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摘要
Based on field observation, petrographic and lithogeochemical results, together with zircon U-Pb chronology results, this paper discusses the intrusive sequence in Anji deposit and their evolution link, tectonic setting, as well as the mineralization implication of varied intrusive units. The magmatic intrusions in this area occur during Late Jurassic-Early Cretaceous (141 similar to 117 Ma), and they are the products of tectonic reactivation and tectonic conversion in eastern China during Late Mesozoic. The intrusive sequences are from early biotite monzonitic granite followed by syenogranite, granodiorite, fine-crystalline granite and bimodal dikes. Except biomodal dikes, the other four units compose the Wushanguan complex. Geochemical affinity and compositions difference of the units in the complex may result from mantle material injection and crystallization differentiation of magma during faults activation at Late Jurassic-Early Cretaceous. The bimodal dikes marked lithospheric thinning peak and mantle material upwelling, as well as the stress field conversion into extension in eastern China. Two metallogenic events are recognized in Anji area including early Fe-Cu metallogenic event which genetically related to granodiorite and late Pb-Zn (Ag)-Mo metallogenic event which is associated with fine-crystalline granite. Geochemically, the granodiorite shows I-type granite character, whereas the fine-grained granite shows the combined character of S-type and I-type granite, and both show more mantle materials input than the other units in Wushanguan complex. Mantle materials involving and strong differentiation may be the reason for metal elements (e. g. Fe, Cu, Mo, Pb, Zn and Ag) enrichment and related mineralization. The causative intrusive units occurs in the west and east part of the deposit respectively, so, the west of the deposit is the favorable Fe-Cu exploration area, and the east of the deposit is the favorable Pb-Zn (Ag) as well as Mo exploration area. Well-developed post-mineralization NE and EW faults have seriously influence to the preservation of ores, so the structure geology studies are very important to further exploration in Anji area.
- 出版日期2012-10
- 单位北京科技大学
