Late Paleozoic slab rollback events in the southeastern part of the Central Asian orogenic belt: Implications for Paleo-Asian Ocean subduction and continental crust growth

• DOI: 10.1130/b37429.1
• Publication Date: 2024-10-15T20:22:43Z
• Authors: Qiang Gao; Mao-Qiang Yan; Jan Marten Huizenga; Lian-Xin Lai; Bin Li; Hong-Hong Zeng; Robert Moritz; Jun-Hao Wei
• Keywords: Adakite

The Central Asian orogenic belt is considered to be the largest Phanerozoic accretive on Earth. late Paleozoic magmatic rocks in central Inner Mongolia are crucial for understanding continental crust growth and tectonic evolution of southeastern part belt. We present comprehensive geochemical, isotopic, geochronological data from three units Mandula area, west Solonker suture zone. Zircon U-Pb dating indicates that these formed during Carboniferous (316−304 Ma). high-Mg diorites exhibit high MgO (3.9−6.5 wt%), Mg# (61−69), depleted Nd-Hf isotopic compositions, generated through interaction between a metasomatized mantle slab melts with overlying sediments. granodiorites display adakite geochemical characteristics Sr/Y mass ratios (29−52), (1.7−2.2 (52−54), by partial melting oceanic addition sediment. Mafic microgranular enclaves have consistent ages, Sr-Nd-Hf isotope hornblende crystallization temperature-pressure conditions their host granodiorite, cognate magma associated cumulate. propose two phases rollback took place southward subduction-accretion Paleo-Asian Ocean. first phase corresponded transformation low- medium-angle subduction, while second led subduction-related extension. Considering tectonic-magmatic evolution, crustal maturity, thickness variations belt, we prolonged subduction promoted growth. coincides temporally spatially Pangea cycle, suggesting continuous supercontinent amalgamation significantly contributed