Published July 2020
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Expedition 384 is scheduled to begin in Kristiansand, Norway, on 20 July 2020 and end in Las Palmas, Spain, on 5 September and is dedicated to engineering testing as it relates to deep (>1 km) drilling and coring in igneous ocean crust. The Deep Crustal Drilling Engineering Working Group convened in 2017 to discuss recent issues with crustal drilling and recommended a number of technologies and tools for potential testing. The JOIDES Resolution Facility Board further prioritized the testing opportunities in 2018. The top priority of all recommendations was an evaluation of drilling and coring bits because coring bit wear, tear, and failure is the prevalent issue in deep crustal drilling attempts, requiring an excessive amount of fishing and hole cleaning time. The primary objective of Expedition 384 is to drill “pilot holes” using three types of drill bits: two tungsten carbide insert (TCI) tricone bits, a polycrystalline diamond compact (PDC) bit, and a TCI/PDC hybrid bit. Additional tests include the deployment of an underreamer as well as a PDC coring bit to obtain samples for engineering testing. The results may lead to an initiative toward developing a better performing coring bit for future use by the International Ocean Discovery Program (IODP).
The site location for these tests has evolved with the multiple postponements of Expedition 384 for various reasons. The current primary site is Proposed Site REYK-13A (1520 m water depth) from postponed IODP Expedition 395; this site has ~210 m of recent to Pliocene clay or ooze overlaying basaltic basement that has not been drilled or cored to date. The plan is to drill 6 holes to ~100 m into the basement each. A second site was selected for operations should time and equipment remain to do so: Integrated Ocean Drilling Program Site U1309 (1653 m water depth), where basaltic and gabbroic rocks are exposed at the seafloor, has been cored to 102 m in Hole U1309B and 1415 m in Hole U1309D. The plan is drill one hole to ~200 m. Operations at Sites REYK-13A and U1309 are projected to take 22.4 days.
Additional operating time became available for Expedition 384 as a result of the latest schedule changes. A secondary objective therefore includes the assessment and potential improvement of current procedures for advanced piston corer (APC) core orientation. A total of 4.6 days is allocated to triple-coring the top 70 m of sediment at Proposed Site REYK-6A (postponed Expedition 395), located 54 nm east of Proposed Site REYK-13A.
This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.