Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The South Liaodong Peninsula massif is the easternmost Mesozoic Metamorphic Core Complex, recognized in Eastern China. It provides a good example of the combination of ductile shearing, synkinematic plutonism and polyphase exhumation. The Jurassic granodioritic plutons, located at the footwall of the detachment normal fault, and dated here at ca 160 Ma, recorded two different phases of cooling. A slow cooling regime of about 3-10°C/my prevailing before 122 Ma, was followed by a significant increase in cooling rate of about 40-55°C/my after that time. By contrast, a single fast cooling path was recorded by the Cretaceous monzogranite situated in the footwall of the detachment normal fault. This result indicates that the Jurassic and Cretaceous plutons recorded different exhumation processes: a Jurassic slow or negligible exhumation and a Cretaceous fast one assisted by normal faulting. These two cooling stages correspond to distinct geodynamic processes during the Jurassic and Cretaceous. Extensional tectonics seems not significant before Early Cretaceous. The second stage, dominated by an extensional regime which develops after ca 120 Ma, is tentatively correlated to the lithosphere removal of the North China Craton.
ISSN: 1367-9120

Droits : http://creativecommons.org/licenses/by-nc-nd/
insu-00528171
https://hal-insu.archives-ouvertes.fr/insu-00528171
https://hal-insu.archives-ouvertes.fr/insu-00528171/document
https://hal-insu.archives-ouvertes.fr/insu-00528171/file/Lin-JAsianEarthSciences-2010.pdf
DOI : 10.1016/j.jseaes.2010.09.007

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
The strike-slip faults of north Tibet accommodate part of the Cenozoic convergence between India and Asia. Along the Karakax valley south of Yecheng and near the Xidatan trough south of Golmud, the active traces of the Altyn-Tagh and Kunlun faults follow narrow belts of metamorphic rocks. The deformation recorded in those mylonites is sinistral strike-slip. Rb/Sr and 40Ar/39Ar ages of deformation from syntectonic fabrics formed at 350–400°C 120 Ma. Argon loss suggests that deformation was associated to a 250–300°C thermal pulse that lasted 5–20 Ma after the onset of movement. Unroofing occurred much later, around 25 Ma when sudden cooling suggests a component of thrusting or more likely normal faulting. The Cretaceous shear may be related to collision between the Qiantang and the Lhasa blocks. The Karakax and Xidatan shear zones may have formed a unique, continuous boundary in the Cretaceous, which was later reused by the Tertiary strike-slip faults, leading to potentially calculable offsets along the Altyn-Tagh fault.
ISSN: 2169-9313

hal-00197562
https://hal.archives-ouvertes.fr/hal-00197562
https://hal.archives-ouvertes.fr/hal-00197562/document
https://hal.archives-ouvertes.fr/hal-00197562/file/Arnaud_JGR000904_def.pdf
DOI : 10.1029/2001JB000904

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Investigation of an eclogite xenolith, discovered in a Cretaceous granite from the Central Domain of the Dabieshan massif in eastern China, yields new petrological insights into the high to ultrahigh-pressure metamorphism, experienced by the Qinling-Dabie orogen. Prior to inclusion as a xenolith in the granite during the Early Cretaceous, this eclogite xenolith had recorded a complex metamorphic evolution that complies with subduction and exhumation processes experienced by the continental crust of the South China Block. Well-preserved mineral parageneses substantiate the prograde and retrograde stages revealed by inclusions in porphyroblastic garnet and zoned minerals such as garnet, comphacite and amphibole in the matrix. The relatively low P/T re-equilibration during a latemetamorphic stage was textually inferred by the presence of aluminous and calcic-subcalcic amphiboles such as katophorite, edenite, taramite and pargasite as main matrix phases. According to our U/Pb, Rb/Sr and new 40Ar/39Ar geochronological results, namely 109 ± 1 and 112 ± 2 Ma plateau ages for muscovite and amphiboles, respectively, two successive but distinct cooling stages account for the thermal history of the granite–migmatite gneiss dome that forms the Central Dabieshan Domain. We argue that prior to the Cretaceous doming, the Central Dabieshan Domain experienced a tectono-metamorphic evolution similar to that observed in the high-pressure to ultra high-pressure units developed in the Southern Dabieshan Domain and Hong'an massif.
ISSN: 1437-3254

hal-00104224
https://hal-insu.archives-ouvertes.fr/hal-00104224
https://hal-insu.archives-ouvertes.fr/hal-00104224/document
https://hal-insu.archives-ouvertes.fr/hal-00104224/file/Lin-IntJEarthSciences-2007.pdf
DOI : 10.1007/s00531-006-0129-z

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
In south China the Lushan massif forms a topographic high of the South China Block south of the Qinling-Dabie belt. The Lushan massif consists of two main lithotectonic units separated by a major tectonic contact: a Neoproterozoic (upper Sinian)-Paleozoic unit comprising primarily unmetamorphosed sandstones overlies a Paleoproterozoic unit mainly composed of low-pressure, high-temperature gneisses and micaschists. Both units are cut by Cretaceous granitic intrusions. Three primary tectono-metamorphic and magmatic events are recognized. The eastern part of the Lushan massif is cut by a NNE-SSW trending ductile normal fault (D3 deformation) coeval to the emplacement of a 100-110 Ma leucogranite dated by 40Ar/39Ar laserprobe on biotite and muscovite. D2 deformation is responsible for the formation of a decakilometer-scale NE-SW trending upright anticline characterized by NE-SW stretching and NW-SE shortening. The age of this folding event is defined by a 127±1 (2σ) Ma U/Pb titanite date obtained for a syntectonic granodiorite and 40Ar/39Ar ages of 133 Ma for amphibole. This Cretaceous age also corresponds to the 40Ar/39Ar ages of 126 Ma found on syntectonic muscovites at the base of the Sinian unit. An older deformation event, D1, characterized by a top-to-the-NW extensional decollement of the Sinian-Paleozoic series above Proterozoic metamorphic rocks is related to the Triassic tectonics of the Dabieshan. Lastly, in the lower part of Sinian rocks, the occurrence of kyanite cataclased during D1 documents an older, poorly preserved, late Paleozoic-early Mesozoic tectonometamorphic event (Dx) related to a blind thrust in the continental crust of the South China Block in the southern foreland of the Dabieshan.
ISSN: 0278-7407

insu-00717721
https://hal-insu.archives-ouvertes.fr/insu-00717721
https://hal-insu.archives-ouvertes.fr/insu-00717721/document
https://hal-insu.archives-ouvertes.fr/insu-00717721/file/Lin-Tectonics-2000.pdf
DOI : 10.1029/2000TC900009

Éditeur(s) : HAL CCSD University of Chicago Press
Résumé : International audience
In the North China block, the south Liaodong Peninsula massif is an elliptical metamorphic core complex (MCC) with a long axis trending NE‐SW. In cross‐section view, it is asymmetric, with a steeply dipping northwestern flank and a gently dipping southeastern flank. It consists of three lithotectonic units: a gneissic migmatite unit, a Paleo‐ to Meso‐Proterozoic micaschist‐slate unit, and a Neoproterozoic to Mesozoic sedimentary cover. Three deformation events related to extensional tectonics are distinguished in the study area: D1 is a ductile deformation related to the exhumation of the MCC; the following event, D2, corresponds to the development of recumbent folds formed during the early exhumation of the MCC; and the youngest event, D3, corresponds to brittle normal faulting that controlled the opening of a Cretaceous continental half‐graben basin. A pre‐D1 event characterized as northward verging is interpreted as the result of N‐S shortening that occurred in the Late Triassic during the final stages of the collision between the North and South China blocks. The ductile and brittle structures were developed coevally, with synkinematic plutonism and formation of half‐grabens. New 40Ar/39Ar and U/Pb Cretaceous ages obtained from the mylonitic granodiorite, gneissic migmatite, orthogneiss, and granite indicate that the south Liaodong Peninsula MCC is contemporaneous with other Cretaceous extensional structures, such as numerous syntectonic plutons bounded by ductile normal faults, MCC, and half‐graben basins, described in eastern China. Among the several hypotheses proposed to account for the Mesozoic extension along the eastern margin of Eurasia, lithosphere convective removal appears to be the most likely.
ISSN: 0022-1376

insu-00362879
https://hal-insu.archives-ouvertes.fr/insu-00362879
https://hal-insu.archives-ouvertes.fr/insu-00362879/document
https://hal-insu.archives-ouvertes.fr/insu-00362879/file/WeiLin-TheJournalofGeology-2008.pdf
DOI : 10.1086/527456