An extensive structural study of Wuyishan and surrounding areas (South China) brings data on the structures formed prior to the Devonian unconformity, building the Lower Paleozoic belt. An Ordovician tectonic event was responsible for: (i) south-directed structures in the Wuyishan proper and its southern border, related to both thin and thick-skinned tectonics, accompanied by metamorphism and crustal thickening; (ii) north-directed structures to the west of Ganjiang Fault and north of Jiangshan-Shaoxing Fault, where only thin-skinned tectonics is visible. The southward deformation accommodating the shortening includes emplacement of thrust sheets, involving deep crustal material and some mantle peridotite, and likely repetition of continental material, both responsible for crustal thickening. The orogeny was due to the underthrusting of the southern part of the South China Block beneath the northern part of this block, closing the pre-existing Nanhua rift, created at around 850-800 Ma, and involving the rift sedimentary fill in the southward thrusting. The synmetamorphic tectonic piling was followed by anatexis and granite emplacement at around 440-390 Ma. Our new U-Th-Pb EPMA monazite dating gives ages of 433 ± 9 Ma and 437 ± 5 Ma (Early Silurian) for the main anatectic event, and a younger age of 412 ± 5 Ma (Late Silurian-Early Devonian) for a late re-heating process. The Lower Paleozoic belt is an intracontinental orogen, without oceanic suture record. It shows some similarities with the Cenozoic European Pyrénées Chain, with a strong asymmetry.

The geodynamic framework of the South China Craton in the Early Paleozoic and Early Mesozoic has been modeled as developing through either oceanic convergence or intracontinental settings. On the basis of an integrated structural, geochemical, zircon U-Pb and Hf isotopic, and mica 40 Ar/ 39 Ar geochronologic study we establish that an intracontinental setting is currently the best fit for the available data. Our results suggest that widespread tectonomagmatic activity involving granite emplacement and mylonitic deformation occurred during two distinct stages:~435-415 Ma and~230-210 Ma. The coeval nature of emplacement of the plutons and their ductile deformation is corroborated by the subparallel orientation of the mylonitic foliation along the pluton margins, gneissose foliation in the middle part of pluton, the magmatic foliation within the plutons, and the schistosity in the surrounding metamorphosed country rocks. Ar furnace step-heating pseudoplateau ages) along an E-W direction. The geological, geochemical, and isotopic signatures likely reflect far-field effects in response to continental assembly events at these times.

of the southern Chinese Tianshan: Insights from structural, chronological and geochemical studies of the Heiyingshan ophiolitic mélange (NW China). Tectonophysics, Elsevier, 2011, 497 (1-4) ABSTRACTIn the southern Chinese Tianshan, the southernmost part of the Central Asian Orogenic Belt (CAOB), widespread ophiolitic mélanges form distinct tectonic units that are crucial for understanding the formation of the CAOB. However, the polarity of oceanic subduction and age of orogeny are still in controversy. In order to better understand these geological problems, a comprehensive study was conducted on the