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1. Expedition 391 Scientific Prospectus Addendum: Walvis Ridge Hotspot

   https://doi.org/10.14379/iodp.sp.391add.2021  

   Sager, W. ; Hoernle, K. ; Petronotis, K. ( February 2021 , Scientific prospectus)

   null (Ed.)

   This addendum to the International Ocean Discovery Program Expedition 391 Scientific Prospectus (Walvis Ridge Hotspot; Sager et al., 2020) incorporates minor coordinate changes to Proposed Sites CT-5A, CT-6A, TT-3A, TT-4A, TT-5A, VB-7A, VB-8A, VB-10A, VB-11A, VB-13A, and VB-14A. The revised site coordinates are documented in Proposal 890-Add2, which is available at http://iodp.tamu.edu/​scienceops/​expeditions/​walvis_ridge_hotspot.html. In addition, because of adjustments to the R/V JOIDES Resolution operations schedule caused by the COVID-19 pandemic, the expedition was postponed by a year. At the time of publication of this addendum, the expedition is scheduled to start in Cape Town, South Africa, on 6 December 2021 and end in Cape Town, South Africa, on 5 February 2022. For a detailed description of the geologic background, scientific objectives, drilling and coring strategy, logging strategy, sample and data sharing strategy, and proposed sites, see Tables T1 and T2 in this report and the Expedition 391 Scientific Prospectus (Sager et al., 2020). 

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2. Expedition 378 Scientific Prospectus Addendum: South Pacific Paleogene Climate

   https://doi.org/10.14379/iodp.sp.378add.2019  

   Thomas, D.J. ; Röhl, U. ; Childress, L.B. ( August 2019 , Scientific prospectus)

   null (Ed.)

   This addendum to the International Ocean Discovery Program (IODP) Expedition 378 Scientific Prospectus details changes to the expedition schedule including additional drilling depth approvals and updates to the operations plans that were presented in the original prospectus. In September 2018, Expedition 378 was rescheduled for 2020 to accommodate the construction and installation of two new propellers for the vessel with minimal disruption to the slate of expeditions scheduled in the Southern Ocean. The change in expedition timing resulted in a change of the port of origination from Lyttelton, New Zealand, to Lautoka, Fiji, and a change in the number of transit days. Consequently, the operations schedule has been revised. The other development prompting an addendum to the Expedition 378 Scientific Prospectus was the approval by the Environmental Protection and Safety Panel (EPSP) to drill deeper at Deep Sea Drilling Project (DSDP) Site 277 than the previous approved maximum depth of 480 meters below seafloor (mbsf) (now approved to 670 mbsf). 

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3. Expedition 359 Scientific Prospectus Addendum: Sea Level, Currents, and Monsoon Evolution in the Indian Ocean

   https://doi.org/10.14379/iodp.sp.359add.2015  

   Betzler, C. ; Eberli, G.P. ; Alvarez Zarikian, C.A. ( April 2015 , Scientific prospectus)

   null (Ed.)

   This addendum to the Expedition 359 Scientific Prospectus (Betzler et al., 2014) addresses a modification to the scientific objectives and operations plan of the expedition. After consultation with and direction from the U.S. National Science Foundation (NSF), the Ancillary Proposal 849-APL will not be implemented as part of Expedition 359, and consequently the proposed sites (KK-03A and KK-03B) originally planned for scientific drilling in the Kerala-Konkan Basin have been dropped from the operations plan. Two new sites are proposed and described in this addendum, and a revised operations strategy and time estimates for seven primary sites in the Maldives archipelago are presented (Fig. F1). Also detailed in this addendum is an extension to the total penetration depth at primary proposed Site MAL-02A from 560 to 1010 meters below seafloor (mbsf). All other details contained within the original Scientific Prospectus published by the International Ocean Discovery Program in November 2014 (Betzler et al., 2014) remain the same. A summary of the primary sites targeted for Expedition 359 is shown in Table T1. The operations strategy and time estimates for the primary sites are presented in Table T2. 

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4. Expedition 368X Preliminary Report: South China Sea Rifted Margin

   https://doi.org/10.14379/iodp.pr.368X.2019  

   Childress, L. ( January 2017 , Preliminary report)

   null (Ed.)

   International Ocean Discovery Program (IODP) Expedition 368X is the third of three cruises that form the South China Sea Rifted Margin program. Expeditions 367, 368, and 368X share the common key objectives of testing scientific hypotheses of breakup of the northern South China Sea (SCS) margin and comparing its rifting style and history to other nonvolcanic or magma-poor rifted margins. Four primary sites were selected for the overall program: one in the outer margin high (OMH) and three seaward of the OMH on distinct, margin-parallel basement ridges informally labeled Ridges A, B, and C from north to south. The ridges are located in the continent–ocean transition (COT) zone ranging from the OMH to the interpreted steady-state oceanic crust (Ridge C) of the SCS. The main scientific objectives include 1. Determining the nature of the basement in crustal units across the COT of the SCS that are critical to constrain style of rifting, 2. Constraining the time interval from initial crustal extension and plate rupture to the initial generation of igneous ocean crust, 3. Constraining vertical crustal movements during breakup, and 4. Examining the nature of igneous activity from rifting to seafloor spreading. In addition, sediment cores from the drill sites targeting primarily tectonic and basement objectives will provide information on the Cenozoic regional environmental development of the Southeast Asia margin. Expedition 368X was planned to reoccupy a site started during Expedition 368. Because of repeated breakdowns of the low clutch diaphragm in the drawworks, Hole U1503A was abandoned after installing casing to 991.5 m. Despite this setback to Expedition 368 and the South China Sea Rifted Margin program, Hole U1503A was completed during Expedition 368X. The overarching scientific goal of IODP Expeditions 367 and 368 was to unveil the mechanisms of continental breakup at the northern SCS margin from rifting through steady-state spreading. A key operational objective of Site U1503 was to sample the lowermost ~300 m of sediments on top of basement to constrain the age and subsidence history of the crust at this location, the timing of normal faulting, and the environment of the early half-graben fill. A second important goal was to sample at least 100 m of the igneous basement. Deep representative sampling of the igneous material at this site will provide an important reference frame for the modeling of breakup and early ocean spreading. In Hole U1503A, the sediment sequence was cored with the rotary core barrel (RCB) system from 995.1 to 1597.84 m (602.74 m penetration; 128.01 m recovered; 21%) and then the underlying basement was continuously cored from 1597.84 to 1710.1 m (112.26 m penetration; 47.91 m recovered; 43%). Although logging deeper than 991.5 m (bottom of casing) was not possible because of unstable hole conditions, Hole U1503A was logged with the Vertical Seismic Imager in the cased portion of the hole. No days were lost to waiting on weather, and the only mechanical downtime was a 1.5 h period when an electrical malfunction caused the top drive to shut down for repairs. Expedition 368X successfully completed the operational objectives in Hole U1503A that were abandoned during Expedition 368. In the SCS margin science program, material recovered during Expedition 368X will contribute toward meeting the four specific objectives of Expeditions 367 and 368. Postexpedition research on the sediments and basalt recovered from Hole U1503A will allow for determination of emplacement age and geochemical analyses of rock composition and assessment of melting processes and age of crystallization. The combination of such analyses will contribute to geochemical or thermomechanical modeling that will constrain mantle origin and melting processes leading to the formation of these basalts. 

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5. Scientific Prospectus Addendum: Dynamics of the Pacific Circumpolar Current (DYNAPACC)

   https://doi.org/10.14379/iodp.sp.383add.2018  

   Lamy, F. ; Winckler, G. ; Alvarez Zarikian, C.A. ( October 2018 , Scientific prospectus)

   null (Ed.)

   This addendum to the International Ocean Discovery Program (IODP) Expedition 383 Scientific Prospectus (Dynamics of the Pacific Antarctic Circumpolar Current; Lamy et al., 2018) addresses the results of the safety review of 10 new proposed drill sites by the IODP Environmental Protection and Safety Panel (EPSP) on 4–6 September 2018 and a change to the operations plan and the end port call for Expedition 383. Because of an adjustment to the R/V JOIDES Resolution 2018–2019 operations schedule, the end port for Expedition 383 has changed from Valparaiso, Chile, to Punta Arenas, Chile. Therefore, at the time of publication of this addendum, the expedition is scheduled to start and end in Punta Arenas, Chile. The dates of the expedition remain unchanged from the original Expedition 383 Scientific Prospectus (Lamy et al., 2018), from 20 May to 20 July 2019. The change in port reduces the distance and hence the transit time between the last drill site in the central South Pacific and the port in Chile, providing ~3 additional days for scientific drilling operations. For that reason, a new proposed primary site (CSP-7A) in the central South Pacific has been added to the original operations plan from Lamy et al. (2018), bringing the total number of primary sites planned for Expedition 383 to seven (Figures F1, F2, F3, F4). The current operations plan and time estimates include 5 days of port call activities, 38.2 days of operations, and 17.7 days of transit. 

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