四川峨眉麦地坪震旦系-寒武系界线剖面的中子活化分析研究  

STUDIES OF THE MAIDIPING SINIAN-CAMBRIAN BOUNDARY SECTION, E'MEI COUNTY, SICHUAN PROVINCE, BASED ON THE NEUTRON ACTIVATION ANALYSIS

作　　者：徐道一[1] 毛雪瑛[2] 张勤文[3] 赵东旭[4] 

机构地区：[1]国家地震局地质研究所 [2]中国科学院高能物理研究所 [3]中国地质科学院地质研究所 [4]中国科学院地质研究所

出　　处：《地质论评》1995年第1期74-81,共8页Geological Review

摘　　要：张勤文等曾对四川峨眉麦地坪震旦系-寒武系界线剖面进行了研究。1991年对此剖面又进行了加密间距采样。中子活化分析结果表明,在震旦系-寒武系界线附近的标本具有较高的Ni,Co,Cs含量,Ir的含量也较上覆、下伏地层的标本为高。因而认为,在麦地坪剖面,把中国C点作为震旦系与寒武系的分界比采用中国A点、B点及D点界线,依据更充足些。Late Sinian and Early Cambrian strata are well developed at the Maidiping Section, Emei County, Sichuan province. Here, the Sinian-Cambrian boundary ( China C point ) is defined by a marked lithological change from carbonate rocks to shale.High-resolution geochemical studies of the Maidiping section show that a ca-30-cm-thick layer at the base of the Jiulaodong Formation from the Sinian-Cambrian boundary upward can be divided into phosphorite, greyish black shale and mudstone. phosphorite and the lower part of black shale are enriched in Ir, Ni, Co, Cr and Fe as well as Cs, Hf, Rb, Ba, Th and U.Therefore, it is more reasonable to take the China C point as the Sinian-Cambrian boundary at the Maidiping section rather than the China A, China B or China D points.

关 键 词：事件地层学 中子活化分析 震旦纪 寒武纪 

分 类 号：P534[天文地球—古生物学与地层学]