| 老挝万象地区基础地质调研的主要进展 |
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| 关键词:Laos Vientiane area fundamental geology main advances |
| 基金项目:国家发展计划委员会“老挝万象平原钾镁盐矿勘查”项目(计外资[1999]2298号) |
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| The Main Advances in the Fundamental Geological Investigation of Vientiane Area, Laos |
| The fundamental geological investigation in Vientiane area of Laos has made outstanding progress on the basis of regional geological reconnaissance, specific researches and drilling. The main achievements are as follows: ① The strata in this region can be divided upward into such formations as Houay Xiangna (P_2hx), Nam La (P_2nl), Nam Khangxang (P_2nk), Nam Lik (J_1nl), Nam Set (J_ 1-2 ns), Ban Hinheup(J_2bh), Phu Phanaphathao (K_1pp), Ban Nate (K_1bn), Ban Thalat (K_1bt), Thangon (E_1tg) and Ban Thabok (E_ 1-2 bt). Their lithostratigraphy can be compared with that of contemporaneous strata in Lanpin-Simao area, western Yunnan of China. ② From the above eleven groups of lithostratigraphic units, paleobiologic materials were obtained, which belong to fourteen biostratic units respectively. Their biostratigraphy can be compared with that of contemporaneous strata in Lanpin-Simao area, western Yunnan of China. ③ The structural features in Vientiane area can be divided into three epochs, namely before salification (Late Cretaceous), during salification (Paleocene) and after salification (Eocene). The first-class structures are Thabok superimposed synclinorium and Banphoukhaoknoay superimposed anticlinorium. ④ The saline strata, i.e., Thangon Formation (E_1tg), comprise a suite of creamy white, rose colored gypsum and halite bed and brownish red, amaranth terrigenous fine clasolite. The gypsum and halite bed and terrigenous fine clasolite constitute three distinct depositional cycles, hereby three members and six beds can be distinguished. Potassium and magnesium mines of economic value are produced in the gypsum and halite bed under Thangon Formation (E_1tg). ⑤ Thangon (E_1tg) can be divided into shore lake, medium and semi-deep lake facies. During salification the precipitation environment experienced obvious transfer and reorganization. The gypsum and halite bed was formed in a precipitation environment characterized by prolonged drought, continual subsidence of basin basement and sustained brine supply. |
| YAN Cheng-min,ZHU Yan-zhe,WU Jun,FENG Ming-gang.2006.The Main Advances in the Fundamental Geological Investigation of Vientiane Area, Laos[J].Acta Geoscientica Sinica,27(1):81-84. |
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