The contribution of calcareous green algae to the production of limestones: a review
The contribution of calcareous green algae to the production of limestones: a review
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DOI：
10.5252/g2012n1a3
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发表时间：
2012-01-01
期刊：
影响因子：
1.8
通讯作者：
Granier, Bruno
中科院分区：
文献类型：
--
作者：
Granier, Bruno
石灰性绿色藻类（CGA）是一种人工合成但高度异质的大型单细胞底栖藻类，具有一个共同的特征：它们都具有在细胞质被膜外侧分泌石灰质涂层的能力。今天，它们是所有尺度的碳酸盐沉积的主要贡献者，从粘土大小的颗粒（文石针状物）到较粗的颗粒（沙子和砾石），甚至到多元沉积结构。有化石类似于上面列出的特征。藻类学家最了解Halimeda，Penicillus，Acetabularia和Cymopolia;微体古生物学家和碳酸盐沉积学家最了解Acicularia，Clypeina，Neoteuloporella，Salpingoporella，Anthracoporella，Boueina和Eugonophyllum。沉淀形成涂层的CaCO 3通常是文石（斜方晶形式），但在地质记录中，其方解石变体（菱面体形式）以离散的物种同时存在的时期很短。最近对Halimeda的研究表明，有些苔藓虫目有能力在真光层的下部强烈钙化（在矿化过程中，呼吸作用比光合作用更重要），并在晴天浪底以下原地产生正沉积地貌（生物丘）。以前的古环境模型认为，Dasycladales或Bryopteriales的存在表明浅水，即上层真光层（从海面到25米），主要是低能量，受保护的泻湖环境。当在颗粒支持相中发现藻类遗骸时，它们被认为经历了动力搬运，因此表明沉积的高能环境。新的深水发现改变了对藻类化石所处环境的解释。目前的概念是，祖先的无关节苔藓虫目可能生长在深度高达-120米（附近的底部较低的欣快带）。这一初步审查的结论与建议的领域继续调查。
Calcareous green algae (CGA) are an artificially united but highly heterogeneous group of large unicellular benthic algae with one character in common: all have the capability of secreting a calcareous coating on the outer side of the cytoplasmic envelope. Today, they are a major contributor to carbonate sedimentation at all scales from clay-sized particles (aragonitic needles) to coarser grains (sand and gravel) and even to plurimetric sedimentary structures. There are fossil analogues to the features listed above. Phycologists know best Halimeda, Penicillus, Acetabularia and Cymopolia; micropaleontologists and carbonate sedimentologists are most knowledgeable about Acicularia, Clypeina, Neoteuloporella, Salpingoporella, Anthracoporella, Boueina, and Eugonophyllum. The CaCO3 precipitated to form the coating is generally aragonite (the orthorhombic form) but there are short periods in the geologic record during which its calcite variant (the rhombohedric form) existed contemporaneously in discrete species. Recent studies on Halimeda have shown that some of the Bryopsidales have the capability to calcify strongly in the lower portion of the euphotic zone (where respiration becomes more important than photosynthesis in the process of mineralization) and to produce positive sedimentary reliefs (bioherms) in situ below the fair-weather wave base. Previous models of paleoenvironments considered the presence of Dasycladales or Bryopsidales to indicate shallow-water, that is the upper euphotic zone (from the sea surface down to 25 m), and predominantly low-energy, protected, lagoonal environments. When the algal remains were found in grain-supported facies, they were taken to have been subjected to dynamic transport and therefore indicative of high-energy environments of deposition. The new deeper-water finds have changed interpretations of the environments ascribed fossil algae. A current conception is that ancestral inarticulated Bryopsidales could have grown at depths as great as -120 m (near the base of the lower euphoric zone). This preliminary review concludes with suggestions about fields for continuing investigations.