摘要
本文讨论的尖晶石橄榄大理岩产于迁安太古代变质铁矿带南区黄柏峪—脑峪门一带。岩体受古断裂构造控制,没有一定层位。其全岩成分、微量元素、稀土模式、矿物学特征及碳、氧同位素资料均表现了岩浆碳酸岩特征,与沉积成因的碳酸盐岩相差甚远。据此认为,该尖晶石橄榄大理岩是区内最早的一次岩浆活动的产物。
The Spinel-chrysolite-marble occurring in the southern part of the Archaean metamorphic iron ore zone, Qian An is controlled by an ancient fracture. The olivine (Fo87) of magmatic origin is a metamorphic relict. The Petrochemical characteristics (SiO_2=16.92％, Al_2O_3=4.07％, K_2O(0.33％)>Na_2O (0.17％), TiO_2=0.18, Fe_2O_3+FeO=9.86％) corresponds to the magmatogenic carbonatite, but differs from the sedimentary carbonate rock. The contents of trace elements (Cr, Ni, Co, Vetc)are very high, in Which the content of chromium (Cr>1000ppm) isthe highest in all the rocks of the area. The total amount of REE is lower(∑REE=16.389ppm),and there is essentially no europium anomaly (Eu/Eu=1.0), Its chondrite normalized REE distribution pattern is a smooth type, consisting with that of the Archaean komatiite. The isotope ratios of C and O (δ^(13)C=-5.129～-5.236, δ^(18)O=8,788～11.352) display the characteristics of a deep source Therefore, the author holds that the nature of protolith of the spinel-olivine marble is of magmatic rock.
出处
《吉林地质》
1990年第2期57-64,共8页
Jilin Geology
关键词
橄榄大理岩
尖晶石
太古代
岩浆
Archaean era spinel-olivine-mable magmatic origin Qian-An Hebei
