Short-lived high-temperature prograde and retrograde metamorphism in Shaerqin sapphirine-bearing metapelites from the Daqingshan terrane, North China Craton

摘要: Abstract The tectonic mechanism responsible for the formation of high-temperature (HT) and ultrahigh-temperature (UHT) granulites (>850 °C) at moderate pressure (7–13 kbar) is diverse contentious, ranging from hot back-arc inversion thickening, to lithospheric extension underplating/intrusion mafic magma, long-lived orogenic self-heating, ridge subduction. fundamental reason this partly related fact that prograde mineral assemblage growth zoning are difficult perserve due HT diffusion, strong deformation fluid/melt existence. However, heating reaction footprint most likely preserved during a rapid tectonothermal process. In current paper, we discovered large-scale Spr-bearing metapelites were originally Sil-Bt metapelite (M1) secondly Spr + Mag (M2) Shaerqin locality in Daqingshan terrane North China Craton. Sapphirine later replaced by spinel cordierite corona (M3), all which further back-reacted overprinted fibrous sillimanite retrograde biotite (M4). well-preserved multistage assemblages suggest A clockwise P-T path confined with peak conditions 860–890 °C 7.5–8.5 kbar, phase equilibria modeling NCKFMASHTO system. It involves evolution (possibly slight decompression), post-peak limited isothermal decompression, final isobaric cooling segments. SIMS zircon monazite U-Th-Pb dating constrained near-peak metamorphic age ca. 1.86 Ga. process recorded 1.86 Ga caused mantle-derived magma controlled an termination Paleoproterozoic continental–continental (or arc) collision amalgamation NCC.