| 川西坳陷中段上侏罗统蓬莱镇组物源及沉积体系研究 |
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| 引用本文： | 叶素娟,李嵘,张庄.川西坳陷中段上侏罗统蓬莱镇组物源及沉积体系研究[J].沉积学报,2014,32(5):930-940. |
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| 作者姓名： | 叶素娟 李嵘 张庄 |
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| 作者单位： | 1.中石化西南油气分公司勘探开发研究院 成都 610041; |
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| 基金项目： | 国家科技重大专项(编号:2011ZX05002-004)资助 |
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| 摘 要： | 作为川西坳陷主要的油气勘探目的层，上侏罗统蓬莱镇组物源区及物源方向的研究是明确沉积体系、砂体及储层空间展布的基础。由于缺乏针对性的系统研究，对于川西坳陷中段蓬莱镇组物源方向及沉积体系展布的研究，长期以来存在较大争议。根据碎屑组分、重矿物、微量元素以及古地貌分析结果，对研究区蓬莱镇物源及沉积体系进行了重新认识。结果表明，川西坳陷中段蓬莱镇组存在龙门山中段、北段、米仓山多个物源区。其中，研究区西部物源主要来自龙门山中段，发育呈北西-南东向展布的近源、短轴三角洲沉积体系，砂岩分选差、粒度相对较粗、矿物成分成熟度相对较低，储层不发育；研究区中东部沉积物则主要来自龙门山北段以及米仓山，发育北东-南西向展布的远源、长轴三角洲沉积体系，砂岩分选好、粒度相对较细、长石含量及矿物成分成熟度较高，物性条件较好。同时，蓬莱镇组不同时期主要物源体系存在差异。自蓬一段至蓬四段，主物源方向由西、北西向北、北东方向转变，主物源区由龙门山中段向龙门山北段迁移。
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| 关 键 词： | 物源及沉积体系 上侏罗统蓬莱镇组 川西坳陷 岩石学及地球化学方法 |
| 收稿时间： | 2013-10-24 |
Provenance Analysis and Depositional System of the Upper Jurassic Penglaizhen Formation in the Middle Part of Western Sichuan,China |
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| Institution: | 1.Exploration and Production Research Institute, Sinopec Southwest Company, Chengdu 610041;2.Chengdu Institute of Geology and Mineral Resources, Chengdu 610081 |
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| Abstract: | The Upper Jurassic Penglaizhen Formation constitutes important gas reservoir in western Sichuan and the study of provenance of the Penglaizhen sandstones is of great importance in determining the spatial distribution of depositional systems and reservoirs. Owing to the absence of systematic studies, the provenance and lateral distribution of Penglaizhen Formation in the middle part of Western Sichuan have long been speculated upon. Based on detrital mineral analysis, trace element geochemistry, and paleogeomorphology, this study reveals that the sediments of the Penglaizhen Formation were derived from the middle and northern segments of Longmen Shan orogenic belt and Micang Shan orogenic belt. The sediments in the western region of depression are mostly coarse-grained, poor-sorted sandstones with low compositional maturity and porosity, and were sourced from the middle segment of Longmen Shan, indicating southeastward delta depositions close to the source area. The deposits in the middle and eastern parts are generally fine-grained, well-sorted sandstones with high feldspar content, compositional maturity, and porosity, and were supplied from the northern segment of Longmen Shan and Micang Shan, suggesting northeast-to-southwest delta depositions far from their sources. Additionally, it is shown that there existed different provenances during different periods and the dominant provenance transferred from the middle to the northern segment of Longmen Shan from J3p1 to J3p4. |
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