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Workshop report: Exploring deep oceanic crust off Hawai'i
- Source :
- Scientific Drilling, Scientific Drilling, Copernicus Publications, 2021, 29, pp.69-82. ⟨10.5194/sd-29-69-2021⟩, Scientific Drilling, Vol 29, Pp 69-82 (2021)
- Publication Year :
- 2021
- Publisher :
- Copernicus GmbH, 2021.
-
Abstract
- For more than half a century, exploring a complete sequence of the oceanic crust from the seafloor through the Mohorovičić discontinuity (Moho) and into the uppermost mantle has been one of the most challenging missions of scientific ocean drilling. Such a scientific and technological achievement would provide humankind with profound insights into the largest realm of our planet and expand our fundamental understanding of Earth's deep interior and its geodynamic behavior. The formation of new oceanic crust at mid-ocean ridges and its subsequent aging over millions of years, leading to subduction, arc volcanism, and recycling of some components into the mantle, comprise the dominant geological cycle of matter and energy on Earth. Although previous scientific ocean drilling has cored some drill holes into old (> 110 Ma) and young (< 20 Ma) ocean crust, our sampling remains relatively shallow (< 2 km into intact crust) and unrepresentative of average oceanic crust. To date, no hole penetrates more than 100 m into intact average-aged oceanic crust that records the long-term history of seawater–basalt exchange (60 to 90 Myr). In addition, the nature, extent, and evolution of the deep subseafloor biosphere within oceanic crust remains poorly unknown. To address these fundamentally significant scientific issues, an international workshop “Exploring Deep Oceanic Crust off Hawai`i” brought together 106 scientists and engineers from 16 countries that represented the entire spectrum of disciplines, including petrologists, geophysicists, geochemists, microbiologists, geodynamic modelers, and drilling/logging engineers. The aim of the workshop was to develop a full International Ocean Discovery Program (IODP) proposal to drill a 2.5 km deep hole into oceanic crust on the North Arch off Hawai`i with the drilling research vessel Chikyu. This drill hole would provide samples down to cumulate gabbros of mature (∼ 80 Ma) oceanic crust formed at a half spreading rate of ∼ 3.5 cm a−1. A Moho reflection has been observed at ∼ 5.5 km below the seafloor at this site, and the workshop concluded that the proposed 2.5 km deep scientific drilling on the North Arch off Hawai`i would provide an essential “pilot hole” to inform the design of future mantle drilling.
- Subjects :
- QE1-996.5
010504 meteorology & atmospheric sciences
Subduction
Mechanical Engineering
Earth science
Scientific drilling
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences
Energy Engineering and Power Technology
Geology
Crust
International Ocean Discovery Program
010502 geochemistry & geophysics
01 natural sciences
Mantle (geology)
Seafloor spreading
Mohorovičić discontinuity
13. Climate action
Oceanic crust
14. Life underwater
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 18163459 and 18168957
- Volume :
- 29
- Database :
- OpenAIRE
- Journal :
- Scientific Drilling
- Accession number :
- edsair.doi.dedup.....11937978250a0082b2cae76f4e1ceeaa