塔里木盆地北部三叠系“二元”层序结构特征及演化模式
摘要: 综合运用露头、测井、岩芯等资料，对塔里木盆地北部库车坳陷库车河野外露头及塔北隆起区三叠系层序结构特征进行了分析。各层序低位体系域，主要是冲积扇、辫状河、辫状河三角洲等粗粒沉积体，层序上部多为湖相泥岩，统称为湖侵—高位体系域，单个层序均具有“下粗上细”的“二元”结构特征。塔北三叠系特殊的层序结构，主要是与三叠纪塔里木盆地的幕式挤压活动有关。挤压初期，物源近且供给充分，可容空间增加缓慢，主要为低位体系域的粗碎屑沉积；随着挤压作用持续增强，湖盆逐渐加深，细粒沉积物为主体的湖侵体系域沉积；最终盆地基底破裂时，湖平面快速下降，高位体系域不甚发育，多为湖相细粒沉积物。据此提出塔北三叠系层序发育模式，认为在构造挤压期，沉积扇三角洲、辫状河三角洲等粗粒低位域沉积；而在构造持续期和卸载期，层序上部发育细粒深湖—半深湖湖侵—高位体系域沉积。由于层序特殊的“二元结构”特征，纵向上构成了较好的生储盖组合。因此，除了构造油气藏外，塔北地区各层序低位体系域的岩性油气藏及岩性—构造油气藏是重要的勘探目标。
“Dual feature” of Sequence Architecture and Sequence Evolution Model of Triassic Northern Tarim Basin
Abstract: Based on integrated investigation of outcrops, well logs and cores, the sequence stratigraphy framework of northern Tarim Basin was set up, and the sequence architecture of Triassic in outcrop of Kuche depression and Northern Uplift of Tarim Basin was studied. In each sequence, coarse grained lithosomic bodies such as alluvial fan, braided river and braided river delta are dominant in the lowstand systems tracts (LST), and the upper parts of the sequences are composed of fine grained lacustrine mudstone which are called lacustrine transgressive-highstand systems tracts (T-HST). Every single sequence is coarse in lower part and fine in the upper part. The special sequence architecture is mainly associated to episodic compressive movement of Tarim Basin in Triassic. At the beginning of the compression, the accommodation increases slowly, for the short distance from provenance to basin and sufficient sediment supply, the LSTs are mainly coarse sediments. The water became deeper with the intensified compressive force, then the fine-grained transgressive systems tracts (TST) are deposited. When the basin base was broken, lake water dropped down quickly, with little mudstone deposited as highstand systems tracts (HST). Finally, a sequence evolution model of Triassic in the northern Tarim Basin was proposed. In tectonic compression period, some coarse-grained lithosomic bodies such as fan delta, braided river delta were deposited; when the compressive force persisted and discharged in a short time, fine-grained lacustrine sediments deposited which were defined as T-HST as the upper parts of sequences. For the special dual feature of the sequences, the coarse-grained lower LSTs are suitable for reservoir, and the upper fine-grained T-HSTs could be the source or seal of the reservoir, so it is indicated that, besides the tectonic reservoir, the lithologic reservoir and lithologic-tectonic reservoir in the LSTs of each sequence are major exploration targets of Triassic in northern Tarim Basin.
塔里木盆地北部三叠系“二元”层序结构特征及演化模式[J]. 沉积学报, 2014, 32(2): 325-333.
| 引用本文: |
塔里木盆地北部三叠系“二元”层序结构特征及演化模式[J]. 沉积学报, 2014, 32(2): 325-333.
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“Dual feature” of Sequence Architecture and Sequence Evolution Model of Triassic Northern Tarim Basin[J]. Acta Sedimentologica Sinica, 2014, 32(2): 325-333.
| Citation: |
“Dual feature” of Sequence Architecture and Sequence Evolution Model of Triassic Northern Tarim Basin[J]. Acta Sedimentologica Sinica, 2014, 32(2): 325-333.
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