地壳硅质岩浆演化的动力学机制SCIEI北大核心CSCD

硅质岩浆的成因及演化机制研究是认识大陆地壳成分结构演化机制的关键途径。地壳硅质岩浆储库的基本性质及其演化的动力学过程是制约硅质岩浆演化及其多样性的根本原因,也是受到广泛关注的前沿和热点问题。本文总结了硅质岩浆储库的基本性质及其演化机制研究的相关进展,重点探讨了岩浆体系演化的动力学机制,即其物质成分及温度压力条件的动态演化过程,亦即岩浆储库在补给驱动下的存留、活化、分异、喷发过程。经由累积生长的方式形于地壳浅部的硅质岩浆储库以晶粥为主要赋存形式,具有较低的温度压力范围和高硅高结晶度高粘度的特征。岩浆储库的基本性质导致其自身不具有持续演化的能力,只有在基性岩浆补给的驱动下才能长时间存留分异或快速活化喷发。基性岩浆的补给及其携带的热及流体/挥发份深刻地改变了岩浆储库的物质成分及物理条件,是导致硅质岩浆分异演化或喷发的根本原因。本文还结合研究进展探讨了东南沿海地区中生代火山-侵入岩的成因演化机制及相关问题。

Dynamic mechanisms of the evolvement of crustal silicic magmas

Studies on the genesis and evolving mechanisms of the crustal silicic magmas are the essential way to reveal the evolving mechanisms of the continental crust both in composition and architecture. Nature and dynamic evolving processes of the silicic magma reservoir in the shallow crust are the essential factors controlling the evolvements and complexities of silicic magmas, which has been being the attractive focus and frontier of the recently researches. Basic properties and progressions in the studies of the evolvement mechanisms of the crustal silicic magma reservoir are summarized in this paper, focusing on the dynamic changes of the compositions, temperature and pressure conditions, that is, dynamic processes of residence, reactivation, fractionation and eruption of the magma reservoir driven by magma recharge. The silicic magma reservoir in the shallow crust, formed by incremental assemble, is mainly composed by magma mush, which is characterized by relatively low temperature and pressure, and high silica contents, high crystallinity and consequently high viscosity. The nature of the crustal silicic magma reservoir makes that the reservoir can only be reactivated to form evolved magmas via fractionation after long residence time or rapidly reactivated to erupt, driven by magma recharges. Recharge of mafic magmas, as well as the carrying fluid/volatile, induced dramatically changes in compositional and physical conditions of the magma system, and also the essence of the magma evolvement or eruption. Additionally, the genesis of the Mesozoic volcanic-intrusive complex in coastal area of southeast China are also discussed combined with these progressions.