Abstract:

Gypsolyte-salt layers of the Middle-Lower Cambrian are widely developed in the southern and eastern Sichuan Basin,resulting in a variety of salt-related structures.Analyses of outcrop,drilling and seismic data reveal that the gypsolyte-salt layers of the Cambrian in Sichuan Basin formed on restricted intra-craton platform and has the characteristics of old age,deep burial depth,uneven thickness,more gypsolyte and less salt,and various associated rock types.The gypsolyte-salt related structures show obvious layering due to the differential gypsolyte and salt mobility,tectonic compression,basement faults,and detachment,.The post-salt structures are mainly anticlines,thrust nappes and faulted-anticlines.The structures within the salt layers are mainly salt pillows,tail structures and plastic flow structures.The presalt structures mainly include imbricate thrusts and pop-up structures controlled by the complex basement faults.The gypsolyte-salt layers of the Cambrian provide good sealing conditions for hydrocarbon accumulation in the Lower Sinian-Lo-wer Cambrian.Meanwhile,they also can improve reservoir quality through TSR and supergene dissolution that they are involved.Even more important,as a region detachment layer,the gypsolyte-salt rock plays an important role in the structural deformation of the post-salt and pre-salt Sinian-Lower Paleozoic,resulting in a series of hydrocarbon traps.According to the characteristics of gypsolyte-salt related structures,the pre-salt faulted anticlines in western Hubei-eastern Chongqing and post-salt faulted anticlines in southeast Sichuan are the favorable exploration targets.

Key words: salt-related structure, gypsolyte-salt rock, control on hydrocarbon, exploration target, Cambrian, Sichuan Basin