uAbstract

uFigures

uGeological settings

uGeometric features

uEvolution

uHydrocarbons

uAbstract

uFigures

uGeological settings

uGeometric features

uEvolution

uHydrocarbons

uAbstract

uFigures

uGeological settings

uGeometric features

uEvolution

uHydrocarbons

Selected Figures

	Figure 1. Division of structural units in the Kuqa fold-and-thrust belt, northern Tarim basin.
	Figure 2. Surface expressions of salt tectonics in the Kuqa fold-and-thrust belt.
	Figure 3. Salt tectonics of varying geometric configurations in the Kuqa fold-and-thrust belt.
	Figure 4. Balanced cross section of salt tectonics in the Kuqa fold-and-thrust belt.
	Figure 5. Growth strata and triangles in the Kuqa fold-and-thrust belt.
	Figure 6. Kela-2 and Dina-2 gas fields in the Kuqa fold-and-thrust belt.

Geological Setting

 The Kuqa foreland fold-and-thrust belt, covering an area of about 28,000 square kilometers, is located in the north of Tarim basin and is bounded to the north and south by the South Tianshan Mountains Orogen and Tabei Uplift, respectively. The Kuqa fold-and-thrust belt is one of the important structural units where hydrocarbons are rich and salt structures are well developed in the Tarim basin. The evolution of the Kuqa fold-and-thrust belt was closely correlated with the Tianshan Mountains Orogenic belt and Tabei uplift. Five subordinate structural units have been recognized, including the Northern monocline belt, Kelasu-Yiqikelike structural belt, Baicheng-Yangxia sag belt, Qiulitage structural belt, and Forbulge (Figure 1). The Paleogene Kumugeliemu Formation and Neogene Jidike Formation contain thick halite layers in the Kuqa foreland fold-and-thrust belt. Approximately bounded by the Kuqa River, the halite in the Kumugeliemu Formation is distributed mainly in the west segment of the Kuqa foreland fold-and-thrust belt, and the halite of the Jidike Formation in the east segment. The maximum thickness of the halite layers is more than 4000 m in the Qiulitage structural belt which is located in the most frontal range of the Kuqa foreland fold-and-thrust belt, where the surface expressions of salt tectonics are varied (Figure 2).

Geometric Features of Salt Tectonics

The Kuqa foreland fold-and-thrust belt is dominated by the complicated salt structural systems, including mainly salt pillows, salt nappes, salt welds, fish-tail structures, etc. (Figure 3).

Evolution of Salt Tectonics

The balanced cross-sections conclude that the intense structural distortion of salt tectonics in the Kuqa foreland fold-and-thrust belt mainly occurred in the late Himalayan period from the Kuqa period to Quaternary (Figure 4). The growth strata and triangles also show the structural evolution of salt tectonics in the Kuqa foreland fold-and-thrust belt (Figure 5).

Relationships of Salt Tectonics to Hydrocarbons

Some large fields which have close relationships to salt tectonics have been discovered in the Kuqa foreland fold-and-thrust belt, such as the Kela-2 gas field, Dina-2 gas field, and Dabei gas field (Figure 6). The relationships of salt tectonics to hydrocarbons can be simply summarized as follows: 1) Salt flowage can change the overburden and then produce various structural and subtle hydrocarbon traps. 2) The thermal conductivity of salt is two to three times higher than that of typical sediments. In the vicinity of salt structures, it produces thermal anomalies which influence hydrocarbon generation, migration, and maturation. 3) The features of compaction and flowage of salt bodies make them very good seal layers. 4) The faults resulting from the salt structural movements can afford good vertical pathways for hydrocarbon migration.

Return to top.

Copyright © AAPG. Serial rights given by author. For all other rights contact author directly.