地质学报2012，Vol.86Issue(2)：316-324,9.DOI:11-1951/P.20120113.0857.006
四川盆地雷口坡组膏盐岩成因及膏盐盆迁移演化与构造意义
Origin of the Leikoupo Formation Gypsum-Salt and Migration Evolution of the Gypsum-Salt Pot in the Sichuan Basin, and Their Structural Significance
摘要
Abstract
Based on regional distribution of gypsum-salt and the detailed analysis of lithological features, the origin of Middle Triassic Leikoupo Formation gypsum and salt in the Sichuan basin was studied, and migration and evolution of gypsum and salt pot and their structural significance were further discussed. The Leikoupo Formation contains two lithological assemblages and distribution patterns. One occurs as laminated gypsum salt intercalated with massive gypsum salt during the Lower submember of the 1st Member of Leikoupo Formation and the Lower submember of the 3rd Member of Leikoupo Formation depositions. It has a thin thickness and stable distribution, suggesting a lagoon origin. The other occurs as massive anhydrite and halite with greatly varied thickness and quick horizontal change. In contrast to the previously-formed gypsum-salt, the depocenter of gypsum-salt migrates westward and northward, suggesting an origin of gypsum-salt pot. Both reflect a structure signature that tectonic stress field of the Sichuan basin was in the transition from tensile stress to compression stress during the Middle Triassic Leikoupo Stage, in which the basin was in tranquil during deposition period of the Lower submember of the 1st Member of Leikoupo Formation and the Lower submember of the 3rd Member of Leikoupo Formation sections, whereas the basin was in active during the period of the Middle submember of the 3rd Member of Leikoupo Formation and the Middle submember of the 4th Member of Leikoupo Formation. NW-SE-trending and NE-SW-tending compressive stress in the basin tended to be active, thus the new depocenter formed. In addition, extensive evaporation caused the gypsum-salt to precipitate quickly in depressed areas. With the basin being more active due to compression, gypsum-salt pots of the Middle submember of the 3rd Member of Leikoupo Formation, the Upper submember of the 3rd Member of Leikoupo Formation and the Lower-Middle submember of the 4th Member of Leikoupo Formation were formed distributing from north to west. West Sichuan depression started and developed at the Middle submember of the 3rd Member of Leikoupo Formation period, and had an initial shape at the Lower-Middle submember of the 4th Member of Leikoupo Formation period. Above understanding will provide new information for studying the origins of Leikoupo gypsum-salt of the Sichuan basin.关键词
四川盆地/雷口坡组/膏盐岩/膏盐盆/迁移/演化/川西凹陷Key words
Sichuan basin/ Leikoupo Formation/ gypsum and salt rocks/ gypsum and salt basin/ migration/ evolution/ West Sichuan depression引用本文复制引用
李凌,谭秀成,邹春,丁熊,杨光,应丹琳..四川盆地雷口坡组膏盐岩成因及膏盐盆迁移演化与构造意义[J].地质学报,2012,86(2):316-324,9.基金项目
本文为中国石油科技创新基金研究项目(编号2011D-5006-0105)、四川省重点学科建设项目(编号SZD0414)资助成果. （编号2011D-5006-0105）
