An accurate record of volcanic ash fall deposition as characterized by dispersed organic matter in a lower Permian tonstein layer (Faxinal Coalfield, Paraná Basin, Brazil)
An accurate record of volcanic ash fall deposition as characterized by dispersed organic matter in a lower Permian tonstein layer (Faxinal Coalfield, Paraná Basin, Brazil)
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DOI：
10.1344/105.000001835
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发表时间：
2013
期刊：
影响因子：
1.5
通讯作者：
Margarete Wagner Simas;M. Guerra-Sommer;J. G. M. Filho;M. Cazzulo-Klepzig;M. Formoso;Isabela Degani-Schmidt
中科院分区：
文献类型：
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作者：
Margarete Wagner Simas;M. Guerra-Sommer;J. G. M. Filho;M. Cazzulo-Klepzig;M. Formoso;Isabela Degani-Schmidt
首次对巴西南巴拉那盆地法克斯纳尔煤田（Sakmarian, Southern Parana Basin）与煤层互层的tonstein层中分散有机质进行了表征。花粉粒簇的沉积受到强烈的灰落过程的高度影响，这可能发生在生殖结构的季节性开裂期间。保存完好的植物碎屑的上部和下部叶角质层粘在一起，表明灰在这种材料上的迅速下降阻碍了有机生物降解。在汤斯坦层顶部保存的似乎是本地的葡萄球菌菌落是这一层的水下沉积的证据。角质层和木质部植物碎屑的变暗可归因于不同的原因：沉积过程中灰落的热影响、灰的化学作用、低水位条件下有机物的长期氧化或野火对植物器官的燃烧。沿顿斯坦层的分散有机质分析表明，有机质演替反映了沉积地点周围不同植物地层（草本蕨类和乔木蕨类）的组成。
For the first time, the dispersed organic matter in the tonstein layer interbedded with a coal seam in the Faxinal Coalfield (Sakmarian, Southern Parana Basin, Brazil) is characterized. The deposition of clusters of pollen grains was highly influenced by the intense ash fall process that probably occurred during seasonal dehiscence of reproductive structures. The well-preserved phytoclasts with their upper and lower leaf cuticles stuck together indicate that the rapid fall of ash on this material hindered organic biodegradation. The preservation of seemingly autochthonous Botryococcus colonies at the top of the tonstein layer is evidence of the subaqueous deposition of this layer. The darkening in cuticles and xylem phytoclasts can be attributed to different causes: the thermal influence of ash fall during deposition, chemical effects of the ash, prolonged oxidation of organic matter in low water level conditions or the burning of plant organs by wildfires. Analyses of dispersed organic matter along the tonstein layer showed that the organic matter succession reflects the composition of different plant strata (herbaceous pteridophytes and arboreal glossopterids-cordaitaleans) around the deposition site.