Structural Properties Of The Laguocuo Ophiolite In Gaize County, Tibet

Shiquanhe-Asuo-Jiali belt is an important tectonic belt in the Qinghai-Tibet Plateau,and is closely related to the evolution of the Bangonghu-Nujiang suture zone. Both theShiquanhe-Asuo-Jiali beltand the Bangonghu-Nujiang suture zone, are all the products ofthe Neo-Tethys Ocean in the Qinghai-Tibet Plateau.Laguoco Ophiolite is one of the most complete ophiolite combination in theShiquanhe-Asuo-Jialibelt, but the studies on itare weak, causing that its genesisisunclear,and its age is controversial.In this paper, we carry out field survey and profile measurement, and conductgeochemistry, zircon LA-ICP-MS U-Pb dating and Lu-Hf isotope analysis on theplagioclase granite and gabbro cumulates of the Laguoco Ophiolite, in order to study thegenesis and age of the Laguoco Ophiolite.Plagioclase granite and gabbro cumulate of Laguoco Ophiolite aredirectly contactin the field, and theirgeochemistry data shows that they are homology, and havesimilarREE patterns that are similar to the E-MORB. Lu-Hf isotope analysis displays that theirmagmatic source is the depleted mantle, whichshow a plurality of components, and maybethe mixing of DDM and EM2. Zircon LA-ICP-MS U-Pb dating yields concordia ages of184.1±0.79Ma and183.5±2.2Ma, representing their forming ages. Combined the geological data and the study in this paper, we infer that that the Shiquanhe-Asuo-JialiOphiolite belt is one part of the Bangong-Nujiang suture zone and the Laguoco Ophioliteformed in back-arc basin environment during the Lower Jurassic.