| Longshoushan sodium metasomatic hydrothermal uranium ore play an important role in the Longshoushan-Qilian Mountain uranium metallogenetic belt of Qilian-Qinling metallogenetic province and it is the most typical areas in China product sodium metasomatic hydrothermal uranium ore. Jiling granite is the main surrounding rock of alkaline metasomatic uranium mineralization in the area. Previous research of Jiling granite is relatively shortage, subject to the limitations of time and research tools, test methods, the study of accurate determination of the granitic formation age and the geological significance is comparatively lagging behind. On the basis of previous studies, this thesis carry out Longshoushan Jiling granite mineralogy, geochemistry and zircon LA-ICP-MS U-Pb dating, etc., and to explore the granite diagenetic age, granite petrogenesis, granite magma source, tectonic and magmatic evolution, made the following major understanding:(1) Field observations and petrographic studies show that Jiling granite lithologie is mainly biotite monzonite granite, monzonitic granite porphyry, granitic aplite and porphyritic biotite monzonitic granite.(2) Jiling granite major elements have low magnesium, rich alkali feature, belongs to quasi-aluminum high potassium calc-alkaline series rocks. The harker diagram shows that Si O2 has a positive correlation relationship with K2 O, and has a negative relationship with Na2 O, Al2O3, Mg O, Ca O, Mn O, Ti O2, and P2O5, indicates the fractional crystallization process of potassium and sodium feldspar and mafic minerals.(3) The REE of Jiling granite has a characteristic of LREE enrichment enrichment, HREE fractionation is relatively not obvious and with large amount of rare earth elements, in addition to a strong Eu negative anomalies of LSS12-05, other samples showed a weak negative and moderate loss of Eu anomaly, which may be related to the residual of partial melting of plagioclase in the magma source.(4) Jiling granite trace elements relatively enriched in Ba, Rb, Th, U and other LILE and relatively poor in Ta, Nb, Zr, Hf, Ti, P and other high HFSE. From different types of granites, in addition to the large differences of granitic aplite trace element content, other types of granite composition have similar characteristics.(5) Jiling granitoid zircon LA-ICP-MS U-Pb dating results show that from early to late, it can be divided into two groups: 428.6 ± 8.1Ma ~ 412.8 ± 9.0Ma and 401.3 ± 5.0Ma, belonging Silurian-Devonian magmatism product, recorded at least experienced two periods of magmatism from the early Hercynian to the late Caledonian in Jiling.(6) The cause of Jiling granitoid is I-type granites, its magma material source is from the shell, and it is likely to mix mantle-derived substances, Jiling granite magma is the product of post-collision tectonic setting.(7) From early to late, Jiling granitoid rock types shift from biotite monzonite granite to monzonite granite porphyry to porphyritic biotite monzonite granite to granitic aplite,the color transformate from gray to red meat. The degree of differentiation, metasomatic texture have a tendency of increasing. Rock-forming minerals of alkali feldspar and quartz increase, as well as accessory mineral types. Major elements of Fe, Mg, Ti decrease, Na increases, REE and LREE content increase before decrease. Key word: granite, petrographic, geochemistry, zircon LA-ICP-MS U-Pb dating, Jiling... |
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