山东燕山晚期岩浆岩的岩石组合与某些岩石化学特征

ROCK ASSEMBLAGE AND SOME PETROCHEMICAL CHARACTERISTICS OF THE LATE YANSHANIAN MAGMATIC ROCKS IN SHANDONG

燕山晚期,山东地域构造—岩浆活动剧烈,特别是沂沭深断裂带(郯庐断裂带山东境内段)活动异常频繁且急烈,切割深度已达上地幔,其两侧的鲁西和鲁东地块亦形成了复杂的断裂系,导致了多旋回的火山喷发和岩浆侵入,各自形成了一套代表性的岩浆岩岩石组合,奠定了三大岩石区之格局。各岩石区之岩浆岩化学成分既有关联性又有差异性,表现在岩浆岩的酸度和碱度具有明显的变异。之所以如此,显然与山东所处的大地构造位置,即太平洋板块与欧亚板块相互碰撞的陆缘地带密切相关。

The tectonic—magmatic activities in Shandong during the late Yanshanian stage were intense. This holds especially true in the Yishu fault zone (a part of the Tanlu fault belt within Shandong), where the activities were quite frequent and the faults thus formed cut deep down into the mantle. On the two sides of the fault zone (i. e. W and E Shandong blocks)complex fault systems were formed, leading to the polycyclic volcanic eruption and magmatic intrusion, which in turn formed a set of typical magmatic rock association, respectively, that has established the framework of the three major petrographic provinces. The chemical compositions of the magmatic rocks from the three petrofacies provinces show both similarities and differences as revealed by the strikingly different acidity and alkalinity of the rocks. This is apparently related to the tectonic setting of Shandong,namely, the continental margin where the Pacific Plate collided against the Eurasian Plate.