Survival of eclogite xenolith in a Cretaceous granite intruding the Central Dabieshan migmatite gneiss dome (Eastern China) and its tectonic implications |
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| Authors: | Wei Lin Masaki Enami Michel Faure Urs Schärer Nicolas Arnaud |
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| Institution: | (1) State Key Laboratory of Lithosphere Tectonic Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, PO Box 9825, Beijing, 100029, China;(2) Department of Earth and Planetary Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan;(3) Institut des Sciences de la Terre d’Orléans, Université d’Orléans, 45067 Orleans Cedex 2, France;(4) UMR Géosciences Azur, Université Nice-Sophia Antipolis, parc Valrose, Nice, France;(5) UMR Dylith, Université de Montpellier II, 34060 Montpellier Cedex 5, France |
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| Abstract: | 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, omphacite and amphibole in the matrix. The relatively low P/T
re-equilibration during a late metamorphic 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, namely109 ± 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. |
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| Keywords: | Eclogite xenolith Mesozoic granite Radiometric ages Exhumation model Dabieshan China |
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