The block-faulted zone in the northern margin of Qaidam Basin is a terrestrial sedimentary region of the Meso-Cenozoic with an area of 30000km

2

.within the province

overthrust faults and folds are well developed with the sediments of the Triassic

Jurassic

Cretaceous

Tertiary and Quaternary.Among them

Jurassic sediments in the type of a piedmont depression

is a major hydrocarbon-producing formation with a thickness of 600m.Organic aboundance of which is high

and organic matters are mainly Ⅲ type which in some places have reached a mature stage.Carboniferous marine sediments of the basement may be a potential hydrocarbon-producing formation.It is believed that all conditions are available for the formation of hydrocarbon reservoirs in this region.Among four secondary tectonic units within the area

Saishiteng sag in the western depression is the most favourable for the prospect of oil and gas

and the central uplift and eastern sag

Ainan slop

on the other hand

is considered to be less favourable.