| PDF: | |
| Time: | 2010 |
| Journal: | Journal of Jilin University (Earth Science Edition) |
| Volumn: | 40 |
| Issue: | 3 |
| Pages: | 469-481 |
| Type: | EI |
| Author: | Pujun Wang,Changhai Yin,Rukai Zhu,Lin Yan,Weihua Bian,Yulong Huang,Yanxiong Wu |
Abstract: | The volcanic products in China were classified into 4 groups including lava, pyroclast bearing lava,tephra and tuffites, according to the research on the ancient volcanic rocks of the Song liao basin in Cretaceous and the Junggar basin in Carboniferous and also on the Quaternary volcanoes like Changbai and Wudalianchi.The former two groups are consolidated by cooling/crystallization and the latter two by compaction. Thirty four essentiall ithofacies/intrafacies were further subdivided and described in detail concerning their structure/texture, composition/component, distribution and origin. Typical examples ancient and modern are presented in photographs related to each intrafacies. There are both sameness and difference between modern and ancient volcanic products. Diversity of lavas such as coherent massive, columnar joint, welded, pillow and breccia can survive in the long geological history, becoming relatively more abundant in the ancient volcanoes. On the other hand, pumice, aa and block lavas become less and less with time owing to their poor preservation because they are generally on top or edge of a volcanic succession and/or with features of being easily eroded and transported. For most ancient volcanoes like those in the Mesozoic Songliao basin, it is very common that eruptions are mixed pattern between the fissure and the central, i.e. most single central vents are associated with or ranged along some major faults. |