青海锡铁山铅锌矿床中发现的宇宙尘及其初步研究

本文对发现于锡铁山铅锌矿床中的磁性小球的化学成分、粒度、硬度、形貌、吸收系数、结构和构造进行了分析研究。结果表明,该磁性小球与前人所报道的其他地区的宇宙尘类似。根据它们的化学成分特征(表2、3、4、5)、方铁矿和磁铁矿构成的外壳和α-Fe内核,初步确定其为下古生代宇宙尘。

FINDING OF THE PALAEOZOIC COSMIC DUSTS IN Pb-Zn ORE DEPOSIT

The Xitieshan Pb-Zn deposit occurs in the greenstone belt. Magnetic spherules (cosmic dusts) are found in stripped calcareous-siliceous sulfide ore and game tiferous chlori-tic quartz albite schist of ore bed floor in the second lithologic member. The grain size, shape, texture and structure of the magnetic spherules are similar to those cosmic dusts re-poted by most geologists. Though Xitieshan magnetic spherules are poor in Ni, they are initially determined as a kind of the lower Palaeozoic cosmic dusts according to their chemical compositions (see Table. 2 and 3), Co/Fe data (see Table. 4), La-Lu abundances (see Table. 5 and Fig. 2), wustite and magnetite makeing up outer crust with an inner core of α-Fe. The major difference from those spherules taken from the other areas in that except wiistite there is Ga-Mg-Al-Si-O glass of 10.13-26.64 wt% (see Table. 3 and Fig. 3, 4) unevenlly distributed in the matrix of steel-grey spherules, coelom spherules and outer crust of steel-grey spherules with an inner core.