摘要
南岭科学钻探一孔(SP-NLSD-1)位于南岭成矿带与武夷山成矿带的交汇部位——赣南银坑矿田,该钻孔总进尺2967.83 m,钻遇了流纹岩、花岗闪长斑岩、花岗斑岩、辉长闪长玢岩等4种岩浆岩。各岩浆岩矿物组成简单,主要为石英、斜长石、钾长石、黑云母、角闪石及副矿物磷灰石、榍石等,岩石多发生绿泥石化、碳酸盐化、白云母化等蚀变。钾长石均以正长石为主。花岗闪长斑岩中的斜长石以中长石为主,少数为钠长石、更长石、拉长石;花岗斑岩中的斜长石以钠长石为主,少数为更长石。黑云母为富镁黑云母和镁铁黑云母。白云母均由黑云母蚀变而来,花岗闪长斑岩中的白云母具有低的AlVI、Fe/(Fe Mg)值,花岗斑岩中的白云母具有高的AlVI、Fe/(Fe Mg)值。磷灰石普遍含F、Cl,且F含量显著高于Cl含量。石榴石属钙铝榴石。绿泥石主要为蠕绿泥石(铁绿泥石)-密绿泥石。黑云母矿物化学特征指示花岗闪长斑岩为壳幔混源花岗岩,具有较高的氧逸度,在演化过程中发生了岩浆混合作用。根据锆石饱和温度计计算出花岗闪长斑岩、花岗斑岩、辉长闪长玢岩的结晶温度分别为810~922℃、764~819℃、742~747℃,成岩后岩浆岩经历了中高温—中低温热液蚀变作用。岩浆岩成岩时代、岩石学和岩相学所反映的岩浆演化过程、成岩物理化学条件、矿物化学特征等方面的综合信息显示,南岭科学钻探一孔中钻遇的花岗闪长斑岩与南岭地区成Cu(-Mo)-Pb-Zn-Au-Ag矿的花岗岩十分相似,应为钻孔中揭露的银金铅锌铜矿化以及牛形坝—柳木坑银金铅锌铜矿的成矿岩浆岩,而钨铋铀矿化与岩浆岩的关系还有待于进一步研究。
The Nanling Scientific Drilling-1(SP-NLSD-1), a subproject of the Sino Probe Program called"Deep Exploration Technology and Experimentation", is situated at the Yinkeng orefield in the junction of Nanling and Wuyi Mountain metallogenic belts. The drilling project, with footage of 2967.83 meters, revealed rhyolite, granodiorite porphyry, granite porphyry and pyroxene diorite porphyry. The magmatic rocks are mainly composed of quartz, plagioclase, potassium feldspar, biotite, amphibole and some accessory minerals, with chloritization, carbonatization and muscovitization. Potassium feldspar is dominated by orthose.Plagioclases are different in granodiorite and granite porphyry. Andesines and albites are dominant in granodiorite porphyry and granite porphyry, respectively. Most of the biotites are eastonites. Derived from biotites, muscovites in granodiorite porphyry have low AlVIand Fe/(Fe Mg) values, while muscovites in granite porphyry have high values. Apatites are rich in F and Cl, and garnet belongs to grossularite. Chlorites are prochlorites and pycnochlorites. The chemical composition of biotite suggests that granodiorite porphyry was formed by magma derived from mixture of crust and mantle with relatively high oxygen fugacity, and had undergone magma mixing during the evolution. Granodiorite porphyry, granite porphyry, and pyroxene diorite porphyry crystallized at temperatures of 810-922° C, 764-819° C, 742-747° C, respectively. Comprehensive study suggests that granodiorite porphyry exposed in the Nanling Scientific Drill Hole is similar to granites related to Cu(-Mo)-Pb-Zn-Au-Ag deposits in Nanling region.The granodiorite porphyry is the ore-forming magmatite of Ag-Au-Pb-Zn-Cu mineralization and Niuxingba-Liumukeng deposit.The relationship between W-Bi-U mineralization and magmatism needs further research.