Geochronology、Geochemistry And Discussion Of Geotectonics Evolution In Aobaote,Dong Ujimuqin,Inner Mongolia

The research area is located in the the middle east of Xingmeng Orogenic belt.Based on the geological mapping,petrologic, geochemical and geochronologicalstuidies were carried out for the north Aobaote-Chaganchulute and magmatite beltand the southwest Asigen-Baolageshan magmatite belt in research area.LA-ICP-MS U-Pb zircon analyses reveal that the emplacement age of the northAobaote-Chaganchuluteand magmatite belt are326.6±1.3Ma、325.0±1.2Ma、321.0±2Ma, suggesting its formation in late stage of early Carboniferous;and that of thesouthwest Asigen-Baolageshan magmatite belt are312.3±1.8Ma、311.6±1.1Ma、310.58±0.88Ma、306.4±2.2Ma、293.3±8.1Ma、289±14Ma, indicating a LateCarboniferous age for the formation of the intrusion.Major and trace element compositions show that the the north Aobaote-Chaganchulute magmatite belt in Carboniferous is of high Kalc-alkaline affinities.They are characterized by enrichment in LREE.In the primitive-mantle-normalizedtrace elements diagrams, it shows LILE depleted and HFSE、compatible elementsenriched.The granites of various types in the southwest Asigen-Baolageshan magmatitebelt in Late Carboniferous are of high Kalc-alkaline affinities.They are characterizedby depletion in LILE. Syenogranite with black mica and medium、fine syenogranite、mid-fine muscovite syenogranite show L REE enriched. The mid-fine muscoviteadamellite shows a spectacular tetrad effect in their REE distribution patterns as wellas non-CHARAC (charge-and-radius-controlled) trace element behavior, caused byintense interaction of the residual melts with aqueous hydrothermal fluids.The granites in the two magmatite belts are I-type granite, the southwestAsigen-Baolageshan magmatite belt’s evolution underwent three stages: magmamixing、fractional crystallization and advanced strong melt-fluid interaction.In combination with the previous studies on two magmatite belts, it can beconcluded that the final collision between the Siberian plate and the North Chinacraton happened Should be later than Late Carboniferous. Suture zone should be located in the north area of research region, supporting Badarch(2002)’s point of viewthat MME as the collisional suture between the Siberian plate and the North Chinacraton.