湘南泥盆系碳酸盐岩中锶的分布特点及其环境意义  

THE DISTRIBUTIVE CHARACTERS AND ENVIRONMENTAL SIGNEFICANCE OF STRONTIUM IN CARBONATE ROCKS OF DEVONEAN IN SOUTHERN GUNAN

作　　者：刘文均[1] 

机构地区：[1]成都地质学院沉积地质矿产研究所

出　　处：《沉积学报》1989年第2期15-20,共6页Acta Sedimentologica Sinica

摘　　要：湘南泥盆系碳酸盐沉积环境,可分为台地和台盆两大类和六种相类型.250块岩样的分析结果表明,Sr和Sr/Ca×1000的含量比值变化与沉积环境密切相关,即由浅水台地相到深水台盆相,其比值从0.27增至2.37.其原因是由于不同沉积环境中碳酸盐矿物组份不同.影响了锶的分布.因此锶的含量可作为相分析的工具.In Devonian period, southern Hunan was situated in the east margin of Hunan, Guangdong, Guangxi neritic shelf basin.During the middle__late Devonian epoch , the carbonate sediments were dominant in this area , which may be divided into two facies area: the platform and the platform__basin , and six such facies types as the restricted platform; open platform; reef; shelf, platform basin with slope margin and platform __basin. 250 samples of fresh carbonate rocks for this study were collected from seven sections of various localities and facies types.The contents of elements in carbonate rocks are detected by ICP__AES (model JA__1160). The strontium is one of the important trace elemint in carbonate rocks .The average Sr contents and Sr / Ca × 1000 ratio in different sedimentary facies are vary widely.The tendency of this varition is closely related to sedimentary environments , i.e.the Sr/ Ca× 1000 ratio tends to increase gradually form restricted platform to open platform to shelf and to platform__basin; and from shallow to bathyal , which is fromO.27 to 0.88 to 0.95__1.18 to 2.37.In the lagoon of restricted platform, the Sr/ Ca×1000 ratio of primary dolomites is higher than that of diagenetic dolomites. Several authers have noted that many ancent carbonate rodks have a wide range and a bimodal dstrivution of Sr and given various explanation for it. We agree upon the idea suggested by J.Veizer et al . (1973, 1974), who hold that in the different sedimentary environments the primary carbonate minerals are different , and the Sr content of these minerals is also various. During the diagenetic process, the content decrease with the neomorphism from instable aragonite aragonite and high-Mg calcite into stable low-Mg calcite , but the Sr content in low- Mg calcite is not to change due to it is stable. Thus a bimodal strontium distribution of carbonate rodks in various fades is caused, and may be a indicator for environments.

关 键 词：碳酸盐 岩石 锶 相标志 泥盆纪 

分 类 号：P578.6[天文地球—矿物学]