Organic matter of various types and different properties is widely distributed in nature, and it plays an important role in both water body and sediments. Therefore, exploring its accumulation and depositional processes is significant for better understanding the sedimentation characteristics and evolution laws of organic matter. Organisms produce abundant organic matter during the process of growth, including the bodies, remains, excreta of organisms and molecular scale of their secretion. The properties of different types of organic matters vary greatly. Organic matter can be divided into particulate organic matter (POM) and dissolved organic matter (DOM) according to the size, and DOM can be further divided into colloidal organic matter (COM) and true DOM. From the point view of aggregation form, there are marine snow and suspension matter. Further analysis shows that morphology of organic matter includes organisms' body, biological residues, excreta and organic matter aggregates in water body, and various types of organic matter can co-exist with inorganic minerals in different forms. In addition, DOM and POM can transform mutually in appropriate conditions. These properties and characteristics bridge the accumulation and deposition of different types of organic matter. It is also found that different types of organic matter, such as organisms, biological residues and amorphous organic matter, are often associated with specific inorganic minerals, such as amorphous mostly concentrated at clay particles, whereas organisms and biological residues mostly concentrate in coarse ones. Further study reveals that the organic matter of sediments is similar to that of water body or organism. The variation of different kinds of organic matter reflects that they deposited via different processes. The mechanically deposited organic matter is mainly composed of inert phytoclasts, the chemically deposited organic matter is mainly composed of amorphous organic matter, and the biologically deposited organic matter is mainly composed of microorganisms and adherents.Both the differences in organic matter deposition and organic matter characteristics and the mineral-organic matter and storage conditions determine the evolutionary fate of organic matter, which has an important impact on organic hydrocarbon generation and carbon cycle, and thus should be highly concerned.%自然界中有机质分布广泛、类型多样且性质各异, 不论在水体还是在沉积物 (岩) 中都扮演着重要的角色.因此, 探讨各类型有机质聚集和沉积过程的差异性, 对深化认识有机质沉积特征和演化规律具有重要的意义.生物体在生长过程中产生了许多有机质, 包括生物体自身、生物残体、动物排泄物以及生物分泌的有机分子等, 各类型有机质的性质差异极大.由于研究方法的不同, 可将海洋中有机质划分为颗粒有机质 (particulate organic matter, POM) 和溶解有机质 (dissolved organic matter, DOM) , 而DOM又可划分为胶体有机质 (colloidal organic matter, COM) 和真溶解有机质;从聚合体形式上看, 又有海雪和悬浮体等存在形式.进一步分析发现有机质的形态包括生物体、生物残体、排泄物和有机质聚合体等, 并且各类型有机质与无机矿物以不同的形式共存.此外, DOM与POM间存在一定的转化关系.这些性质和特征架起了不同类型有机质间聚集和沉积的桥梁.在沉积物 (岩) 中通过粒度或密度分级分离及孢粉相分析, 也发现不同类型的有机质, 如生物体、生物残体和无定形等, 它们常与特定的无机矿物共生, 如无定形多富集在黏粒级颗粒中, 而生物体和生物残体多富集在粗颗粒中.进一步溯源发现沉积物 (岩) 中的各类有机质与生物有机质或海洋中有机质的类型极具相似性, 这些特征展现各类型有机质在沉积过程中的差异性.综合有机质的形态、性质以及与矿物共生关系, 认为有机质可通过机械沉积、化学沉积和生物沉积等3种不同的方式沉积保存, 其中机械沉积的有机质以惰性的生物残体为主, 化学沉积的有机质以活性极强的无定形为主, 生物沉积有机质以活性较强的微生物和粘附物为主.有机质沉积方式及有机质特征、矿物—有机质间关系和保存条件的差异, 决定了有机质的演化命运的不同, 进而对有机质生烃以及碳循环产生重要的影响, 因而应引起人们的高度关注.
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