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 language | English |
|---|---|
| Pages (from-to) | 1-24 |
| Number of pages | 24 |
| Journal | Geological Magazine |
| Volume | 156 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2019 Jan 1 |
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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 journal › Review article
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TY - JOUR
T1 - Further evidence for an impact origin of the Tsenkher structure in the Gobi-Altai, Mongolia
T2 - Geology of a 3.7 km crater with a well-preserved ejecta blanket
AU - Komatsu, Goro
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
AU - Demberel, Sodnomsambuu
PY - 2019/1/1
Y1 - 2019/1/1
N2 - 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.
AB - 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.
KW - breccia
KW - ejecta
KW - impact crater
KW - maar
KW - Mongolia
KW - raised rim
KW - Tsenkher
UR - http://www.scopus.com/inward/record.url?scp=85059911695&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85059911695&partnerID=8YFLogxK
U2 - 10.1017/S0016756817000620
DO - 10.1017/S0016756817000620
M3 - Review article
VL - 156
SP - 1
EP - 24
JO - Geological Magazine
JF - Geological Magazine
SN - 0016-7568
IS - 1
ER -