摘要
钙芒硝是一种常见的盐类矿物,共生矿物有石盐、石膏、硬石膏和无水芒硝;主要产状有薄层状、层状及星散状等,在地层剖面上可构成4种剖面类型.根据其地质特征,笔者认为钙芒硝主要产于陆相含盐盆地,是在浓缩卤水的淡化阶段,直接从卤水中快速结晶形成.除了盐类矿物所需要的共同条件以外,钙芒硝的沉积还需要某些特殊条件和环境.因此研究其成因和沉积环境,对于含盐盆地及含盐地层的研究,具有重要的地质意义.
Glauberitc is a common evaporitc mineral which consists of calcium sodium sulfatc. In this paper, the geological characteristics of glaubcrite in Mcsozoic-Ccnozoic dcpositional basines of East China is described in d tail, the origin and sedimentary environment is analysed, the sense of glaubcrite in studing basin dcp sitional dcvclopemcnt and exploring other cvaporite deposits have yet to be explicitly formulated.
The giaubcrite mainly dcposilcs in saline strata of contincntial basin. Its crystals often arc well with cuhcdral s( micuhcdral rhombohcdron and plate-shaped. The common associated minerals are halite, anhydrite, gypsum and thcnardile. The main occurrences arc bcdcd, thin bcded and scattered etc, imerbcdding with halite, mud and clastic sediment. There arc four types of section, synthesized the distributioi al features in stratigraphical section. These mean four different evolutionary steps of ancient lake water.
According to the texture and tectonic, author point out that glaubcrite is direct deposited from brine when the cmcentrated brine suddenly flush by inflow. The special dcpositional condition for glaubcrite is transient. Tne form model of glauberitc as follows: when the sodiun sulfatc brine have been concentrated in a step a which NaCl (Na2SO4) has reached saturation or near saturation, the inflow which produced by c imatic variety carry a lot of calcium into the lake. Therefor glaubcrite was formed insicad of NaCl or N i2SO4minerals bcacase the condition is satisfactary for its. The glaubcrite deposited in different occurrence in the section because of varing inflow water by climatic variety.
Bccau of the special conditiom, glaubcrite is a useful indicator of dctcrming water types of ancient lake and ex ming climatic events and evolution of lake brine. It is also useful to research basin sedimentary cnvironme
出处
《沉积学报》
CAS
CSCD
北大核心
1989年第3期137-141,共5页
Acta Sedimentologica Sinica
