溧阳戴埠火山沉陷和古火山群特征及成因演化探讨

ON THE VOLCANIC DEPRESSION AND PALEOVOLCANIC CLUSTER AND ITS GENESIS EVOLUTION IN DAIBU,LIYANG

本文利用卫片资料和实际工作资料详细论述了漂阳戴埠古火山群的外形、构造、寄生火口等特征。用古生物资料证明了该古火山群形成的时间,对其形成机理进行了初步的探讨,认为它是一个受早期东西向和北东、北西向构造控制的一套多中心、多旋回、多韵律、多塌陷的火山喷发产物。

There are mary paleovolcanic craters in Daihu,Liyang county in which the caldera,ring structure and radiator struc- ture and parasitic structure are well-developed.The Daibu volcanic depression is a large scale ring caldera taking Daibu as the centre.On satallite images,the Daibu area appears a three-layer ring which are composed of inner bright-grey,middle grey and outer shallow-grey.The outer ring shows upper Jurassic trachy andesite and crystal tuff.The middle ring is com- posed of ignimbrite and the central ring is reflected by rhyolite and rhyolite-pophyry.There develops fault between each ring with the intrutions of igneous rock.The parasitic crater has evolved through three uplift stages and two collapse stages.In each uplifting stage,several small parsitic craters were formed.