个旧锡矿玄武岩及其成矿作用研究

【作者】 倪春中；

【导师】 秦德先；

【作者基本信息】 昆明理工大学 ， 矿产普查与勘探， 2005， 硕士

【摘要】 个旧锡矿区开发历史悠久,地质研究程度较高。但前人大量的研究工作多注重花岗岩成矿理论及模式的建立,认为个旧锡多金属矿床主要与燕山期花岗岩有关,成矿时间集中在燕山中晚期。本文通过对个旧组地层、玄武岩及花岗岩的岩石学、岩石化学、地球化学分析及区域地质综合研究,主要获得如下认识: 1、基本查清了个旧锡矿区内基性火山活动及期次。个旧锡矿区玄武岩,分布于中三叠个旧组和法朗组,至少由三期多个旋回作用形成。最早期为个旧组中玄武岩,主要产于个旧东区个旧组下段（T₂g₁¹）,分布于卡房新山、老厂、南麒麟村一带,分布面积约125Km²;第二期基性火山岩产于个旧西区法郎组下段（T₂f¹）,主要有两层,厚度约70m与炭质泥灰岩、硅质岩互层整合产出,分布于水塘寨、保和及木花果一带,展布面积达40Km²;第三期火山岩产于个旧西区法郎组下段（T₂f¹）,与页岩、泥灰岩互层产出,分布于他白、翡姑龙一带,尤其在他白最典型。 2、个旧东区玄武岩顶板位置标高总体上北高南低。从玄武岩顶板等高线图可以看出,由于受整个区域玄武岩分布的影响,玄武岩的分布大致呈北东向分布。从总体上看,玄武岩在喂牛塘断裂与半坡断裂的交界一带顶板所处的位置较低,标高大约在1800m,而在仙人洞断裂与新山断裂之间玄武岩所在的位置较高,大约在2000m。从新山断裂往南,玄武岩标高位置有所降低,降到了1850m。再往北东向,到了大白岩玄武岩顶板的标高又有所抬升,约2100m,过了大白岩到达老熊硐断裂附近,玄武岩的标高降低到1700m左右。在拉里黑断裂北侧,玄武岩地层标高陡然上升,到了竹叶山附近达到最高值,约为2200m。而在老厂矿田的5号矿体白虎山一带,玄武岩顶板标高同样也达到了2200m以上。玄武岩岩石类型可分为3大类,即熔岩、熔结凝灰岩-凝灰熔岩和玄武质凝灰岩。熔岩具有典型的块状、片状、气孔、杏仁构造及粒状变晶、鳞片变晶、变余斑状结构。熔结凝灰岩-凝灰熔岩大多数变质为鳞片状阳起石金云母岩和金云母阳起石岩。玄武质凝灰岩蚀变成具千枚状和鳞片状的绢云母化金云母变碱性玄武质凝灰岩或金云母变碱性玄武凝灰岩,金云母含量60%。 3、玄武岩控制了花岗岩的形态,从而间接控制了凹陷带矿体的分布。个旧组中玄武岩,在个旧东区主要产于个旧组下段（T₂g₁¹）,与碳酸盐岩呈互层产出,当花岗岩体侵入到个旧组下段（T₂g₁¹）互层带时,由于碳酸盐岩化学性质较活泼,玄武岩性情,在岩体浸入时,灰岩被同化吞蚀,惰性的玄武岩则深陷于花岗岩中,造成花岗岩的凹陷构造,同时玄武岩受到花岗岩所提供的热能作用,发生变质作用,铜进一步得到富集,形成变玄武岩铜矿。卡房“磨姑状”、竹林“塔松式”花岗岩体及其凹陷带矿体的形态产状均间接地受玄武岩控制。老厂、竹林一带花岗岩的东、西凹陷带及其中矿体的形态产状也间接地受玄武岩控制。 4、按照上述成矿预测准则,绘制玄武岩顶底板等值线图和花岗岩等深线图,在综合分析的基础上,提出了4个成矿有利的靶区,分析了4个预测区内的找矿前景。更多还原

【Abstract】 The history of gejiu tin mine area development is long, and the geology research degree is higher.But a lot of research which has been done makes a point of granite mineral theories and modes establishment, thought that gejiu tin mine area metalses deposit is main to have something to do with yanshan period granite, and mineralization time concentrates in yanshan later period. This paper through the gejiu stratum, basalt and lithology of granite, rock chemistry, geochemistry analysis and The district geology synthesizes research, the following cognitions are obtained:1. The basic volcano activity and how many times have been investigated this time. The basalt in gejiu tin mineral area Distribute in middle Trias group and falang group, at least contain three periods and several gyration functions. The earliest Period basalt is in the gejiu group.lying in the gejiu group next segment. （T₂g1¹） in east gejiu area distribute in xinshan kafang, laochang and south qiling village, the area roughly covers 125 square meter; the second period volcano rock is located in gejiu west area next segment of falang group,（ T₂f¹） which involves primarily two layer, The thickness is roughly 70m, and with the charcoal-marlite, argillite each other. They distribute in shuitang stockaded village、 baohe and muhuaguo, roughly cover 40 square meter; the third period volcano rock is located in gejiu west area next segment of falang group（ T2f1）, and with the shale、 marlite each other, distributing in tabai and feigulong,specially in tabai.2. As a whole, the elevation of basalt’s top ceiling position is generally lowing from north to south. And the basalt affects by the region basalt distribution, it distributes along north-east. Generally speaking, the basalt’s position is lower in the joint between weiniutang faultage and banpo faultage, the elevataion about 1800m. But the position is higher in the joint between xianrendong faultage and xinshan faultage, about 2000m. In the south of the xinshan faultage, the basalt’s elevatation becomes low, and about 1850m. And in the north-east of here, the big white rock basalt’s top ceiling becomes high again, the elevation about 2100m, and near the laoxiongdong faultage, the basalt’s position is lowest, 1700m or so. In the north of lalihei faultage, the basalt’s elevation becomes high quickly, and in the zhuyeshan the position is highest, about 2200. in laochang mineral field white tiger, the basalt has the same position. The basalt’s rock can be divided into three types. That is lava, melt-combine tuff and basalt tuff. The lava is of nubbly、 sheet, air vent and amygdale structure and graininess change crystal, squama change crystal, change remainder spot configuration. Most of The melt-combine tuff have metamorphosed squama actinolite phlogopite rock and phlogopite actinolite rock. The basalt tuff metamorphosed squama sericite phlogopite changing alkalescence basalt tuff or phlogopite changing alkalescence basalt tuff, and the phlogopite content covers 60 percent.3. In east gejiu area, the basalt mainly lies in lower segment in gejiu group （T2g1¹）, and presents with the carbonate rock each other. When granite body intrudes into the lower segment in gejiu group （T2g1¹）, carbonate rock’s chemistry character is active, and the basalt’s not so active, so carbonate rock is more easily eroded, add the basalt still locates there, thus makes granite’s sunken structure. At the same time basalt is heated by the magma, and then happens metamorphose, as a result the element Cu is becoming enrichment, forming basalt type Cu mineral. The granite body with "mushroom shape" in laochang mineral field and "pagoda shape" in zhuling mineral field and sunken mineral body shape are all controlled by the basalt. the east、 west sunken zone in zhuling laochang field is also controlled by the basalt.4. According to above mineral-forming forecast principle, protract basalt coping, bottom isoline graph, in the basis of comprehensive analysis, put forward 4 beneficial mineral-forming area, finally analysis foreground in this 4 forecast area.更多还原