This paper reports the analysis on cores and rock slices, data on seismic and logging activities, characteristics of core samples, and the paleogeographic background of the Yingcheng Formation of the Xujiaweizi faulte...This paper reports the analysis on cores and rock slices, data on seismic and logging activities, characteristics of core samples, and the paleogeographic background of the Yingcheng Formation of the Xujiaweizi faulted depression in the Songliao Basin. The results show that some of the volcanic rocks were formed during subaquatic eruptions. These subaqueous volcanic rocks are further characterized by the interbedded black mudstone and tuffite, the presence of double-layer perlite enclosing aphyric or sparsely phyric rhyolite, the presence of a bentonite layer, and the coefficient of oxidation （Fe203/FeO）. The types of rocks are volcanic breccia, lava breccias, perlite, rhyolite, tuff and sedimentary tuff. The subaquatic eruptions are distributed mainly in Wangjiatun, Shengping, Xuxi, Xuzhong, and Xudong. The XS-I area is the most typical. The organic abundance of over- burden mud rocks within the volcanic rocks of the Yingcheng Formation indicates that these rocks represent high-quality source rocks. The analysis also shows that continental subaquatic volcanic eruptions provide a rich supply of minerals and en- ergies for the lake basin and increase the organic matter content in the water. Moreover, the water differentiation provides a good reducing environment for the conservation of organic matter, and is beneficial for the formation of high-quality source rocks. Finally, we propose a hypothesis to describe the mode of subaquatic eruptions and the formation of high-quality source rocks.展开更多
基金supported by National Basic Research Program of China(Grant No.2009CB219306)Key-Lab for Evolution of Past Life and Environment in Northeast Asia of Ministry of Education,211 Project of Jilin University and Basic Scientific Research Business Funds Program of Ministry of Education in 2009(Innovative Team Development Plans of Jilin University)
文摘This paper reports the analysis on cores and rock slices, data on seismic and logging activities, characteristics of core samples, and the paleogeographic background of the Yingcheng Formation of the Xujiaweizi faulted depression in the Songliao Basin. The results show that some of the volcanic rocks were formed during subaquatic eruptions. These subaqueous volcanic rocks are further characterized by the interbedded black mudstone and tuffite, the presence of double-layer perlite enclosing aphyric or sparsely phyric rhyolite, the presence of a bentonite layer, and the coefficient of oxidation （Fe203/FeO）. The types of rocks are volcanic breccia, lava breccias, perlite, rhyolite, tuff and sedimentary tuff. The subaquatic eruptions are distributed mainly in Wangjiatun, Shengping, Xuxi, Xuzhong, and Xudong. The XS-I area is the most typical. The organic abundance of over- burden mud rocks within the volcanic rocks of the Yingcheng Formation indicates that these rocks represent high-quality source rocks. The analysis also shows that continental subaquatic volcanic eruptions provide a rich supply of minerals and en- ergies for the lake basin and increase the organic matter content in the water. Moreover, the water differentiation provides a good reducing environment for the conservation of organic matter, and is beneficial for the formation of high-quality source rocks. Finally, we propose a hypothesis to describe the mode of subaquatic eruptions and the formation of high-quality source rocks.
