华北地台金伯利岩岩浆活动时代讨论

The Discussion on the Ages of Kimberlitic MagmaActivity in North China Platform

华北地台金伯利岩岩浆活动可分为三个时期：（１）中元古代金伯利岩和钾镁煌斑岩岩浆活动期，以鄂尔多斯陆核边缘山西阳高岩区为代表（１６４９～１８１１Ｍａ）；（２）古生代金伯利岩岩浆活动，以冀鲁辽陆核边缘的铁岭岩区、中部的复县和蒙阴岩区为代表（含矿金伯利岩，４５７～４６２Ｍａ）；（３）中～新生代金伯利岩岩浆活动时期，以鹤壁和涉县岩区为代表（１１７～５２Ｍａ）。含矿金伯利岩岩浆活动与华北地台中奥陶世晚期的造陆抬升作用有关。这类岩浆形成时必须处于克拉通岩石圈底部有小的热扰动以及流体作用的条件，而过高的地温梯度反而起到破坏金刚石保存的作用。

Three main periods of primarily kimberlitiic magma activity can be divided, namely (1)mid Proterozoic kimberlitic and lamproitic magma activity represented by Yanggao field, the margin of Ordoscontinental nucleus in North China platform (1649～1811Ma), (2) Palaeozoic kimberlitic magma activity represented by Tieling, Fuxian and Menyin fields, the Ji-lu-liao continental nucleus in north China platform, the diamondiferous kimberlites were emplaced in 457～462Ma. (3) Mesozoic-Cenozoic kimberlitic magma activity represented by Hebi and Shexian fields, Ji-lu-liao continental nucleus (52～117Ma). Diamondiferous kimberlite aetivity related to epeirogeny and uplift of North China platform in mid Ordovician. Origin of kimberlitic magmaonly needs a little heat disturbance with deep-seated fluid supply in lithospheric root (the base of thick lithosphere) at shield geotherm structure. In contrast, overheating condition of lithosphere will not preserve diamonds in the mantle. Therefore, orogenic movement with rising temperature and uplifting as thenosphere is notfavorable for the formation of diamondiferous kimberlites.