| 中新生代柴达木叠合盆地解析、动力学机制探讨及对油气控制意义研究 |
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| 引用本文：王桂宏,周川闽,夏响华,张永庶,赵孟军,王点奥,吕杰堂,王根久,张铭.2019.中新生代柴达木叠合盆地解析、动力学机制探讨及对油气控制意义研究[J].地球学报,40(6):805-815. |
| DOI：10.3975/cagsb.2019.090301 |
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| 基金项目:中国石油天然气股份有限公司重大专项“柴达木盆地油气勘探开发关键技术研究”(编号: 07-01Z-01-05) |
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| 中文摘要:柴达木盆地位于青藏高原北部, 受喜马拉雅运动影响比较直接, 构造复杂, 以致对中新生代盆地的性质一直存在较大争论。通过对盆地地震大剖面和测井资料地质解释与统计成图, 并结合前人研究成果, 提出柴达木盆地中新生界三大构造层对应三类盆地, 具体以古近系底(TR)与下油砂山组顶的不整合面(T2’), 将中生界划为下构造层, 古近系路乐河组、上下干柴沟组、新近系下油砂山组构成中构造层, 新近系上油砂山组、狮子沟组与第四系组成上构造层，其分别对应三种不同构造背景的原型盆地。下构造层为燕山运动阶段形成, 为侏罗纪早期伸展断陷、中后期坳陷盆地, 主要分布于盆地北半部及柴西地区, 现为残留盆地; 中构造层发育于早喜马拉雅期, 主体厚度区位于盆地西半部的菱形块体内, 阿尔金断裂带的走滑与南祁连西段的顺时针旋转是中构造层盆地发育的主要动力学机制, 原型盆地为走滑旋转盆地。一里坪—南八仙构造线以北一带因主要断裂带的走滑反转作用成为中、下构造层主要叠合区。上构造层盆地为晚喜马拉雅运动阶段走滑挤压构造背景下形成, 沉积沉降中心具有由西向东迁移的明显特征, 为走滑盆地。一里坪—东台吉乃尔湖一带为中、上构造层盆地叠合区, 叠合机制为盆地基底持续挠曲坳陷作用。分析认为, 盆地所处的大地构造背景及特殊的深部地质结构所导致的主要大断裂多次反转作用是造成盆地反转与走滑叠合的关键动力学机制。文章同时简述了对油气勘探的参考意义。 |
| 中文关键词:柴达木盆地 中新生界 构造层序 叠合特征 油气分布 |
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| Superposition Process and Dynamic Mechanism of Mesozoic–Cenozoic Qaidam Basin and Their Influence on Hydrocarbon Accumulations |
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| Abstract:The characteristics of Qaidam basin in northern Tibetan Plateau have been long controversial. In this study, on the basis of profile interpretation and well data, the Mesozoic-Cenozoic is separated into three parts separated by base of Tertiary and unconformity T2’ which is the top of Xia Youshashan Formation (N1 2). Mesozoic is the lower tectonic layer, E-N1 2 is considered to be intermediate tectonic layer, and N2 2-Q is upper tectonic layer. This delimitation is different from previous study which set the unconformity of Q and N3 2 as the major boundary, or separated Mesozoic-Cenozoic into two parts rather than three parts as held in this paper. The delimitation of three parts illustrates three styles of basin development which controlled different petroleum systems. The lower tectonic layer of Mesozoic were developed in northern parts of Qaidam basin, and intermediate tectonic strata overlapped on it, which matured the Jurassic soil rocks in early Tertiary during the basin expansion and subsidence. The intermediate tectonic strata mainly developed over west part of Qaidam basin which might have undergone rotation of basement blocks with some minor faulted depressions formed. The upper tectonic layer developed under the control of boundary strike-slip faulting and basement flexure, and depocenters of N2 2, N3 2 and Q migrated eastward. Superimposition between intermediate and lower tectonic layer was controlled by inverted strike-slip of major basement faults while the superimposition feature of upper and intermediate tectonic layer seems to be basement flexural with depressions continuous developing. Multiphase inversions of major faults were controlled by tectonic setting and special structures at the depth of Qaidam basin, which may be the critical dynamic mechanism for inverted strike-slipped and continuous basement warping of basins superimposing. Significance of three tectonic layers for hydrocarbon exploration is also discussed in this paper. |
| keywords:Qaidam basin Mesozoic to Cenozoic tectonic layers superimposition features oil & gas distribution |
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