塔中志留系层序及其可容纳空间分析

Sequence stratigraphy of the Silurian strata and accommodation spaces in central Tarim Basin,Xinjiang

关键词:  塔中  志留系  潮坪  层序地层学  可容纳空间  新疆

Key words:  central Tarim Basin  Silurian  tidal flat  sequence stratigraphy  accommodation space  Xinjiang

摘要:

根据经典层序地层学理论,综合研究野外露头、测井、地震等资料,将塔中地区志留系划分为5个层序,每个层序均由海侵和高位体系域两部分组成。除SQ₁为Ⅰ型层序外,其余4个层序均为Ⅱ型层序,而且SQ₃为一个三级中间体系域。受加里东运动影响,隆升后的塔中地区在晚奥陶世遭受剥蚀,地形变得平缓,在此基础上形成了以潮坪沉积为主的志留纪滨浅海沉积。在志留纪塔中地区构造稳定,海平面的升降决定了可容纳空间的大小。潮坪沉积相带的迁移反映了在全球海平面升降形成的异旋回中发育的潮坪自旋回沉积,可容纳空间动态变化是外在的表现形式。

Abstract:

The Silurian strata in central Tarim Basin,Xinjiang may be grouped,on the basis of classical sequence stratigraphic theory,and outcrops,well logs and seismic sections,into five sequences,of which four are assigned to the type 2 sequence except SQ1 as the type 1 sequence.Each of them consists of transgressive and highstand systems tracts.SQ3 is interpreted as a third-order intermediate system tract.Influenced by the Caledonian orogeny,the uplifted central Tarim Basin area was subjected to the erosion during the Late Ordovician,followed by the deposition of the tidal flat-dominated Silurian littoral and shallow marine deposits.The Silurian time was tectonically quiet in this area.The eustatic fluctuations may exercise a major control on the sizes of the accommodation spaces.The migration of the tidal-flat facies has mirrored the variations in accommodation space and tidal energy,and represents the products originated from the combination of autocyclic and allocyclic deposition in response to the global eustatic fluctuations.The dynamic patterns of the accommodation spaces may be the external expressions of tidal cyclicity.