| 咸化湖盆高频湖平面升降特征及地质意义 |
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| 引用本文： | 乔艳萍,谭秀成,刘耘,熊鹰,伍坤宇,张永庶,杨勃,任灵.咸化湖盆高频湖平面升降特征及地质意义[J].沉积学报,2020,38(6):1152-1165. |
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| 作者姓名： | 乔艳萍 谭秀成 刘耘 熊鹰 伍坤宇 张永庶 杨勃 任灵 |
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| 作者单位： | 1.油气藏地质及开发工程国家重点实验室·西南石油大学，成都 610500 |
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| 基金项目： | 国家科技重大专项2016ZX05004002?001 |
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| 摘 要： | 以柴达木盆地英西地区下干柴沟组上段（E32）为例，基于钻井岩芯、测录井和配套分析等资料发现，英西地区下干柴沟组上段（E32）整体为干旱、咸化背景下的湖相混合沉积，但内部岩石组分和结构产状变化频繁，表现为周期性垂向叠置的湖平面升降沉积旋回。旋回界面以层状岩盐、含膏斑块状灰质云岩、块状砂岩等顶部的岩性转换面或局部存在的暴露侵蚀面为典型标志。单个旋回多表现为短暂湖侵—持续湖退的向上变浅和咸化沉积序列，构成薄层状/块状灰质云岩—含膏斑块状灰质云岩、薄层状/块状灰质云岩—含膏斑块状灰质云岩—层状岩盐、薄层状/块状灰质云岩—块状砂岩等旋回结构类型。不同沉积旋回在空间的叠置组合受湖盆水动力能量、湖水盐度及古气候频繁波动的共同控制。通过旋回对比，利用井间旋回厚度差异近似反映相对古地貌起伏，研究区整体具有西高东低的古地貌格局，盆内则为低起伏的凹隆相间特征，自下而上各井区间的旋回厚度和地貌差异逐渐减小，反映湖盆填平补齐、逐渐咸化萎缩的演变规律。
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| 关 键 词： | 咸化湖盆 高频旋回 湖平面升降 下干柴沟组上段 英西地区 柴达木盆地 |
| 收稿时间： | 2019-08-19 |
Characteristics of High?frequency Lake?level Fluctuations in the Saline Lacustrine Basin and Its Geological Significance: A case study from the upper member of the Paleogene Lower Ganchaigou Formation in the Yingxi area,Qaidam Basin |
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| Institution: | 1.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China2.PetroChina Depositional Laboratory of Key Laboratory of Carbonate Reservoirs, Southwest Petroleum University, Chengdu 610500, China |
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| Abstract: | Based on analysis of cores， thin sections， scanning electron microscopy， well?logging ， and correlation analytic data of the upper member of the Paleogene Lower Ganchaigou Formation （E32） in the Yingxi area of Qaidam Basin， the results show that E32 consists of mixed sediments under the conditions of arid and salinized settings， but its internal rock constituent and occurrence change frequently， indicating the periodic vertical?superimposed sedimentary cycle. The cycle interface is characterized by a lithologic transition surface at the top， such as layered halite， patch gypsiferous limy dolomite， and massive sandstone， or by locally exposed erosional surfaces. A single cycle generally shows an upward shallowing and salinizing sequence under the condition of temporary lake transgression?permanent lake regression， building various kinds of cycles， such as laminal or massive limy dolomite?patch gypsiferous limy dolomite， laminal or massive limy dolomite?patch gypsiferous limy dolomite?layered halite， and laminal or massive limy dolomite?massive sandstone. Superposition of different sedimentary cycles in space is jointly controlled by the hydrodynamic energy in the lake basin， salinity of the lake water， and frequent fluctuations of the paleoclimate. Through cycle comparison， the interwell cyclic thickness difference is adopted to reflect approximately the relative paleo?geomorphic fluctuation. It suggests that the study area is higher in the east but lower in the west， and the intrabasin is characterized by low?relief sags alternated with uplifts. Thickness and geomorphic difference from the bottom up in the well field decreases gradually， reflecting the lake basin had been backfilled， salinizing， and shrinking gradually. |
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