白马铁矿青杠坪矿段顶部细粒橄榄辉长岩中富角闪石细脉成因及其找矿意义
发布时间：2018-07-29 12:57
【摘要】：攀枝花式铁矿赋存岩体顶部普遍发育有富角闪石细脉。本文报道了白马铁矿青杠坪剖面顶部细粒橄榄辉长岩中富角闪石细脉、蚀变带和寄主岩中代表性斜长石、磁铁矿、钛铁矿、角闪石、黑云母和磷灰石等矿物的电子探针分析。岩相学观察表明,细脉中矿物主要为大颗粒角闪石,其间充填钛铁矿、斜长石、方解石;蚀变带中矿物为角闪石、辉石、斜长石、黑云母、磁铁矿及钛铁矿,矿物普遍发生蚀变(如黑云母绿泥石化),斜长石边部也发生溶蚀;靠近蚀变带的寄主岩中矿物主要为斜长石、单斜辉石(二者含量相近),另含少量角闪石、黑云母、磁铁矿和钛铁矿,在钛铁氧化物周围还有黄铁矿、黄铜矿和磷灰石,矿物也发生了轻微的蚀变;而远离细脉的新鲜寄主岩中矿物主要为新鲜的斜长石、单斜辉石(二者含量相近),少量橄榄石、角闪石、黑云母、磁铁矿及钛铁矿。电子探针数据表明,寄主岩中的斜长石An比细脉及蚀变带中的斜长石An要高。新鲜寄主岩中的斜长石主要为拉长石,蚀变带中的斜长石主要为中长石,而细脉中出现了钠长石。运用角闪石全铝压力计对富角闪石细脉中的角闪石颗粒进行了压力和深度的计算,从中心到边部所估算的压力表现出先增大后减小的趋势:69MPa→121MPa→167MPa→128MPa;运用磁铁矿-钛铁矿共生的温度计和氧逸度计,计算了寄主岩中磁铁矿和钛铁矿平衡时的温度和氧逸度,结果表明,磁铁矿和钛铁矿平衡的温度较低为546~574℃,氧逸度(logfO2)为-20.41~-23.83。另外,根据黑云母的Ti-Mg/(Mg+Fe)温度估算图解,靠近蚀变带寄主岩中黑云母的结晶温度为700~720℃。通过讨论分析得出结论:(1)青杠坪镁铁质侵入体侵位后顶部及周围先固结形成顶部细粒橄榄辉长岩带,对底部的含矿流体成矿起到屏蔽层的作用。(2)细脉和蚀变带中斜长石更富Na;由角闪石核部电子探针数据计算出的侵位深度为岩石的真实侵位深度,而由边部电子探针数据计算的深度为流体高压导致的"假"侵位深度;从富角闪石细脉到蚀变带再到寄主岩,矿物的结晶温度逐渐降低,对应流体高温到低温的扩散特点。(3)这种富角闪石细脉可以作为深部矿床的浅部标志,对深部矿床的勘察找靶提供了一种方法。
[Abstract]:Hornblende veins are commonly developed at the top of Panzhihua iron ore deposit. In this paper, the electron probe analysis of typical plagioclase, magnetite, ilmenite, hornblende, biotite and apatite minerals in amphibole veins, altered zones and host rocks at the top of Qingzangping section of Baima Iron Mine is reported. The petrographic observations show that the minerals in the vein are mainly large grained hornblende, filled with ilmenite, plagioclase and calcite, and the minerals in the altered zone are hornblende, pyroxene, plagioclase, biotite, magnetite and ilmenite. Alteration of minerals (such as biotite greenstone) and dissolution of plagioclase edge are common, and the host rocks near the altered zone are mainly plagioclase, clinopyroxene (similar in both contents), and a small amount of hornblende and biotite, Magnetite and ilmenite, as well as pyrite, chalcopyrite and apatite around the titanium-iron oxides, have also undergone slight alteration, while the minerals in the fresh host rocks far from the veins are mainly fresh plagioclase. Clinopyroxene (similar in content), a small amount of olivine, hornblende, biotite, magnetite and ilmenite. The electron probe data show that the n of plagioclase in host rock is higher than that in vein and alteration zone. The plagioclase in the fresh host rock is mainly elongated, the plagioclase in the alteration zone is mainly meso-feldspar, and albite appears in the vein. The pressure and depth of hornblende particles in the rich amphibole veins were calculated by using the amphibole all-aluminum pressure gauge. The estimated pressure from the center to the edge shows a trend of first increasing and then decreasing. The temperature and oxygen fugacity of magnetite and ilmenite equilibrium in host rock are calculated by using the thermometer and oxygen fugacity of magnetite and ilmenite symbiosis, using the temperature and oxygen fugacity of magnetite and ilmenite in the host rock. The results show that the equilibrium temperature of magnetite and ilmenite is lower than that of ilmenite, and the oxygen fugacity (logfO2) is -20.41 ~ 23.83 鈩，
本文编号：2152743
[Abstract]:Hornblende veins are commonly developed at the top of Panzhihua iron ore deposit. In this paper, the electron probe analysis of typical plagioclase, magnetite, ilmenite, hornblende, biotite and apatite minerals in amphibole veins, altered zones and host rocks at the top of Qingzangping section of Baima Iron Mine is reported. The petrographic observations show that the minerals in the vein are mainly large grained hornblende, filled with ilmenite, plagioclase and calcite, and the minerals in the altered zone are hornblende, pyroxene, plagioclase, biotite, magnetite and ilmenite. Alteration of minerals (such as biotite greenstone) and dissolution of plagioclase edge are common, and the host rocks near the altered zone are mainly plagioclase, clinopyroxene (similar in both contents), and a small amount of hornblende and biotite, Magnetite and ilmenite, as well as pyrite, chalcopyrite and apatite around the titanium-iron oxides, have also undergone slight alteration, while the minerals in the fresh host rocks far from the veins are mainly fresh plagioclase. Clinopyroxene (similar in content), a small amount of olivine, hornblende, biotite, magnetite and ilmenite. The electron probe data show that the n of plagioclase in host rock is higher than that in vein and alteration zone. The plagioclase in the fresh host rock is mainly elongated, the plagioclase in the alteration zone is mainly meso-feldspar, and albite appears in the vein. The pressure and depth of hornblende particles in the rich amphibole veins were calculated by using the amphibole all-aluminum pressure gauge. The estimated pressure from the center to the edge shows a trend of first increasing and then decreasing. The temperature and oxygen fugacity of magnetite and ilmenite equilibrium in host rock are calculated by using the thermometer and oxygen fugacity of magnetite and ilmenite symbiosis, using the temperature and oxygen fugacity of magnetite and ilmenite in the host rock. The results show that the equilibrium temperature of magnetite and ilmenite is lower than that of ilmenite, and the oxygen fugacity (logfO2) is -20.41 ~ 23.83 鈩，
本文编号：2152743
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