摘要
西沙群岛西琛1井碳酸盐岩地层可分为3个白云岩层和4个石灰岩层。白云岩层白云石矿物体积分数为91.1%-100%,其他矿物小于8.9%,以泥晶为主,分布在岩石的骨架颗粒和孔隙充填物等各种结构组分中。白云岩δ^13C为0.80‰-3.16‰,平均为2.24‰;δ^18O为0.56‰-5.23‰,平均为2.56‰。这些特征反映了白云石化作用发生在准同生超浓缩卤水条件下,古盐度为36.88%,古温度为1.07℃。石灰岩层白云石矿物体积分数多在25%以下,以亮晶为主,在孔隙或裂缝发育部位富集,而坚硬的骨架部位几乎没有白云石。白云石流体包体的均一温度为102.5296℃,平均为156.3℃;盐度为0.55%-6.25%,平均为3.75%;密度为0.950.99 g/cm^3,平均为0.97 g/cm^3;压力为20.6542.65 MPa,平均为33.65 MPa。这些特征反映了白云石化作用可能与成岩期后热水作用相关。
Carbonate rock strata in well Xichen 1, Xisha islands consist of 3 layers of dolostone and 4 layers of limestone. In dolostone layers, the micritic dolomite, containing 91. 1%- 100% of dolomite, can distribute in all kinds of contents such as framework grains and inter-grain fillings. Isotopes of the dolomite are as follows,δ^13C varies from 0.80‰ to 3.16‰, averaging 2.24‰; δ^18O varies from 0.56%0 to 5.23‰, averaging 2.56‰. These characteristics reflect that dolomitization occurred in synsedimentary heavy brine environment when paleosalinity is 36.88‰ and paleotemperature is 1.07℃. The limestone layers with dominant calcsparite contain dolomite in general less than 25 %, in which dolomite are concentrated in pore or fissure fillings and absent in framework grains. The fluid inclusion homogenization temperature measured in domolite range 102.5-296℃ with an average of 156.3℃; the salinity is 0.55%- 6.25%, averaging 3.75%; the density is 0.95-0.99 g/cm^3, averaging 0.97 g/cm^3; the pressure is 20.65 42.65 MPa, averaging 33.65 MPa. These characteristics reflect that dolomitization may be in connection with post diagenetic hydrothermal event.
出处
《吉林大学学报（地球科学版）》
CAS
CSCD
北大核心
2008年第2期217-224,共8页
Journal of Jilin University：Earth Science Edition
基金
国家自然科学基金重点项目(40234048)
中国地质大学(北京)优秀博士论文扶持奖励基金([2005]115号)
关键词
碳酸盐岩
白云石化
成因机制
西沙群岛西琛1井
carbonate rock
dolomitization
formation mechanism
well Xichen - 1 in Xisha islands
