The genesis of the purplish-red dolostone in the Middle Devonian Guanwushan Formation, Northwest Sichuan Basin
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摘要: 川西北地区泥盆系观雾山组是新发现的重要天然气产层。在青川何家梁以及葛底坝等地区，泥盆系观雾山组存在一种特殊紫红色调的白云岩，目前对该白云岩成因及形成环境的研究较为薄弱。本次研究采用宏观与微观、矿物学与地球化学相结合的方式对该白云岩进行了系统分析。该类白云岩呈紫红、肉红等色调，单层厚度3~50cm，显微镜下岩石本身呈晶粒结构。对其成因初步分析认为：白云岩中的紫红色、肉红色是一种次生色，是铁元素富集后被氧化的颜色；白云岩存在暴露、岩溶、垮塌现象，指示其形成于古地貌相对较高的局限蒸发环境；只有白云石核心变色，说明其形成时间较早，应为准同生期在相对局限的环境下，颗粒被富含铁元素的水体浸泡侵染所致，随后颗粒外继续形成白云石胶结物将其包裹。紫红色白云岩相对发育的地层往往白云岩的储层厚度大，物性好，岩溶现象发育，储集空间类型多样，是该地区油气勘探的一种重要指示标志。Abstract: The Devonian Guanwushan Formation in northwest Sichuan Basin is a newly discovered important stratigraphic horizon for exploration of gas. The dolostone of the Middle Devonian Guanwushan Formation in Hejialiang and Gediba areas is with purplish-red or yellow-brown colors. Previously, the research on the genesis and forming environment of the dolostone is relatively weak. Based on studies of mineralogy, geochemistry, lithology and experimental analysis data of field samples, the genesis of the dolostone with purplish-red or yellow-brown colors is detailedly analyzed in this paper. The single layer thickness of dolostone with purplish-red or flesh-red colors is between 3cm and 50cm. It has obvious grain structure under microscopes. The preliminary analysis of its genesis is as follow:1) The purplish-red color showed in the dolostone is a secondary color, which was caused by the oxidation of the ferric element;2) Exposure, karst and collapse were common in this kind of dolostone, meaning it was formed in a limited evaporation environment with relatively high paleogeomorphology;3) Only the cores of the dolomite are with different colors, indicating that they were formed earlier than their cement outsides. It is believed that during the contemporaneous period, carbonate grains were dyed by enriched irons in a relatively confined environment, then, they were wrapped by cement outsides. Dolostone with purplish-red, flesh-red or yellow-brown colors is usually with large thickness, good reservoir, developed karst phenomenon and various reservoir space types. It is one of important indications for oil-gas exploration in the region.
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Keywords:
- northwest Sichuan Basin /
- Devonian /
- the Guanwushan Formation /
- purplish-red dolostone /
- genesis
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[1] 四川油气区石油地质志编写组. 中国石油地质志,卷十,四川油气区[M].北京:石油工业出版社, 1989. [2] 谢增业,张本健,杨春龙,等.川西北地区泥盆系天然气沥青地球化学特征及来源示踪[J].石油学报,2018,39(10):1103-1113. [3] 鲜思远,陈继荣,万正权. 四川龙门山甘溪泥盆纪生态地层、层序地层与海平面变化[J].岩相古地理,1995,15(6):11-21. [4] 陈留勤. 龙门山地区泥盆纪层序地层及海平面变化——以四川北川桂溪剖面为例[J].西北地质,2007,40(4):58-66. [5] 赵兵. 四川龙门山中段泥盆纪层序地层[J].沉积与特提斯地质,2000,20(4):89-96. [6] 熊连桥,姚根顺,沈安江,等. 川西北部泥盆系观雾山组沉积相新认识——以大木垭剖面与何家梁剖面为例[J].海相油气地质,2017,22(3):1-11. [7] 熊连桥,姚根顺,倪超,等. 龙门山地区中泥盆统观雾山组岩相古地理恢复[J].石油学报,2017,38(12):1356-1370. [8] 曾允孚,黄思静. 四川甘溪泥盆系观雾山组白云岩特征与其形成条件的关系[J].沉积学报,1988,6(4):12-21. [9] 熊连桥,姚根顺,倪超,等. 川西北地区中泥盆统观雾山组储集层特征、控制因素与演化[J].天然气地球科学,2017,28(7):1031-1042. [10] 邓予炜,侯明才,陈安清,等. 川西北观雾山组白云岩稀土元素特征及其对白云岩化流体性质的指示[J].成都理工大学学报(自然科学版),2018,45(3):282-291. [11] 沈浩,汪华,文龙,等. 四川盆地西北部上古生界天然气勘探前景[J].天然气工业,2016,36(8):11-21. [12] 朱筱敏.沉积岩石学第4版[M].北京:石油工业出版社,2008. [13] VEIZER J, ALA D, AZMY K, et al. 87Sr/86Sr, δ13C and δ18O evolution of Phanerozoic seawater[J]. Chemical geology,1999, 161(1/3)59-88.
[14] 曾允孚,夏文杰.沉积岩石学[M].北京:地质出版社,1986. -
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