CAJ | 학술논문

元素地球化学研究结果表明，苍山变质带内发育两类正变质基性岩：一类为形成于富集型MORB构造环境的变拉斑玄武岩，另一类为形成于板内构造环境的变碱性玄武质岩墙。Sm-Nd同位素体系研究表明，变拉斑玄武岩形成于晚古元古代至中元古代(2.0～1.4Ga)；变碱性玄武质岩墙形成于中新元古代(1.3～0.8Ga)。已发表的Sm-Nd等时线年龄(2408 Ma)其Sm/Nd比值变化很小，故没有实际的地质意义。
원소지구화학연구결과표명，창산변질대내발육량류정변질기성암：일류위형성우부집형MORB구조배경적변랍반현무암，령일류위형성우판내구조배경적변감성현무질암장。Sm-Nd동위소체계연구표명，변랍반현무암형성우만고원고대지중원고대(2.0～1.4Ga)；변감성현무질암장형성우중신원고대(1.3～0.8Ga)。이발표적Sm-Nd등시선년령(2408 Ma)기Sm/Nd비치변화흔소，고몰유실제적지질의의。
Two types of metabasites have been recognized on the basis of elemental geochemical studies in the Cangshan metamorphic belt in Yunnan. The Ti-Zr-Y diagram and REE patterns indicate that one is a metatholeiite formed in an E-MORB setting, and another is a metamorphosed alkaline basaltic dyke formed in a within-plate setting. The metatholeiites show higher 143Nd/144Nd (0.5126～0.5128) and alkaline meta basaltic dykes show larger variation range of 143Nd/144Nd (0.5118～ 0.5127).Sm-Nd isochron trend suggest that the metatholeiites were formed in the period of late Paleoproterozoic to Mesoproterozoic (2.0～1.4Ga), and the metamorphosed alkaline basaltic dykes were formed during Mesoproterozoic to Neoproterozoic (1.3～0.8Ga). The published Sm-Nd isochron of 2 408 Ma is actually a false isochron, and does not reflect an actual geological event due to too narrow interval of Sm/Nd ratios.