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141.
This paper describes simulation experiments in which glucose and cellulose were reacted with polysulphide and hydrogen sulphide at ambient temperatures in an aqueous environment. Organic sulphur containing compounds were formed that yield several thiophenes upon pyrolysis/evaporation. The experiments show that interaction of carbohydrates with hydrogen sulphide or polysulphides is a possible way for carbohydrates to react in very recent sediments. From the results of this study it can be concluded that carbohydrate carbon can be preserved in sediments in a form that is resistant to microbial attack and that will have a greater potential for survival during diagenesis than the carbohydrate precursor. 相似文献
142.
This study provides information on non-aromatic hydrocarbons contained in thick Palaeogene halite sequences in the Bresse region (France). The presence of almost uniquely biological markers and the absence of thermogenic compounds denote the low maturity of the corresponding samples consistent with Rock-Eval pyrolysis data. The distribution of n-alkanes enables the distinction of three main biological signatures: algal (mode in nC17–nC18); terrestrial (mode in nC29–nC31) and bacterial (mode in nC25–nC26 with no odd-even carbon number predominance). As to the cyclic biomarkers, hopanes and hopenes are largely predominant over steranes and diasterenes in samples having received appreciable amounts of terrestrial inputs (Type B) and conversely for the samples containing high proportions of algal debris (Type A, Type C). 相似文献
143.
Recent sediments from Bransfield Strait, Antarctica have been analyzed for triterpenoid and steroid hydrocarbons, sterols and steroid ketones to consider the effects of hydrothermal fluids on the sedimentary organic matter. The steroid distributions in unaltered and altered sediments are controlled more by inputs from source organisms than by the effects of hydrothermal activity, which is suggested to be limited to low temperature alteration. Nevertheless, chemical reactions occurred in altered sediments and include dehydration of sterols to sterenes, isomerization of triterpenes and sterenes, rearrangement of sterenes to diasterenes and reductive processes leading to generation of phytane from phytol via phytenes. 相似文献
144.
大灰厂组沉积在北京西部大灰厂一带发育良好。该组由陆相火山碎屑砂岩、粉砂岩、页岩及砾岩组成,富含狼翅鱼、叶肢介、拟蜉蝣等动物化石和孢子花粉化石,厚度120-200米。与下伏东狼沟组整合接触,与上覆辛庄组假整合接触。其孢粉组合是以classopollis占显著优势为特征(60-80%).含有较多Cicatricosisporites,Lygodiumsporites及少量Cicatricosisporites、Appendicisporites、Aequitriradites、Hsuisporites及Densoisporitesvelatus,D.microrugulatus等。与国内外早白垩世的孢粉组合比较,时代为早白垩世韦尔登期。属于旱的热带和亚热带气候。 相似文献
145.
A series of novel long-chain 3,4-dialkylthiophenes (C36–C54) was identified in a number of sediments ranging from Pleistocene to Cretaceous. The identifications were based on mass spectral characterisation, desulphurisation and mass spectral data of synthesised model compounds. These organic sulphur compounds are probably formed by sulphur incorporation into mid-chain dimethylalkadienes with two methylenic double bonds. These putative precursor lipids are unprecedented and may be considered rather unusual. The distribution of 3,4-dialkylthiophenes in sediments varies considerably with the depositional palaeoenvironment, indicating that these compounds have a potential as molecular markers reflecting changes in palaeoenvironment. 相似文献
146.
147.
In a study on the diagenesis of carbohydrates in a recent stromatolitic deposit (Solar Lake, Sinai) monosaccharides are quantitated after mild acid hydrolysis and gas chromatographic analysis as alditol acetates. From the depth profiles of the individual monosaccharides relative to the total organic carbon three categories of carbohydrates can be distinguished. The behaviour of the various categories upon burial is discussed in terms of their potential to become a part of the organic matter that survives geological periods. The distribution patterns of especially the mono-O-methyl monosaccharides at various depths are characteristics for the bacterial communities present in the corresponding parts of the sediment column. 相似文献
148.
本文在1:5万尤溪县等四幅区域调研工作的基础上,就本区广泛分布的梨山组沉积岩的沉积环境。通过沉积地层的基本层序划分、地方性剖面模式层序的建立及采用相分析,划分出辫状河及交织河沉积。辫状河积的河道宽、深化值大、沙滩及坝形成侧向连续的带状砂体。细粒沉积薄而少,多呈不连续状,构成“砂包泥”的宏观特征,交织河流具低梯度、低弯度、快速填积的低能及广阔的洪泛盆地,河道沉积的砂体在侧向上包含于细粒沉积物中,由于 相似文献
149.
江西修水二叠系-三叠系界线地层有一段特殊构造的地层,下部为灰色部分和红色部分组成的斑状构造,上部为灰色部分和黄色部分组成的树枝状构造。这种树枝状构造的岩石与前人报道自重庆老龙洞剖面的微生物岩非常相似。岩石薄片观察表明,树枝状构造的暗色部分为残留的灰泥岩;浅色部分为灰岩经过重结晶、白云石化去白云石化作用改造而成。在暗色的残留灰岩里有保存很好的丰富的球状微生物化石。研究认为,岩石中暗色部分和浅色部分的原始组分是同时沉积的;是成岩作用控制了浅色部分的形成。这一成果应当对认识老龙洞剖面树枝状微生物岩的成因有借鉴作用。 相似文献