Study on petrochemistry and hafnium isotope in Yishui Complex, Shandong Province
山东沂水杂岩岩石化学及锆石Hf同位素研究

Yishui Complex in Shandong Province is mainly composed of meta-basic rocks with high amphibolite facies to granulite facies metamorphism and (hypersthene-bearing) granite bodies. In this article, the authors researched the petrochemical and hafnium isotopic characters of zircons of four kinds of rocks including hypersthene-bearing biotite plagio-amphibolites, garnet-bearing hornblende two-pyroxene plagioclase granulites, spinel and garnet-bearing hornblende two-pyroxene granulites and Yinglingshan granite-gneiss. The research results are as follows: (1)Hypersthene-bearing biotite plagio-amphibolites and garnet-bearing hornblende two-pyroxene plagioclase granulites have different enrichment of Sr, K, Rb, Ba, Ce, Th and light rare earth elements, these indicate that their primary rocks experienced different degree of partial melting; (2)Yinglingshan granite-gneiss was formed by partial melting of meta-basic rocks came from the depleted mantle; (3)All the depleted mantle model ages of Hf of the studied meta-basic rocks are younger than the Yinglingshan granite-gneiss, it may show that the studied meta-basic rocks are not the primary rocks of Yinglingshan granite-gneiss and older meta-basic rocks must be exist in Yishui Complex. Or show that their capacity in conserving hafnium isotopic system are different; (4)Consulting ages from other published literatures, the authors consider that the crustal growth of Yishui area was started at about 3000Ma years ago and large scale of growth was during 2530~2740Ma.