Sequence Stratigraphy of the Desert System: A Case Study of the Lower Cretaceous in the Kuqa Basin in Xinjiang, Northwestern China

Abstract  The Lower Cretaceous strata in the Kuqa Basin in Xinjiang are marked by a set of arid red beds. Several types of sedimentary facies can be identified in this set of arid red beds: mudstones of the plaza and intracontinental sebkha, aeolian sandstones, sandy conglomerates of the intermittent river, conglomerates of the pluvial fan, etc. These types of sedimentary facies constitute a typical desert system. Therefore, the Cretaceous strata in the Kuqa Basin provide a favorable condition for studies of sequence stratigraphic divisions of the desert system. With the rise and fall of the base level of the sedimentary basin, cyclicity is clearly revealed in stratigraphic records, which helps the identification of the third‐order sequences. Based on the cyclicity in stratigraphic records, 5 third‐order sequences can be found in the strata of the Early Cretaceous in the Kuqa Basin. These sequences comprise a second‐order tectonic sequence. The primary feature of these third‐order sequences is of an upward‐fining sedimentary succession formed by a succession of “coarse sediments of the alluvial system‐fine sediments of the lake system”. The result of this study shows that aeolian sandstones are the best reservoirs of natural gas in the Cretaceous strata in the Kuqa Basin, and that the Kela‐2 gas field is the first large gas field dominated by aeolian sandstone reservoirs in China.

[1]  Mei Ming-xiang,et al.  Basic Lithofacies‐Succession Model for the Wumishan Cyclothems: Their Markov Chain Analysis and Regularly Vertical Stacking Patterns in the Third‐Order Sequences , 2001 .

[2]  Howell,et al.  Aeolian architecture, bedform climbing and preservation space in the Cretaceous Etjo Formation, NW Namibia , 2000 .

[3]  Cross,et al.  STRATIGRAPHIC CONTROLS ON RESERVOIR ATTRIBUTES IN CONTINENTAL STRATA , 2000 .

[4]  D. Jerram,et al.  Climate, sediment supply and tectonics as controls on the deposition and preservation of the aeolian-fluvial Etjo Sandstone Formation, Namibia , 1999, Journal of the Geological Society.

[5]  Sweet.  Interaction between aeolian, fluvial and playa environments in the Permian Upper Rotliegend Group, UK southern North Sea , 1999 .

[6]  Z. Chenglin,et al.  Cycle—Sequences, Carbon Isotope Features and Glacio–Eustasy of the Triticites Zone in Southern Guizhou , 1997 .

[7]  P. Mccabe,et al.  Perspectives on the Sequence Stratigraphy of Continental Strata , 1994 .

[8]  J. Wagoner,et al.  High-frequency sequences and their stacking patterns: sequence-stratigraphic evidence of high-frequency eustatic cycles , 1991 .

[9]  H. Posamentier,et al.  An Overview of the Fundamentals of Sequence Stratigraphy and Key Definitions , 1988 .

[10]  R. Blakey.  Basin tectonics and erg response , 1988 .

[11]  P. Vail,et al.  Seismic stratigraphy and global changes of sea level, Part 4 : Global cycles of relative changes of sea level , 1977 .

[12]  Jean Lajoie,et al.  Sand and Sandstone , 1974 .