河南省泌阳凹陷安棚地区古近系核桃园组含碱地层层序特征及其意义

泌阳凹陷位于南襄盆地东南缘,为一西北浅、东南深的陆相断陷型盆地,其沉降中心安棚地区古近纪发育巨厚的白云岩地层,主要天然碱矿层赋存于核桃园组核三段上部和核二段下部,并与白云岩地层密切相关。基于岩心、录井与地震等资料,该区古近系核桃园组含碱岩系地层划分为3个二级旋回,进一步划分为8个三级旋回。所含天然碱矿层位于基本层序顶部、二级或三级旋回的上部,含碱岩系地层层序由(纹层状)白云岩到天然碱矿层规律性变化。根据天然碱矿层垂向变化规律进行找矿预测和钻探中预判矿层位置,已经取得较好效果。同时根据该区盐类矿产沉积旋回的研究,一级旋回顶部有钾盐的显示,预示该区有寻找钾盐的可能。

Sequence stratigraphy characteristics and its significance of alkaliferous strata of the Paleogene Hetaoyuan Formation in Anpeng area,Biyang sag in Henan Province

Biyang sag,located in the southeast margin of the Nanxiang Basin,is a continental faulted basin and shallower in the northwest than in the southeast. In the central part of Anpeng area,dolostones with huge thickness developed in the Paleogene. The main ore deposits occurred in the upper Member 3 and the lower Member 2 of the Hetaoyuan Formation,and is closely related to dolomitic strata. Based on cores,logging and seismic data,the alkaline rock series stratum of the Paleogene Hetaoyuan Formation can be divided into three second-order cycles,and further can be divided into eight third-order cycles. The trona ore seam is located at the top of the basic sequence and the upper parts of the second-order cycle or third-order cycle,and the alkali rock stratigraphic sequence varies regularly from the laminated dolostone to the trona ore seam. According to trona ore seam vertical change rule, prospecting prediction and predicting seam position in drilling have made good effect. And according to the research of the salt mineral depositional cycle,there may be a potassic salt at the top of the first-order cycle,which indicates the possibility of discovery of potash deposits.