知识与财富的链接
熔积岩指的是侵入、混合到未固结或弱固结的湿沉积物中的熔浆分解、原位形成的一类特殊岩石。正确地认识该类岩石,有利于增进人们对岩浆-水(沉积物)相互作用过程的理解,恢复古环境。在青海南部沱沱河地区发现了一套角砾为撕片状、锯齿状及浑圆状的安山岩,胶结物为铁硅质组合的特殊熔积岩。研究表明,该熔积岩的角砾为岩浆遇水后快速淬火、裂解的产物,铁硅质组合为海底喷气沉积形成的含铁建造;且安山岩与含铁建造发生混合时,含铁建造尚未固结。该套熔积岩的发现,改变了长期以来对开心岭铁矿为火山热液交代安山岩而形成的认识,对于在矿区寻找VMS型矿床、区域内寻找海底热水喷流沉积型矿床具有重要的启示意义。
Peperite, a genetic term for a rock formed essentially in-situ by disintegration of magma intruding and mingling with unconsolidated or poorly consolidated, typically wet sediments. The study of peperite is important for several reasons. It can provide field evidence for the mechanism of magma-water/sediment interaction, and is of great value in palaeoenvironmental reconstruction. The peperite identified in south Qinghai mainly consists of zigzag, subrounded andesitic clasts and sediments composed of cherts, hematite and magnetite. A detailed petrological study indicates that most of the zigzag clasts were generated by in-situ quench fragmentation of andesitic magma. The sediments were formed by sedimentary exhalation, and remained wet when mingling happened. Therefore, the Kaixinling iron deposit, which was originally thought to be a product of hydrothermal replacement, should be a VMS deposit.
