[S-CG55] Ocean Floor Geoscience

[SCG55-09] Studying Oceanic Lithosphere via Cosmic-ray Muography of Samail Ophiolite

*Laszlo Olah^1,6, Susumo Umino², Yuki Kusano³, Tomoaki Morhishita², Said M. Al Musharrafi⁴, Ibrahim Al Sawafi⁴, Nasser Saif Said El-Maawali⁴, Hiroyuki K.M. Tanaka^5,6, László Tercsi¹, Dezső Varga^1,6 (1.HUN-REN Wigner Research Centre for Physics, Hungary, 2.Kanazawa University, Japan, 3.Geological Survey of Japan, Japan, 4.Ministry of Energy and Minerals, Sultanate of Oman, 5.The University of Tokyo, Japan, 6.International Virtual Muography Institute (VMI), Global)

Keywords:oceanic lithosphere, Moho, ophiolite, muography

HUN-REN Wigner Research Centre for Physics in Hungary, Kanazawa University, the University of Tokyo, and the Ministry of Energy and Minerals of the Sultanate of Oman are pursuing an international collaborative project to visualize the density structure of the major lithologic boundaries of the Oman Ophiolite using muography to understand the relationship between seismic velocity structure and geology in oceanic lithospheres.

Only a small portion of the oceanic lithosphere has been explored to date. The physical nature and geological meaning of the upper and lower crust boundaries and Mohorovičić discontinuity (Moho) between the crust and upper mantle are poorly understood. Direct observations of oceanic crust have already been conducted in two oceanic drilling holes, however the Moho has not yet been assessed by drilling experiments. Former Moho transition zones are exposed on land in numerous ophiolites around the world. The Samail Ophiolite is one of the most promising analogues for the oceanic lithosphere. We apply cosmic-ray muography for scanning the internal density structure of Samail ophiolite [1]. This procedure is based on the measurement of the yield of cosmic-ray induced atmospheric muon particles which penetrated across the ophiolite segment. The first muographic image of a Moho transition zone has been produced at Wadi Fizh, Sultanate of Oman [2]. In a preliminary muographic image, two different regions can be distinguished: (1) a low-density region for the lower crust and (2) a high-density region for the Moho and upper mantle and Moho. We present our experimental setup, muographic data processing and discuss the observations.

[1] L. Oláh, S. Umino, et al. Plans for Muography of Samail Ophiolite. Journal of Advanced Instrumentation in Science. JAIS-499, 2024. DOI: 10.31526/JAIS.2024.499
[2] L. Oláh, S. Umino, et al. First Muography of Samail Ophiolite at Wadi Fizh. Journal of Geography (Chigaku Zasshi). 2025. [Accepted short paper.]