成烃生物组合对烃源岩干酪根碳同位素组成的影响:以塔里木盆地下古生界烃源岩为例

油气生成的母质是地质历史上沉积有机质,这些有机质是生物体埋藏演化的结果,其中形成具有生烃能力的沉积有机质的那部分生物称为成烃生物。不同成烃生物的碳同位素组成不同,导致不同成烃生物组合烃源岩的干酪根的碳同位素组成明显不同,因而成烃生物及其碳同位素组成是油源对比(特别是高过熟烃源岩)的重要手段。通过对塔里木盆地早古生代各层段烃源岩成烃生物组合面貌的研究,发现从早寒武世早期以底栖藻类为主,到晚寒武世逐渐过渡底栖藻类和浮游藻类共存,从早奥陶世开始,底栖藻类有增多的趋势,但仍以浮游藻类为主。结合烃源岩干酪根碳同位素组成分析,表明以底栖藻类为主的烃源岩干酪根碳同位素一般轻于-34‰,而以浮游藻类为主的烃源岩干酪根碳同位素一般重于-30‰。底栖藻类和浮游藻类在碳源利用以及光合作用对碳同位素分馏差异是导致其碳同位素组成不同的重要原因。

四川省地质灾害避险搬迁安置相关问题研究

四川省滑坡、崩塌和泥石流等地质灾害多发频发,灾情险情严重。在过去十年里四川省率先开展了一系列地质灾害避险搬迁安置工程,对降低广大丘陵山区,特别是农村地区地质灾害风险,减轻灾害损失发挥了巨大作用。但同时,出现了一系列诸如搬迁安置地选址困难、搬迁户因贫困而搬不起、搬迁户签订搬迁协议后出现反悔、旧房拆除困难和非本地户口居民不能纳入搬迁计划等问题。为此,文章提出创新工作机制、广泛筹集资金、关注弱势家庭、根据搬迁紧迫性分期搬迁、加强迁入人口管理、严格宅基地危险性审查和审批等有针对性的对策建议。

The Original Organism Assemblages and Kerogen Carbon Isotopic Compositions of the Early Paleozoic Source Rocks in the Tarim Basin, China

Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.

Retracted: The Original Organism Assemblages and Kerogen Carbon Isotopic Compositions of the Early Paleozoic Source Rocks in the Tarim Basin, China

The above article from Acta Geologica Sinica(English Edition),published online on 27 December 2018 in Wiley Online Library(wileyonlinelibrary.com)and in Volume 92,Issue 6,pp.2297-2309,has been retracted by agreement between the authors,the journal Editor in Chief,Professor Zengqian Hou and John Wiley&Sons Ltd.The retraction has been agreed due to major overlap with a previously published article from the same group of authors published in Chinese.

中国南方海相烃源岩中细菌状化石识别

在常规地球化学分析基础上,通过对烃源岩薄片和扫描电镜观察,发现中国南方海相低演化烃源岩和煤层中存在菌胶团化石,大小在数十纳米到数微米之间,形状为圆形、椭圆形以及扁圆形的细菌状化石。二叠系烃源岩中确认的细菌状化石主要为与石膏共生硫细菌形成,城口剖面寒武系地层中存在大量的纳米细菌状化石,多为杆状—短柱状;二叠系、志留系与寒武系高演化烃源岩扫描电镜下观察到大量可能的细菌状化石。研究认为:细菌状化石在烃源岩中普遍存在,与烃源岩具有共生关系,发现泥岩、硅质岩和含石膏煤系等若干地层中存在细菌状化石。其中泥岩层面上的细菌构成菌席;硅质岩中的细菌具有溶硅的习性;煤系地层中和石膏共生的细菌被解释为对形成石膏起重要作用的硫细菌。细菌状化石在地质历史时期对页岩气形成和储集具有重要的作用。