GEOCHEMICAL CHARACTERISTICS OF HYDROCARBON SOURCE ROCKS IN THE QILIAN MOUNTAIN PERMAFROST AND GAS SOURCES FOR GAS HYDRATE

90 samples from Muli of the Qilian Mountain permafrost are collected and analyzed. Results show that the Carboniferous-Triassic source rocks remain in a high mature stage; the organic matters mainly belong to the type Ⅱ, indicating a mixed sources of higher plants and lower aquatic organisms deposited in an environment of epicontinental sea and its coasts and deltas. The organic matter abundance is relatively high, belonging to a moderate-good source rock. The Jurassic source rocks are also in a mature stage, consisting of organic matters of typeⅡ₂-Ⅲ, indicating a source of higher plants. They are formed in the environment of a swamp; and the abundance of organic matter is also relatively high, belonging to the kind of moderate to good source rocks. The gas hydrate is mainly composed of crude oil cracked gas. The Triassic source rocks seem to be the major oil-type gas contributor for the natural gas hydrate with the Jurassic as the second. That Jurassic coal could be partly the coal-type gas source contributor for the natural gas hydrate as well.