New Rock Magnetic Analysis of Ultramafic Cores From the Oman Drilling Project and Its Implications for Alteration of Lower Crust and Upper Mantle
Hong, Gilbert; Till, Jessica Lynn; Greve, Annika; Lee, Sang-Mook; Oman Drilling Project Science Team
(2022) Journal of Geophysical Research: Solid Earth, volume 127, issue 7, pp. 1 - 21
(Article)
Abstract
Detailed magnetic analyses of ultramafic rock samples recovered from the Wadi Tayin massif as part of the Oman Drilling Project provide a unique opportunity to understand the magnetic properties of oceanic lithosphere and its alteration since obduction. We examined 300- to 400-m-long cores from 3 sites (BA1B, BA3A, and BA4A)
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that transected the crust-mantle boundary. Serpentinization that produces a small amount of magnetite from olivine alteration plays an important role in shaping the magnetic signature of the rocks recovered from these holes. Our investigation reveals new features, which have not been reported in previous studies of ophiolite largely based on surface rock samples. It appears that when serpentinization reaches a certain point (65%), a sharp increase in magnetic susceptibility occurs. Such pattern opens the possibility of additional production of magnetic minerals induced by various reactions (e.g., further hydration of Fe-rich serpentine minerals), which may have occurred, while the rocks were being serpentinized. In general, the uppermost section (0–40 m) shows higher susceptibility than the deeper part. Also, higher susceptibility is found in dunite-dominated sections than those composed of harzburgite. Overall, our observations suggest that mantle rocks of Semail ophiolite have undergone multiple stages of serpentinization over different time periods.
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Keywords: Oman Drilling Project, ophiolites, rock magnetism, serpentinization, Taverne, Geophysics, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Space and Planetary Science
ISSN: 2169-9313
Publisher: Wiley
Note: Funding Information: Funds for this study was provided by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20168510030830). This work used samples and data hosted by the Oman Drilling Project (OmanDP). The OmanDP has been supported by co-mingled funds from the International Continental Scientific Drilling Project (ICDP; Kelemen, Matter, Teagle Lead Principal Investigators (PI)), the Sloan Foundation—Deep Carbon Observatory (Grant 2014-3-01, Kelemen PI), the National Science Foundation (NSF-EAR-1516300, Kelemen lead PI), NASA—Astrobiology Institute (NNA15BB02A, Templeton PI), the German Research Foundation (DFG: KO 1723/21-1, Koepke PI), the Japanese Society for the Promotion of Science (JSPS no:16H06347, Michibayashi PI; and KAKENHI 16H02742, Takazawa PI), the European Research Council (Adv: no.669972; Jamveit PI), the Swiss National Science Foundation (SNF:20FI21_163073, Früh-Green PI), JAMSTEC, the TAMU-JR Science Operator, and contributions from the Sultanate of Oman Ministry of Regional Municipalities and Water Resources, the Oman Public Authority of Mining, Sultan Qaboos University, CNRS-Univ. Montpellier, Columbia University of New York, and the University of Southampton. A.G. also acknowledges funding through NWO DeepNL (Grant no. 2018.040). We especially thank the members of the physical properties team of the ChikyuOman Phase 2 Leg 4 for their effort on magnetic susceptibility measurements. We also acknowledge Gyuseung Park and Sarang Choi for advice on SEM operation and mineralogical interpretation. We greatly thank the anonymous reviewers who have provided constructive advices that helped improving this paper. Funding Information: Funds for this study was provided by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20168510030830). This work used samples and data hosted by the Oman Drilling Project (OmanDP). The OmanDP has been supported by co‐mingled funds from the International Continental Scientific Drilling Project (ICDP; Kelemen, Matter, Teagle Lead Principal Investigators (PI)), the Sloan Foundation—Deep Carbon Observatory (Grant 2014‐3‐01, Kelemen PI), the National Science Foundation (NSF‐EAR‐1516300, Kelemen lead PI), NASA—Astrobiology Institute (NNA15BB02A, Templeton PI), the German Research Foundation (DFG: KO 1723/21‐1, Koepke PI), the Japanese Society for the Promotion of Science (JSPS no:16H06347, Michibayashi PI; and KAKENHI 16H02742, Takazawa PI), the European Research Council (Adv: no.669972; Jamveit PI), the Swiss National Science Foundation (SNF:20FI21_163073, Früh‐Green PI), JAMSTEC, the TAMU‐JR Science Operator, and contributions from the Sultanate of Oman Ministry of Regional Municipalities and Water Resources, the Oman Public Authority of Mining, Sultan Qaboos University, CNRS‐Univ. Montpellier, Columbia University of New York, and the University of Southampton. A.G. also acknowledges funding through NWO DeepNL (Grant no. 2018.040). We especially thank the members of the physical properties team of the ChikyuOman Phase 2 Leg 4 for their effort on magnetic susceptibility measurements. We also acknowledge Gyuseung Park and Sarang Choi for advice on SEM operation and mineralogical interpretation. We greatly thank the anonymous reviewers who have provided constructive advices that helped improving this paper. Publisher Copyright: © 2022. American Geophysical Union. All Rights Reserved.
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