Zircon U-Pb-Hf Isotopes, Biotite 40Ar/39Ar Geochronology, and Whole-Rock Geochemistry of the Baogeqi Gabbro in the Northern Alxa, Southernmost Central Asian Orogenic Belt
نویسندگان
چکیده
The final closure time of the Paleo-Asian Ocean and Permo-Carboniferous tectonic settings in northern Alxa are very important but controversial issues. geochronology petrogenesis mafic igneous rocks superior clarifying regional settings. Here, we report on zircon U-Pb-Hf isotopes, biotite 40Ar/39Ar whole-rock geochemical data hornblende gabbro from Baogeqi pluton Alxa. LA-ICP MS U-Pb analysis grains yield a weighted mean age 262.7 ± 2.3 Ma (2σ, MSWD = 0.74), manifesting that emplacement was during late Middle Permian (Capitanian). dating yields plateau 231.3 1.6 0.55), indicating cooled to below 300 ℃ Triassic. samples calc-alkaline with metaluminous character, show enrichment large ion lithophile elements (e.g., Rb, Ba, Sr, K) depletion Nb, Ta, P, Th, Ti relative primitive mantle. Combined positive εHf(t) values (+4.9–+9.4), suggest magmas formed partial melting depleted mantle were metasomatized by slab-derived fluids. Together geology, these an intracontinental extension setting, further closed prior (Capitanian), this region post-collision extensional setting Capitanian-Late Permian. In addition, Triassic cooling may be record decline post-collisional basin due far-field effect subduction-collision Paleo-Tethys Ocean.
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ژورنال
عنوان ژورنال: Minerals
سال: 2022
ISSN: ['2075-163X']
DOI: https://doi.org/10.3390/min12050656