Sedimentation season of an early Holocene event deposit estimated from the reproductive organs of <I>Machilus thunbergii</I>

• Kobayashi Makiko

  Graduate School of Horticulture, Chiba University

• Momohara Arata

  Graduate School of Horticulture, Chiba University

• Okazaki Hiroko

• Okamoto Tozo

  Faculty of Letters, Chiba University

• Yanagisawa Seiichi

  Faculty of Letters, Chiba University

Bibliographic Information

Other Title

• タブノキの生殖器官化石に基づく前期完新世のイベント堆積物の季節推定
• タブノキ ノ セイショク キカン カセキ ニ モトズク ゼンキ カンシンセイ ノ イベント タイセキブツ ノ キセツ スイテイ

Abstract

An early Holocene fluvial event deposit with a well-preserved plant macrofossil assemblage including reproductive organs of Machilus thunbergii was found at the Okinoshima archaeological site, Tateyama, Chiba Prefecture, central Japan. To estimate the sedimentation season of the plant macrofossil assemblage, we observed seasonal changes in the morphology, size distribution, and decay process of the reproductive organs of M. thunbergii on the soil surface in an evergreen broadleaved forest. Flowers and fruits of M. thunbergii decomposed soon after they dropped to the ground. Perianth and fruits became damaged and/or chewed by insects, and size distribution of the fruit diameter changed with a lapse of time. Fossil reproductive organs of M. thunbergii from Okinoshima site included intact ovaries and perianths, and the maximum ovary diameter was between 5.0 and 5.5 mm. This means that the macrofossil assemblage had been deposited between late May and middle June. The alternating sand and mud layers including these plant assemblages seem to correspond with a flood caused by heavy rain in early summer. Our study showed that the condition of reproductive organs composing a plant macrofossil assemblage is an important clue for estimating the season of a sedimentation event.

Journal

• The Quaternary Research (Daiyonki-Kenkyu)

  The Quaternary Research (Daiyonki-Kenkyu) 48 (6), 395-404, 2009

  Japan Association for Quaternary Research

Keywords

• Holocene
• plant macrofossils
• sedimentation season
• event deposit
• <I>Machilus thunbergii</I>

Details

• CRID: 1390282681472777600
• NII Article ID: 10026427984
• NII Book ID: AN0034136X
• DOI: 10.4116/jaqua.48.395
• ISSN: 18818129
• ISSN: 04182642
• NDL BIB ID: 10513735
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I10513735
• Web Site: https://www.jstage.jst.go.jp/article/jaqua/48/6/48_6_395/_pdf
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed