Sedimentology of Quaternary Anastomosing River Systems in the Sanshui Basin, Guangdong, China
-
摘要: 珠江三角洲西北部的三水盆地范围内发育典型的网状河体系。它们具有重复分叉合并、坡降低以及河道深且窄的特点，并且发育天然堤、河间湖泊和洼地等地貌单元。钻井资料显示，网状河的沉积记录以泛滥平原地区沉积的悬浮负载的细粒沉积物为主，由砂砾和砂组成的河道沉积物分布比较局限，呈较窄的带状，被包裹在细粒的泛滥平原积物之中。主干河道表现出较高侧向稳定性垂向继承性，形成了较厚的砂体。较小的分叉河道则容易发生决口改道，沉积了较薄的砂体。河间湖泊沉积主要为含植物碎片的灰黑色粉砂质淤泥，沼泽中植物遗体的堆积形成了泥炭层。晚更新世以来的构造沉降、全球海平面上升以及河流搬运物质的快速加积是珠江三角洲平原地区形成网状河体系的主要原因.Abstract: Anastomosing river systems in the Sanshui Basin, northwestern part of the Pearl River deltaplain,were studied.They are multi-channel systems showing low gradients, low width /depth ratios and re-peated branching and rejoining.Channels, natural levees, interchannel lakes and wetlands are importantmorphological and sedimentary units.Well data revealed that the depositional records of the anastomos-ing river systems are mainly composed of fine grained sediments deposited in interchannel areas, coarsegrained channel deposits, on the other hand, are string-like and of limited lateral extent, and encased inthe overbank fine sediments.Trunk channels are more stable and often associated with deposits of thickchannel sand-bodies.Smaller channels are more easily abandoned bacause of crevasse and avulsion, thusthin sand-bodies are deposited in the fine-sediment-dominated deposits.Pet and silt rich in organic mate-rials are deposited in swamps and interchannel lakes.Tectonic subsidence and eustatic sea level haverisen since the Late Pleistocene, and the rapid vertical accretion in the floodplain hase been the maincause for the development of anastomosing river systems in the Pearl River deltaplain.
-
Key words:
- anastomosing river deposit /
- Quaternary /
- Sanshui Basin /
- Pearl River delta
-
[1] (1) Smith D G, Smith, N D.Sedimentation in anastomosed rov ersysterms: examples from alluvial valleys near Banff, Alberta,J.Sed.Petrol., 1980, 50: 157～ 164.
(2) Smith D G.Anastomosed fluvial deposits: modem examplesfrom Westem Canada, Spec.Publ.Int.Assoc.Sedimentol,1983, 6: 155～168.
(3) 彭苏萍.复合型三角洲平原上的网状河的基本特征.科学通报, 1989, 17: 1326～1328.
(4) 张周良,刘少宾.中国的网状河体系.应用基础与工程科学学报, 1994, 2(2 — 3): 204～ 212.
(5) 黄镇国,李平日,张仲英等.珠江三角洲形成发育演变.科学普及出版社广州分社, 1982, 1～250.
(6) 缪鸿基,沈灿桑,黄广耀等.珠江三角洲水土资源.珠江三角洲研究丛书 (三),广州:中山大学出版社, 1988, 15～31.
(7) 中山大学地理系珠江三角洲研究丛书编辑委员会.珠江三角洲的自然资源与演变过程.珠江三角洲研究丛书 (一),广州:中山大学出版社, 1988, 48～65.
(8) 张显球,周晓萍,陈修奕.三水盆地白垩— 第三纪钻井地层划分对比图集.海洋出版社, 1993, 3～44.
(9) Haq B U, Hardenbol J, Vail P R.Chronolog y of fluctuatingsea levels since the Triassic, Science,1987, 235, 1156～1167. -
点击查看大图
计量
- 文章访问数: 492
- HTML全文浏览量: 7
- PDF下载量: 432
- 被引次数: 0
下载:
