冀东迁安英云闪长质杂岩体的成因与演化

迁安地区英云闪长质杂岩是部分熔融产生的岩浆沿迁西群与单塔子群两个变质地体之间的接触部位上侵形成的,经历了结晶分异作用演化,构造应力场对杂岩体有着重要影响,岩石学,地球化学等方面的特征反映着杂岩体的形成是该区太古代末期地壳活动中的重要地质事件之一.

THE ORIGIN AND EVOLUTION OF TONALITIC COMPLEX IN QIANAN, EASTERN HEBEI PROVINCE

In Qianan District, Eastern Hebei Province Crops a series of gneissic tonalitic-granodioritic complex formed in Archean, Which lies in the boundary area between Qianxi Group metamorphic rocks of granulite facies and Dantazi Group metamorphic rocks of amphibolite facies. This set of complex has its typical characeristics in the aspects of the petrological characters, the intrusive state and the tectonic baekground of its formation, which is one of the most important events of crust movement in later Archean in this district.1. The tonalitic complex is originated from tonalitic-granodiortic magma which is a product of partial melting of basic rocks rich in LREE and intrudes up along weak structure and crystallizes in it.2. The tonalitic-granodioritic magma experienced crystallization differentiation so that granitic magma had been formed in later stage of the evolution.3. The formation and evolution of the tonalitic complex is because that it occure in such an active tectonic environment which is in the connected area betweem two different tectonic units, i. e., metamorphic terrain of Qianan Group and Dantazi Group. Tectonic stress field plays an important role in this event.4. The activity of large nappe structure thrusts the deep-seated tonalitic complex to upper levels, so that the tonolitic complex in the west is situated in the same horizon in the earth''s crust as the granodioritic-granitic complex in the east.