甘肃景泰县老虎山地区蛇绿岩及其上覆岩系中枕状熔岩的地球化学特征

甘肃景泰县老虎山地区蛇绿岩之上覆盖着一套镁铁质的喷出岩和沉积岩组合，位于蛇绿岩的枕状熔岩之上，不是蛇绿岩的成员，为蛇绿岩的上覆岩系。蛇绿岩的枕状熔岩具Ｎ－ＭＯＲＢ的特征，而其上覆岩系中的枕状熔岩类似Ｅ－ＭＯＲＢ。前者来自扩张脊的下部岩浆房；后者推测源于扩张脊之外的岩浆房，也是软流圈地幔中等至高程度部分熔融的产物，不过，可能有少量来自下地幔的物质的加入

Geochemical Characteristicts of Pillow Lavas in Ophiolite and It's Overlying Rock Sequence in the Laohushan Area from Jingtai County, Gansu Province

The Early Paleozoic ocean crust of the Laohushan area consists of two parts of rocks: the lower part composed of ophiolite and the overlying rock sequence on the ophiolite, which is included in sediment rocks and extrusive mafic and andesitic rocks. The overlying rock sequence belongs to off axis magma series but not to ophiolite member. The pillow lava from the ophiolite has the characteristics of N MORB, and those from the overlying rock sequence are similar to E MORB by geochemistry. The former is from the magma chamber below the spreading ridge. The latter is supposed to be from the magma chamber out of the spreading ridge and also the products of middle high degree partial melting of asthenospheric mantle, but maybe with adding of a few materials from lower mantle.