古湖泊学研究——以桦甸断陷盆地为例
- 收稿日期:
1900-01-01
- 修回日期:
1900-01-01
- 刊出日期:
2010-10-10
摘要: 古湖泊学是研究湖泊系统历史演变的科学,是一门综合性很强的地球科学。本文综述了古湖泊学的定义、研究现状及常用的研究方法,并以吉林桦甸古近纪断陷含油页岩湖盆为例进行了应用。桦甸盆地为小型半地堑盆地,盆地南缘F1断裂控制了古近系湖泊演化特征。桦甸盆地富含油页岩资源,具有开展古湖泊学研究的优势条件。桦甸油页岩具明显的黑白相间的双层结构特征,有机质条带和陆源碎屑颗粒呈现良好的韵律互层,有机质呈现褐色或黑色条带,夹杂石英、长石颗粒的粘土矿物呈白色条带。根据泥岩和油页岩的有机碳含量垂向变化特征,桦甸组古湖泊生产力演化趋势为:中部含油页岩段>上部含煤段>下部含黄铁矿段,反映油页岩沉积时,湖盆古湖泊生产力最高。根据油页岩岩石学特征、V/(V+Ni)、Sr/Ba和B/Ga等元素比值分析,中部含油页岩段时期,表现出一种淡水与半咸水—咸水交替变化的沉积演变过程,可以形成一定程度的盐度分层,使底层水处于缺氧环境,有利于有机质的保存。随着古湖泊学的不断发展,它已经在油气资源勘探开发及全球环境与气候变化等领域发挥了重要作用,但仍存在一些理论及方法问题需要湖泊地质工作者的不断努力与探索。
Paleolimnology Study: Taking Huadian Fault Basin as an example
- College of Earth Sciences, Jilin University, Changchun 130061
- Received Date:
1900-01-01
- Rev Recd Date:
1900-01-01
- Publish Date:
2010-10-10
Abstract: Paleolimnology is a science to study the historical evolution of lake systems, which belongs to highly comprehensive geosciences. This paper presents a review on the definitions, research status and commonlyused research methods in paleolimnology, and takes the Paleogene oil shale bearing lake in Huadian basin, Jilin Province, as a case study. Huadian Basin is a smallscale halfgraben basin, and F1 fault in the southern margin of the basin controls the Palaogene lake evolution. Huadian Basin that is rich in oil shale resources has unique advantages for paleolimnological studies. Huadian oil shale shows characteristics of doublelayered structure, which consists of alternatively white and black thin layers. The organic and terrestrial mineral detritus layers rhythmically alternate each other the organic layers show black or brown, while the other ones of quartz, feldspar and clay minerals show white. According to the vertical variations of TOC content, we interpret that the paleoproductivity of Huadian Basin varies as Middle Member(oilbearing) > Upper Member (coalbearing) > Lower Member (pyritebearing). Such a variation indicates that paleoproductivity was the highest when the oil shale was forming. From the petrography and mineral features of oil shale, the ratios of V/V+N, Sr/Ba and B/Ga, we conclude that the paleowater characterizes as alternatively variation of fresh to brackishsaline water, which was a preferment environment for the lake stratified. The organism was well preserved because of the stratifyingcaused anoxic in the bottom water. With the development of paleolimnology, it is acting as an important role in the fields of hydrocarbon exploration and the studies for global environment and climate changes. However, challenges in theories and methods show up in front of paleolimnologists which are waiting for continuous endeavor and exploration.