JaLCDOI 10.18926/ESR/49211
Title Alternative The oldest fossil forest in Japan discovered from the Upper Triassic Nariwa Group, Okayama Prefecture, SW Japan -Implication for reconstruction of depositional environment and paleovegetation-
FullText URL esr_019_1_025_037.pdf
Author Yukawa, Hirokazu| Terada, Kazuo| Sun, Ge| Suzuki, Shigeyuki|
Abstract Erect fossil stumps were found from the outcrop of the Upper Triassic Hinabata Formation, the uppermost part of the Nariwa Group at Hinabata, Nariwa-cho,Takahashi City, Okayama Prefecture, SW Japan. They are evidence of the oldest fossil forest in Japan. The Upper Triassic Nariwa Group is mostly composed of non-marine deposits except the marine Jito Formation and characterized by the abundance in plant fossils. The marine Jito Formation is characterized by occurrence of Norian Monotis ochotica. On the basis of detailed observation of the occurrence of erect fossil stumps, as well as sedimentary facies of fossil-bearing unit, the fossil forest was interpreted to have grown on the top of the natural-levee units. One of the erect fossil stumps was identified as Xenoxylon sp.
Keywords erect fossil stump fossil forest Nariwa Group Upper Triassic Xenoxylon
Publication Title Okayama University Earth Science Report
Published Date 2012-12-26
Volume volume19
Issue issue1
Start Page 25
End Page 37
ISSN 1340-7414
language 日本語
Copyright Holders © 2012 by Okayama University Earth Science Reports Editorial Committee All Rights Reserved
File Version publisher
NAID 120005232329
JaLCDOI 10.18926/ESR/56691
Title Alternative Non-calcareous beachrock found in Akagurisaki, Ohi Town, Fukui Prefecture
FullText URL esr_025_001_005.pdf
Author Suzuki, Shigeyuki| Azuma, Yoichi| Deyama, Yasuyo| Yukawa, Hirokazu| Usui, Mayumi|
Abstract Beachrock which was formed about 0.5 meter higher than high tide is found in Akagurisaki, Ohi Town, Fukui Prefecture. The outcrops always get wet by spring water. The sediments are composed of well sorted rounded gravels and sands but calcareous shell is not found at all. Intergranular space is occupied by white amorphous cement. Magnesium and silicon rich composition of the cement is obtained by EPMA analysis. There is a conjecture that the magnesium rich cement was precipitated in spite of solution of calcareous shell under saturated state by spring water, because calcium has a higher tendency to ionize than magnesium.
Keywords Beachrock Akagurisaki non-calcareous cement ionization tendency
Publication Title Okayama University Earth Science Report
Published Date 2018-12-27
Volume volume25
Issue issue1
Start Page 1
End Page 5
ISSN 1340-7414
language 日本語
Copyright Holders © 2018 by Okayama University Earth Science Reports Editorial Committee All Rights Reserved
File Version publisher