Review on coal petrographic indices and models and their applicability in paleoenvironmental interpretation
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- 作者：Souvik Sen
- 关键词：Key wordscoal ; maceral ; petrographic indices ; peat forming environment
- 刊名：Geosciences Journal
- 出版年：2016
- 出版时间：October 2016
- 年：2016
- 卷：20
- 期：5
- 页码：719-729
- 全文大小：478 KB
- 刊物类别：Earth and Environmental Science
- 刊物主题：Earth sciences
Geosciences - 出版者：The Geological Society of Korea, co-published with Springer
- ISSN：1598-7477
- 卷排序：20
文摘
Organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions. This allows the relation of coal composition to mire ecosystems or environments. Coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments. Many authors proposed relations between specific maceral assemblages and/or micro-lithotypes and peat forming environments. The key controlling factors which affect peat environment include hydrogeology, redox, pH, vegetation type, clastic influx, sedimentation and peat accumulation rate etc. Recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models. The main reasons for the failure of the petrographic models are–over-simplification of the effects of humification on tissue preservation vs. destruction, the use of post-diagenetic processes (e.g., geochemical gelification) in determining depositional environments, changes in petrographic composition related to floral evolution, geological age, rank increase and compaction, lack of distinction between different inertnite maceral in some models. Here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo-environmental reconstruction are discussed. A multi-disciplinary approach including petrography, palynology, chemistry etc. has been recommended, which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation.