt, Eastern Anhui Province

Deliang

Acta Geologica Sinica (Eng)

et al. 1998

“…The large fault zone is a weak zone in the lithosphere; it is very sensitive to regional tectonic movement and is the best record of the regional dynamic evolutionary history (Zhu et al, 2018). The NNE–trending Tan–Lu Fault zone (TLFZ) is the largest strike–slip fault at the East Asian continental margin (Xu, Wang, Ching, & Ye, 1986; Xu et al, 1987; Xu, Ma, Tong, Zhu, & Lin, 1993; Song, Zhu, Liu, Niu, & Liu, 2003; Zhu et al, 2004, 2005, 2009, 2018; Li, Cawood, et al, 2020, Li, Song, et al, 2020; Figure 1b). Its Late Mesozoic deformation history depicts the Jurassic–Cretaceous tectonic evolution of eastern China.…”

Section: Introductionmentioning

confidence: 99%

Deformation history of the Feidong Segment of the Tan–Lu Fault zone in the Early Cretaceous: Implications for the tectonic evolution in eastern China

Chen

Yuan

et al. 2022

Geological Journal

The Tan–Lu Fault zone (TLFZ) is the largest fault zone in eastern China and a typical and representative structure of the Circum–Pacific tectonic domain. The Late Mesozoic tectonic evolution of the TLFZ is greatly significant, since it revealed the Jurassic–Cretaceous tectonic evolution of eastern China and the subduction history of the Palaeo–Pacific Plate. However, its tectonic evolution in the Early Cretaceous remains controversial. Based on geological mapping, microstructural analysis, and LA–ICP–MS zircon U–Pb dating, we constrained the deformation history of the Feidong Segment of the TLFZ in the Early Cretaceous. Results showed that the Feidong Segment of the TLFZ experienced a strong sinistral strike–slip movement at the beginning of the Early Cretaceous (~143 Ma); it was subsequently subjected to normal faulting during the Early Cretaceous (135–102 Ma), which controlled the strong magmatic activities within the Feidong area. At the end of the Early Cretaceous (~100 Ma), a weak sinistral strike–slip movement occurred again along the TLFZ. The deformation temperatures of the two sinistral strike–slip shearing stages were 500–550°C and 400–450°C, respectively. The regional comparison indicated that the Early Cretaceous tectonic evolution of the TLFZ was actually the epitome of the contemporaneous tectonic evolution of eastern China and was the result of strain localization in the Cretaceous tectonic framework of eastern China.

“…(b) Tectonic outline of southern segment of Tan-Lu Fault Zone, with chronological data [Colour figure can be viewed at wileyonlinelibrary.com] Zhao, Zhu, Lin, Yan, et al, 2014;Zhao, Zhu, Lin, Wang, et al, 2016;Zhao, 2016;Figure 1b). It has therefore been suggested that the earlier phase of sinistral shearing along the Tan-Lu Fault Zone occurred during collision between the North China and South China plates (Xu et al, 1986;Xu et al, 1992;Li et al, 1993;Yin & Nie, 1993;Li, 1994;Wan, Zhu, Zhao, et al, 1996;Zhang, 1997;Dong et al, 1998;Chung, 1999;Wang, 2000;Xiao et al, 2000;Yang & Yu, 2001;Tang et al, 2003;Zhao, Zhu, Lin, Song, 2014;Zhao, Zhu, Lin, Yan, et al, 2014;Zhao, Zhu, Lin, Wang, et al, 2016;Zhao, Zhu, Xiang, et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Due to the chronological data (181–244 Ma) yielded in Lujiang area, the eastern margin of the Dabie Orogenic Belt, the western margin of the Sulu Orogenic Belt and the Zhangbaling Uplift, the first stage of activity along the Tan‐Lu Fault Zone occurred during the Middle–Late Triassic (Li & Xia, 1995; Chen et al, 2000; Grimmer et al, 2003; Wang et al, 2005; Zhu, Wang, Niu, et al, 2004; Zhu, Liu, et al, 2004, 2009; Zhu, Xie, et al, 2005; Zhang et al, 2007, 2008; Zhao, Zhu, Lin, Yan, et al, 2014; Zhao, Zhu, Lin, Wang, et al, 2016; Zhao, 2016; Figure 1b). It has therefore been suggested that the earlier phase of sinistral shearing along the Tan‐Lu Fault Zone occurred during collision between the North China and South China plates (Xu et al, 1986; Xu et al, 1992; Li et al, 1993; Yin & Nie, 1993; Li, 1994; Wan, Zhu, Zhao, et al, 1996; Wan and Zhu, 1996; Zhang, 1997; Dong et al, 1998; Chung, 1999; Wang, 2000; Xiao et al, 2000; Yang & Yu, 2001; Tang et al, 2003; Zhang et al, 2008; Zhao, Zhu, Lin, Song, 2014; Zhao, Zhu, Lin, Yan, et al, 2014; Zhao, Zhu, Lin, Wang, et al, 2016; Zhao, Zhu, Xiang, et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Timing of deformation along theTan‐LuFault Zone in eastern China: Constraints from zircon U–Pb geochronology of the Malongshan Shear Zone

Song

et al. 2020

Geological Journal

The Tan‐Lu Fault Zone is a major fault system in eastern China, and its timing of activity has been the focus of much research. We studied a ductile segment of the Tan‐Lu Fault Zone, the Malongshan Shear Zone, which is located in the Feidong Complex (the southern part of the Zhangbaling Uplift). A dark biotite‐adamellite mylonite has been recognized in the Malongshan Shear Zone, and the mylonitic foliation strikes NNE, consistent with the regional orientation of the Tan‐Lu Fault Zone. The occurrence of abundant syn‐tectonic leucocratic veins within the biotite‐adamellite mylonite indicates that ductile shearing was accompanied by hydrothermal activity. To constrain the timing of deformation along the Malongshan Shear Zone, we dated the biotite‐adamellite mylonite and the leucocratic veins using zircon U–Pb geochronology. The weighted mean ages of zircon grains from the biotite‐adamellite mylonite (159.0 ± 5.5 Ma) and the captured Group 2 (156.3 ± 3.7 Ma and 173.2 ± 4.2 Ma) of leucocratic veins are interpreted as the ages of protoliths of the biotite‐adamellite mylonite during the Jurassic. Additional weighted mean age of the hydrothermal zircon grains (130.9 ± 3.6 Ma) represents the timing of crystallization of the veins. Therefore, the results indicate that the Malongshan Shear Zone (and hence the southern segment of the Tan‐Lu Fault Zone) was active during the Early Cretaceous (~131 Ma). Based on the present results and existing data, we consider that sinistral shearing of the Tan‐Lu Fault Zone during the Early Cretaceous was controlled by oblique subduction of the Pacific Plate at a high angle.