Hardened faecal pellets as a significant component in deep water, subtropical marine environments
Hardened faecal pellets as a significant component in deep water, subtropical marine environments
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硬化粪便颗粒是深水、亚热带海洋环境的重要组成部分
DOI：
10.1002/dep2.64
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Hideko
中科院分区：
文献类型：
--
作者：
Reuning;Petrick;Benjamin;Takayanagi;Hideko
非骨架碳酸盐颗粒被经典地解释为形成于浅层的热带环境。在深海、亚热带海洋条件下沉积的贝壳类研究很少。位于亚热带Carnarvon斜坡(澳大利亚西南陆架)的IODP站点U1460恢复了几乎连续的上新世外陆架和斜坡沉积的最新记录。球团的相对丰度在细砂到中砂的0%-67%之间变化，平均占所有颗粒的4%。利用配备能量色散X射线能谱仪的扫描电子显微镜、光学显微镜、X射线衍射和稳定同位素分析对这些球团的来源和组成进行了研究。这些小球的大小和形状都是一致的，被解释为粪便小球。它们主要由海鞘针状体、浮游有孔虫和海绵针状体等骨骼碎片组成，在泥浆大小的基质中含有丰富的球粒岩板。矿物学分析表明，球团矿由文石、方解石和白云石组成。球团具有与周围基质相同的矿物学成分和骨架组合，表明它们是在原地形成的。它们在间冰期出现得更多，当时该地点位于海浪底部以下的更深水域，想必是因为颗粒受到保护，不会解体，因此可以胶结。球团中的框状黄铁矿表明细菌硫酸盐还原(BSR)。BSR过程中产生的硫化氢对铁的还原降低了pH值，并可能解释了观察到的文石溶解。文石溶解可能会增加碱度，从而导致方解石和白云石胶结物的析出。这里提出，由于这种靠近海底的早期胶结作用，球团矿变硬了，增加了保存在化石记录中的可能性。
Non‐skeletal carbonate grains are classically interpreted to form in shallow, tropical environments. Peloids deposited in deep, subtropical marine conditions are poorly studied. IODP site U1460 on the subtropical Carnarvon Ramp (Southwest Shelf of Australia) recovered a nearly continuous Pliocene to Recent record of outer shelf and slope sediments. The relative abundance of peloids varies between 0% and 67% of the fine to medium sand fraction, and contributes on average ~4% of all grains. The origin and composition of these peloids were investigated using scanning electron microscopy equipped with an energy‐dispersive X‐ray spectrometer, light microscopy, X‐ray diffraction and stable isotope analysis. The peloids have a uniform size and shape and are interpreted as faecal pellets. They are mainly composed of skeletal fragments such as ascidian spicules, planktic foraminifera and sponge spicules in a mud‐sized matrix containing abundant coccolith plates. Mineralogical analysis show that the pellets consist of aragonite, calcite and dolomite. The pellets have an identical mineralogical composition and skeletal assemblage as the surrounding matrix, indicating that they have formed in situ. They occur more abundantly during interglacials when the site was situated in deeper waters below the swell wave base, presumably because the pellets were protected from disintegration and therefore available for cementation. The presence of framboidal pyrite within the pellets indicates bacterial sulphate reduction (BSR). The reduction of iron by hydrogen sulphide produced during BSR decreases the pH and likely explains the observed aragonite dissolution. Aragonite dissolution likely increases the alkalinity, and in consequence causes the precipitation of calcite and dolomite cements. It is suggested here that pellets are hardened due to this early cementation close to the sea floor increasing the potential for preservation in the fossil record.
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碳酸盐岩滩和波浪建造平台沉积，埃德尔省，鲨鱼湾，西澳大利亚
DOI：
--
发表时间：
1974
期刊：
影响因子：
--
作者：
J. F. Read
通讯作者：
J. F. Read
新西兰旺加努伊大陆架混合硅质碎屑骨架碳酸盐岩相：对温带碳酸盐岩模型的贡献
DOI：
--
发表时间：
1997
期刊：
影响因子：
--
作者：
J. Gillespie;C. Nelson
通讯作者：
C. Nelson
影响因子：
2.3
作者：
Gischler, E;Zingeler, D
通讯作者：
Zingeler, D
影响因子：
2
作者：
N. James;L. Collins;Y. Bone;P. Hallock
通讯作者：
N. James;L. Collins;Y. Bone;P. Hallock
生物群落和底部相，大巴哈马浅滩。
影响因子：
3.5
作者：
N. D. Newell;J. Imbrie;E. G. Purdy;D. Thurber
通讯作者：
D. Thurber