辽东半岛早白垩世地壳运动性质——来自兰河峪岩体的证据

THE CRUSTAL MOVEMENT CHARACTERISTICS OF LIAODONG PENINSULA IN EARLY CRETACEOUS EPOCH: Evidence from the Lanheyu intrusive rock

通过对辽东半岛兰河峪岩体锆石SHRIMP U-Pb年龄和地球化学特征进行研究,将兰河峪岩体高钾钙碱性系列岩石形成时代归入早白垩世.本溪县兰河峪岩体形成的压力环境为0.8-1.0 GPa,推测本区的花岗岩岩浆形成时源区物质来源于30-40 km的地壳深处,地壳较薄.在花岗岩Rb-（Y＋Nb）图和Y-Rb图解中,所有的样品都落入板内花岗岩区内,判断当时辽东陆块处在后造山期,岩石圈减薄环境中,反映当时处于伸展构造环境中.兰河峪花岗岩为辽东陆块在早白垩世处于伸展环境中提供了又一有利的证据.

With study on the zircon SHRIMP U-Pb age and geochemical characteristics of the Lanheyu intrusive rock inLiaodong peninsula, the high-K calc-alkali series rock is proved to be formed in Early Cretaceous Epoch. According to theformation pressure of 0.8 - 1.0 GPa of the Lanheyu rock body in Benxi region, it is speculated that the source materials ofgranite magma came from 30 - 40 km deep below the thin crust. In the Rb-（Y＋Nb） and Y-Rb diagrams of granite, all thesamples fall into the WPG （within plate granite） area, concluding the Liaodong block was in the post-orogenic stage withlithosphere thinning, which reflected an extensional tectonic environment. The Lanheyu granite provides a favorableevidence for the extensional environment during the Early Cretaceous Epoch of Liaodong continental block.