摘要
白云岩成因一直是地质学研究的热点领域。塔里木盆地塔东低隆起古城低凸起中—下奥陶统鹰山组发育厚层白云岩。为研究这些白云岩的成因,在岩心、薄片观测基础上,按照晶体粒度大小将白云岩分为泥晶白云岩、粉晶白云岩、细晶白云岩、中晶白云岩、粗晶白云岩,并对各类白云岩及缝洞充填物进行了稀土元素地球化学特征的研究。结果表明,各类白云岩及缝洞充填物稀土元素NASC配分模式分为6种类型:δCe弱正异常δEu正异常型、δCe负异常δEu强正异常型、δCe强负异常型、微右倾型、微左倾型和平坦型。分析上述6种白云岩及缝洞充填物的成因为:前2种类型形成于两期热液或不同演化阶段的同一期热液环境;第3种类型形成于蒸发泵模式;第4和第5种形成于两种性质不同的埋藏白云化流体;第6种则由渗透回流作用形成。古城地区鹰山组白云岩的成因非常复杂,成因模式多样,包括蒸发泵模式、渗透回流模式、埋藏白云化模式、热液白云化模式4种。
The origin of dolomites is still the hot spot in the geological research. The dolomites of the Yingshan Formation in Gucheng in the Tadong low uplift is discussed in this paper. Based on thin sections and cores, in accordance with the crystal size, the dolomites were divided into five types：micritic, powder crystalline, fine crystalline, medium crystalline, and coarse crystalline dolomites. Meanwhile, the REE geochemical characteristics of various types of dolomites and cave fillings were studied. Based on the results, the NASC（North American average shale） normalized REE distribution patterns of the dolomites and cave fillings in Yingshan Formation showed in the six types：weakly positive anomaly of δCe with positive anomaly δEu, negative anomaly of δCe with heavy positive anomaly δEu, heavy negative anomaly of δCe, tiny right deviation, tiny left deviation, and the flat types. Further, the study showed that the first two kinds of dolomites were formed in a hydrothermal environment; the third kind dolomite was formed in an evaporation pump mode; the fourth and fifth kind dolomites were formed in a buried dolomitizing fluid; and the last kind dolomite was formed in a seepage reflux mode. The dolomite origin of the Yingshan Formation in Gucheng is very complex with various genetic models, including the evaporation pump mode, seepage reflux mode, burial dolomitization mode, and hydrothermal dolomitization mode.
作者
郭春涛
李如一
陈树民
Guo Chuntao;Li Ruyi;Chen Shumin(College of Architecture and Surveying Engineering,Datong University of Shanxi,Datong 037003,Shanxi,China;Postdoctoral Research Station of Daqing Oilfield Company,Daqing 163453,Heilongjiang,China;Exploration and Development Research Institute of Daqing Oilfield Company,Daqing 163453,Heilongjiang,China)
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2018年第4期1121-1134,共14页
Journal of Jilin University：Earth Science Edition
基金
国家科技重大专项(2016ZX05047-001)~~
关键词
古城地区
鹰山组
白云岩
地球化学
稀土元素
成因
塔里木盆地
Gucheng area
Yingshan Formation
dolomite
geochemistry
rare earth element
origin
Tarim basin
