准噶尔盆地西南缘构造模式、演化及其油气

通过地震勘探、钻井、地面地质资料综合分析,列出了6点依据,认为,盆地南缘西部构造特征是3个深浅层次的北凸孤形滑脱体。它们分别为燕山和喜山运动由南向北的侧向挤压造就而成。圈闭的含油气性,总的说来西段较东段好。     

Organic geochemical evidence for environmental changes since 34,000 yrs BP from Lago di Mezzano, central Italy

The composition of organic matter in a 34,000 yr sediment profile from Lago di Mezzano, central Italy, was investigated by bulk organic geochemical methods and analyses of lipid distributions. High relative amounts of long-chain fatty acids, n-alkanols and n-alkanes from the cuticular waxes of terrestrial plants in the Late Pleistocene sediments indicate a high relative proportion of allochthonous organic matter. In the Holocene sediments higher relative amounts of algal and bacterial lipids are detected which indicate a higher relative contribution of autochthonous organic matter. These results are corroborated by Hydrogen Index (HI) and Oxygen Index (OI) values from Rock-Eval pyrolysis which show a good general correlation with the TOC content indicating significant variations of the organic matter composition. Variations of HI and OI observed for different lithozones of the sediment profile can be related to environmental and climatic changes throughout the lake history. Both bulk organic geochemical and molecular data point to a good overall preservation of the organic matter.