New insights into Phanerozoic tectonics of South China: Early Paleozoic sinistral and Triassic dextral transpression in the east Wuyishan and Chencai domains, NE Cathaysia

Abstract

The northeast Cathaysia area is characterized by an archetypical, transpressional system with widespread strike‐slip shear zones whose geometries, kinematics, and ages are critical for deciphering the Phanerozoic tectonic evolution of South China. We present new structural, geochronological and thermochronological data from the shear zones in the east Wuyishan and Chencai domains, which record two phases of deformation. The first phase corresponds to sinistral oblique shearing along arrays of NNE oriented, steep‐dipping zones under amphibolite facies conditions. The sinistral oblique shearing commenced at ~451 Ma, concurrently with regional NW/SE directed thrust shearing and folding; the coexistence of sinistral and thrust structures indicates NW‐SE transpressive shortening deformation. Dating by 40Ar/39Ar shows that such deformation terminated before 400 Ma and was followed by cooling through ~450–350°C at ~400–370 Ma. Our results, merged with published data, aid in tracing an Early Paleozoic orogen that extends through the Jiangnan domain into the northeast Cathaysia, with the southeast Yangtze acting as a foreland belt. The synorogenic shortening was interpreted as resulting from underthrusting of the Cathaysia beneath the east Yangtze. The second phase involved dextral oblique shearing associated with NNE‐SSW transpression under greenschist to amphibolite facies conditions at 245–228 Ma, which was followed by postkinematic magmatism and cooling at ~221–200 Ma. In the Cathaysia, similar Middle Triassic dextral shear zones were widespread and operated with approximately east striking thrusts as mutually complementary structures; their kinematic coupling can be explained by a contractional termination model. Geodynamically, we attributed Middle Triassic dextral transpression to the collisions of South China with North China and Indochina.

Magnetotelluric Evidence for Asymmetric Simple Shear Extension and Lithospheric Thinning in South China

“…Topography and simplified tectonic map of south China (modified from Li et al, ). Red and gray dashed lines delineate the inferred location of the Jiangshan‐Shaoxing Fault (JSF) and major fault zones.…”

Integrated Zircon U-Pb-O-Hf and Whole-Rock Sm-Nd Studies of Paleozoic Amphibolites in the Chencai Area of the Cathaysia Block, South China

“…There are also other interpretations that this rock association might represent the uplifted middle-to lower-crustal component during the Paleozoic orogeny (Z.-X. Li et al 2010c;J. Li et al 2017).…”

Role of inherited structure on granite emplacement: An example from the Late Jurassic Shibei pluton in the Wuyishan area (South China) and its tectonic implications

“…After the Neoproterozoic amalgamation of the Cathaysia and Yangtze blocks, Late Neoproterozoic rifting generated the Nanhua rift associated with intraplate magmatism that is documented in the Cathaysia Block Li et al, 2008;Shu et al, 2011;Zhao et al, 2018 and references therein). Early Paleozoic tectonics are characterized by an intracontinental orogeny, which deformed the Late Neoproterozoic to Ordovician terrigenous rocks and carbonate by producing S-verging and NW-verging thrust in different parts of the Cathaysia Block associated with locally developed sinistral shearing at ~450-400 Ma (Lin et al, 2008;Faure et al, 2009;Charvet et al, 2010;Li et al, , 2017Shu et al, 2014). The Precambrian basement of the Cathaysia Block was also reworked under amphibolite facies metamorphic conditions, as represented by widespread migmatites and S-type granites dated at ~450-420 Ma in the Wuyi and Yunkaidashan domains (Lin et al, 2008;Liu et al, 2010;Wang et al, 2010Wang et al, , 2013aWang et al, , 2013bWang et al, , 2014Xu et al, 2011Xu et al, , 2015Shu et al, 2015;Chen et al, 2018).…”

“…Mesozoic tectonic and thermal events affected most parts of the Cathaysia Block and produced the Late Triassic intracontinental Xuefengshan Belt along the NW margin of the Cathaysia Block (Chu et al, 2012a(Chu et al, , 2012b(Chu et al, , 2018, and locally developed dextral shear zones inside of the Cathaysia Block (Zhang and Cai, 2009;Xu et al, 2011;Li et al, 2017). All pre-Triassic rocks were involved in the Middle Triassic orogeny.…”

“…NCC: North China Craton, SCB: South China Block, TC: Tarim Craton. (b) Tectonic framework and distribution of Mesozoic magmatism in the South China Block (modified fromFaure et al, 2016 andLi et al, 2017).…”