铜陵鸡冠山岩体中的堆晶淬冷包体

Cumulus-Quenched IncIusions in the Jiguanshan Pluton of Tongling,Anhui Province

安徽省铜陵市鸡冠山岩体中发现一种新型的岩石包体──堆晶淬冷包体。这是一种辉石堆晶岩，中粒，含辉石８０％，磷灰石８％，磁铁矿４％，基质８％。基质只存在于部分辉石粒间，以斜长石为主，细粒结构，向包体边缘变为微粒结构的淬火边。这是辉石等矿物堆积后，粒间熔体尚未固结时，被对流岩浆冲碎带向浅部骤冷形成的。包体与寄主岩石具有一致的辉石成分和Ｎｄ、Ｓｒ同位素初始比值，表明包体属同源包体。

A new type of inclusions, cumulus-quenched rock inclusions,was disco- vered in the Jiguanshan pluton of Tong ling,Anhui Province.Being a kind of cumulus rock with fine-grained texture,the inclusions consist approxima- tely of 80%pyroxene,8%apatite,4%magnetite and 8%groundmass. The groundmass,noted for the domination of plagioclase and fine-grained te- xture,is merely present among some pyroxene grains and grades into a que- nched rim towards the edge of an inclusion. This rim was formed by quen- ching when a pyroxene inclusion was broken and brought to the shallow pla- ce after the cumulation of pyroxene but before the crystallization of inte- rgranular melt.The inclusions are consistent with the host rocks in pyroxene composition and initial Nd and Sr isotopic ratios,suggesting that they are cognate inclusions.