摘要： 根据Gr值、TH/U值和成像测井等测井资料,以及岩心、薄片等反映沉积基准面和沉积相变化的资料,在哈萨克斯坦Marsel探区下石炭统碳酸盐岩台地内划分出18个高频层序(四级层序),其中杜内阶和维宪阶高频层序界面类型主要为瞬时加深淹没间断面,谢尔普霍夫阶高频层序界面类型主要为瞬时暴露间断面。高频层序一般厚十几米至几十米,杜内期—维宪早期厚度较薄且差异不大,维宪中晚期—谢尔普霍夫期厚度差异增大,最终使下石炭统整体呈西薄东厚、北薄南厚的特征。杜内—维宪早期高频层序下部主要发育蒸发潟湖和局限潟湖亚相,上部主要为局限潮坪亚相;维宪中晚期—谢尔普霍夫期高频层序下部主要发育局限潮坪亚相,向上变为蒸发潮坪和台内浅滩亚相。通过对高频层序的成因分析认为,周期性高频海平面升降变化和气候是高频层序发育的主控因素,气候对维宪晚期—谢尔普霍夫期高频层序发育的影响更大。Marsel探区在早石炭世位于镶边台地内部,先后经历了早期(杜内期)局限台地—蒸发台地、中期(维宪期)局限台地—蒸发台地和晚期(谢尔普霍夫期)开阔台地—局限台地—蒸发台地这3期沉积演化过程。高频层序的研究为建立高精度层序地层格架和有利储集层的精细划分、对比及预测奠定了基础。

关键词: 哈萨克斯坦, Marsel探区, 下石炭统, 碳酸盐岩, 高频层序, 沉积演化

Abstract: Based on GR and TH/U values and imaging logging data as well as cores and thin sections which could reveal base level and facies changes,18 high-frequency sequences(fourth-order sequences)are identified in the Lower Carboniferous in Marsel block of southern Kazakhstan. Of them, the Tournasion and Viscan sequences are mainly bounded by instantaneous exposed punctuated surfaces and the Serpukhovian sequence by drowned punctuated surfaces. The high-frequency sequence is usually ten meter to several tens meter thick. The tournasian-early Visean high-frequency sequence is relatively thin and does not vary much in thickness,leading to the result that the whole Lower Carboniferous is thinner in the west and north. Lagoon subfacies on both evaporative and restricted platforms,and tidal flat subfacies on restricted platform were developed respectively in lower and upper part of Tournasian-early Visean high-frequency sequences;subfacies in high-frequency sequences of middle-late Visean-Serpukhovian,is changed from tidal flat on restricted platform to tidal flat and shoal-reef complexities on evaporate platform upwards. After genetic analysis of these high-frequency sequences,it is supposed that periodic high-frequency sea-level and climate changes are dominant factors for high-frequency sequence development,however,climate has a more significant influence on later high-frequency sequence development. What’s more,it is indicated that the Marsel block was located in the inner part of a regional rimmed carbonate platform,mainly evolved through three stages in Early Carboniferous: Early(Tournasian)restricted-evaporative platform,middle(Visean)restricted-evaporative platform and late(Serpukhovian)open-restricted-evaporative platform. Obviously,the study of high-frequency sequence could lay the foundation for high-resolution sequence stratigraphic framework construction and detailed favorable reservoir identification,correlation and prediction.

Key words: Kazakhstan, Marsel block, Lower Carboniferous, carbonate rock, high-frequency sequence, sedimentary evolution

中图分类号: 

• P539.2