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本文通过对海拔高度在2500~4500 m的甘肃南部和祁连山、青海东部、西藏东部林中表土、林间表土、森林上限表土、森林下限表土、森林上限高山草甸土,以及青海玉树冬给错纳地区亚高山荒漠—草甸土中可溶有机质正构烷烃分析,利用检测出的类异戊二烯烃的分布特征,对Pr(姥鲛烷)、Ph(植烷)的成因特征进行研究。结果表明,在不同地理环境土壤中均有明显的Pr、Ph存在,Pr/Ph(姥植比)主要为0.6~1.4,平均0.95;Pr/n-C17值主要为0.2-1.2,平均0.64;Ph/n-C18值主要为0.4~1.4,平均0.85。Pr和Ph不仅在水体中生成,在土壤环境中也可以形成。Pr/Ph值与不同生态环境土壤之间没有明确的相关性,但与不同地理区域有一定的联系。在较为温湿的土壤中Pr优势,可能与微生物活动强烈,采用有氧呼吸方式降解有机质有关;干旱、寒冷土壤中Ph优势,可能主要与厌氧发酵有关。由于生成Pr、Ph有机母质及演化途径的差异,以及热演化、成岩过程中的转变,其比值很大程度上影响对沉积盆地原始介质环境信息的判断。
In this paper, the topsoil, forest topsoil, forest upper limit topsoil, forest lower limit topsoil, forest upper limit alpine meadow soil, and Qinghai Yushu winter are given to the south of Gansu and Qilian Mountains, eastern Qinghai and eastern Tibet in the 2500 ~ 4500 m altitude. Based on the distribution characteristics of isoprenoid detected, the genetic characteristics of Pr (pristane) and Ph (phytane) were studied. The results showed that there were obvious Pr and Ph in different geographical environments. The Pr / Ph ratio was 0.6-1.4 with an average of 0.95. The Pr / n-C17 values were 0.2-1.2 with an average of 0.64. The Ph / n-C18 values were mainly 0.4-1.4 with an average of 0.85. Pr and Ph are not only formed in the water but also formed in the soil environment. There is no clear correlation between Pr / Ph and different ecological environment soil, but it has some connection with different geographical regions. The Pr preponderance in relatively warm and humid soils may be related to the strong activity of microorganisms and the degradation of organic matter by aerobic respiration; and the predominance of Ph in arid and cold soils may be mainly related to anaerobic fermentation. Due to the differences of the organic parent materials and evolutionary pathways of Pr and Ph, as well as the transitions during thermal evolution and diagenesis, the ratio of them greatly influences the judgment of the original media environmental information in the sedimentary basin.