藏北羌塘地区岛弧花岗岩和外弧花岗岩

羌塘地区花岗岩类岩体大多数沿羌塘陆块的冈玛错-西亚尔岗岛弧分布。岩石类型有花岗岩、黑云母花岗岩,花岗闪长岩、石英闪长岩、闪长岩等,有的岩体还与酸—基性火山岩伴生。侵入体同位素年龄值为135.3—302Ma,为多期侵入,主要为燕山早期(135.3—186.3Ma),少数为燕山晚期。个别同位素年龄值为74.2和99.6Ma,最早不超过燕山晚期。花岗岩类岩体另一分布区是改则-色哇缝合带北侧。岩石类型较单一,主要是酸性岩类的花岗岩、花岗斑岩、黑云母花岗岩、角闪黑云花岗岩等,几乎不出现中性岩。同位素年龄值为120.9—129.8Ma,为燕山晚期产物。     

湖南东坡矿田铅锌矿成矿地质背景及成矿作用

湖南东坡矿田铅锌矿床是典型的沉积-热液改造(叠加)型层控矿床。含矿岩系为中、上泥盆统。该区在早泥盆世末期就开始了拉张盆地的演化,拉张盆地的热沉降导致了成矿物质的早期富集和矿化。铅锌矿的形成经历了三个阶段:盆地演化的同生断裂阶段成矿物质的初步富集、后生断裂阶段早期铅锌矿体的形成、千里山花岗岩的侵入。     

藏北改则—色哇地区的蛇绿岩特征

藏北改则-色哇缝合带的蛇绿岩,与特罗多斯、岛湾的蛇绿岩剖面对比,区别是厚度小和缺乏席状岩墙。该区的变质超镁铁岩属阿尔卑斯橄榄岩-蛇纹岩组合,其化学成分与玄武岩互补,说明玄武岩浆系地幔岩分熔的产物。     

X射线荧光分析方法在毒重石-钡解石-钡白云石型钡矿评价中的应用

XRFA technology can effectively locate ore bodies in exploring and evaluating the witherite-barytocalcite-barytodolomite type barium deposit. The regression equation for identifying rich, middle-rich, and poor ore and rocks is BaO=0.5614-3.127×10^-5I_f. The X-ray fluorescence intensity limitation for ore and rock is I_f=24 350, those for the poor ore and middle-rich ore, and the middle-rich ore and rich ore are I_f=29 467 and I_f=33 000, respectively. The determined X-ray fluorescence intensity curves vary little in amplitude, and the patterns go gently and stable. So XRFA can be used to survey geological-geochemical profiles and trace back ore bodies. There is no systematic error between the ore grade measured by XRFA and the Ba content measured by chemical analysis. This confirms the effectiveness of XRFA in evaluating this type of barium ores.     

湖南东坡矿田伴生银的赋存状态

湖南东坡矿田铅锌矿床中的伴生银主要以独立银矿物形式存在,有银黝铜矿、黝锑银矿、碲银矿、硫银锡矿、深红银矿等;有少量的银以晶格银和超显微包体银矿物的形式赋存于方铅矿等矿石矿物中。文章还就银的富集规律作了初步探讨。