FTIR microspectroscopy of Ediacaran phosphatized microfossils from the Doushantuo Formation, Weng'an, South China

Motoko Igisu, Tsuyoshi Komiya, Mika Kawashima, Satoru Nakashima, Yuichiro Ueno, Jian Han, Degan Shu, Yong Li, Junfeng Guo, Shigenori Maruyama, Ken Takai

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Phosphatized microfossils from ca. 580Ma from the Doushantuo Formation in the Weng'an region of South China were analyzed by Fourier transform infrared (FTIR) microspectroscopy for their chemical characterization. Two morpho-types of phosphatized embryo-like fossils (Megasphaera and Megaclonophycus) were analyzed, together with algal fossils. Transmission IR spectra of the microfossils have absorption bands of around 2960cm-1 and 2925cm-1, indicating the presence of aliphatic hydrocarbon (anti-symmetric aliphatic CH3 and aliphatic CH2), and have an additional band of around 1595cm-1, probably derived from aromatic moieties (aromatic CC). In addition, IR microscopic mapping shows that aliphatic hydrocarbon and aromatics are distributed inside the embryo-like fossils. The embryo-like fossils appear to show three types of CH3/CH2 peak height ratios (R3/2) and aromatic CC/CH2 peak height ratios (RCC/2 values): (1) high-R3/2/low-RCC/2 type (R3/2=~0.2-1.0 and RCC/2~0-2), (2) low-R3/2/medium-RCC/2 type (R3/2=~0.2-0.6 and RCC/2=~1-4); and (3) low-R3/2/high-RCC/2 type (R3/2=~0.2-0.6 and RCC/2~1-8). All three types are contained in both Megasphaera and Megaclonophycus. Raman spectra for the carbonaceous matter within the rock sample show a similar degree of thermal alteration, indicating that the organics were embedded in situ prior to thermal maturation. The IR spectroscopic differences might reflect differences in original organic compositions of microorganisms, and/or immediate post-mortem alteration. This suggests that the origins of phosphatized embryo-like fossils are more diverse than was previously recognized on the basis of their morphology. A comparison of R3/2 and RCC/2 values in the embryo-like fossils with those of the algal fossils and the extant microorganisms indicates the possible interpretation that some of the embryo-like fossils belong to animal embryo, others are algae, but none of them originate from bacteria.

Original languageEnglish
Pages (from-to)1120-1138
Number of pages19
JournalGondwana Research
Volume25
Issue number3
DOIs
Publication statusPublished - Apr 2014
Externally publishedYes

Fingerprint

Ediacaran
microfossil
Fourier transform
embryo
fossil
aliphatic hydrocarbon
microorganism
thermal alteration
maturation
alga
bacterium
animal

Keywords

  • Algal fossils
  • Aliphatic hydrocarbon
  • Doushantuo Formation
  • Embryo-like fossil
  • Micro-FTIR

ASJC Scopus subject areas

  • Geology

Cite this

Igisu, M., Komiya, T., Kawashima, M., Nakashima, S., Ueno, Y., Han, J., ... Takai, K. (2014). FTIR microspectroscopy of Ediacaran phosphatized microfossils from the Doushantuo Formation, Weng'an, South China. Gondwana Research, 25(3), 1120-1138. https://doi.org/10.1016/j.gr.2013.05.002

FTIR microspectroscopy of Ediacaran phosphatized microfossils from the Doushantuo Formation, Weng'an, South China. / Igisu, Motoko; Komiya, Tsuyoshi; Kawashima, Mika; Nakashima, Satoru; Ueno, Yuichiro; Han, Jian; Shu, Degan; Li, Yong; Guo, Junfeng; Maruyama, Shigenori; Takai, Ken.

In: Gondwana Research, Vol. 25, No. 3, 04.2014, p. 1120-1138.

Research output: Contribution to journalArticle

Igisu, M, Komiya, T, Kawashima, M, Nakashima, S, Ueno, Y, Han, J, Shu, D, Li, Y, Guo, J, Maruyama, S & Takai, K 2014, 'FTIR microspectroscopy of Ediacaran phosphatized microfossils from the Doushantuo Formation, Weng'an, South China', Gondwana Research, vol. 25, no. 3, pp. 1120-1138. https://doi.org/10.1016/j.gr.2013.05.002
Igisu, Motoko ; Komiya, Tsuyoshi ; Kawashima, Mika ; Nakashima, Satoru ; Ueno, Yuichiro ; Han, Jian ; Shu, Degan ; Li, Yong ; Guo, Junfeng ; Maruyama, Shigenori ; Takai, Ken. / FTIR microspectroscopy of Ediacaran phosphatized microfossils from the Doushantuo Formation, Weng'an, South China. In: Gondwana Research. 2014 ; Vol. 25, No. 3. pp. 1120-1138.
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AU - Ueno, Yuichiro

AU - Han, Jian

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N2 - Phosphatized microfossils from ca. 580Ma from the Doushantuo Formation in the Weng'an region of South China were analyzed by Fourier transform infrared (FTIR) microspectroscopy for their chemical characterization. Two morpho-types of phosphatized embryo-like fossils (Megasphaera and Megaclonophycus) were analyzed, together with algal fossils. Transmission IR spectra of the microfossils have absorption bands of around 2960cm-1 and 2925cm-1, indicating the presence of aliphatic hydrocarbon (anti-symmetric aliphatic CH3 and aliphatic CH2), and have an additional band of around 1595cm-1, probably derived from aromatic moieties (aromatic CC). In addition, IR microscopic mapping shows that aliphatic hydrocarbon and aromatics are distributed inside the embryo-like fossils. The embryo-like fossils appear to show three types of CH3/CH2 peak height ratios (R3/2) and aromatic CC/CH2 peak height ratios (RCC/2 values): (1) high-R3/2/low-RCC/2 type (R3/2=~0.2-1.0 and RCC/2~0-2), (2) low-R3/2/medium-RCC/2 type (R3/2=~0.2-0.6 and RCC/2=~1-4); and (3) low-R3/2/high-RCC/2 type (R3/2=~0.2-0.6 and RCC/2~1-8). All three types are contained in both Megasphaera and Megaclonophycus. Raman spectra for the carbonaceous matter within the rock sample show a similar degree of thermal alteration, indicating that the organics were embedded in situ prior to thermal maturation. The IR spectroscopic differences might reflect differences in original organic compositions of microorganisms, and/or immediate post-mortem alteration. This suggests that the origins of phosphatized embryo-like fossils are more diverse than was previously recognized on the basis of their morphology. A comparison of R3/2 and RCC/2 values in the embryo-like fossils with those of the algal fossils and the extant microorganisms indicates the possible interpretation that some of the embryo-like fossils belong to animal embryo, others are algae, but none of them originate from bacteria.

AB - Phosphatized microfossils from ca. 580Ma from the Doushantuo Formation in the Weng'an region of South China were analyzed by Fourier transform infrared (FTIR) microspectroscopy for their chemical characterization. Two morpho-types of phosphatized embryo-like fossils (Megasphaera and Megaclonophycus) were analyzed, together with algal fossils. Transmission IR spectra of the microfossils have absorption bands of around 2960cm-1 and 2925cm-1, indicating the presence of aliphatic hydrocarbon (anti-symmetric aliphatic CH3 and aliphatic CH2), and have an additional band of around 1595cm-1, probably derived from aromatic moieties (aromatic CC). In addition, IR microscopic mapping shows that aliphatic hydrocarbon and aromatics are distributed inside the embryo-like fossils. The embryo-like fossils appear to show three types of CH3/CH2 peak height ratios (R3/2) and aromatic CC/CH2 peak height ratios (RCC/2 values): (1) high-R3/2/low-RCC/2 type (R3/2=~0.2-1.0 and RCC/2~0-2), (2) low-R3/2/medium-RCC/2 type (R3/2=~0.2-0.6 and RCC/2=~1-4); and (3) low-R3/2/high-RCC/2 type (R3/2=~0.2-0.6 and RCC/2~1-8). All three types are contained in both Megasphaera and Megaclonophycus. Raman spectra for the carbonaceous matter within the rock sample show a similar degree of thermal alteration, indicating that the organics were embedded in situ prior to thermal maturation. The IR spectroscopic differences might reflect differences in original organic compositions of microorganisms, and/or immediate post-mortem alteration. This suggests that the origins of phosphatized embryo-like fossils are more diverse than was previously recognized on the basis of their morphology. A comparison of R3/2 and RCC/2 values in the embryo-like fossils with those of the algal fossils and the extant microorganisms indicates the possible interpretation that some of the embryo-like fossils belong to animal embryo, others are algae, but none of them originate from bacteria.

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