作　　者： ; ; ; ;

机构地区： 中国科学院地球化学研究所

出　　处： 《地质论评》 2004年第6期577-586,共10页

摘　　要： 本文从岩石学和地球化学方面对鲁西地区淄博盆地几个岩区的基性脉岩的成因和源区性质进行了探讨。脉岩的 K- Ar年龄 (72 .2～ 116 .3Ma)表明其为晚中生代 (白垩纪 )岩浆作用的产物。主量元素显示该脉岩总体属钙碱性系列。微量元素特征表明脉岩为交代富集地幔部分熔融作用的产物 ,成岩过程可能同时经历了橄榄石、单斜辉石、Ti- Fe氧化物以及少量斜长石的分离结晶作用。 Pb同位素组成 :2 0 8Pb/2 0 4 Pb=36 .30 8～ 38.32 9;2 0 7Pb/2 0 4 Pb=15 .170～ 15 .6 32 ;2 0 6 Pb/2 0 4 Pb=16 .6 5 8～ 18.4 70 ,可以和下地壳组成相比 ,暗示成岩过程中存在大量下地壳物质的参与。岩浆在构造上受控于燕山造山带坍塌和沂沭断裂带 (郯庐断裂山东段 )的活动 (左行平移和伸展 ) ,但在上升侵位过程中没有遭受地壳物质的混染 ,且具有大陆边缘弧玄武岩的特性。这暗示岩浆早期鲁西地区存在古大洋板块 (苏 -鲁洋 )的俯冲作用 (即古俯冲作用 ) In this paper, analyses of major elements and trace elements for mafic dikes in several rock areas of the Zibo basin in West Shandong Province are reported. The K Ar ages of the dikes range between 72.16 Ma and 116.3 Ma, indicating that the mafic dikes are part of the result of Late Mesozoic magmatism. Based on petrology and geochemistry, the genesis and the source features of the dikes were studied. As a whole, the dikes are attributed to the calc\|alkaline series in terms of major elements. As regards trace elements characteristics, the dikes resulted from partial fusion of mantle source rock and, at the same time, might undergo fractional crystallization of ol, cpx, Ti-Fe oxide and weak plagioclase during the lithogenic process. 208 Pb / 204 Pb =36.308~38.329, 207 Pb / 204 Pb =15.170~15.632 and 206 Pb / 204 Pb =16.658 ~18.470,are similar to those of the lower crust, indicating that there exist a lot of lower crust material in the reservoir. During emplacement, magmas were not subjected to crustal contamination, but the dikes are controlled by the collapse of the Yanshanian orogenic belt and the action (left handed advection and extension) of the Tanlu fault, showing characteristics of CABM. This shows that there existed subduction of the paleo ocean plate (the Su Lu ocean) (namely paleosubdution) before magmatism.

关 键 词： 晚中生代 源区 地球化学 下地壳 岩石学 岩浆 鲁西地区 受控 性质 上升

领　　域： [天文地球] [天文地球] [天文地球] [天文地球]