太湖西缘击变角砾岩的岩相学特征及其研究意义——太湖冲击成因又添新证据  

The petrography features of impact breccias in the Western Taihu Lake,Jiangsu,China

作　　者：王鹤年[1,2] 钱汉东[1,2] 黄钟谨 施贵军[1,2] 

机构地区：[1]南京大学内生金属矿床成矿机制研究国家重点实验室 [2]南京大学地球科学与工程学院,南京210093

出　　处：《南京大学学报（自然科学版）》2015年第1期87-98,共12页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(40972030);南京大学内生金属矿床成矿机制研究国家重点实验室自主研究课题基金(2008-II-04)

摘　　要：冲击变质作用是变质作用的一种新类型,是指由陨石或彗星高速降落所产生的高压冲击波,瞬间经过或穿过靶岩所引起的岩石及矿物中的所有变化,击变岩是冲击变质作用的典型产物.近年来国外在这一领域发展很快,但国内尚无详细的研究成果报道.近期在太湖西缘发现了这类击变角砾岩.根据国外研究总结提出的诊断性特征和有效的岩相学研究方法,本文对击变角砾岩中面型微裂隙(PFs)、面型微页理(PDFs)、击变矿物玻璃(diaplectic glass)、击变高温矿物玻璃及熔体(焦石英lechatelierite)及岩石相的转变(岩石熔融)等标志性特征的研究,确证了太湖西缘这类击变岩的存在.研究对推动国内击变岩的研究和发展将起到积极促进作用,并为"太湖冲击事件"增添新的证据.Impact metamorphism is a new type of metamorphism.It refers to all changes in rocks caused by high-speed impact of meteorite or comet,during which high-pressure shockwaves passed by or penetrated through these target rocks.Impactite is a typical product of impact metamorphism.Research of this field has developed rapidly in some countries,yet no detailed research result was reported in China.In recent years the present authors found some impact breccias in the western margin of Taihu Lake.Petrographic features of these impact breccias are studied based on the identification criteria summarized from previous research experience,together with effective petrographic research methods.Some distinguishing characteristics,e.g.planar fissures（PFs）,planar deformation features（PDFs）,diaplectic glass,impact-induced high-temperature glasses and melts（lechatelierite）,and the phase change of rocks（melting）are recognized,which confirm the existence of impactite in western Taihu area.The present study not only provides new evidence for the existence of the＂Taihu Lake impact event＂,but also actively promotes the further impactite research in China.

关 键 词：击变岩 冲击变质作用 击变角砾岩 太湖冲击事件 

分 类 号：P554[天文地球—构造地质学]