缅甸第三纪断陷盆地中的次生油青种翡翠的形成机理研究

RESEARCH ON MECHANISM OF THE SECONDARY OILY MASS GREEN JADEITE JADE OF MYANMAR JADE BOULDER IN TERTIARY FAULTED BASIN

为了解缅甸第三纪断陷盆地中的次生油青种翡翠的形成机理,利用ICP-MS分析、电子探针微区分析对缅甸次生翡翠矿床的油青色带及原生区部位的元素和矿物分布特征进行对比研究,利用成因矿物学原理推测出断陷盆地未抬升前的埋藏深度在1.2km～2.4km;与原生翡翠相比,次生油青色带中的微量元素Fe,Mg,Co,Mn,Ni,Ca,Ag,Sr,Ce,Y,Ag明显增多、Na,Al,Mo的明显减少;研究表明,翡翠砾石的油青色带形成于原生翡翠砾石被深埋于断陷盆地之后,形成油青色带所需要的铁族元素主要来自于一同深埋入断陷盆地中的超基性碎屑物质提供;断陷盆地中形成的流体经历了酸性阶段和晚期的碱性阶段,在从早期的酸性流体对深埋于其中的原生翡翠砾石进行溶蚀,并携带铁、镁等元素进入翡翠的颗粒间隙和裂隙中,后期,即深埋期流体性质变为碱性流体阶段,此阶段翡翠颗粒间隙中的Fe,Mg等元素发生沉淀形成绿泥石,从而形成了次生的油青种翡翠。

The formation mechanism of the secondary oily mass green jadeite jade and the burial diagenesis processes of Myanmar Jade Boulder, the migration characteristics of the elements in the fog zone and crust of boulder has been studied by using electronic microprobe and ICP-MS. The results of genetic mineralogy analysis showed that the burial depth of this boulder formation was 1.2 km-2.4 km. Compared to the origin zone inside of boulder,the contents of elements Na,Al, Mo decrease significantly and those of Fe, Mg, Co, Mn, Ni, Ca, Ag, Sr, Ce, Y, Ag increase significantly in the blue fog zone. As the iron group elements increase significantly in the blue fog zone, there was a migration of foreign substances into the boulder＇s fog zone. The study indicates that the fluid nature changed from acid to alkaline during the diagenetic phase in the faulted basin to form the oily mass green jadeite jade.