In-situ analyses of phosphorus contents of carbonate minerals: Reconstruction of phosphorus contents of seawater from the Ediacaran to early Cambrian
In-situ analyses of phosphorus contents of carbonate minerals: Reconstruction of phosphorus contents of seawater from the Ediacaran to early Cambrian
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碳酸盐矿物磷含量原位分析：埃迪卡拉纪至早寒武世海水磷含量重建
DOI：
10.1016/j.gr.2013.08.001
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发表时间：
2014-04
影响因子：
6.1
通讯作者：
Tsuyoshi Komiya
中科院分区：
文献类型：
--
作者：
Takafumi Hirata;Jian Han;Degan Shu;Tsuyoshi Komiya
埃迪卡拉纪和寒武纪是生命演化最重要的时期之一。生物多样性在这一时期急剧增加。然而，起源仍然是模糊的，因为地表环境的变化，通过时间还没有得到很好的理解。利用激光烧蚀-电感耦合等离子体质谱（LA-ICP-MS）对埃迪卡拉纪至早寒武世海水中碳酸盐矿物的磷含量进行了原位分析。碳酸盐岩中不仅含有碳酸盐矿物，还含有硅酸盐、磷酸盐等碎屑和自生物质。因此，碳酸盐岩的全岩成分与海水成分没有直接关系。为了避免磷酸盐矿物的影响，我们进行了显微观察，Si，Ca，Mg，Fe和P含量的电子探针分析仪（EPMA）的元素图谱，和Ca，Sr，Mn，P，La和Ba的信号强度的时间剖面的LA-ICP-MS研究。具有低Mn/Sr比值和橄榄石等原生结构可用于碳酸盐岩中原生磷含量的估算，岩心和露头样品中的磷含量化学地层学研究表明，碳酸盐岩中的磷主要来自于含量从Ca. 400 ppm在埃迪卡拉纪通过约。埃迪卡拉纪末期和寒武纪初期至约200 ppm。在寒武纪早期的50 ppm。埃迪卡拉纪至寒武纪剖面的87 Sr/86 Sr化学地层学研究表明，埃迪卡拉纪中期和前寒武纪-寒武纪（PC/C）界线附近存在相对较高的大陆流入。埃迪卡拉纪的高磷含量可能是由于高大陆通量。另一方面，前人对埃迪卡拉纪至寒武纪剖面碳酸盐碳同位素的化学地层学研究表明，埃迪卡拉纪和前寒武纪-寒武纪（PC/C）界线附近存在较大的负异常，并认为负异常是由溶解有机质的分解和呼吸作用引起的。有机质的降解也是埃迪卡拉纪中高磷含量的原因。海水中高磷含量有利于初级生产力的提高和磷块岩的形成。海水中的高磷含量可能通过初级生产力的提高和海水中氧含量的增加而导致大型活动生物的出现。
The Ediacaran and Cambrian periods were one of the most important periods for the evolution of life. The biodiversity drastically expanded in the period. However, the origins are still ambiguous because surface environmental changes through the time have not been well understood yet. We conducted in-situ analyses of the phosphorus contents of carbonate minerals with a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) to estimate the phosphorus contents of seawater from the Ediacaran to the early Cambrian. Carbonate rocks contain not only the carbonate minerals but also detrital and authigenic materials such as silicate and phosphate minerals. Therefore, the whole rock compositions of carbonate rocks are not directly related with seawater composition. To avoid the influence of the involvement of the phosphate minerals, we performed the microscopic observation, elemental mapping of Si, Ca, Mg, Fe, and P contents with an electron probe microanalyzer (EPMA), and investigation of time profiles of signal intensities of Ca, Sr, Mn, P, La and Ba with the LA-ICP-MS. Especially, samples with low Mn/Sr ratios and primary textures such as oolites are suitable to estimate the primary phosphorus contents of the carbonates.The chemostratigraphy of the phosphorus contents of carbonates from the drill core and outcrop samples displays that the phosphorus contents decrease from ca. 400 ppm in the Ediacaran through ca. 200 ppm around the terminal Ediacaran and the beginning of the Cambrian to ca. 50 ppm in the early Cambrian. Previous works on87Sr/86Sr chemostratigraphy from the Ediacaran to the Cambrian sections suggested relatively high continental influx in the middle Ediacaran, and around the Precambrian–Cambrian (PC/C) boundary. The high phosphorus content in the Ediacaran was possibly due to the high continental flux. On the other hand, previous works on chemostratigraphy of carbon isotope values of carbonate carbon from the Ediacaran to the Cambrian sections showed some large negative anomalies in the Ediacaran and around the Precambrian–Cambrian (PC/C) boundary, and suggested that the negative anomalies were caused by remineralization and respiration of dissolved organic matter. The degradation of the organic matter also accounts for the high phosphorus contents in the Ediacaran. The high phosphorus content of seawater favors enhancement of primary productivity and formation of phosphorites. The high phosphorus contents in the seawater possibly led to the emergence of the large, and motile organism through the enhancement of primary productivity and the consequent increase of oxygen content of the seawater.
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影响因子：
1.9
作者：
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通讯作者：
S. Willman;M. Moczydłowska;K. Grey
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影响因子：
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影响因子：
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作者：
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通讯作者：
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影响因子：
5.8
作者：
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通讯作者：
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影响因子：
6.1
作者：
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通讯作者：
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