摘要
本文对陈蔡群变质岩进行了４０Ａｒ－３９Ａｒ年龄测定。其中在诸暨陈蔡测得的４１５．１Ｍａ的坪年龄代表了主变质晚期的冷却年代。采自义乌尚阳的样品受燕山期火山活动影响有明显的氩丢失，与主变质有关的年龄亦明显降低，仅３１５．３Ｍａ。在龙泉东书获得的年龄谱和当地广泛发育的混合岩化作用有关，２７６．９Ｍａ的坪年龄为这次热事件的冷却年代。根据对现有年代资料的讨论，可以认为不同衰变体系记录了陈蔡群主变质事件的演化。Ｒｂ－Ｓｒ体系在变质早中期实现均匀化，年龄值为５５２．４～６６０．６Ｍａ。锆石、磷灰石在变质高峰期形成的铅丢失年龄为５０８，４～５７８Ｍａ。上述资料表明陈蔡群主变质年代属加里东期。
Metamorphic rocks of Chencai group were dated by 40Ar-39Ar method in this paper.The plateau age of 415.1 Ma obtained in Chencai,Zhuji represents the cooling time of the main metamorphic event. The sample from Shangyang Yiwu is affected by Yanshanian volcanismand has apparent argon loss. The age related to the main metamorphism is also lowered,which is only 315. 3 Ma. A plateau age of 276. 9 Ma is obtained from Dongshu, Longquan,which can be regarded as the cooling age of the widely developed migmatization in this area. Based on a discussion on the up-to-date chronological data, the authours pointed out that the evolution of the main metamorphism of Chencai group was recorded by different decay series,i.e., Rb-Sr isotope was homogenized in 552. 4 to 660. 6 Ma, correspondent to the early and middle stage of the metamorphism. The U-Ph system in zircon and apatite redistrutednear the summit of the event and is recorded by the lead loss ages of 508. 4 to 578 Ma. Allthe above data confirm that the main metamorphism of Chencai group took place in Caledonian period.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1994年第2期193-201,共9页
Acta Petrologica Sinica
基金
国家自然科学基金
国家教委留学归国人员研究基金
关键词
变质岩
变质年代
氩同位素定年
Chencai Group
^(40)Ar-^(39)Ar chronology
Metamorphic age
