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

通过分析阿曼蛇绿岩和ODP 1256站点的体岩、矿物组成和结构，研究了蛇绿岩的脊外大熔岩流，了解了其侵位过程和岩浆成因。两股熔岩流均以低挤压速率挤压形成复合流瓣，并合并成较厚的大流瓣。合并的流瓣随着后续熔岩注入流瓣的熔融核心而内生变厚。岩浆成分在喷发过程中发生了变化，导致了岩浆的混合。伴生碱玄武岩表现出介于洋岛玄武岩和富洋中脊玄武岩之间的中间特征，表明大熔岩流的来源较洋岛玄武岩岩浆浅。

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.