甘肃花海盆地下新民堡群的有机地球化学——干酪根的演化问题

ORGANIC GEOCHEMISTRY OF THE LOWER XINMINGBU GROUP IN THE HUAHAI BASIN,WESTERN GANSU-EVOLUTION OF KEROGEN

Kerogen extracted from drilling cores at the depth between 1357 m and 2998m in a thick homogeneous sedimentary series of the Huahai Basin, Western Gansu, was analyzed by elemental analysis procedure, i.r. spectrophotometry, electron paramagnetic resonance spectrometry, and the reflectance of vitrite determined by microscopephotometer. The following conclusion are given: l) Kerogen in question seems to have been derived from the same type of orgunic matter, mostly of land-plant origin. 2) With the increase of burial depth, kerogen structure in the Lower Xinimgbu(iroup underwent four evolutionary stages: relative stablization, destruction of polynmerie substances, cracking and cracking-repolymerization--relative symmetrization. 3) Hydrocarbons in petroleum were largely generated at the cracking stage of kerogen structure, the critical depth being about 2100 m.

Kerogen extracted from drilling cores at the depth between 1357 m and 2998 m in a thick homogeneous sedimentary series of the Huahai Basin, Western Gansu, was analyzed by elemental analysis procedure, i.r. spectrophotometry, electron paramag-netic resonance spectrometry, and the reflectance of vitrite determined by microscope-photometer. The following conclusion are given:1) Kerogen in question seems to have been derived from the same type of organic matter, mostly of land-plant origin.2) With the increase of burial depth, kerogen structure in the Lower Xinimgbu Group underwent four evolutionary stages: relative stablization, destruction of poly-meric substances, cracking and cracking-rep olymerization-relative symmetrization.3) Hydrocarbons in petroleum were largely generated at the cracking sfage of kerogen structure, the critical depth being about 2100 m.