【摘要】 地处粤西和桂东南的云开地区前寒武系顶部的硅岩沉积建造（“震旦系Ｄ 组”），具有层状、纹理状、块状和假角砾状构造。其中的元素显著地贫ＴｉＯ２ 和Ａｌ２Ｏ３， 大部分微量元素相对于地壳克拉克值亏损， 但Ｂａ、Ｓｂ、Ｈｇ、Ａｇ 和Ｂｉ等少数几种元素例外地富集； 在Ａｌ－ Ｆｅ－ Ｍｎ 三元图中投影落在热水沉积区域； 以ＲＥＥ总量低为特征， 平均稀土元素分布型式落在世界上已知典型热水沉积物的上、下限之间。上述特征说明， 该硅岩建造是典型的热水沉积成因产物。更多还原

【Abstract】 The Sedimentary chert formation (Sinian D fromation) at the top of the Precambrian in Yunkai area,western Guangdong and southeastern Guangxi displays banded,lamellated,massive and pseudobrecciated structures.This formation is poor in TiO 2 and Al 2O 3 with most of the trace elements depleted in relation to their clarke values,although a few including Ba,Sb,Hg,Ag and Bi are exceptionally enriched;in Al-Fe-Mn triangular diagram,the sample points fall into the hydrothermal sedimentary field;total REE is characterized by low value and the average REE distribution pattern conforms with those of the worlds typical hydrothermal sediments.All these features are indicative of a typical hydrothermal derivation.更多还原