| 川西北下二叠统栖霞组微生物丘的发现及地质意义* |
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| 引用本文： | 全子婷,谭秀成,张本健,唐浩,罗冰,杨迅,张亚,肖笛,汤艳玲.川西北下二叠统栖霞组微生物丘的发现及地质意义*[J].古地理学报,2021,23(6):1110-1124. |
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| 作者姓名： | 全子婷 谭秀成 张本健 唐浩 罗冰 杨迅 张亚 肖笛 汤艳玲 |
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| 作者单位： | 1.西南石油大学油气藏地质及开发工程国家重点实验室,四川成都 610500;2.中国石油集团碳酸盐岩储层重点实验室西南石油大学研究分室,四川成都 610500;3.西南石油大学四川省天然气地质重点实验室,四川成都 610500;4.中国石油西南油气田公司勘探开发研究院,四川成都 610041;5.中国石油西南油气田公司重庆气矿,重庆 400021;6.中国石油西南油气田公司川西北气矿,四川江油 621700 |
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| 基金项目： | *国家自然科学基金项目(编号: 41802147)和中国石油—西南石油大学创新联合体科技合作项目联合资助。 |
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| 摘 要： | 通过野外露头与钻井剖面的室内外分析,确认在四川盆地西北部(川西北)下二叠统栖霞组中发育有微生物丘,它们主要由凝块灰(云)岩、叠层灰(云)岩和微生物粘结颗粒灰(云)岩等组成。这些微生物碳酸盐岩发育较为典型的凝块、叠层、窗格、粘结等组构。微生物丘大小不一,实测高度一般为几十厘米至几米,宽度通常变化于几米至几十米之间,具有底平顶凸的典型丘形外貌,以发育向上变浅的沉积序列为特征,一般由丘基、丘核、丘盖3个微相组成,也可与颗粒滩共同构成微生物丘滩复合体。基于区域古地理背景和微生物丘特征的剖析,认为川西北地区栖霞期沉积环境总体受限,推测为半局限—局限台地环境,水深较浅,能量普遍不高;海平面频繁的相对升降变化和微生物丘的侧向迁移叠置,导致发育于缓坡背景下的碳酸盐岩台地极易受限,引起早期沉积物发生与丘滩发育密切相关的准同生期白云石化作用。因此,微生物丘滩复合体是栖霞组白云岩储集层发育的物质基础,台缘坡折带、台内缓坡折带和高地是栖霞组白云岩储集层发育的有利区带,这对寻找规模性层位不稳定的带状白云岩储集层具有重要的指导作用,并将大大拓展栖霞组白云岩储集层的勘探领域。
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| 关 键 词： | 微生物丘 微生物岩 沉积环境 栖霞组 下二叠统 四川盆地 |
| 收稿时间： | 2021-03-12 |
Discovery of microbial mounds of the Lower Permian Qixia Formation in northwestern Sichuan Basin and its geological significance |
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| Quan Zi-Ting,Tan Xiu-Cheng,Zhang Ben-Jian,Tang Hao,Luo Bing,Yang Xun,Zhang Ya,Xiao Di,Tang Yan-Ling.Discovery of microbial mounds of the Lower Permian Qixia Formation in northwestern Sichuan Basin and its geological significance[J].Journal of Palaeogeography,2021,23(6):1110-1124. |
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| Authors: | Quan Zi-Ting Tan Xiu-Cheng Zhang Ben-Jian Tang Hao Luo Bing Yang Xun Zhang Ya Xiao Di Tang Yan-Ling |
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| Abstract: | Through analysis of outcrops and drilling profile data in the field and laboratory,microbial mounds were found in the Lower Permian Qixia Formation in the northwestern Sichuan Basin. The microbial mound is mainly composed of thrombolites,stromatolites,and microbial bindstones. These microbial carbonates are characterized by development of typical clots,stromatolitic,fenestral,and microbial bonding fabrics. Microbial mounds of the Qixia Formation are typical mound-shaped with flat bottom and convex-up top,and various in size. They range from tens of centimeters to several meters in height and from several meters to tens of meters in width. The mounds are characterized by shallowing-upward sequences,which are generally composed of mound base,core and cap,and also may form a mound-bank complex with carbonate shoals. Analysis of regional paleogeographic background and the characteristics of microbial mounds suggests that the Qixia period in northwestern Sichuan was deposited in a semi-restricted platform,with shallow-water and the relatively low-energy conditions. The high-frequency sea-level change,lateral migration,and superposition of microbial mounds lead to the restricted environment on carbonate platform with ramp background,which results in penecontemporaneous dolomitization in earlier sediments. Microbial mound-bank complexes provide basis for development of the dolomite reservoirs in the Qixia Formation. The slope-break belt of platform margin,gentle slope break belt,and local highland inside carbonate platform are favorable zones for the development of the dolomite reservoirs in the Qixia Formation. This understanding plays an important guiding role in finding banded dolomite reservoirs with unstable scale horizons,and will greatly expand the exploration field of dolomite reservoirs in the Qixia Formation. |
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| Keywords: | microbial mound microbialite sedimentary environment Qixia Formation Lower Permian Sichuan Basin |
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