-
摘要:
西沙群岛永兴岛西永2井和石岛西科1井均发现铁白云岩。主要通过X光粉晶衍射、偏光显微镜和扫描电镜技术完成测试,分析白云岩-铁白云岩分布及岩相学特征。X光粉晶衍射测试结果及综合分析表明,西科1井发育11层铁白云岩,西永2井发育8层铁白云岩。通过偏光显微镜鉴定,发现西永2井中新世白云岩主要为生物碎屑白云岩,白云石晶体呈粉晶—细晶结构;某些层段含较高铁白云石,呈微晶—粉晶状。通过薄片观察分析发现,西科1井发育大量物碎屑白云岩,多细晶—粉晶结构,自形—半自形为主,部分样品可见黑色铁质氧化物或者胶结物。扫描电镜观察发现2个井多数白云石为典型菱形多面体结构,白云化程度高。
Abstract:Ferroan dolomite is found in well Xiyong 2 of Yongxing Island and well Xike 1 of Shidao Island in Xisha Islands. Through three methods including X-ray powder diffraction quantification, polarized light microscopy and scanning electron microscopy, distribution and petrographic characteristics of ferroan dolomite in the aboved two wells were discussed. The X-ray powder crystal diffraction analysis and comprehensive study show that eleven layers of ferroan dolomites are developed in the well Xike 1 of Shidao Island, and eight layers ferroan dolomites in the well Xiyong 2 of Yongxing Island. It was found by polarized light microscopy that the Miocene dolomite in the well Xiyong 2 of Yongxing Island is dominated by bioclastic dolomite, and the dolomite crystals are powder-fine grained; the content of ferroan dolomites is higher in some layers, and the crystal is mainly microcrystal-powder crystal dolomite. Through observing and analyzing the casting thin slices , it is found that a large amount of clastic dolomite is developed in well of Xike 1 and the crystals are mostly fine-grain crystal structure, self-formed to semi-self-shaped, and some samples are black ankerite oxide or cement. Under the scanning electron microscopy, samples from well Xike 1 in Shidao Island and well Xiyong 2 in Yongxing Island show that the dolomite crystals present rhombohedral polyhedral structures, with a high degree of dolomification.
-
Key words:
- Shidao Island /
- Yongxing Island /
- dolomite /
- ferroan dolomite /
- petrography
-
-
表 1 西永2井X射线粉晶衍射数据
Table 1. X-ray powder crystal diffraction data of well Xiyong 2
深度/m 矿物相 d(104)值 白云石/% 方解石/% 395.04~396.58 铁白云石 2.906 1 93.15 6.85 397.11~400.26 白云石 2.911 1 93.77 6.33 401.51~404.05 铁白云石 2.906 2 97.25 2.75 404.01~404.62 白云石 2.900 0 95.00 5.00 404.81~405.71 铁白云石 2.906 3 96.53 3.47 410.00~410.35 白云石 2.900 6 97.38 2.62 420.00~420.31 白云石 2.904 4 96.87 3.13 422.50~422.90 白云石 2.9079 94.92 5.08 425.20~425.70 白云石 2.907 9 92.09 7.91 426.00~429.30 方解石 3.033 1 32.54 67.46 430.00~431.80 方解石 3.037 2 38.57 61.43 432.75 白云石 2.900 6 37.52 62.48 435.00 白云石 2.904 4 98.69 1.31 446.51~447.23 白云石 2.904 2 96.65 3.35 451.20~451.70 白云石 2.907 2 99.73 0.27 452.96~456.93 铁白云石 2.9062 99.42 0.58 457.50~458.80 铁白云石 2.906 0 98.25 1.75 460.51~461.71 铁白云石 2.906 1 99.13 0.87 466.30~466.60 白云石 2.902 4 99.26 0.74 469.87~470.91 铁白云石 2.906 1 95.88 4.12 473.55~477.15 白云石 2.908 0 97.68 2.32 517.50~518.00 白云石 2.902 5 95.42 4.58 527.30~527.50 白云石 2.896 9 99.12 0.88 529.01~532.05 白云石 2.902 1 96.35 3.65 540.05~545.23 铁白云石 2.906 2 98.46 1.54 555.20~555.40 白云石 2.898 9 99.33 0.67 570.07~573.94 方解石 3.027 5 21.98 78.02 578.00~579.36 白云石 2.904 3 96.86 3.14 580.02~583.60 铁白云石 2.906 1 98.59 1.41 585.11~589.33 白云石 2.895 2 97.32 2.68 592.31~593.56 铁白云石 2.906 2 97.56 2.44 594.22~598.00 白云石 2.886 0 99.64 0.36 599.05~599.78 铁白云石 2.906 1 99.47 0.53 600.00~600.23 白云石 2.907 9 97.83 2.17 表 2 西科1井铁白云石赋存深度与含量
Table 2. Sample depths and contents of ferroan dolomites in well Xike 1
深度/m 矿物相 d(104)值 白云石/% 方解石/% 434.74~435.78 铁白云石 2.906 2 96.25 3.75 453.95~455.95 铁白云石 2.906 1 97.11 1.89 533.56~533.64 铁白云石 2.906 2 93.74 6.26 550.03~550.09 铁白云石 2.906 2 95.223 4.777 764.27~767.84 铁白云石 2.906 1 98.26 1.74 971.80 铁白云石 2.906 1 99.01 0.89 972.20 铁白云石 2.906 3 99.03 0.87 984.00~989.16 铁白云石 2.906 2 99.53 0.47 1 110.90~1 112.80 铁白云石 2.906 1 93.22 6.78 1 121.80~1 124.70 铁白云石 2.906 2 94.27 5.73 1 146.50~1 149.90 铁白云石 2.906 2 98.21 1.79 1 166.50~1 167.60 铁白云石 2.906 1 96.00 4.00 -
[1] 魏喜,祝永军,尹继红. 南海盆地生物礁形成条件及发育趋势[J]. 特种油气藏,2006,13(1):10-15. doi: 10.3969/j.issn.1006-6535.2006.01.003
[2] 何起祥,张明书. 西沙群岛新第三纪白云岩的成因与意义[J]. 海洋地质与第四纪地质,1990,10(2):45-55.
[3] 许红,张金川,蔡峰. 西沙群岛中新世生物礁矿物相研究及其意义[J]. 海洋地质与第四纪地质,1994,14(4):15-23.
[4] 魏喜,祝永军,许红,等. 西沙群岛新近纪白云岩形成条件的探讨:C、O同位素和流体包裹体证据[J]. 岩石学报,2006(9):2394-2404. doi: 10.3321/j.issn:1000-0569.2006.09.016
[5] 于亚苹,刘立,徐守立,等. 西沙群岛西科1井梅山组一段储层物性特征及储集评价[J]. 世界地质,2015,34(4):1069-1078. doi: 10.3969/j.issn.1004-5589.2015.04.019
[6] 李晓,刘娜,吴仕玖,等. 南海西沙群岛西科1井上新统-全新统碳酸盐岩微相分析[J]. 科技导报,2016,34(7):103-110. doi: 10.3981/j.issn.1000-7857.2016.07.009
[7] 张海洋,许红,赵新伟,等. 西永2井中新世白云岩储层特征及成岩作用[J]. 海洋地质前沿,2016,32(3):41-47.
[8] XU H,ZHANG W,WEI K,et al. Ferroan dolomites in Miocene sediments of the Xisha Islands and their genetic model[J]. Journal of Oceanology and Limnology,2018,36(1):165-180. doi: 10.1007/s00343-018-7136-3
[9] 郭鸿烈,张佛生. 菱铁矿、白云石—铁白云石及方解石差热曲线规律的初步分析[J]. 云南化工,1981(4):41-42.
[10] 饶玉学. 红外吸收光谱在鉴定白云石—铁白云石系列矿物中的应用[J]. 地质与勘探,1986(4):41-42.
[11] 郑荣才,王成善,朱利东,等. 酒西盆地首例湖相“白烟型”喷流岩:热水沉积白云岩的发现及其意义[J]. 成都理工大学学报(自然科学版),2003,30(1):1-8.
[12] 戴朝成,郑荣才,文华国,等. 辽东湾盆地沙河街组湖相白云岩成因研究[J]. 成都理工大学学报(自然科学版),2008,35(2):187-193.
[13] 柳益群,焦鑫,李红. 新疆三塘湖跃进沟二叠系地幔热液喷流型原生白云岩[J]. 中国科学(D辑:地球科学),2011,41(12):1862-1871.
[14] 高翔,王平康,李秋英. 松科1井嫩江组湖相含铁白云石的准确定名和矿物学特征[J]. 岩石矿物学杂志,2010,29(2):213-218. doi: 10.3969/j.issn.1000-6524.2010.02.010
[15] 黄成刚,袁剑英,曹正林,等. 咸化湖盆碎屑岩储层中铁白云石的溶蚀作用模拟实验研究[J]. 石油实验地质,2014,36(5):650-655. doi: 10.11781/sysydz201405650
[16] 史同强,许红,张海洋,等. Fe同位素研究现状及其在西沙群岛铁白云岩研究中的应用[J]. 海洋地质前沿,2018,34(6):50-55.
[17] 宋红瑛. 南海西部新近系生物礁碳酸盐岩孔渗层变化与成因特征研究[D]. 青岛: 中国海洋大学, 2012.
-