台湾西南部乌山顶泥火山的成因机制初探

摘要

乌山顶泥火山位于台湾西南部旗山断层沿线.由于台湾西南部具有独特的地质构造背景,沿着古亭坑背斜和旗山断层沿线分布了许多泥火山.本文以乌山顶泥火山为例,研究泥火山的成因.在了解泥火山地质背景、活动现状的基础上,分析了喷出物的矿物组成、古生物组合、流体地球化学特征.喷出的主要矿物有石英、伊利石、高岭石-蒙脱石混层矿物、伊利石-蒙脱石混层矿物,古生物有Reticulofenestra minuta、 Sphenolithus abies等,流体中的离子主要是Cl~-、Na~+等.由此探讨了泥浆来源和成因机制,认为泥火山的活动与深部古亭坑组地层存在异常高压有关,构造活动是泥火山活动的主要诱发因素.%The Wushanding mud volcano is located along the Chishan fault in southwestern Taiwan. Due to the unique tectonic setting, there exist many mud volcanoes along the Gutingkeng anticline and the Chishan fault in southwestern Taiwan. Investigation was conducted on the genesis of the Wushanding volcano. Based on a field investigation of the Wushanding mud volcano, the authors analyzed mineral components, fluid geochemistry and micropalaeontological assemblage of the muddy eructation. The main mineral components include quartz, illite, kaolinite-smetice, illite-smecite, with such fossils as Reticulofenestra minuta and Sphenolithus abies. Fluid ions are composed mainly of Cl~- and Na~+ . It is thought that bodi the overpressure of the Gutingkeng Formation and the structural extrusion in Quaternary must have played the crucial roles in the formation and activity of the mud volcano.