The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / Entrance Hall (1st floor), National Institute of Polar Researc

Ippei Kitano

Masahiro Ishikawa

Takuma Katori

Tomokazu Hokada

Tsuyoshi Toyoshima

National Institute of Polar Research Repository

    Pseudotachylytes from Langhovde and Skarvsnes in the Lützow-Holm Complex, East Antarctica, and their conditions of formation  Tsuyoshi Toyoshima1, Masahiro Ishikawa2, Ippei Kitano3, Takuma Katori1 and Tomokazu Hokada4 1Niigata University 2Yokohama National University 3Kyushu University 4National Institute of Polar Research Pseudotachylytes were found north of Mt. Futago (Futago-yama) of northern Langhovde and north of Lake Naga (Naga-ike) and Lake Kikuno (Kikuno-ike) of southwestern Skarvsnes in the Lützow-Holm Bay region. They are called Futagoyama PST, Naga-ike PST and Kikuno-ike PST, respectively. We preliminarily report field observation of the PSTs. The Naga-ike PST is associated with an ENE-WSW trending main fault (Naga-ike Fault) that steeply dips north and a length of more than 300 m. The Kikuno-ike PST is associated with an NNW-SSE trending main fault (Kikuno-ike Fault) that moderately dips east and a length of more than 100 m. The Naga-ike and Kikuno-ike Faults, which cut gneissose structures of surrounding rocks, consist of pseudotachylytes, cataclasites, brittle fractures, echelon faults and spray structures. Field observation of the Naga-ike Fault and PST indicates that dextral faulting earthquakes occasionally occurred. Field observation of the Kikuno-ike Fault and PST also indicates that other dextral faulting earthquakes occasionally occurred under a different stress field from the Naga-ike faulting. Two faultings appear to have resulted from different earthquakes under different tectonics. Part of pseudotavhylytes and cataclasites of the Naga-ike and Kikuno-ike Faults have a reddish color. The field evidence suggests that the Naga-ike and Kikuno-ike Faults and PSTs were formed under oxidizing conditions at shallow depths. The Futago-yama PST is associated with an NNE-SSW trending main fault (Futago-yama Fault) that moderately dips east and a length of more than 660 m. The Futago-yama Fault is parallel to gneissose structures of surrounding rocks. The Futago-yama Fault and PST are alongside the eastern margin of s NNE-WWS trending granitic mylonite zone (Futago-yama mylonite zone). The Futago-yama mylonite zone has been derived from a granitic sheet. The Futago-yama Fault consists of pseudotachylytes, mylonites, foliated cataclasites and echelon faults. Field observation of the Futago-yama Fault and PST indicates that normal faulting earthquakes occasionally occurred on faults dipping <42° in the brittle-ductile (frictional-to-viscous) transition.  

Pseudotachylytes from Langhovde and Skarvsnes in the Lützow-Holm Complex, East Antarctica, and their conditions of formation

https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=15736&item_no=1&attribute_id=16&file_no=1

Pseudotachylytes from Langhovde and Skarvsnes in the Lützow-Holm Complex, East Antarctica, and their conditions of formation

Abstract

Similar works

Full text

Available Versions

National Institute of Polar Research Repository