Middle Triassic foraminifers from northern Laos and their paleobiogeographic significance

Akira Miyahigashi, Hidetoshi Hara, Ken ichiro Hisada, Nobuhiko Nakano, Thasinee Charoentitirat, Punya Charusiri, Keo Khamphavong, Rossana Martini, Katsumi Ueno

研究成果: ジャーナルへの寄稿記事

2 引用 (Scopus)

抄録

Triassic foraminifers are reported for the first time from limestones in the upper part of the Nam Sam Suite distributed in the Sam Neua area of northern Laos. The study area is located in the northern part of the Indochina Block, based on the basic geotectonic subdivision of mainland Southeast Asia. The fauna consists of 17 taxa and includes age-diagnostic Pilammina densa, Pilamminella grandis, Citaella dinarica, C.? deformata, Arenovidalina amylovoluta, and Diplotremina astrofimbriata. It is referable to the middle Anisian (Pelsonian) of the Middle Triassic. The microfacies of the studied samples are subdivided into three types, suggesting low wave-energy uppermost subtidal, moderately wave-agitated uppermost subtidal, and intertidal environments, respectively. Two species are specific to the intertidal microfacies. A notable paleontological feature is the dominance of P. densa, shown by the large number of individuals in the foraminiferal assemblage. This could be related to its opportunistic nature in the stressful conditions of the intertidal environment. We also consider that C.? deformata may be ecologically adapted to a hypersaline environment. The Sam Neua fauna shares several important species, such as C. dinarica, P. densa, P. grandis, and A. amylovoluta, with those found in the Sibumasu Block, Sukhothai Zone, and South China Block, suggesting that these major geotectonic domains in mainland Southeast Asia formed a single paleobiogeographic province during Anisian time. In view of paleogeography, the present results point toward a rather restricted (narrow) Paleo-Tethyan ocean basin allowing faunal interchanges among separated Eastern Tethyan continental blocks during the Middle Triassic.

元の言語英語
ページ(範囲)441-451
ページ数11
ジャーナルGeobios
50
発行部数5-6
DOI
出版物ステータス出版済み - 12 1 2017

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Laos
Southeast Asia
foraminifera
Anisian
Triassic
microfacies
intertidal environment
animals
hypersaline environment
fauna
subtidal environment
subdivisions
limestone
ocean basin
paleogeography
wave energy
China
oceans
energy

All Science Journal Classification (ASJC) codes

  • Stratigraphy
  • Space and Planetary Science

これを引用

Miyahigashi, A., Hara, H., Hisada, K. I., Nakano, N., Charoentitirat, T., Charusiri, P., ... Ueno, K. (2017). Middle Triassic foraminifers from northern Laos and their paleobiogeographic significance. Geobios, 50(5-6), 441-451. https://doi.org/10.1016/j.geobios.2017.09.004

Middle Triassic foraminifers from northern Laos and their paleobiogeographic significance. / Miyahigashi, Akira; Hara, Hidetoshi; Hisada, Ken ichiro; Nakano, Nobuhiko; Charoentitirat, Thasinee; Charusiri, Punya; Khamphavong, Keo; Martini, Rossana; Ueno, Katsumi.

:: Geobios, 巻 50, 番号 5-6, 01.12.2017, p. 441-451.

研究成果: ジャーナルへの寄稿記事

Miyahigashi, A, Hara, H, Hisada, KI, Nakano, N, Charoentitirat, T, Charusiri, P, Khamphavong, K, Martini, R & Ueno, K 2017, 'Middle Triassic foraminifers from northern Laos and their paleobiogeographic significance', Geobios, 巻. 50, 番号 5-6, pp. 441-451. https://doi.org/10.1016/j.geobios.2017.09.004
Miyahigashi A, Hara H, Hisada KI, Nakano N, Charoentitirat T, Charusiri P その他. Middle Triassic foraminifers from northern Laos and their paleobiogeographic significance. Geobios. 2017 12 1;50(5-6):441-451. https://doi.org/10.1016/j.geobios.2017.09.004
Miyahigashi, Akira ; Hara, Hidetoshi ; Hisada, Ken ichiro ; Nakano, Nobuhiko ; Charoentitirat, Thasinee ; Charusiri, Punya ; Khamphavong, Keo ; Martini, Rossana ; Ueno, Katsumi. / Middle Triassic foraminifers from northern Laos and their paleobiogeographic significance. :: Geobios. 2017 ; 巻 50, 番号 5-6. pp. 441-451.
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abstract = "Triassic foraminifers are reported for the first time from limestones in the upper part of the Nam Sam Suite distributed in the Sam Neua area of northern Laos. The study area is located in the northern part of the Indochina Block, based on the basic geotectonic subdivision of mainland Southeast Asia. The fauna consists of 17 taxa and includes age-diagnostic Pilammina densa, Pilamminella grandis, Citaella dinarica, C.? deformata, Arenovidalina amylovoluta, and Diplotremina astrofimbriata. It is referable to the middle Anisian (Pelsonian) of the Middle Triassic. The microfacies of the studied samples are subdivided into three types, suggesting low wave-energy uppermost subtidal, moderately wave-agitated uppermost subtidal, and intertidal environments, respectively. Two species are specific to the intertidal microfacies. A notable paleontological feature is the dominance of P. densa, shown by the large number of individuals in the foraminiferal assemblage. This could be related to its opportunistic nature in the stressful conditions of the intertidal environment. We also consider that C.? deformata may be ecologically adapted to a hypersaline environment. The Sam Neua fauna shares several important species, such as C. dinarica, P. densa, P. grandis, and A. amylovoluta, with those found in the Sibumasu Block, Sukhothai Zone, and South China Block, suggesting that these major geotectonic domains in mainland Southeast Asia formed a single paleobiogeographic province during Anisian time. In view of paleogeography, the present results point toward a rather restricted (narrow) Paleo-Tethyan ocean basin allowing faunal interchanges among separated Eastern Tethyan continental blocks during the Middle Triassic.",
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