二论蒙阴地区金刚石原生矿的形成时代

The Second Discussion on the Age of Primary Diamond Ore-forming in Mengyin Area of Shandong Province

摘要:

目前不少学者认为，蒙阴地区金刚石原生矿形成于加里东期。然而这一观点，与依据多年来野外工作取得的实际资料所给出的结论不符。加里东期鲁西地区NW向断裂还不存在，NNE走向的上五井断裂更不会存在，这些晚于加里东的断裂不可能是金伯利岩储存的场所。大量金伯利岩岩脉、岩管的展布特点，岩体的完好程度，以及它们与上述断裂的相互关系，和金伯利岩切穿辉绿岩、斜长煌斑岩、正长斑岩等，都说明了金刚石原生矿的形成时代不是在加里东期，而是在中生代后期。

Abstract:

At present, many scholars believe that the age of primary diamond ore-forming is in Caledonian. However, this view is not accordance with the conclusion gained by field work. The fault with the trend of NW was not existed in Luxi area in Caledonian, and Shangwujing fault with the trend of NNE in western Shandong was not existed as well. The forming age of these faulst was later than Caledonian, so they can not be the storage space for the forming of kimberlite. The distribution characteristics of kimberlite vein or pipe, the soundness of kimberlite rock, the relation with the above mentioned faults, and the diabase, lamprophyre and syenite porphyry was cut through by kimberlite all showed that the ore-forming age of primary diamond was in the late Mesozoic, not in Caledonian.