摘要
分析川西北地区泥盆系观雾山组白云岩形成过程的流体特征,探讨其形成机理。通过对江油县马角坝、青川县何家梁及平武县甘溪剖面观雾山组白云岩的岩石学特征研究,按照晶粒大小将其分为细-粉晶白云岩、细晶白云岩和中晶白云岩3类;根据稀土元素研究流体性质,推测白云岩成因。白云岩稀土总含量较低,3种白云岩具有相似的稀土配分模式,并且都与泥晶灰岩配分模式类似,表现出轻稀土富集、重稀土亏损;样品均呈现Ce不明显负异常(均值0.94)、Eu负异常(均值0.81)、Y明显的正异常(均值2.98)。稀土元素地球化学特征指示白云岩化流体主要是海源性流体,成岩环境为相对封闭的还原环境。
Based on the study of petrology characteristics of dolomite from three outcrops, the fluid characteristics in the formation process of dolomite in Devonian Guanwushan Formation, northwest Sichuan Basin are analyzed and its formation mechanism is investigated. Dolomite in this area can be divided into three types in terms of grain size： silty fine grained dolomite, fine grained dolomite and medium grained dolomite. The analysis of REE shows that all the three types have low REE content expect few samples, with average of 25 ppm for silty fine grained dolomite, 18.4 ppm for fine grained dolomite and 18 ppm for medium grained dolomite. It also indicates that the dolomite possesses relatively high Y/Ho ratios （〉40） and most of samples lie in the ranges of 43.5-86.9, characteristic of ocean environment. The dolomite is enriched in LREE and depleted in HREE, with negativeanomalies of Eu （average 0.94）, slight negative anomalies of Ce （average0.81）,positive anomalies of Y （average 2.98） and positive anomalies of La. The poor correlation of RE Mn contents suggests a limited effect of terrigenous clastics on the dol dolomite have similar REE patterns and similar to that the dolomite is formed by fluids of marine system 81）, positive anomalies of REE＋Y content with Fe and omite. Different types of the REE patterns of limestone. The study indicates origin in a relatively close and reducing digenetic system.
作者
邓予炜
侯明才
陈安清
马华灵
董翼昕
罗文
黄树光
DENG Yuwei;HOU Mingcai;CHEN Anqing;MA Hualing;DONG Yixin;LUO Wen;HUANG Shuguang(State Key Laboratory of Oil and Gas Reser＇voir Geology and Eccploitation,Chengdu University of Technology,Chengdu610059,China;North-crest Sichuan Gas Field,South-crest Oil and Gas Field Branch,PCL,Jiangyou 621709,China)
出处
《成都理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2018年第3期282-291,共10页
Journal of Chengdu University of Technology: Science & Technology Edition
基金
国家科技重大专项(2017ZX05008-005-009)
关键词
白云岩
稀土元素
观雾山组
泥盆系
川西北
dolomite
rare earth element
Guanwushan
Formation
Devonian
Sichuan Basin
