| 火山地层中的沉积层特征及其地层对比意义:以松辽盆地营城组为例 |
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| 引用本文： | 陈崇阳,高有峰,张晓东,印长海,赵然磊,潘一,李存磊,王璞珺.火山地层中的沉积层特征及其地层对比意义:以松辽盆地营城组为例[J].地球科学,2018,43(3):812-826. |
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| 作者姓名： | 陈崇阳 高有峰 张晓东 印长海 赵然磊 潘一 李存磊 王璞珺 |
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| 作者单位： | 1.辽宁石油化工大学石油天然气工程学院, 辽宁抚顺 113000 |
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| 基金项目： | 国家自然科学基金项目重大项目41790453辽宁石油化工大学引进人才科研启动基金2016XJJ-110中国地质调查局项目DD20160207 |
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| 摘 要： | 火山地层常具穿时和倒转现象，并且缺少化石资料，致使其地层序列划分和对比困难.营城组火山地层序列是松辽盆地火山岩油气勘探的基础和关键，火山岩中的厚层沉积夹层（营城组二段）在火山地层序列划分中可作为标志层，是营城组进一步分段的关键层位.从盆缘露头剖面入手，根据实测剖面、钻井、测井、地震、同位素年龄等资料，证实徐家围子断陷存在营二段地层，通过地层对比，总结其地层发育时限、岩性及序列特征、地层分布规律及其成因、地球物理识别标志，并将其作为标志层对火山地层进行准确划分和对比.结果显示:营二段形成于早白垩世Albian期（110~108 Ma），沉积时限2~3 Ma；以富含凝灰质夹煤层为主要特征，其碎屑粒度自下至上呈现"粗-细-粗"的全韵律；断陷内营二段地层厚度变化大，平面上存在着两类沉积中心:（1）与营一段火山岩最大厚度中心重叠的火山期后热沉降中心；（2）继承性古地貌凹陷.不同成因地层其地球物理识别特征不同.以营二段为标志层可将徐家围子断陷营城组分为3段，其中一段和三段均以火山岩为主.而原分层中的营四段实属盆地不同充填期的两套地层:下部细粒砂泥岩段应为断陷期的营二段，上部粗粒砂砾岩段应为拗陷期的登娄库组一段.该方法可为其他地区火山地层划分与对比提供借鉴.
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| 关 键 词： | 火山地层序列 地层划分与对比 营城组 松辽盆地 沉积学 |
| 收稿时间： | 2017-10-10 |
Sedimentary Interlayer in Volcano Strata: Characteristics and Significance of Stratigraphic Correlation: Taking Yingcheng Formation,Songliao Basin as an Example |
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| Abstract: | Diachronous and inversion phenomenon often occurs in volcano strata, coupled with the lack of fossil data in the volcanic rock, it is difficult to determine the volcano stratigraphic sequence.The stratigraphic sequence of Yingcheng Formation is the basic and key to volcanic oil and gas exploration in Songliao basin. The sedimentary layers (the Second Member, Yingcheng Formation) between lower and upper volcanic of Yingcheng Formation play an important role in the division of stratigraphic sequence as a marker bed. Based on cross section, core sections/cuttings, well-logs of boreholes, 3D seismic, and isotopic age data, we compare the cross section at the basin margin and boreholes in Xujiaweizi graben to analysis whether the Second Member, Yingcheng Formation is widespread in Songliao basin and summary the time interval, lithology and sequence features, plane distribution, and geophysical characteristics of the Second Member, Yingcheng Formation which can be used to divide and correlate volcano strata accurately as a marker bed. Through stratigraphic correlation we consider that the Second Member, Yingcheng Formation is indeed widespread in Songliao basin, and its age can be well constrained to Albian with a chronology age ranging from 110 Ma to 108 Ma. There was enough time to form the sedimentary bed during 2-3 Ma volcanic eruption interval. The main lithology features of the Second Member, Yingcheng Formation is rich in tuffaceous and contain coal seams occasionally, and the complete lithologic sequence from the bottom showing "coarse-fine-coarse" variation. There are different sedimentary centers of the Second Member, Yingcheng Formation. One type is mainly influenced by the thermal subsidence after the volcanic eruption, and another type is mainly controlled by the palaeogeomorphology. Two types of strata have different geophysical response characteristics due to their different origin. The stratigraphic sequence of Yingcheng Formation can be divided to three member when use the sedimentary layers (the Second Member, Yingcheng Formation) as a marker bed, the First Member and the Third Member are volcanic, and the former Forth Member should be divided to two parts, the lower part of fine sand-mud layers belong to the Second Member, and the upper part of conglomerate layers should be a part of Delouku Formation. This method can be used as a reference for stratigraphic sequence division and correlation in other volcanic areas. |
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