胶东地区晚侏罗世玲珑期花岗岩

Granites in Late Jurassic Linglong Period in Jiaodong Area

摘要:

玲珑期花岗岩是胶北地区出露规模最大的中生代岩体，与胶东金矿在空间上关系密切，主要岩性有细粒混合岩化花岗岩、细粒二长花岗岩、中细粒二长花岗岩、中粒二长花岗岩、中粗粒二长花岗岩、含斑粗中粒二长花岗岩及花岗伟晶岩，含特征矿物石榴石，暗色矿物黑云母以铁质黑云母为主，少量镁质黑云母，为一套弱过铝质高钾钙碱性岩系的铁质花岗岩，具有富集大离子亲石元素Rb、K、Ba及高场强元素U，亏损Nb、P、Ti等元素，富集Zr、Hf元素，Sr元素多数正异常等特征，形成时代为146～166Ma，属于晚侏罗世。该期花岗岩为地壳重熔型花岗岩，具有复杂的物源组成，以新太古代胶东岩群及TTG质岩石、古元古代变质地层为主，同时苏鲁造山带新元古代花岗质片麻岩及晚三叠世同造山岩石也有参与。玲珑期花岗岩的形成与华北板块与扬子板块陆陆碰撞造山密切相关，是地壳持续增厚，中下地壳部分熔融的产物。

Abstract:

Granites in Linglong period is the most widely distributed Mesozoic rock in Jiaobei area. It is closely related to Jiaodong gold deposit in space. Main lithologies of Linglong period granites are fine grained migmatitic granites, fine grained monzonite, medium-fine grained monzonite, medium-grained monzonite, medium-coarse grained monzonite, coarse-grained monzonite and granitic pegmatite. It contains garnet with characteristic mineral. The biotite is mainly iron biotite with a small amount of magnesium biotite. It is a set of weak peraluminous high-K calc-alkaline rock series iron granite. It is characterized by enrichment of large-ion lithophile elements Rb, K, Ba and high field strength element U, depletion of Nb, P, Ti, enrichment of Zr, Hf, and most of the positive anomalies of Sr. It is formed in 146~166Ma in late Jurassic. Granites in Linglong period is crustal remelting type granite with complex material source composition, and dominated by Archean Jiaodong group and TTG rocks and Paleoproterozoic metamorphic strata. At the same time, Neoproterozoic granitic gneiss and late Triassic synorogenic rocks in Sulu orogenic belt are also involved. Granites in Linglong period is the product of continuous thickening of the crust and partial melting of the lower and middle crust, which is closely related to the continental collision of the North China Plate and the Yangtze Plate.