辽东半岛早第三纪饮马湾山辉长岩体的基本特征及岩浆结晶过程

General characteristics and crystallization process of Early Tertiary Yinmawanshan gabbro in Liaodong Peninsula

辽东半岛饮马湾山辉长岩体为早第三纪晚期的侵入岩体，是东北地区最年轻的镁铁质侵入体之一。对该岩体进行了岩石学和地球化学方面的研究，并采用PELE（硅酸岩熔体结晶计算软件）模拟了岩浆结晶过程。研究表明，饮马湾山辉长岩具有高的Al2O3含量（16.28％～19．27％）和低的MgO含量（3．63％～5．57％），属于高铝玄武质。该辉长岩主要造岩矿物有橄榄石、单斜辉石、磁铁矿、钛铁矿、黑云母、斜长石和钾长石。辉长岩所具有的辉绿辉长结构、大量细长针状磷灰石、单斜辉石中较低的Al^Ⅵ／Al^Ⅳ值（0．00～0．28，平均为0．12）及橄榄石中较低的CaO含量（0．04％～0．24％，平均为0．12％），均体现出浅成侵入岩的特点。PELE硅酸岩熔体结晶模拟结果和岩石结构特征表明，辉长岩中矿物结晶顺序依次为：斜长石、橄榄石、磁铁矿、单斜辉石、钛铁矿、磷灰石、黑云母、钾长石。该辉长岩是高铝玄武质岩浆快速侵位至近地表处冷却结晶的产物，可能是该地区新生代强烈的岩浆底侵作用在浅部的表现。

The Yinmawanshan gabbro in southern Liaodong Peninsula is one of the youngest plutons in Northeast China. In this paper, the gabbro was investigated by petrologic and geochemical methods and calculated by means of PELE program （a silicate liquid crystallization progrmn）. The gabbro has high Al2O3 （16.28%-19.27%） and low MGO（3.63%-5.57%）, belonging to high aluminum basalt. The gabbro has the assemblage of divine ＋ clinopyroxene ＋ magnetite ＋ ilmenite ＋ biotite ＋ plagioclase ＋ K-fddspar. The ophitic and subophitic textures, elongated apatite crystals, low Al^Ⅵ/Al^Ⅳ ratios （0.00-0.28, 0.12 on average） in dinopyroxene, and low CaO content in divine （0.04 %-0.24 %, average 0.12 % ） indicate that the gabbro was crystallized at a low pressure. The sequence of mineral crystallization in the gabbro is as follows： ptagioclase, olivine,＇ magnetite, clinopyroxene, ilmenite, apatite, biotite, K-feldspar, as revealed by petrography combined with the calculation using PELE program. The gabbro is indicative of intense magmatism in Cenozoic in Northeast China.