PROBLEMS ON PRECAMBRIAN STRATA OF THE JIAOBEI TERRANE,SHANDONG PROVINCE

An intensive study of Precambrian strata of the Jiaobei terrane is of great significance forsolving the problems on geological evolution,tectonic framework and mineralization,The au-thors hold that the Jiaodong Group can be dismembered into three units:the strata older than2500 Ma are the first-phase greenstone,those ranging in age from 2500 to 2300 Ma are the sec-ond-phase greenstone,and those from 2300 to 1850 Ma are khondalite. It is advisable that Sini-an be still applied for the age of the Penglai Group before enough evidence is obtained to negatethis age. Based on the above-mentioned stratigraphic sequences,the Precambrian tectonicframework of the Jiaobei terrane can be described as an onion-shaped structure with the meta-morphic core composed of the Jiaobei and Qishan Groups as the center surrounded by the Fen-zishan Group.