摘要
山东昌乐地区广泛分布晚第三纪碱性玄武岩。该时代的玄武岩浆喷出活动在构造上受到大陆裂谷型沂沐断裂带的控制。玄武岩浆活动是喷溢型而不是喷发型。富含蓝宝石的寄主玄武岩比不含蓝宝石的玄武岩含Ｎａ２Ｏ＋Ｋ２Ｏ、Ａｌ２Ｏ３和ＴｉＯ２高，而含ＳｉＯ２低，其成分投影点落入（Ｋ２Ｏ＋Ｎａ２Ｏ）－ＳｉＯ２图中的碱性玄武岩区。含蓝宝石的玄武岩中含有大量的二辉橄榄岩，该种岩石是上地幔部分熔融出玄武岩熔体后的上地幔残留物。二辉橄榄岩中的矿物都处于平衡状态。用地质温度和压力计估算的二辉橄榄岩中的矿物平衡温度和压力分别为１１００℃和１．５ＧＰａ。蓝宝石是碱性玄武岩浆早期结晶的产物，而且与单斜辉石、长石。
Late Tertiary basalts are widely distributed in the Cha ngle area, Shandong provine. The
eruption of basalts in this period was tectonic ally controlled by the Yimu fault of the continental
rifting type. The eruption of the basalt magma was flooding rather than explosive. The host
basalts of sap phires have higher K 2O+Na 2O, Al 2O 3 and TiO 2 and lower SiO 2, than sap
phire_free basalts.The data points fall in the alkali basalt field on the (K 2O +Na 2O)_SiO 2
diagram. The sapphire_bearing basalts contain abundant iherzolit es that belong to the
remnants of the upper mantle left after the removal of bas altic melts from partial melting of the
upper mantle.Minerals in iherzolites are in an equilibrium state . Using the geothermometer
and geobarometer , the equil ibrium temperature and pressure of the minerals in iherzolites
were estimated to be 1100 ℃ and 1.5 GPa, respectively. The sapphires are the product of
early cry stallization of alkali basalt magma and intergroom with clinopyroxene, feldspar,
garnet and zircon megacrysts.
基金
国家自然科学基金
关键词
蓝宝石
碱性玄武岩
幔源岩石包体
山东
矿床成因
sapphire alkali basalt mantle_derived xenolith
Changle area in Shandong
