云南省金平白马寨铜镍矿区镁铁-超镁铁岩群地球化学特征

金平地区镁铁岩区位于扬子克拉通西南缘哀牢山深大断裂南西侧的金平-黑水河裂谷带北段,由5个主要相对集中的(超)基性岩群(带)组成,以白马寨岩群岩体分异最强,矿化规模最大.通过对金平白马寨(超)镁铁质侵入岩的岩石化学特征、微量元素及稀土元素特征等方面的研究,初步认为,金平白马寨(超)镁铁岩具有低钛低磷的化学成分特征,岩石主要属钙碱性岩系,具岛弧带和造山带的特征,岩石含镁较高并具苦橄岩的成分特点,表明岩石形成温度较高,可能与地幔柱尾部的岩浆演化有关.

GEOCHEMICAL CHARACTERS OF MAFIC-ULTRAMAFIC SWARMS IN THE BAIMAZHAI NICKEL AND COPPER DEPOSIT, JINPING, YUNNAN

Mafic-ultramafic rock swarms, consisting of 5 clustered areas, in Jinping area are distributed in the northern section of the Jinping-Songda (Vietnam) Paleozoic rifting zone which is located in the SW side of the Ailaoshan structured zone in the southwest margin of the Yangtze Craton. Among the 5 mafic-ultramafic clustered areas, the Baimazhai mafic-ultramafic complex is well-differentiated and mineralized. Through the detail study on the major, trace elements and REE, it is concluded preliminarily that the rocks from the Baimzhai complex share the similar chemical composition feature of high content of MgO and low content of TiO_2 as that of picrite. The rock type from the Baimazhai mafic and ultramafic complex is belonging to the calc-alkaline rock series with the characteristics of rocks from arc island and orogenic belts. The rocks from the Baimazhai mafic-ultramafic complex may be formed in relatively higher temperature environment, which show the rocks may be related to the magma evolution of the tail of the mantle plume.