中南大学学报（自然科学版）Issue(1)：187-197,11.DOI:10.11817/j.issn.1672-7207.2016.01.026
贺兰山北段古元古代S型花岗岩岩石地球化学、锆石U-Pb年代学及其地质意义
Zircon U-Pb age and geochemical characteristics of the Paleoproterozoic S-type granite in the northern part of Helanshan and its geological significance
摘要
Abstract
Petrographic, geochemical and zircon U-Pb geochronological studies were performed on porphyritic granite in northern part of Helanshan area to discuss its formation mechanism and the nature of its source rocks. The results show that porphyritic granite has high n(Al 2 O 3 )/n(Na 2 O+K 2 O)(i.e., A/CNK, 1.18−1.29), low w(FeOt)/w(MgO) ratios (less than 10), low P2O5 (mass fraction ranging from 0.15%to 0.22%) and high K2O (mass fraction varying between 5.09%and 5.86%) contents, indicating that it belongs to peraluminous S-type granite. It is enriched in light rare earth elements (LREE) with significant differentiation between LREE and heavy rare earth elements (HREE), and shows markedly negative Eu anomalies (δ(Eu)=0.19−0.49). It is also enriched in large ion lithophile elements (LILE), e.g. K and Rb, and depleted in high field strength elements (HFSE), such as Nb, Ta, Zr, Hf and Ti. The porphyritic granite has similar trace and rare earth element characteristics to those of khondalites, suggesting it could be derived from the partial melting of khondalites. Low w(CaO)/w(Na2O), high w(Rb)/w(Sr) and w(Rb)/w(Ba) suggest that the protolith of khondalites could be pelite, or high mature sedimentary rocks with predominant proportion of pelite, indicating they are deposited in a passive rather than an active continental margin. LA-ICP-MS zircon U-Pb age of porphyritic granite is (1 922±31) Ma, which is contemporaneous with 1.92−1.90 Ga magmatic and metamorphic events in Khondalite Belt, and that reflects the tectonic transformation from compression to extension.关键词
S型花岗岩/孔兹岩带/贺兰山北段/古元古代/地球化学/华北克拉通Key words
S-type granite/Khondalite Belt/northern part of Helanshan/Paleoproterozoic/geochemistry/North China Craton分类
天文与地球科学引用本文复制引用
刘金科,张道涵,魏俊浩,付乐兵,谭俊,王大钊,施海鹏,王艺龙..贺兰山北段古元古代S型花岗岩岩石地球化学、锆石U-Pb年代学及其地质意义[J].中南大学学报（自然科学版）,2016,(1):187-197,11.基金项目
国家自然科学基金资助项目(41302065，41102047)；中央高校基本科研业务费专项资金资助项目(CUG120702， CUG120842)(Projects(41302065,41102047) supported by the National Natural Science Foundation of China （41302065，41102047）
Projects(CUG120702, CUG120842) supported by the Fundamental Research Founds for National University, China University of Geosciences (Wuhan)) （CUG120702, CUG120842）
