Li Y.,China University of Geoscinces |
Li Y.,Shillazhuang University of Economics |
Wang J.,Shillazhuang University of Economics |
Li H.,Shillazhuang University of Economics |
Dong P.,Shillazhuang University of Economics
Yanshi Xuebao/Acta Petrologica Sinica | Year: 2015
Firstly recognized Meilaotewula ophiolite occurs in Xing' anling-Mongolian Orogenic Belt (XMOB) between the Sino- Korean Paleoplate and the Siberian Paleoplate in the central sector of Inner Mongolia. Based on the regional geology, the Meilaotewula ophiolite can be the eastward extension of the Erlianhaote-Hegenshan ophiolite zone. According to field geological investigation and the preliminary results of petrology and geochemistry, we found Meilaotewula ophiolite is about 6 ~ 11km wide, and extends 24km in a ENE-NE direction , and it outcrops completely , including augite peridotite , beded-massive gabbro , diabase , piilow basalt , augitophyre , and chert. The augite peridotites are characterized by low SiO2 , high MgO , U-shaped chondrite-normalized REE patterns , represent a typical mantle section of the supra-subduction zone ( SSZ) setting. Piilow basalts and diabase are characterized by low K2 of ( average 0. 82% ) and TiO2 (0. 8% ~ 1. 2% ) , and have flat to slightly LREE-depleted chondrite-normalized REE patterns. In MORB- normalized spider diagrams , piilow basalts and diabase are enriched in Sr , K , Rb and Ba , and depleted in Nb , Th , Ta , Zr and Ti , displaying the Unity of the supra-subduction zone (SSZ) setting. LA-ICP-MS U-Pb dates on zircon of massive gabbro yield ages of 308.5 ± 2. 2Ma , which is the crystallizatioan age of gabbro , indicating a Late Carboniferous age of Meilaotewula ophiolite. All the research results above provide important evidence in exploring the tectonic evolution of Xing' anling-Mongolian Orogenic Belt (XMOB).