塔里木盆地东南缘安南坝地区透辉石 碳酸岩成因及其地质意义.

Carbonate rocks, as one of the magmatic rocks with little but significant geological significance in nature, are generally considered to be mantle-derived causes, and shell-derived causes are rarely reported. The exposed dioprosene carbonate in the Annamba area of the southeast edge of the Tarim Basin is irregular and vein-like intrusive into the surrounding rock, and the surrounding rock trapper body can be seen inside the rock, and has a dense block structure and fine grain structure, indicating that it is an igneous carbonate rather than a sedimentary carbonate rock. The geochemical characteristics of rocks show that the carbonate-rich CaO (content (mass fraction, the same below) is 24.63%-33.20%), SiO (33.11%-40.07%), poor MgO (2.25%-3.21%), FeO (1.38%-2.03%), the total rare earth element content ((45.44-91.47) ×10) and the total light rare earth element content ((42.83-86.06)×10) are significantly lower, and the relative enrichment Rb is significantly lower Large ionic lithophilic elements such as Ba, Th, Sr, etc., with losses of Nb, Ta, Zr, Hf and other high field strength elements, are obviously different from mantle-derived carbonate rocks, and similar to shell-derived carbonate rocks. Zircon in the dioprose carbonate develops oscillating ring band structure, with obvious Ce positive anomaly, weak Eu negative anomaly and low Th/U value (average value 0.24), indicating that it is metamorphic deep molten zircon. The study of the U-Pb-Lu-Hf isotope of zircon zircon showed that the age of the zircon Hf isotope pattern had an age peak of about 2.59 Ga, and the age of lithogenesis was (1 910±13) Ma, which was consistent with the formation era of the Milan rock group and the era of hemp grain phase metamorphism, respectively. Combined with the comprehensive analysis of the previous research results, it is believed that the dipyrene carbonate in the Annamba area may be the product of the deep melting action of the Diopline Dali rock of the Milan rock group under the condition of hemp granular phase metamorphism, which is the response of the Columbia supercontinent aggregation event in the southeast edge of the Tarim Basin [ABSTRACT FROM AUTHOR]