Further evidence for an impact origin of the Tsenkher structure in the Gobi-Altai, Mongolia: Geology of a 3.7 km crater with a well-preserved ejecta blanket

Goro Komatsu, Jens Ormö, Togookhuu Bayaraa, Tomoko Arai, Keisuke Nagao, Yoshihiro Hidaka, Naoki Shirai, Mitsuru Ebihara, Carl Alwmark, Lkhagva Gereltsetseg, Shoovdor Tserendug, Kazuhisa Goto, Takafumi Matsui, Sodnomsambuu Demberel

    Research output: Contribution to journalReview article

    Abstract

    The Tsenkher structure in the Gobi-Altai, Mongolia is a c. 3.7 km diameter crater with a well-preserved ejecta blanket. It has been hypothesized to be either of impact or volcanic origin in our previous work. Observations during our 2007 expedition and related sample analyses give further support for an impact origin. The evidence includes the presence of a structurally uplifted near-circular rim surrounded by an ejecta blanket, and abundant breccias, some of which are melt- A nd millimetre-scale spherule-bearing. Planar deformation features (PDFs) were found in one quartz grain in a breccia sample. Fe-rich grains are found in a vesicular melt sample that is also characterized by elevated platinum group element (PGE) abundances with respect to the sedimentary bedrock of the area (approximately an order of magnitude). Noble gas analysis of one breccia sample yielded an elevated 3He/4He value of (5.0±0.2) × 10-6. Although not conclusive alone, these geochemical results are consistent with a contribution of meteoritic components. A volcanic origin, in particular a maar formation, would require explanations for the unusual conditions associated with Tsenkher, including its large size occurring in isolation, the structurally uplifted rim and the lack of a bedded base surge deposit. A pronounced rampart structure observed at the eastern ejecta is also unusual for any volcanic origin. 40Ar-39Ar dating of a vesicular melt sample gives an age of the Tsenkher structure of 4.9±0.9 Ma. The rampart structure could provide insights into the formation of similar ejecta morphologies associated with numerous impact craters on Mars.

    Original languageEnglish
    Pages (from-to)1-24
    Number of pages24
    JournalGeological Magazine
    Volume156
    Issue number1
    DOIs
    Publication statusPublished - 2019 Jan 1

    Fingerprint

    ejecta
    crater
    geology
    melt
    breccia
    maar
    spherule
    noble gas
    platinum group element
    Mars
    bedrock
    quartz

    Keywords

    • breccia
    • ejecta
    • impact crater
    • maar
    • Mongolia
    • raised rim
    • Tsenkher

    ASJC Scopus subject areas

    • Geology

    Cite this

    Further evidence for an impact origin of the Tsenkher structure in the Gobi-Altai, Mongolia : Geology of a 3.7 km crater with a well-preserved ejecta blanket. / Komatsu, Goro; Ormö, Jens; Bayaraa, Togookhuu; Arai, Tomoko; Nagao, Keisuke; Hidaka, Yoshihiro; Shirai, Naoki; Ebihara, Mitsuru; Alwmark, Carl; Gereltsetseg, Lkhagva; Tserendug, Shoovdor; Goto, Kazuhisa; Matsui, Takafumi; Demberel, Sodnomsambuu.

    In: Geological Magazine, Vol. 156, No. 1, 01.01.2019, p. 1-24.

    Research output: Contribution to journalReview article

    Komatsu, G, Ormö, J, Bayaraa, T, Arai, T, Nagao, K, Hidaka, Y, Shirai, N, Ebihara, M, Alwmark, C, Gereltsetseg, L, Tserendug, S, Goto, K, Matsui, T & Demberel, S 2019, 'Further evidence for an impact origin of the Tsenkher structure in the Gobi-Altai, Mongolia: Geology of a 3.7 km crater with a well-preserved ejecta blanket' Geological Magazine, vol. 156, no. 1, pp. 1-24. https://doi.org/10.1017/S0016756817000620
    Komatsu, Goro ; Ormö, Jens ; Bayaraa, Togookhuu ; Arai, Tomoko ; Nagao, Keisuke ; Hidaka, Yoshihiro ; Shirai, Naoki ; Ebihara, Mitsuru ; Alwmark, Carl ; Gereltsetseg, Lkhagva ; Tserendug, Shoovdor ; Goto, Kazuhisa ; Matsui, Takafumi ; Demberel, Sodnomsambuu. / Further evidence for an impact origin of the Tsenkher structure in the Gobi-Altai, Mongolia : Geology of a 3.7 km crater with a well-preserved ejecta blanket. In: Geological Magazine. 2019 ; Vol. 156, No. 1. pp. 1-24.
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    abstract = "The Tsenkher structure in the Gobi-Altai, Mongolia is a c. 3.7 km diameter crater with a well-preserved ejecta blanket. It has been hypothesized to be either of impact or volcanic origin in our previous work. Observations during our 2007 expedition and related sample analyses give further support for an impact origin. The evidence includes the presence of a structurally uplifted near-circular rim surrounded by an ejecta blanket, and abundant breccias, some of which are melt- A nd millimetre-scale spherule-bearing. Planar deformation features (PDFs) were found in one quartz grain in a breccia sample. Fe-rich grains are found in a vesicular melt sample that is also characterized by elevated platinum group element (PGE) abundances with respect to the sedimentary bedrock of the area (approximately an order of magnitude). Noble gas analysis of one breccia sample yielded an elevated 3He/4He value of (5.0±0.2) × 10-6. Although not conclusive alone, these geochemical results are consistent with a contribution of meteoritic components. A volcanic origin, in particular a maar formation, would require explanations for the unusual conditions associated with Tsenkher, including its large size occurring in isolation, the structurally uplifted rim and the lack of a bedded base surge deposit. A pronounced rampart structure observed at the eastern ejecta is also unusual for any volcanic origin. 40Ar-39Ar dating of a vesicular melt sample gives an age of the Tsenkher structure of 4.9±0.9 Ma. The rampart structure could provide insights into the formation of similar ejecta morphologies associated with numerous impact craters on Mars.",
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    AU - Ormö, Jens

    AU - Bayaraa, Togookhuu

    AU - Arai, Tomoko

    AU - Nagao, Keisuke

    AU - Hidaka, Yoshihiro

    AU - Shirai, Naoki

    AU - Ebihara, Mitsuru

    AU - Alwmark, Carl

    AU - Gereltsetseg, Lkhagva

    AU - Tserendug, Shoovdor

    AU - Goto, Kazuhisa

    AU - Matsui, Takafumi

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