| 滇西保山地块中-晚二叠世地层划分、对比的现状和问题 |
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| 关键词:Yunnan Baoshan Block Permian subdivision and correlation |
| 基金项目:科技部科技基础性工作专项(编号:2006FY120300-9); 中国地质调查局项目(编号:1212010611801) |
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| Subdivision and Correlation of Mid-Late Permian Successions of the Baoshan Block,Western Yunnan:Status and Problems |
| Due to the rapid increase of magnesium carbonate and scarcity of fossils in the upper part of Middle-Late Permian sediments, as well as some historical and artificial reasons, the subdivision and correlation of successions of the said periods on the Baoshan Block remain uncertain. During the mapping course of geological maps of the scale of 1∶200,000 some 20 years ago, a number of formations were erected. Those comprise Middle-Late Permian sediments are the Bingma, Daaozi and Hewanjie formations in northern part of the Baoshan Block, the Yongde, Shazipo and Hewanjie formations in southern part, and the Manli and Shazipo formations in southwestern part. The shortcomings of the work at that time, which resulted in confusion in subdivision and correlation of the Middle-Late Permian sediments are: ①the Hewanjie Formation in the northern part was assigned to the Middle Triassic based on some bivalves, while the Permian foraminifers in its lower part were not properly studied; ②the Yongde Formation erected in the southern part included not only the red and variegated clastics in the lower part but also argillaceous limestones in the upper part; ③age indicated by fossils found in some beds were treated as the age of the whole formation, while the thickness of the formation and the corresponding temporal span were neglected. Scrutiny of the mapping data and extensive fieldwork permit us to make following interpretations: 1) the Manli Formation of the southwestern part, the lower part of the Yongde Formation in the southern part and the Bingma Formation in the northern part can be well correlated; 2) the Shazipo Formation of the southwestern part can be correlated with the limestones in the upper part of the Yongde Formation plus the Shazipo Formation in the southern part, and with the Daaozi Formation and the most of the Hewanjie Formation ( "Cracked limestone" ) in the northern part; 3) the Hewanjie Formation in the southern part can be correlated with the limestones and dolomitic limesones (often not well exposed or absent) in the top part of the Hewanjie Formation or even some of the overlying Dashuitang Formation in the northern part. |
| JIN Xiao-chi,HUANG Hao,CHEN Yang,WANG Yi-shao.2008.Subdivision and Correlation of Mid-Late Permian Successions of the Baoshan Block,Western Yunnan:Status and Problems[J].Acta Geoscientica Sinica,29(5):533-541. |
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