Fundamental study on the mode of transportation and sedimentation of subaqueous tephras

水下火山灰搬运与沉积方式的基础研究

• 批准号: 63540607
• 负责人: KUROKAWA Katsuki
• 金额: $ 1.09万
• 依托单位: Niigata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63540607/
• 关键词: Subaqueous tephra; Ash flow turbidite; The Joetsu Ash; The SK020 Ash; The Sug-a Ash; Facies model; Osumilite; Andalusite; Ash How turbidite; Sug-a火山灰; 層相モデル; テフラの堆積構造; テフラの粒度特性; 中央油帯; 浜忠層; 西山層

Mode of transportation and sedimentation of subaqueous tephras was investigated especially on those intercalated in the upper Miocene to lower Pleistocene in the Niigata backarc basin, central Japan. They were classified in four categories; (1)subaqueous fallout, (2)ash cloud, (3)subaqueous flow and (4)their epiclastic reworks. Fourteen facies models of these tephras were established in respect to grain-size populations; TypeA1-A5 for silt to medium sand-sized tephras (Population A), TypeB1-B5 for medium sand to granule-sized tephras(Population B) and Type C1-C4 for those containing considerable amounts of pumice clasts larger than granule size(Population C).It is noteworthy that among these subaqueous tephras, subaqueous flows which were directly transformed from subareal ash flows or subaqueous dense ash clouds are not uncommon regardless of their grain-size population; fine-grained ones(TypeA3), medium-grained ones(TypeB4) and coarse- grained-ones(TypeC3). They show inverse-to-normal grading, containing mud balls or rip-ups, and flowed more than 50km with little decrease of thickness. In this research, they are named ash flow turbidites. The Joetsu Ash (Kurokawa and Hirata,1986) is a representative of the ash flow turbidites of TypeB3. It is cordierite-cummingtonite bearing ash of subareal ash flow origin, flowed into water.The basic sequence containing the ash flow turbidites was clarified; the ash flow turbidite unit occupies the base of the sequence (Unit I), overlaid by thin alternations of fine-grained ashes (Unit II) and pumice-rich ashes (Unit III). This sequence suggests the flow differentiation from subareal ash flow or subaqueous ash cloud.Besides, osumilite and magmatic andalusite were found from Pliocene subaqueous tephra (the Sug-a Ash) in the course of this study.

研究了日本中部新泻弧后盆地上中新世至下更新世水下冰盖岩层间的输运和沉积模式。它们被分为四类：(1)水下散落，(2)火山灰云，(3)水下流动和(4)它们的喷发改造。建立了14种不同粒度群的沉积相模式：A1-A5型为粉砂-中砂级群(A群)，B1-B5型为中砂-粒级群(B群)，C1-C4型为含有大量大于颗粒大小的浮石碎屑(群C)。值得注意的是，在这些水下群中，由水下灰流或水下致密灰云直接转化而来的水下流无论其粒度群如何，都不少见；细粒型(A3型)、中粒型(B4型)和粗粒型(C3型)。它们表现出与正常相反的级配，含有泥球或裂隙，流动超过50公里，厚度几乎没有减少。在本研究中，它们被命名为灰流浊积岩。Joetsu Ash(Kurokawa and Hirata，1986)是B3型火山灰流浊积岩的代表。厘清了含灰流浊积岩的基本层序，灰流浊积单元位于层序的底部(单元I)，上覆有细粒灰岩(单元II)和富浮石灰岩(单元III)的薄层蚀变。此外，在本研究过程中，在上新世水下火山灰(Sug-a Ash)中还发现了蛇纹石和岩浆红柱石。

项目成果

Kurokawa.K.,Fujiwara,Y.and Konishi,H.: "Finding of osumilite and naymatic andalnsite from the Pliocene Sug-a Ash in Niigata Prefecture,central Japan"

Kurokawa.K.、Fujiwara,Y. 和 Konishi,H.：“在日本中部新泻县的上新世 Sug-a Ash 中发现锇硅石和水性安柱石”

黒川勝己・丸山悦子・沢栗隆之: "新潟県中央油帯北部における椎谷層・西山層中の水底堆積テフラ" 新潟大学教育学部紀要(自然科学編). 30-(2). 39-64 (1989)

Katsumi Kurokawa，Etsuko Maruyama，Takayuki Sawaguri：“新泻县北部中央石油带的Shiiya组和Nishiyama组的水下火山灰”，新泻大学教育学部通报（自然科学版）30-（2）。 39-64（1989）

黒川勝己・庭山かおる・寺井直子: "テフラ鍵層からみた新潟県西山油帯南部の鮮新世堆積作用" 新潟大学教育学部紀要(自然科学編). 31-(1). 15-42 (1989)

Katsumi Kurokawa，Kaoru Niwayama，Naoko Terai：“从火山灰关键层看新泻县西山石油带南部的上新世沉积”新泻大学教育学部通报（自然科学版）31-。 (1). 15-42 (1989)。

Kurokawa, K., Niwayama, K. and Terai, N.: "Pliocene sedimentation in the southern Nishiyama Oil Field, Niigata Prefecture, with special reference to tephra markers." Mem. Fac. Educ., Niigata Univ. (Natural Sciences), 31-1, pp.15-42(1989).

Kurokawa, K.、Niwayama, K. 和 Terai, N.：“新泻县西山油田南部的上新世沉积，特别参考火山灰标记。”

黒川勝己・藤原啓美・川崎浩子: "新潟県出雲崎町久田における上越火山灰の発見とその意義" 新潟大学教育学部紀要(自然科学編). 30-(1). 19-26 (1988)

黑川胜美、藤原惠美、川崎宏子：“新泻县出云崎町久田的上越火山灰的发现及其意义”新泻大学教育学部通报（自然科学版）30-(1)。 19-26 (1988)