浙江拔茅破火山剥蚀程度的判别与古火山复原

形成于95－110Ma前的拔茅破火山至今已经历过明显的剥蚀、夷平和后期的构造改造。本义根据该破火山内岩相组合面貌、定位于其中的银矿成矿深度、围岩蚀变分带特征、成矿元素地球化学分带规律、矿脉中黄铁矿品体的标型特征、岩石剥蚀速率的估算等多种方法确定拔茅被火山已被剥离了约500m．属于一种小等偏低剥蚀程度的古火山。以此为依据，结合火山岩层序和岩相分布特征．对投茅破火山的形成过程及其原始形态进行了复原。此外．本文还根据东南沿海火山带的实际，将古火山分为浅剥蚀、中等剥蚀和深剥蚀三类，总结了判别不同剥蚀程度破火山的综合标志。

GRADATION OF DENUDATION AND RECONSTRUCTION OF BAMAO CALDERA, ZHEJIANG PROVINCE

The Bamau caldera has undergone denudatiun, leveling and postmagmatic reformation since it appeared about 95- 110 Ma ago. According tu the characteristics uf lithufacies assemblages,the metallogenetic depth of the electrum lucated in the caldera, the characteristics of wall-rock alteration zonation, the regularity uf metallugenic element zonatiun,the typomorphuc characteristic uf pyrite in the vein, and the estimation uf denudatiun rate, the Bamao caldera has been denuded abuut 500m,be longing to a type of palaeuvolcanu with muderate to weak denudation. From that,and combined with the volcanic strata and lithufacies distributive features, the palaeo-shape and evolution of Bamao caldera were rehabilitated. In this paper l palaeovolcanoes were classified -into three types: weak, moderate and strong denudations, and an overall indicatur of calderas denuded at variuus degrees has been suggested.