Intracontinental subduction: a possible mechanism for the Early Palaeozoic Orogen of SE China

Abstract

International audienceThe Early Palaeozoic Orogen of SE China consists of three litho-tectonic elements, from top to bottom: a sedimentary Upper Unit, a metamorphic Lower Unit and a gneissic basement. The boundaries between these units are flat lying, south directed, ductile decollements. The lower one is coeval with an amphibolite facies metamorphism (M1). The belt is reworked by migmatite-granite domes, high-temperature metamorphism (M2) and granitic plutons related to post-orogenic crustal melting. We date here the syn-M1 ductile shearing at 453 +/- 7 Ma by U-Th/Pb method on monazite. Previous ages and our ne

Geochronological and geochemical constraints on the petrogenesis of Middle Paleozoic (Kwangsian) massive granites in the eastern South China Block

“…Contemporaneous mantle-derived rocks have not been identified in these domains so far (e.g., Shu et al, 2008c;Wang et al, 2010). These observations, together with the Kwangsian thrust-dominated compressive setting of the eastern SCB (e.g., Charvet et al, 1996Charvet et al, , 2010Faure et al, 2009;Shu et al, 1991;1999), indicate an insignificant magma underplating into the crust. We propose that the generation of the granitic melts in the eastern SCB may have been controlled by crustal thickening under the condition of high heat production in the source.…”

“…However, Yu et al (2007) suggested that the Kwangsian orogenesis likely resulted from the amalgamation and collision of the Yangtze Block with northern Gondwanaland. Faure et al (2009) recently pointed out that the early Paleozoic Orogen of Southeast China is an intracontinental belt, in which decollements accommodated the northward subduction of the Cathaysia continent with no preceding oceanic subduction. Recent studies (e.g.…”

“…400-440 Ma) for several plutons (e.g., Cheng et al, 2009;Li and Gui, 1992;Shen et al, 2008;Shu et al, 2008b;Xiang et al, 2008;Xu et al, 2009;Zhang et al, 2010a,b). In addition, due to the lack of systematical geochemical data for the Kwangsian massive granites in the eastern SCB, the tectonic nature of the Kwangsian event and correlation between the Yangtze and Cathaysia Blocks remain unclear (e.g., Charvet et al, 1999;Faure et al, 2009;Guo et al, 1989;Jahn et al, 1990;Li et al, 2010b;Liu and Xu, 1994;Ma et al, 2004;Shu, 2006;Shu et al, 2008b, c;Wang et al, 2007cWang et al, , 2010Wang et al, , 2011Xu et al, 1996). In this paper, to advance the understanding of the temporal and spatial pattern of the Kwangsian massive granites and their petrogenesis and tectonic implications, we present a set of new systematic geochronological and geochemical data for the representative granitic intrusions in Hunan, Jiangxi, eastern Guangxi and western Guangdong Provinces, which have not been paid much attention previously.…”

Kwangsian and Indosinian reworking of the eastern South China Block: Constraints on zircon U–Pb geochronology and metamorphism of amphibolites and granulites

“…Controversies on the nature of both events for the SCB still exist, with the key disputing point on the subduction/collision scenario versus intracontinental regime (e.g., Charvet et al, 1999Charvet et al, , 2010Faure et al, 1996Faure et al, , 2009Guo et al, 1989;Holloway, 1982;Hsü et al, 1990;Li et al, 2011b;Liu and Xu, 1994;Ma et al, 2004;Shu et al, 2008aShu et al, , 2008bShu et al, , 2011Wang et al, 2005b;Y.J. Wang et al, 2007aY.J.…”

Petrogenesis of the early Paleozoic strongly peraluminous granites in the Western South China Block and its tectonic implications

“…As for the nature of the orogeny, some researchers believed that the mountain-building event was the result of the finial closure of the Huanan/Paleotethys Ocean and subsequent collision of the Yangtze and Cathaysia Blocks (e.g., Guo et al, 1989;Hsü, 1994;Chen et al, 2006;Yan et al, 2006). However, the absence of the subduction-related rock associations (e.g., ophiolites, magmatic arc, subduction complexes and high-pressure metamorphic rocks) in the whole SCB convincingly precludes the existence of an ocean basin between the Yangtze and Cathaysia Blocks during early Paleozoic time, which led some researchers to propose an intracontinental orogenic event (e.g., Charvet et al, 1996Charvet et al, , 2010Faure et al, 2009;Li et al, 2010). More recently, on the basis of the fact that the 460-400 Ma event was mainly restricted to the Cathaysia Block, Zhao and Cawood (2012) further suggested that the early Paleozoic (460-430 Ma) orogeny in the Cathaysia Block was a continentcontinent collisional event.…”