老挝万象盆地通芒地区盐构造特征及成因机制

Salt Tectonic Characteristic and Genetic Mechanism of Thongmang Region in Vientiane Basin,Laos

万象坳陷盆地腹地通芒地区古新世—始新世沉积了巨厚的膏盐岩,塔贡组下盐层钾镁盐矿体呈盐构造,钾镁盐矿体与上覆碎屑岩之间整合接触,在喜马拉雅运动中晚期的强烈挤压与差异载荷等作用下,形成通芒地区狭长形隆起的盐背斜构造。研究表明通芒地区盐构造的成因受多重作用影响,差异负载是通芒地区盐构造初始形成时的动力来源,盐上盖层快速沉降是盐构造生长缓慢的主要原因。强烈的区域挤压作用促进了差异负载、重力作用与浮力作用的进一步发展,所形成的构造样式相对较简单,以发育盐构造初期的盐枕及盐背斜为主。盐构造对于研究钾镁盐体的成因、运动规律和成矿作用具有重要意义。

Palaeocene-Eocene deposited thick gypsum-salt rock layer in Thongmang area which is located in the hinterland of Vientiane basin. Potassium and magnesium salt deposit of Tagong group and overlying clastic rock have a conformable contact. A strip shaped uplift of the salt anticline was formed in Thongmang area because of strong extrusion and difference of overlying weight in middle and late Himalayan movement. The salt tectonic was influenced by many factors in Thongmang region. Difference of overlying weight was the power source of forming salt structure, and rapid settlement of the cap layer was the main reason for slow salt tectonic growth. And strong regional squeezing action accelerated further development of overlying weight differences, gravity and buoyancy. The patterns of salt anticline tectonic are relatively simple which mainly being salt pillow and salt anticline. Research on salt tectonic has great significance for studying the causes of potassium and magnesium salts, teetonization and mineralization.