一、区域火山地质概述 浙江省中生代陆相火山岩区的东缘有一系列大型环状火山机构,已经调查过的有:矾山火山洼地、望州山破火山口、大罗山火山洼地、北雁荡山破火山口等(图1)。仙岩明矾石—黄铁矿矿区位于大罗山火山洼地西南部次级火山构造发育区内。 大罗山火山洼地面积二百五十余平方公里,大致呈等轴状,核心被钾长花岗岩(43.42平方公里)侵位(图2)。该火山洼地的确定有以下一些依据: I. Overview of Volcanic Geology in the Region There are a series of large-scale annular volcanic structures on the eastern edge of the Mesozoic continental volcanic rock region in Zhejiang Province. Investigations include the volcanic valleys in Fanshan, the caldera in Wangzhou Mountain, the volcanic depressions in Dayuoshan, Mountain Caldera etc (Figure 1). The Xianyan alunite-pyrite deposit is located in the secondary volcanic tectonic development zone in the southwestern part of the Dalauo volcano depression. The Mount Luohe volcanic depression covers an area of ​​250 square kilometers and is roughly equiaxed, with the core emplaced by the potash-bearing granite (43.42 km2) (Figure 2). The volcanic depression to determine the following basis: