Analysis of crystallographic directions of calcareous microfossils produced by the past tiny phytoplankton : crystalline nature of some calcareous nannofossil species, Florisphaera profunda and discoasters, and its meanings
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- Kameo Koji
- Marine Biosystems Research Center, Chiba University, c
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- Furukawa Noboru
- o Department of Earth Sciences, Chiba University
Bibliographic Information
- Other Title
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- 過去の微小藻類が作る石灰質微化石の結晶方位の解析 : 石灰質ナンノ化石Florisphaera profundaとDiscoaster属の結晶構造とその意味
- 過去の微小藻類が作る石灰質微化石の結晶方位の解析--石灰質ナンノ化石とFlorisphaera profundaとDiscoaster属の結晶構造とその意味
- カコ ノ ビショウ ソウルイ ガ ツクル セッカイシツ ビカセキ ノ ケッショウ ホウイ ノ カイセキ セッカイシツ ナンノ カセキ ト Florisphaera profunda ト Discoasterゾク ノ ケッショウ コウゾウ ト ソノ イミ
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Abstract
Selected area electron diffraction (SAED), high-resolution transmission electron microscopic and scanning electron microscopic analyses were performed to determine crystal faces of two nannoliths from Florisphaera profunda and discoasters, the exoskeltons of a certain unicellelar alga, calcareous nannofossils. A specimen of F profunda is a pentagonal-shaped plate and its [0001] direction (c-axis) is oriented parallel to its surface and in the elongation axis of the plate-like element. Its crystallographic nature mostly resembles a proximal shield element of Emiliania huxleyi, one of the most common coccolithophorids observed in the present ocean. On the other hand, a nannolith of Discoaster specimens is a star-shaped calcite crystal and is composed of several numbers of bent, bar-shaped calcite elements, called 'rays.' Based on results of the SAED observation and calcite decoration on specimens, each ray apparently seems to be a single calcite crystal in all types of discoasters. The [0001] direction is likely perpendicular to the tangential plane of the central area and each ray joins together in the plane that is parallel to [0001]. The difference of crystallographic nature between nannoliths and heterococcoliths suggests that the phylogenetic origin and the evolutionary history of nannolith-producing phyioplankton are different from those of heterococcolith-bearing coccolithophores.
Journal
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- Fossils
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Fossils 76 (0), 23-31, 2004
Palaeontological Society of Japan
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Keywords
Details 詳細情報について
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- CRID
- 1390282679411926144
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- NII Article ID
- 110002704321
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- NII Book ID
- AN00041606
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- ISSN
- 24242632
- 00229202
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- NDL BIB ID
- 7105745
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- Text Lang
- ja
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- Data Source
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- JaLC
- NDL
- CiNii Articles
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- Abstract License Flag
- Disallowed