| 摘要: |
| 孝泉—新场—合兴场地区上三叠统须家河组四段以发育扇三角洲沉积体系为主,其砂体成因类型为扇三角洲前缘水下辫状分流河道(含砾)中—粗粒砂岩夹少量碎屑流沉积砾岩。须家河组四段可划分为1个长期、3个中期和18个短期基准面旋回层序,主要砂体合并为6套砂组。各砂组分布与由基准面变化引起的可容纳空间和沉积物供给量比值密切相关:低位体系域沉积期,基准面上升缓慢,沉积物供给(远)大于可容纳空间,沉积作用以主动进积为主,砂体不断向湖盆方向推进;湖侵体系域沉积期,基准面快速上升,沉积物供给量逐渐减少而(远)小于可容纳空间,沉积作用由进积逐渐转入加积和退积;高位体系域沉积期,基准面由缓慢上升逐渐进入到快速下降,可容纳空间由缓慢增加突变为迅速减小,而沉积物供给由小于或略等于可容纳空间逐渐变为(远)大于可容纳空间,沉积作用由弱进积、加积迅速变为强迫进积。 |
| 关键词: 德阳 上三叠统 须家河组 沉积相 四川 |
| DOI： |
| 附件 |
| 投稿时间：2006-04-15 |
| 基金项目:中石化西南分公司重大科技攻关项目“孝泉—新场—丰谷地区须家河组高分辨率层序地层与砂体分布研究”(ZGJ-0401)。 |
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| Sedimentary facies and sandstone distribution in the 4th member of the Upper Triassic Xujiahe Formation, Deyang, Sichuan |
| GAO Hong-can, ZHENG Rong-cai, YE Tai-ran, WEI Qin-lian |
(1. Stata Key Laboratory of Oil and Gas Reservoir Geology and Exploration, Chengdu University of Technology, Chengdu 610059, Sichuan, China;
2. Southern Branch, SINOPEC, Deyang 618000, Sichuan, China) |
| Abstract: |
| The fan delta depositional systems are developed in the 4th member of the Upper Triassic Xujiahe Formation in the Xiaoquan-Xinchang-Hexingchang zone, western Sichuan depression. The sandstone types consist dominantly of fan delta frontal subaqueous braided distributary channel (gravel-bearing) medium-to coarse-grained sandstone intercalated with debris flow conglomerates. The 4th member of the Upper Triassic Xujiahe Formation comprises one long-term, three medium-term and eighteen short-term base-level cyclic sequences grouping into six sets of sandstones. The distribution of individual sandstone sets are closely bound up with the ratios of sediment supply and accommodation spaces.The sediment input was much greater than the accommodation spaces due to the slow rise of the base levels during the deposition of the lowstand systems tract. The deposition occurred in the active progradational modes, and the sandstone bodies migrated towards the lake basin.The sediment supply was much smaller than the accommodation spaces due to the rapid rise of the base levels during the deposition of the transgressive systems tract. There were gradations from the progradation to the aggradation and retrogradation modes of deposition. Finally the sediment supply was also much greater than the accommodation spaces due to the rapid fall of the base levels during the deposition of the highstand systems tract. The deposition took place in forced progradation modes. |
| Key words: Deyang Upper Triassic Xujiahe Formation sedimentary facies Sichuan |
