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| 陆丰地区古近系恩平组沉积演化特征及沉积模式 |
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焦鹏1,2,郭建华1,2,张向涛3,刘辰生1,2,郭祥伟1,2,王玺凯1,2
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(1.中南大学地球科学与信息物理学院,湖南长沙 410083;2.有色金属成矿预测与地质环境监测教育部重点实验室(中南大学), 湖南长沙 410083;3.中海石油(中国)有限公司深圳分公司,广东深圳 518054)
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| 摘要: |
| 在岩心观察的基础上,结合地震、钻井、测井、薄片等资料,对珠江口盆地陆丰地区古近系恩平组沉积特征进行研究,并结合构造背景、古地貌建立其沉积相模式。研究表明:陆丰地区恩平组裂陷Ⅱ幕发育4个三级层序,主要发育3类沉积相,即扇三角洲、辫状河三角洲和湖泊;恩平组沉积早期,研究区发育的3个洼陷互不连通,洼陷陡坡带发育扇三角洲,缓坡带发育辫状河三角洲。沉积中期,洼陷主控断裂活动强度由南向北增强,沉降中心和沉积中心逐渐向北迁移,洼陷相互连通,主物源区经历了由盆内基底凸起和东沙隆起向北部隆起带的转换,以发育大范围展布辫状河三角洲、滨浅湖滩坝为特色。沉积晚期,主控断裂活动减弱,湖盆淤浅萎缩,四周辫状河三角洲进积,发育薄煤层;主控断裂活动为沉积物提供可容空间,控制洼陷几何形态,一级断层转换带控制主物源方向,二级断层转换带分割主物源通道,影响沉积砂体再分配,沉积体系发育与砂体分布则与古地貌密切相关;滨浅湖滩坝是研究区最有利的储集相带,其次是扇三角洲前缘水下辫状河道及河口砂坝,最末为辫状河三角洲前缘水下分流河道及河口砂坝。 |
| 关键词: 断陷湖盆 沉积相 沉积模式 恩平组 陆丰地区 珠江口盆地 |
| DOI：10.3969/j.issn.1673-5005.2017.05.002 |
| 分类号::TE 122.2 |
| 文献标识码:A |
| 基金项目:国家科技重大专项(2011ZX05023-001);中国海洋石油总公司综合科研项目(YXKY-2015-SZ-02) |
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| Sedimentary evolution characteristics and sedimentary model of Paleogene Enping Formation, Lufeng area, Pearl River Mouth Basin |
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JIAO Peng1,2, GUO Jianhua1,2, ZHANG Xiangtao3, LIU Chensheng1,2, GUO Xiangwei1,2, WANG Xikai1,2
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(1.School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;2.Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring (Central South University), Ministry of Education, Changsha 410083, China;3.Shenzhen Branch of CNOOC Limited, Shenzhen 518054, China)
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| Abstract: |
| Based on core observations and data from seismics drilling and well logging as well as slice, the sedimentary characteristics of the Enping Formation in Lufeng area of the Pearl River Mouth Basin were studied. The sedimentary models have been established by combining information from construction background and paleo-geomorphology. The study shows that four 3rd-order sequences were developed in the rift stage periods Ⅱ(Enping Formation) in Lufeng area, which mainly compose of three types of sedimentary facies, namely, fan delta, braided river delta and lacustrine. In the early sedimentary stage of Enping Formation, three separated depressions were formed. The fan delta was formed in the fault steep slopes, and the braided river delta in the gentle slope. During the middle stage of depositional progress, with active intensity of main-controlled fault enhancement from south to north, the subsidence center and depocenter gradually migrated to north. The main provenance experienced internal uplifts of the basin and the transition of Dongsha Massif to the northern uplift belt, characterized as broad distributed braided river delta and beach bar. During the late stage of sedimentary progress, with a weak main-controlled fault activity, the lacustrine basin became smaller. Progradational braided river delta and thin coal seam developed afterwards. The activity of the main-controlled fault provides the accommodation space for the deposits, and controls the geometric shapes of depressions. The first-order fault transfer zones control the orientation of the main provenance, while the secondary ones carve its channels, influencing the redistribution of sand. The development of the sedimentary system and the distribution of sands are closely related to paleo-geomorphology. In the study area, beach bar is the most favorable reservoir facies belt,followed by underwater braided channel and mouth bar deposits of the fan delta front, and the underwater distributary channel and mouth bar deposits of braided river delta front. |
| Key words: rifted lacustrine basin sedimentary facies depositional model Enping Formation Lufeng area Pearl River Mouth Basin |
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