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Characterizing Hydration of the Ocean Crust Using Shortwave Infrared Microimaging Spectroscopy of ICDP Oman Drilling Project Cores

Crotteau, Molly A. and Greenberger, Rebecca N. and Ehlmann, Bethany L. and Rossman, George R. and Harris, Michelle and Kelemen, Peter B. and Teagle, Damon A. H. (2021) Characterizing Hydration of the Ocean Crust Using Shortwave Infrared Microimaging Spectroscopy of ICDP Oman Drilling Project Cores. Journal of Geophysical Research: Solid Earth, 126 (11). Art. No. e2021JB022676. ISSN 2169-9313. doi:10.1029/2021jb022676.

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Although ocean crust covers over 60% of Earth's surface, the processes that form, cool, and alter the ocean crust are not completely understood. We utilize shortwave infrared micro-imaging spectroscopy of ∼1.2 km of rock cored by the International Continental Scientific Drilling Program's Oman Drilling Project to quantify hydration of basaltic dikes and gabbros from the Samail ophiolite as a function of depth, mineralogy and deformation. We develop a regression (R² = 0.66) between area of the ∼1,350–1,650 nm OH/H₂O absorption and measurements of loss on ignition of samples and apply this relationship to generate quantitative ∼250 μm/pixel hydration maps for all cores. The lowest mean hydration is observed in the most pervasively altered dike-gabbro boundary (GT3A, H₂O_(mean) = 2.1 ± 1.6 wt%), consistent with the low H₂O content of the dominant alteration minerals, amphibole and epidote. The highest H₂O content occurs in deeper foliated and layered gabbros (GT2A, H₂O_(mean) = 3.2 ± 3.0 wt%) and layered gabbros (GT1A, H₂O_(mean) = 2.8 ± 3.1 wt%). The greater prevalence with depth of zeolite alteration as opposed to lower wt% H₂O amphibole at shallow stratigraphic depths, as well as the occurrence of zones of intensive hydration associated with fault zones (H₂O_(mean) = 5.7 ± 4.0 wt%) lead to greater hydration of the lower ocean crust. This new approach provides an objective quantification of hydration in these cores, enabling an improved understanding of quantities and characteristics of ocean crust hydration. It highlights the importance of specific phases and faulting in controlling hydration, which has implications for ocean crust cooling, rheological properties, and the role of alteration in global biogeochemical cycling.

Item Type:Article
Related URLs:
URLURL TypeDescription
Crotteau, Molly A.0000-0001-7888-0093
Greenberger, Rebecca N.0000-0003-1583-0261
Ehlmann, Bethany L.0000-0002-2745-3240
Rossman, George R.0000-0002-4571-6884
Harris, Michelle0000-0001-9618-2862
Kelemen, Peter B.0000-0003-4757-0855
Teagle, Damon A. H.0000-0002-4416-8409
Additional Information:© 2021. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Issue Online: 24 November 2021; Version of Record online: 24 November 2021; Accepted manuscript online: 01 November 2021; Manuscript accepted: 27 October 2021; Manuscript revised: 14 October 2021; Manuscript received: 24 June 2021. Thanks to the scientific and technical staff of the Chikyu for facilitating acquisition of the imaging spectrometer data. This study used data from the Oman Drilling Project, which has been possible through co-mingled funds from the International Continental Scientific Drilling Project (ICDP; Kelemen, Matter, Teagle Lead PIs), 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_163,073, 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, CRNS-Univ. Montpellier II, Columbia University of New York, and the University of Southampton. BLE acknowledges a Rose Hills Foundation grant for supporting acquisition of the imaging spectroscopy data. MAC was supported by a George R. Rossman SURF fellowship at Caltech. We also thank a grant through the US NSF/GEO - UK NERC Lead Agency Opportunity (NSF MG&G grant 2129700 to RG and BLE and NERC grant NE/W007517/1 to DAHT and MH) for supporting the completion of this work. We thank Natsue Abe for discussion of the implications of these results for the physical properties of the ocean crust. Finally, the authors thank Jeff Alt and one anonymous reviewer for their constructive reviews that improved the quality of this paper, and we thank Associate Editor Phil Janney and Editor Mark Dekkers for editorial handling. Data Availability Statement: The LOI measurements used in this study were published in Kelemen et al., (2020), and data are available from ICDP. The underlying imaging spectroscopy data set used is archived through CaltechDATA (Greenberger et al., 2021, H2O maps of each core section are also available as PDF images (Crotteau et al., 2021a, and .img files through CaltechDATA (Crotteau et al., 2021b, Regions of interest corresponding to the LOI samples are also archived on CaltechDATA (Crotteau et al., 2021a,
Funding AgencyGrant Number
International Continental Scientific Drilling ProjectUNSPECIFIED
Alfred P. Sloan Foundation2014-3-01
Deutsche Forschungsgemeinschaft (DFG)KO 1723/21-1
Japan Society for the Promotion of Science (JSPS)16H06347
Japan Society for the Promotion of Science (JSPS)16H02742
European Research Council (ERC)669972
Swiss National Science Foundation (SNSF)20FI21_163073
Japan Agency for Marine-Earth Science and Technology (JAMSTEC)UNSPECIFIED
Texas A&M UniversityUNSPECIFIED
Oman Ministry of Regional Municipalities and Water ResourcesUNSPECIFIED
Oman Public Authority of MiningUNSPECIFIED
Sultan Qaboos UniversityUNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Columbia UniversityUNSPECIFIED
University of SouthamptonUNSPECIFIED
Rose Hills FoundationUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Natural Environment Research Council (NERC)NE/W007517/1
Subject Keywords:Oman Drilling Project; ocean crust; ophiolite; crustal hydration; water quantification; infrared imaging spectroscopy
Issue or Number:11
Record Number:CaltechAUTHORS:20211116-205022497
Persistent URL:
Official Citation:Crotteau, M. A., Greenberger, R. N., Ehlmann, B. L., Rossman, G. R., Harris, M., Kelemen, P. B., et al. (2021). Characterizing hydration of the ocean crust using shortwave infrared microimaging spectroscopy of ICDP Oman Drilling Project cores. Journal of Geophysical Research: Solid Earth, 126, e2021JB022676.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111909
Deposited By: Tony Diaz
Deposited On:16 Nov 2021 22:16
Last Modified:30 Nov 2021 16:58

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