Petrologic Characteristics of Quaternary Reef-Carbonate Rocks in Well Xike-1, Xisha Area
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摘要: 从西科1井生物礁-碳酸盐岩的岩心观察和岩石学特征的分析入手, 重点刻画了第四系全新-更新统乐东组生物礁-碳酸盐岩的岩石类型和生物礁类型.543片铸体薄片分析和214.89 m岩心观察表明: 岩石类型主要为粒泥灰岩、泥粒灰岩和骨架灰岩, 其次为粘结灰岩、颗粒灰岩、漂砾灰岩和砾屑灰岩.在纵向上, 埋深0~10 m层段以颗粒灰岩为主, 埋深10~22 m层段为生物碎屑砂分布段, 埋深22.00~214.89 m层段以粒泥灰岩、泥粒灰岩和骨架灰岩为主.生物礁类型以骨架礁为主, 造礁生物为珊瑚和少量珊瑚藻.骨架礁在埋深0~214.89 m均有发育, 丛状和块(段)状礁仅分布于埋深83~98 m.Abstract: The reef-carbonate rock types and reef types are described based on the core observation and petrologic characteristic analysis of reef-carbonate rocks in well Xike-1. Analyses of 543 casting lamellas and observation of 214.89 m core samples indicate that the reef-carbonate rock types are composed mainly of wackstone, packstone and framestone, and secondly of bindstone, grainstone, floatstone and rudstone. Vertical variations of rock types are characterized by dominant grain stone at a depth of 0-10 m, bioclastic calcarenite at a depth of 10-22 m, and wackstone, packstone and framestone at a depth of 22-214.89 m, respectively. It is concluded that the reef types are frame reefs and main reef-building organisms consisting of corals and a few coralline algae by the quantitative analysis results. Frame reefs develop at the depth of 0-214.89 m, and cluster and segment reefs only develop at the depth of 83-98 m.
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Key words:
- Xisha area /
- Quaternary /
- reef /
- carbonate rock /
- rock type
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图 1 西科1井第四系生物礁岩石类型显微照片
a.骨架灰岩(埋深25.21 m,单偏光,铸体薄片),造架生物为六射珊瑚(SC),发育生长格架溶蚀孔(GFD);b.粘结灰岩(埋深120.97 m,单偏光,铸体薄片),造架生物为珊瑚藻(CA),发育粒内溶孔(WPD),被粘结的生物多数为骨骼碎屑;c.粒泥灰岩(92.51 m,单偏光,铸体薄片),骨架颗粒多数破碎成骨架碎屑,发育粒内溶孔(WPD);d.泥粒灰岩(20.36 m,单偏光,铸体薄片),骨架颗粒不同程度破碎,保存较好的为有孔虫(F)和珊瑚藻(CA),发育粒间孔(BP);e.颗粒灰岩(10.55 m,单偏光,铸体薄片),可识别出的骨架颗粒为珊瑚藻(CA)和有孔虫(F),发育粒内孔(WP)、粒间孔(BP)和铸模孔(MO),发育新月形胶结物(CC);f.漂砾灰岩(152.61 m,单偏光,铸体薄片),砾屑为六射珊瑚碎块(SC),发育生长格架溶蚀孔(GFD)
Fig. 1. Micro-images of casting lamella of Quaternary reef in well Xike-1
图 3 西科1井第四系生物礁类型
a.据Riding(1977); b.据Riding(2002);数据点为本次研究结果
Fig. 3. Quaternary reef types in well Xike-1
表 1 西科1井第四系生物礁中骨架颗粒类型
Table 1. Skeletal grain types of Quaternary reef in well Xike-1
颗粒类型 下属种类 钙藻 红藻门珊瑚藻 钙藻 绿藻门仙掌藻 珊瑚 六射珊瑚 有孔虫 浮游有孔虫 有孔虫 底栖有孔虫 棘皮动物 软体动物 苔藓动物 -
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