Syn-collisional transform faulting of the Tan-Lu fault zone, East China

Abstract

Origin of the continental-scale Tan-Lu fault zone (TLFZ), East China, remains controversial. About 550 km sinistral offset of the Dabie orogenic belt (DOB) and Sulu orogenic belt (SOB) is shown along the NE-NNEstriking TLFZ. Syn-collisional, sinistral ductile shear belts in the TLFZ have been identified. Thirteen phengite bulk separates from the mylonites were dated by the 40 Ar/ 39 Ar method. They gave cooling ages of the 198-181 Ma for the shear belts along the eastern margin of the DOB and 221-210 Ma from the western margin of the SOB. Distribution of the foreland basin deposits suggests that sinistral offset of the DOB and SOB by the TLFZ took place prior to deposition of the Upper Triassic strata. The marginal structures around the DOB and SOB support syn-collisional faulting, and indicate anticlockwise rotation of the DOB during the displacement. The folding and thrust faulting related to crustal subduction, coeval with the TanLu faulting, is older than the foreland basin deposition related to the orogenic exhumation. Several lines of evidence demonstrate that the TLFZ was developed as a syncollisional transform fault during latest Middle to earliest Late Triassic time when the DOB and SOB experienced crustal subduction of the South China Block (SCB). Eastward increase of the crustal subduction rates is believed to be responsible for the sinistral transform faulting.

Cenozoic evolution of the Tan–Lu Fault Zone (East China)—Constraints from seismic data

“…The TLFZ experienced obvious sinistral motion during the Mesozoic (Xu et al, 1987;Xu and Zhu, 1994;Gilder et al, 1999;Zhu et al, 2005;G. Zhu et al, 2009;Zhu et al, 2012), whereas it experienced dextral motion during the Cenozoic (Allen et al, 1997;Hsiao et al, 2004;Gong et al, 2010;Huang et al, 2012a,b).…”

“…Zhu et al, 2009;Zhu et al, 2012), whereas it experienced dextral motion during the Cenozoic (Allen et al, 1997;Hsiao et al, 2004;Gong et al, 2010;Huang et al, 2012a,b). Compared with the history of Mesozoic sinistral motion constrained by geochronological data (Yin and Nie, 1993;Zhu et al, 2005;G. Zhu et al, 2009;Zhu et al, 2012), the history of dextral motion during the Cenozoic has not been constrained by any Gondwana Research xxx (2014) xxx-xxx methods and therefore, a significant unresolved question is when did the dextral motion occur.…”

“…Since being discovered in 1957, it has been widely discussed due to its significance in many research fields: (1) it is considered that the TLFZ records the evolutionary history of plate interactions in East Asia during Mesozoic and Cenozoic times, therefore its evolutionary history has been used to indicate the regional tectonic evolution (e.g. Xu et al, 1987;Okay and Sengor, 1992;Yin and Nie, 1993;Xu and Zhu, 1994;G. Zhu et al, 2009;Yin, 2010;Li et al, 2012aLi et al, ,b, 2013Suo et al, 2013); (2) many magmatic rocks evolving from ultrabasic, to basic-felsic and alkaline intruded along the TLFZ, resulting in the formation of a variety of ore deposits (including diamond, chromium, nickel, copper, iron-bearing magmatic deposits, gold, silver, molybdenum, tungsten, tin, lead, zinc, antimony, mercury, and gemstone-bearing hydrothermal ore deposits), and therefore it has been investigated as major corridor for magmatism and metallogeny (e.g.…”

Mesozoic basin development and its indication of collisional orogeny in the Dabie orogen

“…The collision along the Mianlue ocean began at its east, causing deep subduction of the Dabie-Sulu orogen, formation of the HP/UHP rocks, and their later rapid exhumation by thrust [54]. Zhu et al [77] also concluded that the Tanlu fault, located between the Dabie-Sulu orogen, underwent a northwest-vergent, strike-slipping subduction and collision in the Late Triassic.…”

Preface to special issue on relationship between continental tectonics and the seismic activities of China, research techniques and methods

“…In addition to the active tectonics taking place in the interior of Chinese mainland, forces from outside have exerted influence to the evolution of Chinese mainland, resulting in tectonic activities along major faults. The R. Gao (&) Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100024, China e-mail: ruigao126@126.com most famous example is the Tanlu fault zone, which was initiated during Indosinian orogeny (Xu et al 1987;Zhu et al 2009) but was reactivated during Cenozoic with a reorganization of the plate tectonics (Chen et al 2006).…”