33. RELATIONSHIPS BETWEEN ORGANIC CARBON PRESERVATION AND MINERAL SURFACE AREA IN AMAZON FAN SEDIMENTS (HOLES 932A AND 942A) 1
33. RELATIONSHIPS BETWEEN ORGANIC CARBON PRESERVATION AND MINERAL SURFACE AREA IN AMAZON FAN SEDIMENTS (HOLES 932A AND 942A) 1
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发表时间：
1997
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通讯作者：
R. Keil;Elizabeth Tsamakis;N. Wolf;J. Hedges;M. Goñi
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作者：
R. Keil;Elizabeth Tsamakis;N. Wolf;J. Hedges;M. Goñi
在海洋钻探计划（ODP）第155条（932A和942A孔）的两个孔中测量了矿物表面积（SA）、中性糖（醇糖）浓度和有机碳含量（OC），并与现代亚马逊河和三角洲的类似物进行了比较。ODP孔中几乎所有（约90%）的OC与矿物相密切相关；两相经超声和密度分馏均不能定量分离。因此，孔932A和孔942A中的有机物在功能上可以定义为被吸附。OC与沉积前的输沙途径有一定的关系。当OC归一化到矿物表面积（OC:SA）时，受河流影响较强的快速沉积沉积物的OC:SA平均比值为0.46和0.39 mgCm -2，孔932A和942A。间接通过nepheloid搬运沉积的沉积物OC:SA比值较低（平均0.32和0.24 mgCm -2）。相比之下，亚马逊河悬浮沉积物的OC:SA比值平均为0.67 mgCm -2，而现代亚马逊三角洲沉积物的OC:SA负荷为~0.30 mgCm -2。虽然孔932A的醛糖浓度下降，但相应的分子组成模式不表明广泛的原位成岩作用。相反，整个孔932岩性亚基IIA和IIB的醛糖组成与现代亚马逊河携带的细悬浮颗粒物质相似，主要由来自植物和河流微生物的降解物质组成。醛糖数据支持Goni（本卷）提出的932A孔II单元陆源-河流有机质的同位素和木质素组成证据。
Mineral surface area (SA), neutral sugar (aldose) concentrations, and organic carbon content (OC) were measured in two holes from Ocean Drilling Program (ODP) Leg 155 (Holes 932A and 942A) and compared to analogues from the modern Amazon River and Delta. Nearly all (>90%) of the OC in the ODP holes was tightly associated with the mineral phase; the two phases could not be quantitatively separated after sonication and density fractionation. Organic matter in Holes 932A and 942A can thus be functionally defined as adsorbed. There is a relationship between OC and a sediment transport pathway prior to deposition. When OC is normalized to a mineral surface area (OC:SA), sediments that were rapidly deposited and strongly influenced by the river had average OC:SA ratios of 0.46 and 0.39 mgCm -2 for Holes 932A and 942A. Sediment deposited indirectly through nepheloid transport had lower OC:SA ratios (average 0.32 and 0.24 mgCm -2 ). For comparison, OC:SA ratios of suspended sediments from the Amazon River average 0.67 mgCm -2 , and modern Amazon Delta sediments have a loading of ~0.30 mgCm -2 . Although aldose concentrations in Hole 932A decreased downcore, corresponding molecular compositional patterns do not suggest extensive in situ diagenesis. Rather, the aldose composition throughout Hole 932 lithologic Subunits IIA and IIB is similar to that of fine suspended particulate materials carried by the modern Amazon River, which are largely composed of degraded material derived from plants and riverine microorganisms. The aldose data support isotopic and lignin compositional evidence for a terrestrial-riverine source of organic matter in Unit II of Hole 932A, as suggested by Goni (this volume).