GEOCHEMICAL CHARACTERISTICS OF CARBONATITES FROM THE QINLING AND DABASHAN AREAS AND THEIR PETROGENESIS

摘要

Qinba area is an important magmatic carbonatite province in China. Carbonatites are found in three alkaline rock regions, which involves Huayin-Luonan, at the south margin of the North China craton, Zhushan-Zhuxi, within the Qinba orogenic belt, and Nanjiang- Wangcang, at the north margin of the Yangtze craton (Fig. 1). The Moho depth ranges from 38 to 40 km. In Table 1, it is showed that the carbonatites from different tectonic units are different in petrography, mode of occurrence, alteration of country rocks and the age of their formation. It should be noted that the length of a single dike within the compound carbonatite