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    大湄公河次地区主要结合带的对比与连接

    Correlation and connection of the main suture zones in the Greater Mekong subregion

    • 摘要: 大湄公河次地区有多条结合带。根据它们及相关构造单元的时空演化和配置关系,对其南北延伸和连接提出了一些新的意见:(1)印缅山脉结合带向北延与葡萄-密支那结合带汇合后,西接雅鲁藏布江结合带;(2)葡萄-密支那结合带西接雅鲁藏布江结合带,向南西被实皆右行断裂错断,其错断部分为西缅中央火山弧带北段的夏杜苏-隆东带,其南段可能潜没在古近纪沉积层之下;(3)班公湖-怒江结合带南延接潞西-抹谷结合带,再南可能潜伏在墨吉群和抹谷群推覆体之下;(4)昌宁-孟连结合带南延接清迈结合带,并在南奔一带与澜沧江结合带相交汇,原先的昌宁-孟连-清迈洋可能与西藏地区的马利-同卡裂谷盆地和双湖-冈玛错小洋盆构成一个类似现今日本海、东海海槽和南海那样呈串珠状分布的盆地带;(5)澜沧江结合带主体为一隐伏在东达山-临沧-景栋花岗岩带推覆体之下的隐伏结合带,向南接清莱-湄他一带的隐伏结合带和马来半岛的文冬-劳勿结合带,向北在西金乌兰湖一带与可可西里-金沙江结合带相交汇,可可西里-澜沧江-文冬-劳勿结合带构成晚古生代冈瓦纲大陆和劳亚大陆的分界;(6)难河-程逸结合带向北延至思茅西边小黑江一带,可能终止在小黑江以北地区,向南接沙缴和贡布-何仙结合带;(7)哀牢山-斯雷博河结合带是新厘定的结合带,从哀牢山向南经南乌河带、老挝奠边府的镁铁质和超镁铁质岩线接黎府结合带和斯雷博河结合带;(8)马江结合带同哀牢山带一样,是一个早、晚古生代两个结合带相叠合的带,早古生代的结合带西接金沙江-哀牢山带,向东经红河左行断裂完全复位后可接越北的斋江结合带(华南洋俯冲形成),与之相应的,它们北面的右江裂谷盆地可与黑河裂谷盆地(或小洋盆)和甘孜-理塘小洋盆相对应,构成一个围绕峨眉地幔柱,并受其影响而形成的晚古生代末-早中生代的盆地带。

       

      Abstract: There are many suture zones in the Greater Mekong subregion. Some views about the N-S extension and connection of these suture zones have been proposed as follows on the basis of the spatio-temporal evolution and arrangement of the suture zones and other tectonic units. (1) The Indo-Burma Ranges suture zone extends northwards connecting with the Putao-Myitkyina suture zone, and then westwards connecting with the Yarlung Zangbo suture zone. (2) The Putao-Myitkyina suture zone is cut off at its southwestern end by the Sagaing dextral fault and the faulted part of the suture zone should be the Xiadusu-Nongdong zone within the northern section of the Inner-Burman central volcanic arc belt. Towards the south, the suture zone may be covered by the Paleogene and Neogene sediments. (3) The Bangong Lake-Nujiang suture zone extends southwards connecting with the Luxi-Mogok suture zone, and towards further south it may hide beneath the nappes of Mergui and Mogok Groups. (4) The Changning-Menglian suture zone extends southwards connecting the Chiang Mai suture zone, and then conjugating the Lancangjiang suture zone. The pre-existing Changning-Menglian-Chiang Mai Ocean together with Mali-Tanggar rift basin and Shuanghu-Gangmarco oceanic basin in Xizang may be aligned like a paternoster, as in the case of the present-day Sea of Japan, East China Sea Trough and South China Sea. (5) The main part of the Lancangjiang suture zone is a concealed suture zone beneath the nappes within the Dongdashan-Lincang-Kengtong granite belt. Towards the south, it connects with the Chiang Rai-Mae Tha concealed suture zone in Thailand and Bentong-Raub suture zone in the Malay Peninsula, and towards the north, it connects with the Hoh Xil-Jinshajiang suture zone in the Xijir Ulan Lake area. The Hoh Xil-Lancangjiang-Bentong-Raub suture zone is interpreted as the boundary between Gondwana and Laurasia during the Late Palaeozoic. (6) The Nan River-Uttaradit suture zone extends northwards to the Xiaohe River west of Simao, Yunnan, and then ends in the area north of it; towards the south, the suture zone connects with the Sa Kaeo and Kampot-Ha Tien suture zone. (7) The Ailaoshan-Srepok suture zone is a newly delineated suture zone, which extends from the Ailao Mountains southwards via the Nam Ou region and Dien Bien Phu mafic and ultramafic rock belt in Laos to Loei suture zone in Thailand and Srepok suture zone in Cambodia. (8) Just like the Ailaoshan suture zone, the Song Ma suture zone is a superimposed zone of the Early and Late Palaeozoic Song Ma suture zones. The Early Palaeozoic Song Ma suture zone connects westwards with the Jinshajiang-Ailaoshan suture zone, and eastwards, if the Red River left-handed fault is completely restorated, it should connect with the Chay River suture zone in northern Viet Nam, which was formed during the subduction of the South China Ocean. The Youjiang rift basin north of the Chay River suture zone can be compared with the Song Da rift basin (or small oceanic basin) in Viet Nam and Garze-Litang oceanic basin in Sichuan, China. All these basins formed a latest Late Palaeozoic-Early Palaeozoic basin belt centred by the Emei mantle plume.

       

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