黔南罗甸沫阳中二叠世茅口组风暴岩沉积特征及地质意义
摘要: 黔南罗甸沫阳剖面中二叠世茅口组以海相碳酸盐为主，下部地层中发育风暴岩，露头特征明显，主要以介壳灰岩为识别标志。风暴沉积构造包括底面侵蚀构造、截切构造、波痕层理、递变层理、块状层理等。风暴沉积主要包括一个底面构造A和B、C、D、E等四个沉积单元：A.侵蚀底面，代表风暴流对海底沉积物的作用；B.介壳灰岩层，代表风暴浪、风暴涡流沉积；C.粒序层，代表风暴衰减期重力分异沉积或风暴浊流沉积；D.块状层，代表风暴快速悬浮沉积；E.波痕层理段，代表风暴衰减后期沉积。它们共组成4种风暴沉积序列，分别代表不同深度的风暴沉积，反映了不同的风暴沉积作用和风暴流的类型。沫阳地区风暴沉积的沉积特征表明，该区风暴沉积主要发育于风暴浪基面之上的内陆棚沉积环境，风暴强度大，为近源风暴岩。仅个别风暴沉积发育于风暴浪基面之下的外陆棚沉积环境，为风暴引起的浊流沉积，为远源风暴岩。风暴岩类型的正确识别，对确定该区沉积相与深入认识扬子碳酸盐台地南部边缘沉积演化提供参考依据。
Sedimentary Characteristics and Geological Implications of the Middle Permian Tempestite in Moyang Section, Luodian, South of Guizhou
Abstract: South Guizhou is located in YunnanGuizhouGuangxi basin, southwest of the Yangtze plate. This area is located in the shallow shelf during the most period of the Permian, dominated by carbonate platform depositional environments. The Moyang Section is just situated in the transitional zone between the carbonate platform and basin, which is an ideal region for preservation of storm deposits. The Maokou Formation of Middle Permian in Moyang Section, Luodian, South Guizhou is mainly composed of marine shelf carbonates. Tempestite occurs in the lower part of this formation, featured by the shell limestone, containing a little rubble with sedimentary structure of storm deposit. Biological shells are severe fragmented and grading is not obvious in the shell limestone. The storm sedimentary structures include bottom erosional surface, truncation, wave ripple bedding, graded bedding, and massive bedding. Storm deposits include bottom erosional surface A and four sedimentary units: B, C, D, E. The unit A, bottom erosional surface, indicates the action of storm flow on marine sediment; the unit B, shell limestone, represents the deposits of storm waves and storm eddy; the unit C, grading layer, records the process of gravitational differentiation or storm turbidity during period of storm decaying; the unit D, massive layer, is produced by rapid accumulation of suspending materials in the late stage of the storm; the top unit E, waves ripple bedding section, is deposited during the later period of the storm. Four successions of storm deposits can be distinguished, correspondent to the waterdepth and storm flow involved. Successions 1, 2 and 3 occur in the inner shelf that between the normal wave base and storm wave base, caused by the intensive proximalstorm. Succession 4 occurs in the outer shelf that below the storm wave base, which is the turbidity deposit brought by the distalstorm. The sedimentary characteristics, types and sequences of the Moyang storm deposit suggest that the preservation of the storm sedimentary sequence closely related to the sedimentary environment, providing a reference for understanding the evolution of the southern margin of the Yangtze carbonate platform.
黔南罗甸沫阳中二叠世茅口组风暴岩沉积特征及地质意义[J]. 沉积学报, 2012, 30(6): 1010-1020.
| 引用本文: |
黔南罗甸沫阳中二叠世茅口组风暴岩沉积特征及地质意义[J]. 沉积学报, 2012, 30(6): 1010-1020.
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Sedimentary Characteristics and Geological Implications of the Middle Permian Tempestite in Moyang Section, Luodian, South of Guizhou[J]. Acta Sedimentologica Sinica, 2012, 30(6): 1010-1020.
| Citation: |
Sedimentary Characteristics and Geological Implications of the Middle Permian Tempestite in Moyang Section, Luodian, South of Guizhou[J]. Acta Sedimentologica Sinica, 2012, 30(6): 1010-1020.
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