摘要
本文阐述了我国西南地区三叠系的含盐层位、盐矿床类型,分布规律,同时结合中新生代构造-岩浆演化特点、成盐条件及找矿标志,探讨了该区三叠系找钾方向和前景。
The triassic is the major period of the formation of salt deposits in south China.The Triassic salt-bearing horizons consist of.the second mere- her of the lower triassic Jialingjiang formation (T_1j^2),the fourth-fifth mem- ber of the lower triassic Jialingjiang formation to the first member of the middle triassio Leikoupo formation (T_1j^(4-5)—T_2L^1),the third member of the middle triassic Leikoupo formation (T_2L^3),the fourth member of the middle triassic Leikoupo formation (T_2L^4),the middle triassic Baishan formation (T_2b),and the Jiapeila formation (T_3j),the Bolila formation (T_3b)and the Sanhetong formation (T_3s) of upper Triassic. Among the above-mentioned salt-bearing horizons,the fourth-fifth mem- ber of the Jialingjiag formation to the first member of the Leikoupo forma- tion (T_1j^(4-5)—T_2L^1)and the fourth member of the Lelkoupo formation (T_2L^4) are the most developed.The salinity of the ancient seawater might have then evolved to sedimentation of potassium-magnesium salts.All other horizon,s contain only gypsums and halites. The triassic saline sediments have the following characterstics: 1.Most of the saline horizons are closely associated with carbonates,a few with red beds.The salt-bearing sediments attain a thickness of about one kilometre,covering an area of about one million square kilometres.Their sedimentation is polycyclic. 2.There are a good variety of the Triassic salt deposit types,including dolomites,gypsums,anhydrites,barites,celestines,halites,polyhalites and salt brine (B,K,Li—),with associated limestones,oil and natural gas. 3.There is a general trend of increasingly higher horizon of the saline sediments from east to west.T_1j^2 for those in western Hubei province, T_1j^(4-5)—T_2L^1,T_2L^3,T_2L^4 for those in the Sichuan basin,northern Guizhou province and southern Shanxi province,T_2b in southwestern Sichuan provin- ce and northwestern Yunnan province,T_3j,T_3b and T_3s in eastern Tibet and northwestern Yunnan province. 4.The triassic saline sediments are characterized by a zonal distribution in plan,especially in depressions of a block,where the saline deposits are concentrically zoned,grading from carbonates at the margin,through sulfa- tes,halites into potassium and magnesium salts in the centre. 5.It is clear that the Triassic saline sedimentation was controlled by tectonic environments.The salts are distributed mainly in two tectonic uni- ts:depressions of a block and transitional belts.Salt layers in the former are stable,while those in the Latter were often deformed to form diapirs or salt domes.There seems to be a larger sedimentation tale in the salt-bearing areas during the Triassic than other geological periods.
出处
《地质力学学报》
CSCD
1991年第1期75-91,共17页
Journal of Geomechanics
基金
国家自然科学基金85029项目
