Magma processes in the Moho Transition Zone: an insight from volcanoes off the fast-spreading ridges

通过对阿曼蛇绿岩和ODP1256站位的大型熔岩脊外流动的研究，通过分析块体岩石和矿物的成分和结构，了解侵位过程和岩浆成因。两个熔岩流都以低挤压速率挤压成复合流动叶，这些流动叶合并成厚的大流叶。当随后的熔岩被注入到叶状熔体的核心中时，合并的流动叶内源增厚。岩浆成分在喷发期间发生了变化，导致了岩浆的混合。伴生的碱性玄武岩具有洋岛玄武岩和富中洋脊玄武岩之间的中介特征，表明大量熔岩流的源区比洋岛玄武岩岩浆浅。

Off-ridge large lava flows in the Oman Ophiolite and in ODP site 1256 were investigated to understand the emplacement process and the magma genesis by analyzing the bulk-rock and mineral compositions and textures. Both lava flows were extruded at low extrusion rates as compound flow lobes, which were merged into thick large lobes. Merged flow lobes thicken endogenously as subsequent lava was injected into the molten core of the lobes. Magma compositions changed during the eruptions, resulted in mixing of magmas. Associated alkali basalts showing intermediated characteristics between ocean island basalts and enriched mid-ocean ridge basalts indicate that the sources for the large lava flows are shallower than ocean island basalt magmas.