| 珠江口盆地惠州凹陷古近纪多幕裂陷旋回的沉积物源响应 |
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| 引用本文： | 王维,叶加仁,杨香华,施和生,舒誉,吴静.珠江口盆地惠州凹陷古近纪多幕裂陷旋回的沉积物源响应[J].地球科学,2015,40(6):1061-1071. |
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| 作者姓名： | 王维 叶加仁 杨香华 施和生 舒誉 吴静 |
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| 作者单位： | 1.中国地质大学构造与油气资源教育部重点实验室，湖北武汉 430074 |
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| 基金项目： | 国家重大油气专项(Nos．2011ZX05023-001-015，2011ZX05023-001-001)． |
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| 摘 要： | 为阐明惠州凹陷古近纪构造活动对物源供给与沉积充填的控制作用，以LA-ICPMS锆石U-Pb定年为主要技术手段，对惠州凹陷古近系不同层段的8件样品中的锆石形态及年代组成进行分析，定量研究其物源供给规律.南部物源，即盆内基岩凸起与东沙隆起，以中生代火成岩为主；北部物源，即盆外华南褶皱带，岩性及年代学复杂.结果显示从下文昌组-上文昌组-恩平组的砂岩样品中，中生代锆石颗粒含量逐渐降低，前寒武-古生代锆石颗粒含量逐渐增加，表明惠州凹陷具有早期南部供源逐渐到晚期北部供源的转换规律.惠州凹陷构造演化分为3幕:裂陷ⅠA、ⅠB和Ⅱ幕.裂陷ⅠA幕，下文昌组沉积时期，凹陷南部断层活动强烈，砂岩中锆石以中生代颗粒为主，沉积相类型以靠近南部断裂带发育的扇三角洲及中深湖相为主；裂陷ⅠB幕，上文昌组沉积时期，北部边界断裂带活动强度增加，中生代锆石颗粒含量为68%，前寒武-古生代颗粒含量为32%，表明该时期南北同时供源，沉积体系以扇三角洲、辫状河三角洲及中深湖相为特色；裂陷Ⅱ幕，恩平组沉积时期，北部断层持续活动，前寒武-古生代锆石颗粒含量为64%，中生代颗粒含量为36%，证实恩平组沉积时期以北部物源为主，发育了浅水辫状河三角洲、滩坝以及薄煤层.
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| 关 键 词： | 惠州凹陷 多幕裂陷 物源转换 锆石U-Pb定年 沉积物 地质年代学 |
| 收稿时间： | 2015-01-22 |
Sediment Provenance and Depositional Response to Multistage Rifting,Paleogene,Huizhou Depression,Pearl River Mouth Basin |
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| Wang Wei,Ye Jiaren,Yang Xianghua,Shi Hesheng,Shu Yu,Wu Jing.Sediment Provenance and Depositional Response to Multistage Rifting,Paleogene,Huizhou Depression,Pearl River Mouth Basin[J].Earth Science-Journal of China University of Geosciences,2015,40(6):1061-1071. |
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| Authors: | Wang Wei Ye Jiaren Yang Xianghua Shi Hesheng Shu Yu Wu Jing |
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| Abstract: | In order to clarify the controlling effects of tectonic activities on the sediment supply and sedimentary filling, the sediment supply of the Huizhou depression is quantitatively studied by analyzing the changes in the shape and chronology of the detrital zircons of eight samples from different formations, with LA-ICPMS zircon U-Pb dating as the main measuring method. The southern provenance areas, Dongsha Massif and the internal uplifts of the basin, are predominantly composed of Mesozoic igneous rocks, while northern provenance areas, South China folded belt, are characterized by complicated lithology and geochronology. The results show that the content of Mesozoic zircon grains decreases while that of Precambrian-Paleozoic zircon grains increases and then prevails gradually from the Lower Wenchang Formation to the Upper Wenchang Formation and to the Enping Formation, confirming that the area provenance system switched a south provenance in the basin to a north provenance out of the basin gradually. The evolution of Huizhou depression in Paleogene can be divided into three rifted stages: periods ⅠA, ⅠB and Ⅱ. During period ⅠA (Lower Wenchang Formation), the southern faults of depression suffered strong activities. All zircon grains are derived from Mesozoic, indicating sediments derived from the southern provenance areas. The related sedimentary facies are characterized by fan delta and middle-deep lake under the conditions of southern steep slope of Huizhou depression. During period IB, corresponding to Upper Wenchang Formation, the tectonic activities are characterized by high subsidence rates in the northern fault zones. The content of Mesozoic grains is 68%, whereas the content of Precambrian-Paleozoic zircon grains is up to 32%, which indicates that sediments are derived from both northern and southern provenance areas. The related sedimentary facies have the characteristics of fan delta, braided river delta and middle-deep lake. During period Ⅱ (Enping Formation), the northern faults stayed active. The content of Precambrian-Paleozoic zircon grains increases to 64% while that of Mesozoic grains decreases to 36%, which indicates that northern provenance areas play a dominant role in this stage. In addition, the related sedimentary facies are characterized by shallower braided river delta, beach bar and thin coal seam. |
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| Keywords: | Huizhou depression multistage rifting provenance switching zircon U-Pb dating sediments geochronology |
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