白云鄂博地区基性岩浆作用与活动大陆边缘动力学研究

The Bayan Obo REE-Nb-Fe Deposit is the largest REE deposit in the world. The ore is embedded in all the dolomitic carbonatites and some vein carbonatites. A comparative study on more than 20 areas of igneous carbonatites in the world sugg.ests that the Bayan Obo region is identical to the others in geology. Petrograph.ically there is here an assemblage of carbonatite+ultrabasic+alkaline basic (inc.luding lava)+alkaline+REE ore+iron ore; and mineralogically an assemblage mainly. of calcite and dolomite with alkali amphibole, felspar, aegirite, apatite, fluo.rite, magnetite and REE minerals. The whole-rock composition, trace elements, REE and Sr, Nb, Pb, C and O isotopes show that the rocks have a relationship and a common source. The rocks occur as sheet, pipe and vein with strong liquation and flow structure. There are buried domes, pipes and intersecting faults. A synthetic analysis of the above features indicates that there are, in the Bayan Obo region, remains of Neoproterozoic damaged volcanic edifices, the host dolomitic carbonatites are igneous intrusions along the bedding, the Main and East ore bod.ies are controlled by two volcanic necks, and the Sumt Deposit to the southwest .of the host dolomitic carbonatite is controlled by buried pipes..

白云鄂博地区存在共生的基性杂岩和碳酸岩脉，它们是大陆分裂区深成岩浆作用的产物。本项目重点研究基性杂岩、碳酸岩脉、赋矿白云岩之间的时空关系、成生联系，及其构造－岩浆类型、大地构造背景；探讨该区大陆分裂、拼贴和焊合的演化及动力学机制；论证深成岩浆作用对白云鄂博矿床形成的贡献。为本区构造和成矿学研究提供深成岩方面的证据。