【摘要】 <正>本文是我们所进行的《中国东部新生代碱性玄武岩及其中上地幔包体形成条件研究》这一科研课题中有关宽甸地区最终成果的一个部分,主要涉及碱性玄武岩岩浆起源问题.其他问题另文叙述.本区玄武岩为碧玄岩—碱性橄榄玄武岩—橄榄拉班玄武岩系列,自底至顶广泛而普遍地分布有二辉橄榄岩、方辉橄榄岩等上地幔包体,经研究,它们代表了玄武岩源区的上地幔岩石.碱性玄武岩浆的形成主要受上地幔橄榄岩部分熔融程度和熔融深度的制约,下面分四方面阐述这一问题.更多还原

【Abstract】 The Huangyishan Quaternary volcanic cone in Kuandian County, Liao-ning Province consists of lavas and pyroclastic rocks. The basic lavas from bottom to top are basanites-olivine alkali basalt-solivine tholeiites, all containing inclusions of lherzolite, harzburgite and pyroxenite, as well as megacrysts of garnet, clinopyroxene and anorthoclase. These ultramafic inclusions represent the upper mantle source rocks of basaltic magma. Those of the spinel Iherzolite generally appear in basanites, but olivine tholeiites mainly contain inclusions of clinopyroxene-poor Iherzolite and harzburgite.The chemical composition of the peridotitc inclusions in basalts shows, from bottom to top, an increasing content of MgO and a decreasing content of Na2O and A12O3, indicating the increase in depletion degree, while the decrease in Na2O + K2O content and the increase in MgO and CaO content in the basalts from bottom to top, indicate the increase in melting degree.The results of the calculations of equilibration between the peri-dotite inclusions and the basalt hosts show that the basanite magma was originated from the depth of 82-69km., 1390-1430C, the alkali olivine basalt magma from the depth 69-66km., 1400-14051C and the olivine tholeiite magma from the depth of 66-59km., 1390-1400C, and that the degree of partial melting is 8%, 12%, and 18.5% respectively.The process of formation of Cenozoic primary basaltic magma was an upwelling event of the upper mantle in the region of Kuandian, Liaoning Province.更多还原