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祥山和于埠变质辉长岩是胶北地块上古元古代变质镁铁质岩石的典型代表，辉长岩侵入古元古代荆山群野头组，产有'祥山式'岩浆熔离型铁矿，成矿的专属性指示辉长岩属于层状侵入体类型，形成于大陆伸展构造背景。在祥山变质辉长岩中获得了1851±9Ma的变质年龄，在于埠变质辉长岩中获得了2052±23Ma的锆石U-Pb成岩年龄和1834±5Ma的变质年龄。~2.05Ga的岩浆结晶锆石的eHf（t）值均为正值（+1.87~+3.64），一阶段Hf模式年龄（tDM）为2292~2381Ma（平均为2327Ma），指示于埠变质辉长岩源自古元古代中期的亏损地幔。于埠变质辉长岩的成岩年龄制约了荆山群野头组的沉积上限，荆山群中至少有一部分形成于2.2~2.05Ga之间，沉积于大陆裂谷-稳定大陆边缘的构造环境。祥山和于埠变质辉长岩中有少量斜长花岗岩与之伴生，这些斜长花岗岩具有类似于大洋斜长花岗岩的岩石特征，低K、Ti、Sr，高Na、Yb，形成于低压背景；从斜长花岗岩中获得了1848±8Ma和1873±5Ma的锆石U-Pb年龄，斜长花岗岩中的锆石Th/U比值较低（0.01~0.29），具有初始熔体中结晶锆石特征。结合斜长花岗岩的地球化学特征，推测它们是辉长岩部分熔融的产物，并指示~1.87Ga已由挤压构造体制转变为伸展构造体制。综合前人研究成果，胶北地块已识别出2.18~2.15Ga、~2.10Ga、~2.05Ga的三期双峰式岩浆岩构造组合，指示2.2~2.05Ga期间总体为伸展构造背景。因此建议胶-辽-吉活动带的形成演化过程划分为两个阶段，早期为大陆裂解-稳定陆缘演化阶段（2.2~2.0Ga），沉积了巨量的陆缘碎屑岩-碳酸盐岩建造；晚期为俯冲-碰撞造山阶段（2.0~1.85Ga），胶-辽-吉活动带褶皱造山。

在对固阳白云常合山花岗岩详细的野外地质调查基础上，对其岩相学、地球化学、锆石U-Pb年代学及Lu-Hf同位素特征进行了综合研究。白云常合山花岗岩的地球化学特征显示其具有高SiO2（70.68%~77.21%）、富碱（7.88%~9.21%）、高Fe2O3T/MgO（12.60~90.38）和10000×Ga/Al（3.63~6.17）值，低Al2O3（11.70%~13.23%）、MgO（0.06%~0.24%）、CaO（0.23%~1.20%）的特征；微量元素富集Rb、Th、K等，亏损Ba、Sr、Eu、Ti、P；稀土元素总量较高，轻稀土富集，重稀土亏损，呈现典型的右倾'海鸥型'分布模式，具有明显的Eu负异常。通过锆石饱和温度的计算，得到白云常合山花岗岩的结晶温度为824~957℃，平均值为903℃，表明其形成于高温环境。这些特征与A型花岗岩相一致。锆石LA-ICP-MS年龄测试结果显示，白云常合山花岗岩形成于~1720Ma；锆石eHf（t）=-1.84~+6.08，以正值为主，单阶段模式年龄和二阶段模式年龄分别为1.9~2.2Ga和2.5~3.2Ga，岩浆源区主要是新太古代新生地壳，在上升过程中可能受到古老地壳物质的混染。构造环境判别图解显示其为A1型花岗岩，且有板内岩浆的特点，因此白云常合山花岗岩应该是大陆裂谷岩浆活动的产物。结合区域上与裂解事件有关地质体的同位素年代学资料，认为白云常合山花岗岩应该是固阳地区年龄可靠的最早响应哥伦比亚超大陆裂解的岩体。

We have conducted an LA-ICP-MS in situ trace element study of garnet, epidote group minerals, phengitic muscovite and paragonite in rocks of basaltic and sedimentary protolith from an ultrahigh pressure metamorphic belt along Western Tianshan, China. The data are used to evaluate the capacity of these minerals for hosting incompatible elements in response to subduction-zone metamorphism (SZM). The results confirm existing studies in that the presence and stability of these minerals largely control the geochemical behaviors of elements during SZM.We found that redistribution of rare earth elements (REEs), Th and U into newly-formed minerals during progressive SZM precludes the release of these elements from the down-going ocean crust, which contradicts the common perception in models of slab-dehydration and flux-melting. This suggests that additional processes, such as the involvement of supercritical fluids or hydrous melts formed at depth are required to supply these elements to the mantle wedge for arc magmatism. In addition, the ready release of large ion lithophile elements (LILEs) by different minerals, and the high immobility of REEs in rocks of basaltic protolith indicate that the contribution of altered ocean crust after SZM may not be responsible for the correlated Sr–Nd (Hf) isotope systematics observed in oceanic basalts. That is, subducted ocean crust that has gone through SZM cannot be the major source material for ocean island basalts.