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岩石学报 2009
Petrogenesis and mineralization chronology study on the Aolunhua porphyry Mo deposit, Inner Mongolia, and its geological implications
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Abstract:
Located in the southern segment of the Da Hinggan Mountains,the Aolunhua Mo deposit is newly found as a porphyry molybdenum deposit to the north of the Xilamulun fault.U-Pb dating for zircons from the Aolunhua granitic porphyry by SHRIMP method yields an age of 134±4Ma.Re-Os isotopic dating by the ICP-MS method on molybdenites separated from the Aolunhua molybdenum deposit yields an isochron age of 132±1Ma(MSWD = 1.12),with model ages ranging from 131±2 to 133±2Ma.The ore-forming time of the porphyry Mo deposit represented by the Re-Os isochron age is almost same as the time of petrogenesis,both in early Cretaceous.Our new age data,along with the published age data of the polymetallic deposits in the Xilamulun metallogenic belt,lead us to suggest that 130~150Ma is the main period of ore-formation in this area,and the ore-forming material for the deposits on both sides of the Xilamulun fault were from different sources.The unique metallogenic characteristics of the polymetallic deposits in the Xilamulun metallogenie belt was probably linked to the composite evolution of the Paleoasian and west circum-Paeifie tectonomagmatic domains.The main metallogenic pulse formed responding to the intensive magmatism and minerogenesis in early Cretaceous during which an extensional back-are regime was developed in the Xilamulun area following accretionary orogenesis and thickening of continental crust.